# US State Boiler Code



## Dan Rowe (Mar 28, 2010)

This thread is my attempt to find rules for US State model or small hobby boiler code or construction rules. These are not easy to find. Please check your state and see if the link is correct or if an exemption has been found. Please post any new information so this first post can be updated.

As far as I know the only country to have a Model Boiler Code is Australia. I actually hope that some one can prove that statement wrong.

In the United States where I live the regulation of most types of boilers is at the State level. This means that there are 51 codes one for each State and one for the US Capitol. I keep a list of State boiler codes that I have found on the web. This stuff keeps moving around and changing so links go dead very frequently.

A few hints on reading one of the State codes and finding the parts needed for hobby use. Search for &#8220;exemptions&#8221; &#8220;hobby&#8221; &#8220;model&#8221; &#8220;miniature&#8221; &#8220;state special&#8221; &#8220;historic&#8221;.

I have not been able in all cases to find exemptions for the model hobby type boilers I do not know if this means the full code applies to model hobby use or not. 

Alabama
http://www.alalabor.state.al.us/PDFs/BoilerRules3_23_06.pdf
Exemptions Section 25-12-7
http://alisondb.legislature.state.al.us/acas/ACASLoginIE.asp


Alaska
Sec. 18.60.210 Exemptions
http://www.labor.state.ak.us/lss/forms/boiler-stats-regs.pdf

Arizona
R20-5-429 Variance
http://www.ica.state.az.us/ADOSH/Forms/ADOSH_Rules_Boilers_2009.pdf

Arkansas
010.01-019 A9 State Special
http://www.arkansas.gov/labor/pdf/boiler_inspection2006.pdf

California
751. Boilers and Fired Pressure Vessels Not Subject to These Orders
http://www.dir.ca.gov/Title8/sub2.html

Colorado
9-4-104. Exemptions
http://oil.cdle.state.co.us/Boiler/Statutes9-4-101-118.asp

Connecticut
http://www.ct.gov/dps/cwp/view.asp?a=2148&Q=294166&dpsNav=|
http://search.cga.state.ct.us/adv/
Exemption
Sec. 29-231. (Formerly Sec. 19-426). Exceptions. The provisions of this chapter shall not apply to: <snip> (6) antique or model boilers used in public, nonprofit engineering or scientific museums and operated for educational, historical or exhibition purposes having a shell diameter of less than twelve inches and a grate surface area of less than one square foot; 

Delaware
5.3 State Special
http://www.dnrec.delaware.gov/BoilerSafety/Documents/Boiler%20Safety%20rules.pdf

Georga
300-6-1-.11 George State special boilers
300-6-1.12 Non-conforming or non-standard boilers
http://rules.sos.state.ga.us/cgi-bi...ILER_AND_PRESSURE_VESSEL_RULES/index.html&d=1

Florida
http://www.myfloridacfo.com/SFM/pdf/FAC_69A-51_03_1118.pdf

Hawaii
http://hawaii.gov/labor/hiosh/standard_pt10.shtml

Idaho
Boiler and pressure rules repealed March 29,2010
http://dbs.idaho.gov/industrial/codes.html

Illinois
Sec. 5 (430ILCS 75/5) Exemptions
(7) Steam boilers of a miniature model locomotive, boat, tractor, or stationary engine constructed and maintained as a hobby and not for commercial use, that have an inside diameter not exceeding 12 inches and a grate area not exceeding 1 1/2 square feet, provided they are constantly attended while in operation and are equipped with a water level indicator, pressure gauge, and a safety valve of adequate capacity.
http://www.ilga.gov/legislation/ilc...ctName=Boiler+and+Pressure+Vessel+Safety+Act.

Indiana
http://www.state.in.us/legislative/iac/title680.html
The definition of "Model Boiler" is now online for Indiana:

680 IAC 2-1-2 Title; scope; applicability; definition

(f) The term "regulated boiler or pressure vessel" does not include any of the following:

(12) Commercial toy boilers and miniature model boilers constructed as a hobby that do not exceed a size specified by the
board.

680 IAC 2-4-30 "Model boiler" defined
Authority: IC 22-13-2-8
Affected: IC 22-12-4; IC 22-15-6
Sec. 30. "Model boiler" means any boiler that does not exceed any of the following limits:
(1) Two (2) cubic feet total gross volume (exclusive of casing and insulation).
(2) One and one-half (1 1/2) square feet of grate area.
(3) One hundred (100) psig maximum allowable working pressure.

Iowa
Enter &#8220;89&#8221; click submit
http://coolice.legis.state.ia.us/Cool-ICE/default.asp?category=billinfo&service=IowaCode

Kansas
44-915.  Act inapplicable to certain boilers and pressure vessels
https://www.dol.ks.gov/safety/html/ws_boilerSafetyLaws.html

Kentucky
http://www.lrc.state.ky.us/KRS/236-00/CHAPTER.HTM

Louisiana
Under Mechanical Safety / boiler
http://sfm.dps.louisiana.gov/

Maine
http://www.maine.gov/pfr/professionallicensing/professions/boiler/pdf/BoilerLawsRulesBook.pdf


Maryland
09.12.01.33. 33 Model Steam Boilers
http://www.dsd.state.md.us/comar/SubtitleSearch.aspx?search=09.12.01.*
Explanation and worksheet
http://calslivesteam.org/calboil.htm
Excel spreadsheet
http://calslivesteam.org/calculations/Calculations.htm

Massachusetts
http://www.massengineers.com/Documents/mass_cmrs_100_to_1700.htm

Michigan
http://www.legislature.mi.gov/(S(3a...=mcl-act-290-of-1965&queryid=39491&highlight=
http://www.state.mi.us/orr/emi/admincode.asp?AdminCode=Single&Admin_Num=40804001&Dpt=CI&RngHigh=

Minnesota
Exemptions
https://www.revisor.mn.gov/statutes/?id=326B.988
https://www.revisor.mn.gov/bin/getpub.php?type=s&num=183.411&year=2007

Mississippi
http://www.msdh.state.ms.us/msdhsite/_static/resources/883.pdf

Missouri
http://www.sos.mo.gov/adrules/csr/current/11csr/11c40-2.pdf
Exemptions
http://www.moga.mo.gov/statutes/C600-699/6500000230.HTM
Missouri Revised Statutes
http://www.moga.mo.gov/STATUTES/C650.HTM



Montana
http://bsd.dli.mt.gov/bc/pdf/bc_rules.pdf

Nebraska
48-726 (8) Boilers of a minature model locomotive or boat or tractor&#8230;&#8230;
http://www.nebraskalegislature.gov/laws/statutes.php?statute=48-726

Nevada
http://www.leg.state.nv.us/NRS/NRS-455C.html

New Hampshire
Section 157-A:6 Exemptions.
http://www.gencourt.state.nh.us/rsa/html/NHTOC/NHTOC-XII-157-A.htm

New Jersey
12:90-4.1 Scope of subchapter
http://lwd.dol.state.nj.us/labor/lsse/laws/boiler_law.html#90-4.1
12:90-4.10 Inspection of boilers
http://lwd.dol.state.nj.us/labor/lsse/laws/boiler_law.html#90-4.10

New Mexico
http://www.nmcpr.state.nm.us/nmac/parts/title14/14.009.0004.htm

New York
http://www.labor.ny.gov/workerprotection/safetyhealth/PDFs/Boilers/boiler.pdf

North Carolina
http://www.nclabor.com/boiler/boiler_safety_act_packet.pdf

North Dakota
http://www.legis.nd.gov/information/acdata/pdf/45-12-01.pdf

Ohio
http://codes.ohio.gov/oac/4101:4-9

Oklahoma
http://www.ok.gov/odol/documents/SSDBoilerBooklet2009.pdf

Oregon
Hobby Miniature Steam Boilers 918-225-0390
http://www.cbs.state.or.us/external/bcd/programs/boiler/2012OregonBoilerPVLaw.pdf

Pennsylvania
ASME Code adopted
http://www.reedconstructiondata.com/building-codes/pennsylvania/
3a.166. Miniature boilers and kitchen equipment
http://www.portal.state.pa.us/portal/server.pt?open=514&objID=552936&mode=2

Rhode Island
http://www.dlt.ri.gov/occusafe/pdfs/boilerregs.pdf
http://www.dlt.ri.gov/occusafe/boiler.htm

South Carolina
http://www.llr.state.sc.us/pol/Boil...CE ACT and Regulations as of June 13 2006.pdf

South Dakota
http://legis.state.sd.us/rules/DisplayRule.aspx?Rule=61:08

Tennessee
http://tennessee.gov/labor-wfd/0800-03-03.pdf

Texas
Sec. 755.022. EXEMPTIONS FOR CERTAIN BOILERS.
http://www.license.state.tx.us/boilers/blrlaw.htm#755022

Utah
http://laborcommission.utah.gov/BoilerandElevatorSafety/pdfs/BLRCompManRev8b.pdf

Vermont
Section 3
http://www.dps.state.vt.us/fire/06firecodeADOPTEDjune15092.pdf

Virgina
40.1-51.8. Exemptions
http://leg1.state.va.us/cgi-bin/legp504.exe?000+cod+40.1-51.8
http://leg1.state.va.us/cgi-bin/legp504.exe?000+reg+16VAC25-50-10

Washington DC
http://os.dc.gov/os/frames.asp?doc=/os/lib/os/info/odai/title_13/title13_chapter8.pdf

Washington (State)
70.79.070 Miniature hobby boilers 
70.79.060 Construction, installation must conform to rules
70.79.320 Operating without inspection certificate prohibited&#8212;Penalty.
http://www.lni.wa.gov/TradesLicensing/Rules/files/boilers/BoilerLawBook.pdf

Wisconsin
http://test.commerce.wi.gov/SB/SB-BoilerAndPressureVesselProgram.html
http://legis.wisconsin.gov/rsb/code/comm/comm041.pdf
41.18 Exemptions from periodic inspections
41.43 Wisconsin special vessels.

Wyoming
No Boiler law


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## tel (Mar 28, 2010)

And the Aus codes can be had *here*


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## steamboatmodel (Mar 29, 2010)

Hi Dan,
I was checking to make sure that what I was posting for Ontario, Canada was current and came across this form ASME;
Boiler and Pressure Vessel Code - 2007 Edition - Codes & StandardsThe 2007 Edition of ASME - International Boiler and Pressure Vessel Code is ... and territories of the United States and all the provinces of Canada. ...
http://www.asme.org/Codes/International_Boiler_Pressure.cfm
Do you know if this has any relevance to our size boilers?
Regards,
Gerald.


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## Dan Rowe (Mar 29, 2010)

Hi Gerald,
I read through the ASME code a few years ago and found a page with the definition of a miniature boiler but not many specific rules pertaining to them.

Several States have addopted the ASME code in whole or part to be the state law, one of these is Pennsylvania.. I just added Washington State (thanks PaulG) and Pennsylvania. If you search the PA code for "miniature" you will find the current ASME definition of the size restrictions for the classification.

Quoted from PA boiler regs:
Miniature boiler--A boiler which is not more than 16 inches inside diameter of the shell, 5 cubic feet gross volume, excluding casing and insulation; 100 psig maximum allowable working pressure; and, 20 square feet of heating surface. 

Cheers Dan


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## xo18thfa (Mar 29, 2010)

Fortunately most of these state codes exempt small boilers used for hobby purposes. They typically exempt things like: under 12" ID, under 150 PSI, under 1.5 sq ft grate, under 5 cu ft capacity, not for commercial use.  Almost no hobby boilers get over those specs.


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## Jasonb (Mar 29, 2010)

This  covers the use and testing of model boilers in the UK.

Jason


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## Quake (Mar 29, 2010)

Indiana -

http://www.state.in.us/legislative/iac/title680.html 

Essentially adopts ASME. You can buy a complete copy of the AMSE Boiler & Pressure Vessel code online for just under US $14,000. .... (so, you are expected to abide by a set of rules that will cost you a fortune to obtain?) If anyone is aware of a cheap, legal way to acquire a copy of the ASME, I'd love to read it.

Indiana has several exemptions - the one I like is farms, provided the boiler is used 'for agriculture purposes'. So, just hook that model steamer up to a battery charger and use those batteries in your flashlight around the family farm and I think you're good. "Model Size Boilers" are also exempt, provided they meet specs established by the boiler board - never been able to find definitely documentation for those; but rumor is they defer to AMSE.

Some model builders I talk to don't like to take the code too seriously - but watch out for home owners insurance - if you try to file a claim for damages caused by a boiler out of code it will probably be declined.

Anybody know of a good deal on a 10+ acre farm in central Indiana???

-Quake


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## GWRdriver (Mar 29, 2010)

It's important when reading this ASME stuff that one be very careful of nomenclature. For decades, to the ASME (and anyone who adopted their code into law), a "*miniature*" boiler did not mean a model or hobby boiler. Miniature boilers were a seperate category of commercial boilers such as laundry and hot water boilers, steam heat boilers, espresso machines, popcorn wagons, etc, so when reading be careful not to assume that by miniature boiler you are reading about a model or hobby boiler.

Also some of the code descriptions of exemptions have nasty little Gotcha's . . for instance one of them gives a list of exclusionary specifications, which would exclude someone with say a 4" diameter model locomotive boiler, and then at the end it says in so many words "provided an ASME approved safety valve is fitted." Even a small ASME compliant steam safety valve is very large compared to a 4" boiler and in most cases would be unworkable, if for no other reason than it could empty the boiler when it opened. In another code essentially the same exclusions are offered but then at the end says in so many words "a fusible plug shall be fitted in the firebox" and this can be a deal breaker. First there is general opinion that fusible plugs in a small copper boilers are a waste of safety effort and a royal PITA, but more problematically if not already fitted at initial construction they are extremely difficult if not impossible to successfully install later.


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## Quake (Mar 29, 2010)

Just ran across this web site with links to state boiler codes:

http://www.stateboilerlaws.com/


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## Dan Rowe (Mar 30, 2010)

To quote Rick in the notice to this section *Don't Guess, Just Ask*!
I wish the answer was that simple with US State Boiler Law.

As Harry mentioned the definitions of the legal terms are important, and they are not used the same way in all cases in different State codes. Even the term hobby can be misleading as it is also used for full size traction engines in some states.

The states where I have found a clear exemption or in the case of Maryland a model boiler code I left a note before the link to help locate the section we are interested in for hobby model use.

In most of the State codes I have read there is no mention of small hobby boilers. I like to find the ones with clear workable exemptions like Texas where I live, or even a model code as Maryland. This is a small hobby and it has a good safety record so it has gone unnoticed by most State Regulators.

The consequence for not keeping a good safety record is clearly stated in the Oregon State Boiler Code under Hobby Miniature Steam Boilers:
(2) This exemption continues as long as:
 (a) There is no explosion;

Oregon and Alaska are two of the states that have one of the gotcha clauses mentioned by Harry and have the requirement of an ASME approved safety valve. I have never seen an ASME {V} stamp safety valve smaller then ½ NPT. These will work fine with large scale models but I agree with Harry they are not useful for small scale boilers. ASME stamp info: http://www.onetb.com/asme_code.htm

The whole ASME code is not needed sections 1 & 2 would be enough but even that is over $1000. This is why I bought all 3 sections of the AMBSC and it is a real bargain for model boiler design information. I could not find the silver solder color code needed to know which alloys to use so I googled the given reference and for a few more dollars I downloaded the section of the Aus welding code I needed. If I had known about this group at the time I am sure that someone here would have been able to supply the color code information.

Dan


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## Tin Falcon (Mar 31, 2010)

I was browsing the NJ Boiler code
http://lwd.dol.state.nj.us/labor/lsse/laws/boiler_law.html#90-4.3


12:90-4.1 Scope of subchapter

(a) This subchapter shall apply to the design, construction, inspection, installation, repair and alteration of steam or hot water boilers, including, without limitation, model steam boilers, except as provided in (b) below.

(b) This subchapter shall not apply to:

  0. Steam boilers having adequate relief devices set to discharge at a pressure not greater than 15 psig when such boilers serve dwellings of less than six family units or other dwellings with accommodations for less than 25 persons;
  0. Hot water boilers having relief devices set to discharge at a pressure not greater than 160 psig and hot water boilers limited to temperatures not exceeding 250 degrees Fahrenheit when such boilers serve dwellings of less than six family units or other dwellings with accommodations for less than 25 persons;
  0. Any steam or hot water boiler having less than 10 square feet of surface;
  0. Any steam or hot water boiler having a heat input of less than 10 kilowatts or less than 40,000 BTU per hour;
  0. Any steam or hot water boiler under the jurisdiction and control of the United States Government when actively regulated by a Federal agency; and
  0. Any steam or hot water boiler used solely for the propulsion of a motor vehicle regulated by the Motor Vehicle Act, Title 39 of the Revised Statutes.
It appears the key here is less than 10 square feet of boiler heating surface and/or less than 10KW /40,000 BTU per hour heat input. to be exempt from the code. 
so you need to burn a bit under under 2 lbs of propane per hour max (BTU per Pound 21,591) a half gallon of ethanol (1 gallon of ethanol 	= 	84,400 Btu) or 3-5 lbs of coal (1 pound of coal 	= 	8,100 to 13,000 Btu)
tin


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## GWRdriver (Mar 31, 2010)

This is where language of codes gets dicey and becomes subject to "interpretation", which means, its depends upon the official you happened to be talking to on that day. There are no "*and/ors*" in the section so my interpretation would be that all you have to do is meet *One* of the exclusionary criteria to be excluded. The wording I see says (for example) if you have less than 10ft/sq of heating area your boiler is excluded and it then doesn't matter how much heat you put to it. However I know from years of dealing with codes that what a literate and rational person might think a code says and what a codes official says it says can be two completely diffierent things.


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## Maryak (Apr 1, 2010)

GWRdriver  said:
			
		

> However I know from years of dealing with codes that what a literate and rational person might think a code says and what a codes official says it says can be two completely diffierent things.



Never have truer words been written. 

Last weeks example. New surveyor arrives at our steam tug for its' annual survey. On inspecting the ships Stability Statement he noted with great concern that some 3 tons of concrete in the bilge under the boiler was not annotated in the statement.

"How long has that been there?" he asked. He was advised by my replacement that it had been there since the ship was built . "Well a verbal advise is not good enough and it will have to be removed." This after a whole 3 secs of consideration and an obvious lack of any understanding of ship stability.

The Director of the Museum rang me asking, what did I know etc. etc. I asked what could I do to help. He asked would I give them a Statutory Declaration saying that I was present when the Inclining Experiment was carried out and that the concrete was under the boiler at that time. This was done and another bureaucrat had covered his backside after 14 years of it not being a problem.

Best Regards
Bob


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## Dan Rowe (Apr 1, 2010)

The exact statement for the New Jersey boiler code exemption is 3. Any steam or hot water boiler having less than 10 square feet of surface; to say that means heating surface or grate surface or any other surface is an assumption made by the reader.

A bit of further reading will take you to: 

12:90-4.10 Inspection of boilers

a) All steam or hot water boilers or similar equipment potentially capable of generating steam as described in (b) below shall be inspected and be subjected to a hydrostatic test, if necessary, at least once each year at 12-month intervals. This inspection shall be a complete internal and external inspection as construction conditions will permit. All hot water heating boilers shall be inspected internally at 24-month intervals and shall be inspected externally every 12 months.
(b) Steam or hot water boilers subject to the inspection of (a) above shall include those listed in (b)1, (b)2 and (b)3 below, except as provided in (c) below:

1.	Steam or hot water boilers having 10 or more square feet of heating surface; 
2.	Steam or hot water boilers having a heat input of 10 kilowatts or more; or 
3.	Steam or hot water boilers having a heat input of 40,000 BTU per hour or more. 

I think that the inspection section clears the air a bit to get to the intended meaning of the code.

I was a marine engineer and US ships are inspected every year. This includes the boilers. I mostly worked on low speed diesel ships but they have a small donkey boiler for steam heat. I will agree that most of the Coast Guard inspectors I met on a professional level were not qualified engineers and really had little knowledge of what they were inspecting. One of the ships I was on had a monotube donkey boiler. This would lead to problems as the standard inspection sheet says to check the low water shut down and alarm. I have seen ships engineers try in vain to explain this to the inspector. the sheet says low water shut down and our logic sounds like BS to him. The USCG approved device for emergency shut down for this boiler is a limit switch mounted on the external boiler insulation cover which is some what flimsy. When the tube coil expands due to lack of water and over heating the limit switch was set to shut down the boiler and sound an alarm. The usual drill after logic failed was to distract the inspector and press the limit switch to simulate a low water shut down and alarm.

On one inspection I had an actual Coast Guard engineer. I explained the system to him and stated that I did not have any confidence in the device but I was willing to give it a go. He simply asked me if I had set the limit switch to factory specifications and I answered with all honesty Yes sir. His response was Good enough for me.

Tin thanks for reading through that one I have updated the list in the first post.
Cheers Dan


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## Dan Rowe (Apr 2, 2010)

The first message on this thread is now a complete picture of the US State Boiler code at this time. The link posted by Quake was a big help as it was mostly correct with a few broken links.

Wyoming and Idaho do not have boiler laws. The law in Idaho was repealed March 29, 2010 due to insufficient funding for the program.

As I said before for the most part the States have adopted the ASME code language which works well for industrial power boilers. Several states have a State Special where a design that does not conform to ASME code can be built. 

The rub is the ASME code is so dang expensive that it does not really work with a hobby budget. There are several books that explain the code and that may be a cheaper way to go to work out a design, but several States require a PE to sign off on the boiler design for a State Special.

It is complex and messy but that is the way it is.

Cheers Dan


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## 1hand (Oct 29, 2010)

I'm not a great reader of mobo jombo, but what I'm gathering from the info down below is that its ok to build and play around with my 3.5" 100psi loco boiler without getting inspected nor going to jail ???
Matt

What are the requirements for pressure vessels in Wisconsin? 
Answer: Code requirements for Pressure Vessels
Comm 41.16 Initial inspections. 
(1) BOILER AND PRESSURE VESSEL INSPECTIONS. (a) Except as provided in par. (b), boilers and pressure vessels shall be inspected by a certified inspector before they are placed in operation.
Note: See s. Comm 41.41 for installation registration requirements.
(b) The inspections specified in par. (a) are not required for boilers and pressure vessels exempted from periodic inspections in s. Comm 41.18.
(c) Where the boilers or pressure vessels specified in par. (a) are installed in a city of the first class and inspections are made by the city, the city shall keep a record of the inspections and shall submit a copy to the department.
(d) Where the inspections specified in par. (a) are performed by a certified inspector other than a department inspector, the certified inspector shall file an inspection report with the department and shall affix the Wisconsin registration number as required in s. Comm 41.36. The inspection report shall be filed with the department within 30 calendar days after completion of the boiler or pressure vessel installation. If the report is not filed within the 30&#8722;day period, the department shall perform the inspection.
Comm 41.18 Exemptions from periodic inspections.
(1) EXEMPTED EQUIPMENT. Except as provided in sub. (2), periodic inspections are not required for:
(a) Boilers or pressure vessels which receive regular inspections by United States government inspectors;
(b) Heating boilers located in private residences or in apartment buildings having less than 3 living units;
(c) Expansion tanks for hot water heating boilers;
(d) Boilers used exclusively for agricultural purposes;
(e) Pressure vessels having an inside diameter not exceeding 6 inches with no limit on pressure;
(f) Pressure vessels having a volume of less than 5 cubic feet and an operating pressure of less than 250 psig;
(g) Pressure vessels with a volume of less than 1&#8722;1/2 cubic feet with no limit on pressure;
(h) Pressure vessels having an internal or external operating pressure of not more than 15 psig with no limitations on size;
(i) Hot water supply boilers and water heaters, and hot water storage tanks in which the temperature does not exceed 210 F;
(j) Vessels used for the storage or processing of cold water, including those with air cushions;
(k) Pressure vessels which are used in accordance with the regulations of the United States department of transportation;
(L) Air receivers having a volume of less than 12 cubic feet and an operating pressure of less than 250 psig; and
(m) Pressure vessels used in processing and storing of fermented beverages at temperatures not exceeding 140 F.
(n) Any pressure vessel used as an integral part of an electrical circuit breaker.
(2) EXCEPTIONS. In individual cases, the boilers and pressure vessels exempted in sub. (1) shall be subject to inspection by or on order of the department upon the complaint of any person or upon the initiative of the department when there is reasonable cause to suspect that the construction, installation, maintenance or operation of the vessel is not in keeping with the general purpose and intent of this chapter.
Comm 41.28 Safety Rules.
(1) MAXIMUM ALLOWABLE WORKING PRESSURE. No boiler or pressure vessel may be operated at a pressure in excess of the maximum allowable working pressure stated on its current permit to operate.
(2) ALTERATION TO SAFETY DEVICES. No unauthorized person may remove or tamper with any connected safety device.
(3) INSTALLATION LOCATION. Boilers and pressure vessels shall be so installed that there will be sufficient room between the vessel and any ceiling, wall, partition or floor to facilitate the connection and operation of valves, pipes and other appurtenances, and shall be installed in a manner that will not block any inspection opening.
Comm 41.32 Pressure gages for air receivers.
(1) GAGE LOCATION. Air receivers shall be equipped with an indicating pressure gage so located as to be readily visible.
(2) GAGE DIAL. The dial of the pressure gage shall be graduated to approximately double the pressure at which the safety valve is set, but may not be less than one and one-half times that pressure.
Comm 41.37 Maintenance. (1) CORROSION PREVENTION. All boilers and pressure vessels shall be installed and maintained in such a manner as to prevent excessive corrosion and deterioration.
Comm 41.41 Installation registration. 
(1) BOILER OR PRESSURE VESSEL INSTALLATION REGISTRATION. (a) Except as provided in par. (b), the installation of any boiler or pressure vessel shall be registered with the department by the installer before the operation of the boiler or pressure vessel. Registration shall be in writing on form SBD&#8722;6314.
Note: Copies of form SBD&#8722;6314 are available at no charge from the Safety and Buildings Division, P.O. Box 2509, Madison, WI 53701&#8722;2509, telephone 608/266&#8722;1818.
(b) Registration with the department is not required for:
1. Boilers and pressure vessels exempted from periodic inspections in s. Comm 41.18; and
2. Installations in cities of the first class if an installation registration form has been filed with the appropriate city official.
Comm 41.42 ASME code vessels. (1) ASME CODE COMPLIANCE. Except as provided in ss. Comm 41.43, 41.44 and 41.45, boilers and pressure vessels shall be constructed and installed in accordance with the ASME code. Boilers and pressure vessels designed to other national or international standards may be approved if the design has been accepted by a nationally recognized independent third party.
Note: The department will recognize the applicable case interpretations of the ASME boiler and pressure vessel code as being acceptable.
Note: The ASME code specifies that persons installing boiler external piping by welding are required to possess the appropriate ASME credentials.
(2) REGISTERING WITH NATIONAL BOARD. (a) Except as provided in par. (b), boilers and pressure vessels constructed and installed in accordance with the ASME code shall have the manufacturers data report registered with the National Board and shall bear a National Board number. Copies of the registration shall be provided to the department when requested
From ASME Section VII Division 1
PRESSURE RELIEF DEVICES
UG&#8722;125 GENERAL
(a) All pressure vessels within the Scope of this Division, irrespective of size or pressure, shall be provided with pressure relief devices in accordance with the requirements of UG&#8722;125 through UG&#8722;137. It is the responsibility of the user to ensure that the required pressure relief devices are properly installed prior to initial operation.
UG&#8722;134 PRESSURE SETTING OF PRESSURE RELIEF DEVICES
(a) When a single pressure relief device is used, the set pressure marked on the device shall not exceed the maximum allowable working pressure of the vessel. When the required capacity is provided in more than one pressure relief device, only one pressure relief device need be set at or below the maximum allowable working pressure, and the additional pressure relief devices may be set to open at higher pressures but in no case at a pressure higher than 105% of the maximum allowable working pressure.


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## Dan Rowe (Oct 29, 2010)

Matt,
The way I read it you are exempt by Comm 41.18 (e), (f), and (g).
One of those exemptions would have been enough but hey three is great.

I have spoken to one of the State Boiler Inspectors from WI at a a steam show in Edgerton WI and he was a very reasonable fellow and had a keen intrest in historic steam.

Dan


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## 1hand (Oct 29, 2010)

Dan would I still be subject to an Initial inspection?

Thanks
Matt


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## Dan Rowe (Oct 29, 2010)

Matt,
As I read it you are not subject to initial inspection, but they can require an inspection if someone complains that there is an unsafe operation.

Although I live in Texas I have emailed the boiler inspector in WI and got an answer in a few hours which was a big surprise to me as it was a Sunday, and it was a clear understandable answer. The same question to the State of TX took a few months and it was clear that the person had no idea what he was talking about.

Dan


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## 1hand (Oct 29, 2010)

Thanks for the info Dan.


Matt


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## Dan Rowe (Apr 4, 2011)

The exemptions for Missouri are not in the code rules they are in a separate location of Missouri revised statues.

Missouri Exemptions
http://www.moga.mo.gov/statutes/C600-699/6500000230.HTM
Missouri Revised Statutes
http://www.moga.mo.gov/STATUTES/C650.HTM


Anyone reading this can help by checking to see if the information for your State is accurate. Simply post with any new information or corrections and I will update the first post.

Thanks
Dan


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## Foozer (Apr 5, 2011)

GWRdriver  said:
			
		

> This is where language of codes gets dicey and becomes subject to "interpretation", which means, its depends upon the official you happened to be talking to on that day. There are no "*and/ors*" in the section so my interpretation would be that all you have to do is meet *One* of the exclusionary criteria to be excluded. The wording I see says (for example) if you have less than 10ft/sq of heating area your boiler is excluded and it then doesn't matter how much heat you put to it. However I know from years of dealing with codes that what a literate and rational person might think a code says and what a codes official says it says can be two completely diffierent things.



Its a Pass, Fail, or Not Applicable methodology, boiler with 9 sq ft heating area might pass one case but would fail the other if 20kw were applied. 

Robert


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## Maryak (Apr 5, 2011)

Here am I thinking state governments area PITA and we only have 6 plus 2 territories.

I certainly don't envy you guys with 50 plus a federal district. 

Best Regards
Bob


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## Dan Rowe (Apr 5, 2011)

Bob,
To make matters worse there are boilers regulated by the Federal Government. 
Locomotive boiler law is in CFR Chapter 49. (Code of Federal Regulations) 
Merchant ship boilers are in CFR Chapter 46 these are the ones I worked on. 

I have never located the regulation for Navy ships or other government installations. 
I mean who repairs the boilers at Fort Knox or Area 51?

The whole point of this thread is to locate any exemptions for model boilers in the state codes. 
Notice the similarity between the language from the Texas code and the Missouri code.

Texas exemption:
3) manually fired miniature boilers that:
(A) are constructed or maintained for locomotives, boats, tractors, or stationary engines only as a hobby for exhibition, recreation, education, or historical purposes and not for commercial use;
(B) have an inside diameter of 12 inches or less or a grate area of two square feet or less; and
(C) are equipped with a safety valve of adequate size, a water level indicator, and a pressure gauge; 

Missouri exemption:
(4) Steam boilers of a miniature model locomotive or boat or tractor or stationary engine constructed and maintained as a hobby and not for commercial use, having an inside diameter not to exceed twelve inches and a grate area not to exceed one and one-half feet and that is equipped with a safety valve of adequate capacity, a water level indicator and a pressure gauge; 

How many other states are using the same rules? This thread has not located exemptions for even half of the US States yet.

The head in the sand approach has never worked well for me... :big: your milage may vary.

Any help reading this code stuff is very welcome.

Thanks 
Dan


----------



## Maryak (Apr 5, 2011)

Dan Rowe  said:
			
		

> Bob,
> I have never located the regulation for Navy ships or other government installations.
> I mean who repairs the boilers at Fort Knox or Area 51?



Gee it was 1966 but the term USN Buships publications comes to mind.

For UK/Oz BR 3000 and BR 3001 (BR=Book of Reference).

BR 3000 is the what when book. BR 3001 is the how book.

Strangely they are 12":1' models.

Hope this Helps

Best Regards
Bob


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## Foozer (Apr 5, 2011)

State of Washington

70.79.080 Exemptions from chapter. This chapter
shall not apply to the following boilers, unfired pressure ves-
sels and domestic hot water tanks:
(1) Boilers and unfired pressure vessels under federal
regulation or operated by any railroad subject to the provi-
sions of the interstate commerce act;
(2) Unfired pressure vessels meeting the requirements of
the interstate commerce commission for shipment of liquids
or gases under pressure;
(3) Air tanks located on vehicles operating under the
rules of other state authorities and used for carrying passen-
gers, or freight;
(4) Air tanks installed on the right-of-way of railroads
and used directly in the operation of trains;
(5) Unfired pressure vessels having a volume of five
cubic feet or less when not located in places of public assem-
bly;
(6) Unfired pressure vessels designed for a pressure not
exceeding fifteen pounds per square inch gauge;
(7) Tanks used in connection with heating water for
domestic and/or residential purposes;
(8) Boilers and unfired pressure vessels in cities having
ordinances which are enforced and which have requirements
equal to or higher than those provided for under this chapter,
covering the installation, operation, maintenance and inspec-
tion of boilers and unfired pressure vessels;
(9) Tanks containing water with no air cushion and no
direct source of energy that operate at ambient temperature;
(10) Electric boilers:
(a) Having a tank volume of not more than one and one-
half cubic feet;
(b) Having a maximum allowable working pressure of
one hundred pounds per square inch or less, with a pressure
relief system to prevent excess pressure; and
(c) If constructed after June 10, 1994, constructed to
American society of mechanical engineers code, or approved
or otherwise certified by a nationally recognized or recog-
nized foreign testing laboratory or construction code, includ-
ing but not limited to Underwriters Laboratories, Edison
Testing Laboratory, or Instituto Superiore Per La Prevenzi-
one E La Sicurezza Del Lavoro;
(11) Electrical switchgear and control apparatus that
have no external source of energy to maintain pressure and
are located in restricted access areas under the control of an
electric utility;
(12) Regardless of location, unfired pressure vessels less
than one and one-half cubic feet (11.25 gallons) in volume
or less than six inches in diameter with no limitation on the
length of the vessel or pressure;
(13) Domestic hot water heaters less than one and
one-half cubic feet (11.25 gallons) in volume with a safety
valve setting of one hundred fifty pounds per square inch
gauge or less. [2009 c 90 § 3; 2005 c 22 § 1; 1999 c 183 § 3;
1996 c 72 § 1; 1994 c 64 § 2; 1986 c 97 § 1; 1951 c 32 § 8.]
FindingIntent1994 c 64: See note following RCW 70.79.095.


70.79.090 Exemptions from certain provisions. The
following boilers and unfired pressure vessels shall be
exempt from the requirements of RCW 70.79.220 and
70.79.240 through 70.79.330:
(1) Boilers or unfired pressure vessels located on farms
and used solely for agricultural purposes;
(2) Unfired pressure vessels that are part of fertilizer
applicator rigs designed and used exclusively for fertilization
in the conduct of agricultural operations;
(3) Steam boilers used exclusively for heating purposes
carrying a pressure of not more than fifteen pounds per
square inch gauge and which are located in private residences
or in apartment houses of less than six families;
(4) Hot water heating boilers carrying a pressure of not
more than thirty pounds per square inch and which are
located in private residences or in apartment houses of less
than six families;
(5) Approved pressure vessels (hot water heaters, hot
water storage tanks, hot water supply boilers, and hot water
heating boilers listed by a nationally recognized testing
agency), with approved safety devices including a pressure
relief valve, with a nominal water containing capacity of one
hundred twenty gallons or less having a heat input of two
hundred thousand b.t.u.s per hour or less, at pressure of one
hundred sixty pounds per square inch or less, and at tempera-
tures of two hundred ten degrees Fahrenheit or less: PRO-
VIDED, HOWEVER, That such pressure vessels are not
installed in schools, child care centers, public and private
hospitals, nursing and boarding homes, churches, public
buildings owned or leased and maintained by the state or any
political subdivision thereof, and assembly halls;
(6) Unfired pressure vessels containing only water under
pressure for domestic supply purposes, including those con-
taining air, the compression of which serves only as a cushion
or airlift pumping systems, when located in private resi-
dences or in apartment houses of less than six families, or in
public water systems as defined in RCW 70.119.020;
(7) Unfired pressure vessels containing liquified petro-
leum gases. [2009 c 90 § 4; 2005 c 22 § 2; 1999 c 183 § 4;
1988 c 254 § 20; 1983 c 3 § 174; 1972 ex.s. c 86 § 2; 1951 c


Main that seems to cover all hobby use


79.070 Existing installationsConformance
requiredMiniature hobby boilers. (1) All boilers and
unfired pressure vessels which were in use, or installed ready
for use in this state prior to the date upon which the first rules
and regulations under this chapter pertaining to existing
installations became effective, or during the twelve months
period immediately thereafter, shall be made to conform to
the rules and regulations of the board governing existing
installations, and the formulae prescribed therein shall be
used in determining the maximum allowable working pres-
sure for such boilers and unfired pressure vessels.
(2) This chapter shall not be construed as in any way pre-
venting the use or sale of boilers or unfired vessels as referred
to in subsection (1) of this section, provided they have been
made to conform to the rules and regulations of the board
governing existing installations, and provided, further, they
have not been found upon inspection to be in an unsafe con-
dition.


*(3) An inspection certificate may also be granted for
miniature hobby boilers that do not comply with the code
requirements of the American society of mechanical engi-
neers adopted under this chapter and do not exceed any of the
following limits:
(a) Sixteen inches inside diameter of the shell;
(b) Twenty square feet of total heating surface;
(c) Five cubic feet of gross volume of vessel; and
(d) One hundred fifty p.s.i.g. maximum allowable work-
ing pressure, and if the boiler is to be operated exclusively not
for commercial or industrial use and the department of labor
and industries finds, upon inspection, that operation of the
boiler for such purposes is not unsafe. [2009 c 90 § 2; 1995 c
41 § 1; 1993 c 193 § 1; 1951 c 32 § 7.]*



So for this State a certificate/inspection is required with the key word *MAY* be granted


Robert



Edit:

70.79.320 Operating without inspection certificate
prohibitedPenalty. (1) It shall be unlawful for any per-
son, firm, partnership, or corporation to operate under pres-
sure in this state a boiler or unfired pressure vessel, to which
this chapter applies, without a valid inspection certificate as
provided for in this chapter.
(2) The department may assess a penalty against a person
violating a provision of this chapter. The penalty shall be not
more than five hundred dollars. Each day that the violation
continues is a separate violation and is subject to a separate
penalty.
(3) The department may not assess a penalty until it
adopts rules describing the method it will use to calculate
penalties for various violations.
(4) The department shall notify the violator of its action,
and the reasons for its action, in writing. The department
shall send the notice by certified mail to the violator that a
hearing may be requested under RCW 70.79.361. The hear-
ing shall not stay the effect of the penalty. [2005 c 22 § 6;
1986 c 97 § 2; 1951 c 32 § 31.]



Operate a home built without paying the fees and the SHALL notify which without a consequence for failure makes it meaningless, WILL become a fine to transfer coin from your pocket to the States


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## Dan Rowe (Apr 6, 2011)

Robert,
I had spotted the exemption but missed the penalty which is considerable at $500 per day.

I added the references to the first post.

Here is another section of the Washington code that states construction must conform to the rules.

70.79.060 Construction, installation must conform to
rulesInspection certificate. (1) Except as provided in
subsection (2) of this section, no power boiler, low pressure
boiler, or unfired pressure vessel which does not conform to
the rules and regulations formulated by the board governing
new construction and installation shall be installed and operated
in this state after twelve months from the date upon
which the first rules and regulations under this chapter pertaining
to new construction and installation shall have
become effective, unless the boiler or unfired pressure vessel
is of special design or construction, and is not covered by the
rules and regulations, nor is in any way inconsistent with
such rules and regulations, in which case an inspection certificate
may at its discretion be granted by the board.
(2) An inspection certificate may also be granted for
boilers and pressure vessels manufactured before 1951 which
do not comply with the code requirements of the American
Society of Mechanical Engineers adopted under this chapter,
if the boiler or pressure vessel is operated exclusively for the
purposes of public exhibition, and the board finds, upon
inspection, that operation of the boiler or pressure vessel for
such purposes is not unsafe. [2009 c 90 § 1; 1984 c 93 § 1;
1951 c 32 § 6.]


----------



## terrywerm (Apr 10, 2011)

The latest model boiler exemption statute for Minnesota was published in 2010, and is available at the following link:

https://www.revisor.mn.gov/statutes/?id=326B.988


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## Foozer (Apr 10, 2011)

Dan Rowe  said:
			
		

> Robert,
> I had spotted the exemption but missed the penalty which is considerable at $500 per day.
> 
> I added the references to the first post.
> ...



Thanks for the fill in, I must of lost it during the cut and paste. This State sure loves its verbiage.

Robert


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## Dan Rowe (Apr 10, 2011)

Thanks Terry,

That exemption is very similar to TX only we do not need an ASME stamp on the safety valve. I added the info to the first post.

Dan


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## Allen (Sep 2, 2012)

The current official Pennsylvania stance is there will be NO exemption based on size. They're saying all boilers operation in public (over 15psi) need a state inspection.

In Ohio, they seem not inclined to bother those with barrels less than 16"


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## Dan Rowe (Sep 2, 2012)

Allen,
What is the source of this information? Is that from a Pennsylvania boiler inspector?

This might cause some of the model shows to rethink their policy. Cabin Fever has always had a Gauge 1 live steam track in operation and G1 boilers have been mostly ignored by state officials.

Dan


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## Allen (Sep 2, 2012)

It came direct from the guy who supervises the inspectors here in Western, Pa. Our local inspector inquired the end of July to see if my roller actually needed inspection, since it doesn't in Ohio.

Cabin Fever, and the various ride on live steamer groups, have pretty much been "flying under the radar". Something which is not really an option at an antique machinery show when the inspector is already there anyway. 

The gauge 1 guys can always try to argue they are "toys", but larger stuff might not fare so lucky if they ever come to the communewealth's attention.

The ghost of John Payton is very much still with us....


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## robcas631 (Jul 10, 2013)

I think every hobby machinist has at one time wanted to use live steam. It's all good until that creeping feeling of knowing you are next to a potential bomb makes you appreciate a good old air pump. Personally, I'd rather be trained by someone that really knows how to operate a boiler!


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## chrsbrbnk (Jul 12, 2013)

I still haven't heard of any incident where someone has actually blown a model up. With reasonable precautions, correct safety components,    decent construction,   and a responsible operator its likely to be statistically safer than driving with a cell phone or gasing up your car.


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## AlanHaisley (Sep 2, 2013)

Don't forget that while your boiler may fit an exemption in your home state it may not in the state where you are showing it. As an example, some rules seem to exempt boilers with an operating pressure of under 150 psi but others seem to exempt at under 100 psi. :wall:
Alan


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## Dan Rowe (Nov 29, 2015)

Quake said:


> Indiana has several exemptions - the one I like is farms, provided the boiler is used 'for agriculture purposes'. So, just hook that model steamer up to a battery charger and use those batteries in your flashlight around the family farm and I think you're good. "Model Size Boilers" are also exempt, provided they meet specs established by the boiler board - never been able to find definitely documentation for those; but rumor is they defer to AMSE.
> -Quake



The definition of "Model Boiler" is now online for Indiana:

680 IAC 2-1-2 Title; scope; applicability; definition

(f) The term "regulated boiler or pressure vessel" does not include any of the following:

(12) Commercial toy boilers and miniature model boilers constructed as a hobby that do not exceed a size specified by the
board.

680 IAC 2-4-30 "Model boiler" defined
Authority: IC 22-13-2-8
Affected: IC 22-12-4; IC 22-15-6
Sec. 30. "Model boiler" means any boiler that does not exceed any of the following limits:
(1) Two (2) cubic feet total gross volume (exclusive of casing and insulation).
(2) One and one-half (1 1/2) square feet of grate area.
(3) One hundred (100) psig maximum allowable working pressure.

I can not figure out how to modify the first post of this thread to add the exemption. Could someone with ADMIN privileges add the exemption and definition to the state of Indiana in the first post. 

Thanks
Dan


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## GailInNM (Nov 30, 2015)

Info for Indiana added to first post.  Please check to see if  that what you needed Dan.
Gail in NM


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## Dan Rowe (Nov 30, 2015)

Thanks Gail,
That was exactly what I tried to do but I could not edit the post. 

Dan


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## kaolsen1728 (Nov 15, 2017)

I have uploaded to our website two documents on miniature hobby boilers in the State of Washington on our website http://www.kitsaplivesteamers.org Click on "Links" to find the documents. My contact information is also noted.


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## Rocket Man (Feb 5, 2020)

I live in Murfreesboro TN.  There is a business in town called, Boiler Supply Co. they, service, sell, repair boilers.   I talked to Dave the owner he gave me a copy of TN State Law.   I can build my own boiler if it is smaller than 5 gallons.  It does not have to be, inspected, tested, licensed, or anything.  I built a 4.9 gallon boiler for my 4"x4" steam engine it ran the engine good.


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## harborfreight8x12 (Feb 6, 2020)

Awesome, you know what you are doing.  Have you looked into the ASME Boiler and Pressure Vessel Code for additional reference?  Just a thought.
Kind regards, Al


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## kaolsen1728 (Feb 6, 2020)

I have uploaded all of the boiler info for the State of Washington on our Kitsap Live Steamer's website at this link: https://kls.clubexpress.com/content.aspx?page_id=22&club_id=96970&module_id=148906
Our state is also more relaxed on hobby boilers than it used to be, but all boilers must be certified, but once this has been done to their satisfaction, they no longer require the annual inspection as in the past. 

However, be careful if you are in the market for a live steam locomotive. I have helped others in the state learn how to do the calculations and prepare the documents for boiler inspections, but I have found three hobby boilers that were a disaster! A 1 1/2 gauge pacific with crown sheet stays that had deteriorated so badly that they no longer connected to each other, another 1 1/2" pacific that the boiler was built with no stays, and a third that had girder stays that were not large enough to support the crown sheet and when we cut into this boiler, the welds were not full penetration.

So just because because our hobby boilers are truly "overbuilt" for the allowable working pressure they were designed for, if they are not properly taken care of, they can become a potential problem.

Ken Olsen


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## harborfreight8x12 (Feb 6, 2020)

A boiler, incorrectly built and maintained, is a ticking bomb.  I worked 38 years on oil platforms in the Gulf of Mexico.  Boilers and pressure vessels were my livelihood.  Our pressure vessels had to undergo periodic non-destructive testing to monitor the wall thickness of the vessel's shell.  Boilers have to be removed from service and sent ashore for complete inspection and evaluation by a certified facility.  Ken, I agree that you can't stress enough the potential dangers that boilers can pose.
Kind regards, Al


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## wazrus (Feb 7, 2020)

As Dan Rowe said, it appears that Australia is the only country which has a miniature boiler safety code. As a model builder, I have built three boilers using the AMBSC (Australian miniature Boiler Safety Committee) code for copper boilers and as Dan's thread suggested, the codes are available through the magazine Australian Model Engineering. The codes are well researched and documented and I do use them as a construction manual. Without looking at them, I think their scope covered boilers up to 12" diameter and I think that was in steel. I think the copper maximum was about 7". I'm a little surprised to see that no Australians have joined the discussion???
Wazrus


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## Brian Hutchings (Feb 8, 2020)

The UK also has its own codes for miniature boilers.
The Boiler Test Code 2018VOLUME 1-Boilers 3 bar litres to 1100 bar litres
The Boiler Test Code 2018VOLUME 2 -Boilers under 3 bar litres
Brian


----------



## steveastrouk_vLn (Feb 8, 2020)

I like the bar litre as the way to define the combination of critical elements.


----------



## TimTaylor (Feb 8, 2020)

I'm retired now, but worked with boilers and steam power systems my entire career - everything from low pressure to super-critical utility boilers.

Any boiler failure can be extremely dangerous - even a small hobby boiler. In the absence of any other mandated safety regulations, there are several things that are a must for a hobby boiler.
1. It should be periodically hydrostatic tested to 1.5 times the maximum operating pressure
2. It should have a tested relief valve
3. There needs to be a means to quickly remove the heat source

Something that most hobby boiler operators rarely take into account is boiler water chemistry. As steam is generated, the dissolved solids in the water (typically calcium & sodium) get left behind, and if allowed to concentrate can form scaling that can promote corrosion and lead to potential failure over time. These deposits also reduce the heat transfer and thermal efficiency of the boiler. Commercial and industrial boilers use a combination of water treatment to inhibit scaling & corrosion, and blowdown to limit the cycles of concentration. For a small hobby boiler, the easiest solution is to flush the boiler with clean water after each use.

Just my $0.02.........


----------



## kaolsen1728 (Feb 8, 2020)

The US ASME boiler code does recognize what they refer to as "Miniature Boilers" under "Part PMB, Requirements for miniature boilers". 
PMB-2 under Scope notes the following:
PMB-2.1 The classification miniature boilers applies
to boilers that do not exceed the following limits:
(a) 16 in. (400 mm) inside diameter of shell
(b) 20 ft2 (1.9 m2
) heating surface (not applicable to
electric boilers)
(c) 5 ft' (0.14 m3
) gross volume,' exclusive of casing
and insulation
(d) 100 psig (700 kPa) maximum allowable working
pressure
PMB-2.2 If a boiler meets the miniature classification,
the rules in this Part shall supplement the rules for power
boilers and take precedence over them when there is conflict.
Where any of the limits in PMB-2.1 are exceeded,
the rules for power boilers shall apply.

However, each state can modify the code. For example note that the ASME code limits for ASME miniature boilers to 100 psi, the State of Washington has set the limit at 150 psi. However, the boiler calculations must show that the weakest component will withstand this pressure. Otherwise, the weakest component will prevail. The exception is that copper boilers are limited to 100 psi. 
Ken


----------



## radial1951 (Feb 8, 2020)

wazrus said:


> ....The codes are well researched and documented and I do use them as a construction manual. Without looking at them, I think their scope covered boilers up to 12" diameter and I think that was in steel. I think the copper maximum was about 7". I'm a little surprised to see that no Australians have joined the discussion???
> Wazrus


*
Ok Wazrus, I'll take the bait! If you are near Sydney, are you a member of a local club? Anyway, as you know, our boiler codes are well researched and documented. They are also used in many parts of the world where live steam builders don't have a suitable local code.

The AMBSC boiler codes are in 4 parts. They are recognised by authorities in all Australian States.

Part 1  Copper boilers 50-203mm dia and 1-25 litres, 100psi, 68pages
Part 2  Steel Boilers (Certified Mild Steel) to 356mm dia and 50 litres, 100psi incl full loco and Briggs types, 66 pages.
Part 3  Sub-Miniature Copper Boilers to 50mm dia and 1 litre, 35psi
Part 4  Duplex Steel Boilers 325mm dia and 50 litres, 100psi, 44 pages

The codes are fully detailed with drawings, charts, plate thickness, flange depth, weld preps, stay dia and spacing, bushes, safety valve design etc etc. No trouble to design and build a complying (safe) boiler or air receiver using these codes, they are very comprehensive.

See Australian Model Engineering Magazine www.ameng.com.au and go to the Shop.


----------



## SirJohn (Feb 13, 2020)

Brian Hutchings said:


> The UK also has its own codes for miniature boilers.
> The Boiler Test Code 2018VOLUME 1-Boilers 3 bar litres to 1100 bar litres
> The Boiler Test Code 2018VOLUME 2 -Boilers under 3 bar litres
> Brian


----------



## SirJohn (Feb 13, 2020)

Alberta, Canada code does not require a boiler to be registered if it is <152mm I.D. and <42.5 litres volume, maximum working pressure <1725kPa which translates to approximately 6" I.D. x 23" long and 250 psi. 
Using copper pipe and the maximum pressure is 100 psi.


----------



## ddmckee54 (Sep 1, 2021)

I think the links to the Washington state boiler code are broken, both the link on the original page, and the link by kaolsen1728 on Feb 6, 2020.  They both give me a page not found error.

Don


----------



## Steamchick (Sep 2, 2021)

I worked 40 odd years as an engineer, designing High voltage switchgear and stuff, car stuff, and was the Ex-spurt Regulation engineer a t the car factory for around 20 years.
I learned that "in the eyes of the Law" ( I.E. words passed by the Legislature that allow anyone to get money from any pot there is.... to pay lawyers, and possibly compensate "injured parties" as they put it!) you shall not intentionally nor innocently break the rules within the Regulations, in case something goes wrong, or someone can challenge your "safety"..... for fear of being caught Breaking the law". 
Exemptions are just there so the lawyers can argue and charge (whoever has the money) for their time.
So I advocate that you comply with ASME regulations to the best of your ability..... e.g. join a club and use their experts to check what you are doing (it is comforting to have someone next to you when you stand in the dock) and if possible have the club's insurance cover your public activities. 
I have spent a lot of time pondering what I know from my engineering expertise to be sensible calculations of the strength of boilers. But I have not yet found any official guide to the calculations required to prove a design. Also, by my cautions demonstrate the weakness of many designs - typically the "pressure of failure" determined is less than 8 times the NWP. (ASME requirement is "more than 8 times.). So I think there are a lot of boilers that "by design" do not have the required Factor of Safety of 8 times NWP. The hydraulic test at 1.5 or 2 x NWP  does NOT prove a good design, just that there is some margin of safety.
I am now de-rating my boilers accordingly...... because to not do so would be "negligent" if it ever came to court.
I cannot responsibly suggest you do anything but try and achieve what the Regulations require....
That's the world we live in and enjoy.
K2


----------



## Steamchick (Sep 3, 2021)

- Incidentally: I can strongly recommend a cheap way to "get the Regulation info" - Buy a back copy of "Live Steam and Outdoor Railroading": Volume 40 No. 6. The article by Kozo Hiraoka is really the best text book I have seen on the subject: He is a genius teacher. - I use this in place of all the other books I have, as it has such clear and uncompromising details on what MUST be achieved as a minimum to be approved to ASME Regulations.
But I must add, that this does not cover any tubes experiencing COMPRESSION forces from the water/steam - such a flue tubes. In the case of COMPRESSIVE forces on COPPER tubes, you need to de-rate the Maximum Permissible Stress to 21% of the Max. Permissible Tensile Stress  - according to the worst case I have read from internet sources....
And considering that many boilers:

with a single fire-tube (for a blow-lamp) have cross tubes,
Outer-shells have penetrations for Steam domes,
Inner firebox tubes on vertical boilers have penetrations for coaling,
there is another ASME regulation applying to pressure vessels - including boilers - that states the STRESS CONCENTRATION FACTOR shall be taken as 3.3 - Whatever else an individual may think, calculate or ignore.... - This has the major effect of reducing the NWP to 30% of that otherwise calculated (I.E. If you have missed/ignored the SCF).
Basically this has caused me to de-rate some of my boilers, because I had originally used other stress concentration factors (typically 2.2 ~2.7 depending on tube size, shape and hole size) because I designed boilers based on my general engineering knowledge, and some text book tables, in ignorance of the ASME requirement.
In summary, unless you feel you can fight a court case for "exemption", you have to do a hell of a lot of research to find the Regulation quirks that affect you designs... And I don't know where I can go to ask for confirmation or correction of what I am doing! Most "inspectors" can inspect to their rules, but can't confirm your calculations, because it isn't their job to know or be able to do so.
And as far as I can determine, outside of the USA, one has to "Do one's best" as the Regs are so hard to find and interpret...
Sorry to be so long-winded about this, but I have pondered and researched for many hours to try and get to this semi-sensible stage...
K2


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## razzle (Nov 24, 2021)

Update to the Texas link. Code reference remains the same.


			HEALTH AND SAFETY CODE  CHAPTER 755. BOILERS


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## wazrus (Nov 25, 2021)

I've missed replying to Radial 1951, as HMEM seems a bit spasmodic with its contacts. Just today, i received an e-mail telling me that the thread seems to have been resurrected!
Radial, what 'bait?'. And no, I'm not a member of any club and never have been. I have my own 5" track of about 300M. I built it around 2004, i think it was. However, some health issues have intervened and I haven't turned a wheel on the track for some years. Before the 'issues', I was in the process of re-aligning the track, as there had been some subsidence and the whole shebang was in the process of being re-sleepered (lots of white ants), re-aligned, re-graded and re-ballasted. The work is unfinished, particularly the sleepering and some of the banks need edges, for which I've started to use concrete blocks. Nor have I been doing much with live steam, although there are some projects in the pipeline. I have (or had) a complete Sweet Pea, which I've dismantled, as the original design of boiler had more than few limitations, which I was in the process of, let's say, 'correcting'.
I did let my AME subscription go some years ago, but I was a contributor since 1993 but, as I said, never a club member. Too much politicking for me.
But I'm still alive! 
Current 'projects' ( ho ho ho) included LPG firing and burners for same, as good steaming coal is hard to get in what is one of the largest coal exporting countries. There's something very peculiar when I see Welsh steam coal being offered.. Now LPG burners are tricky little buggers and I'd like to place 'em in the flue(s) of my latest creations, as that Finnish gentleman has done, but without the 'glow cones'. Then, too, I've seen somebody else on HMEM remark about the paucity of data on the _compressive_ stress of copper tube and this is a concern with larger boiler flues.
I'm in New South Wales, in Sydney. I'll look for your contact.


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## Steamchick (Nov 25, 2021)

Thanks Russ, I am working through this  tome, to try and find the relevant stuff for copper boilers up to 100psi. It seems all boilers in Texas below 160psi are called "hot water boilers". I must read more. 
But as I am in the UK, I am not obliged to meet Texas , nor ASME, Regulations. However, the ASME Regs were written by engineers cleverer and more experienced than I, and as such I feel it is foolish to ignore them. "What price for Safety?".
K2


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## Steamchick (Nov 27, 2021)

Hi Wazrus. Good luck in finding burners for your loco project.  Having been interested in this for a few years, the most successful  gas powered locos seem to have dedicated designs suited to gas firing. For all designs though it seems most important to not just have a burner system that draws in adequate primary air for full and complete combustion, but the fire needs to have radiant elements to improve the heat flow from flame to copper.
Simply:a hot flame has the coldest part against the boiler wall, and the conduction of heat from hot gas to cold wall is poor. But if the flame heats some medium to red or orange heat, then the radiant heat is transmitted into the boiler walls very efficiently. Additionally, the volume of exhaust gas from flames is large, but the same burner with radiant element has a lower volume (due to the lower temperature) of exhaust gas. As most boilers are limited by exhaust gas versus flue size - so coal fired loco boilers force this with the exhaust steam blast - gas fired boilers need significantly larger flues to avoid back-pressure affecting the burners. The mathematics of all this are hugely complex (beyond my capabilities). So copy someone else's successful design for an easy life!
On tubes in compression. The tensile strength limit for copper is derated by temperature. When doing calcs at room temp. ASME permits 6700psi. Max. But at 100psi (the ASME limit for Silver soldered boilers) the Max. permissable Tensile stress is derated to 3142psi. Now from my research, the compressive stress is derated to 21% of the tensile stress, that means when you do the hoop stress calculations for the fire-tubes, you can only have a max. compressive stress of 660psi - relating back to ASME limiting tensile stress. Actually, for thick-walled copper flue tubes this is usually manageable. But for larger tubes for fire-tubes, etc. this means additional reinforcement of the tubes is necessary. Further, if you have cross-tubes, the stress concentration factor that must be used is 3.3 - defined by other ASME pressure vessel regulations for ANY side penetration of a tube in compression - means this is further derated to 200psi. MAX.
But please note, I am only a jobbing engineer (I did the job for 40 years in industry all to national standards and international regulations - not back-street mechanics "it's looks OK to me, Mister"), I'm not an expert in this field, so if any experts want to correct me I will listen closely!
Cheers,
K2


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## Steamchick (Nov 27, 2021)

Wazrus, I'll try and show some examples:
Tubal cain quotes an example of a 1" dia copper tube - 0.048" thick wall collapsing at 330psi: This means a factor of safety of 8 would give a NWP of 41.25psi: Except he did his test cold: (Max permissable tensile of 6700psi). But if we run a boiler at 41.25 psi the temperature is around 290F. So the max permissable tensile stress would be near 4157psi. I.E. 4157/6700 =  62% so if the test had been with steam at this pressure, we should expect a failure at ~205psi. - De-rate this by a factor fo 8 and we get a NWP of 25psi!
Martin Evans proposes 1" OD x 0.064" wall thickness should be OK for 100psi NWP... but I have calculated it is OK for 80psi NWP to ASME and other physical limits if you really apply all the factors and Factor of safety of 8. As the heaviest standard 1"OD tube listed is 0.080" wall, this is good for 95psi NWP for a FOS over 8 - meeting ASME as a fire tube with external pressure, but with NO cross-tubes. This also implies the tube is straight, and undeformed, as a non-straight tube, or oval or deformed tube must be derated a lot for external pressure. 
For 100 psi NWP for a fire-tube - to meet all the requirements for safety from Regualtions, etc. I propose a 1" OD tube should be at least 0.085" wall  thickness.
Cheers.
K2


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## Steamchick (Nov 27, 2021)

More stuff...
(Enjoy?)
K2


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## wazrus (Nov 27, 2021)

G'day, Steamchick. Many, many thanks for your input, especially the discussion of compressively stressed copper tube. I do have Kozo Hiraoka's book 'The Pennsy Switcher' and he uses larger flues in its coal-fired boiler. He reckons that fewer large flues are to be preferred. That suits me and my gas intentions, except that he calls up flues of .787" OD x .047" wall thickness, which he says should be doubled if in 7-1/4" gauge, (.094"). Both of these seem a bit light to me at 80 psi., and in fact, I'm considering using .125"x1.75"x450 long tubes for my flues, but I have my doubts about the compressive stress at those sizes, especially as we are, I understand, talking about _annealed_ copper tube. Another project I have on the back-burner, is rebuilding a 6" dia. stationary boiler I built years ago, which has a 4-1/2" (approx) inner firebox. All from 3mm copper tube and the inner firebox has bulged inwards: the project is rebuilding and installing radial stays at the firebox. The design was from Model Boilers and Boilermaking, by K N Harris, design no 9, page 163. As you say, better to use somebody else's design.....hmmmm.....
My Sweet Pea-type boiler, with round firebox, will certainly be stayed. That's one of the 'improvements'!
I've been fiddling for what seems to be ages with gas burners/burner configurations and as you say, enough primary air is THE issue and nozzles are 'interesting', shall we say. I'm pretty competent with 0.4mm holes! I have a 'range' of jets in 0.4, 0,.5, 0.6, 0.8mm etc sizes and all sorts of weird and wonderful gadgetry, to supposedly control air. I have quite a few venturis, but my reading on these seems to show that a pipe reducer might do the same job! My venturis are 'sophisticated' by comparison, fabricated from 2mm copper, finally shaped with a very nice(!) steel taper mandrel (2" dia) and a fly press and die. They look a bit like the bell of a small trumpet.
It seems, too, that my 'in flue' burners might be better served with what I've seen called a 'glow cones' and I've tried these, but they're a bugger to make and support in the flue and they are relatively short-lived. I have a burner 'stick', which has burner 'mounts' along it, intended to have about eight gas nozzles evenly spaced along the flue, but I haven't yet tried it out in a flue. I suspect it'll probably self-extinguish and just how to support it in the flue is interesting, too.
Ragards
Wazrus


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## wazrus (Nov 27, 2021)

Further on the flue size discussion: A correction. Kozo Hiraoka, at the end of the Pennsy Switcher book, goes into more detail about the 7-1/4" gauge version and does not, as I have said, simply 'double' the sizes. While that is true of most other bits and pieces, he _does_ revise the boiler flues, in that he specifies _seven_ flues out of 1"x.078", not three as in the smaller version. He also downrates the pressure of the larger boiler to 70 PSI, with, he reckons, little difference in the boiler's performance. I'd like to rate my boiler(s) at 100 PSI., which again raises questions about the compression ability of even my 1.75"x .125" thick tube, at 450mm long. Using flue tube burners or glow cones I can't see how my flues can be effectively stayed.
Wazrus


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## wazrus (Nov 27, 2021)

And Again! I hadn't 'loaded' the pix etc Steamchick sent re the flue tube burners: my apologies. Good stuff, those and certainly offer a few more insights. 'My' newer boilers are intended for gas, i.e., 'gas specific'. I have considered the loco type with gas burner in the 'conventional' firebox and this is still possible, to some extent, but the flue tube burners and the simplicity of the gas-specific cylinder have most appeal.
Wazrus


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## Steamchick (Nov 28, 2021)

Hi Wazrus, I am interested in your investigations for a "sensible" gas fire boiler. I recently (this year) had discussions with a VERY clever guy in Spain. A Professional plant engineer for Chemical plant, he has made a 5" Pacific loco - non-conventional - for gas firing. Joan Llutch is the guy. He is on the (Spanish) web with lots of information and videos of him driving his finished loco. 

The Burner he uses is a 4" diameter x 4" high unit he got from Bekeart., who now make various smaller sizes as well as full industrial sizes. 
*heating.bekaert.com › ~ › mediaPremix gas burner solutions - Bekaert*

Also I have read the design notes by Susan Parker of her design of boiler. There is a lot more on the internet - as some things do get updated - and her whole design document is a hundred pages or so (if memory serves?). I made a short note - see attached - as a personal reminder of her ideas. Check her web pages for lots more detail, including strengthening work on the fire-tubes.
She adheres to Australian Miniture Boiler regs:
*catalogue.nla.gov.au › Record › 1728816AMBSC code, part 1, issue 7 copper boilers / Australian ...*

Hope this is useful?
K2


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## Steamchick (Nov 28, 2021)

Hi Wazrus, another bit of my research: 
K.N. Harris Design no9 firebox. 
By my calculations, for a FOS of 8.8 this is limited to 40psi NWP. (5.25"OD x .125" thk). But then I applied the required SCF of 3.3 for the coal hole penetration into the side of the firebox and this reduced the NWP to: *12psi*, in order to get a FOS of 8.5!!
You are using .125"x 1.75"x 450 long tubes for your flues (is the 450 in mm or inches?). I reckon good for NWP = 100 psi with a FOS = 10. Excellent!
You mention flues out of 1"x.078"  - I reckon these have a FOS of ~15 at 70psi, and FOS of 10.8 at 100psi. - so OK by me? - without any side penetrations. - But do they have cross-tubes? - in which case the FOS at 70psi becomes an "irregular" 4.7! - so the NWP should be only *39psi*!!!
Maybe copying "old" designs is not always good for current regulations. 
But if the other people's designs tell you how much flue area for a particular design of boiler then maybe there is some useful information? - e.g. other designs of boiler using gas firing?
Cheers!
K2


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## wazrus (Nov 28, 2021)

Steamchick: your 'handle' intrigues me, as it seems you are male, despite the 'chick'! I'm trying not to be rude or invasive. Ho ho ho. Nevertheless,
did you ever spend time on Bougainville Island? I knew an English bloke there named Chick, who was a train nut. Couldn't possibly be.....However, I note your references to the Spanish bloke and I'll certainly have a look at his stuff. Speaking of others involved with gas-specific boilers, there's another bloke in Finland who has a couple of operating gas-fired locos. If I recall, his website was called sauhnalati, or something very like that and I did make contact with him yonks ago and that's where I saw the 'glow cone' (his words) idea. I did in fact try out the cones (not in a loco, but in a !-1/2" flue) and I could see the idea working, but, as I said, the cones were a bugger to make and support and didn't last very long at all and most of the 'glowing' seemed to be at the end. So I started casting around for 'something else'.
That vertical boiler I built was my first and it turned out quite a reasonable, tight job (ahem!) . I was a bit miffed when I saw the firebox walls buckling inwards. And it was all built to the 'words and music'!! I fired it once or twice on coal, but quickly went to gas, using an adaptation of what the culinary set call a 'mongolian cooker', which is a set of about eight burners arranged around a cast-iron ring. The cast ring wouldn't fit in the firebox, so I rebuilt the 'idea', into a much more compact burner head, which produced a nearly ideal flame: the flames were _just_ blue-tinged, in a nice, tidy ball. In fact, the flame was almost invisible.
As per your Spanish contact, the Finnish bloke can be seen driving his 'gassies', too. Jan-Eric was his name, as i just now recalled.
I will _try_ to include some pix in future, but I'm pretty much computer-illiterate and you'll have to grin and bear it.
Regards
Wazrus


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## Steamchick (Nov 29, 2021)

Hi Wazrus: The "Chick" is from the family name - going back to 1605... and ignoring all the "Fowl"-named like "KFC" I am the original Ken Chicken (Not to be confused with "Kenticky Chicken"!) I.E. The English family has just over 7000 on the whole family tree (over the 400-odd years). But many countries have their own family trees going that far back as in Japan I met a "Niwatori-San", and in France a "Madame Poullet". Your mate "Chick" was just a N. American twist on the name I guess?
Just like Smith and Weaver, we were named because our ancestors were Chicken farmers.
Possibly the most populous family name, as Googel tells us there are 27 Billion Chickens on this planet.... ( typical googelism, as there are only 8 Billion humans!).   
And yes, I am male - for the record.

Back to burners: Ceramic burners - as used for grills for cooking, or in model boilers, burn out - but if kept below 950 degrees C this takes a long time (>1000 hours?). Over that temperature (I had one white hot for 10 minutes!) it accelerates the ageing.





Stainless steel is good for 1050 deg. C. Above that it deteriorates (burns away) rapidly. But that is what we get cheaply as modellers.
Special materials used industrially can run up to 1450 deg.C. - But it is really Expensive - as you can only buy industrial quantities of "orders over $100" and 5 sq.m area. - which is hundreds of $..!
If you can get hold of Nichrome electrical resistance wire you can weave your own fabric that will last last longer than wire containing iron...
But I am trying to develop a simple and cheap wire construction (to easily replaced, and not expensive) so am working on stainless steel wire mesh in a cylinder (I may consider a cone for "flame structure" reasons) which is covered in cheap stainless steel wire wool. Cheap because it can be bought for stuffing car silencers. Apparently, some people using stainless steel report using 2 or 3 "cones" - or whatever shape - of S/S mesh per season, but some say 1/year is enough. That - to me - is a serviceable part , especially if relatively cheap (Less cost than the fuel burnt).
Keep in touch,
K2


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## Steamchick (Nov 29, 2021)

A couple of pictures of other burners I have tried to develop... But I reckon I can only make 1/3rd of the heat of "the best".

First is a burner made from lots of 1mm holes in a tin, covered in wire mesh.
Second is a 4" diameter x 4" high copy of the Bekaert burner for Joan Llutch... but using cheap S/S mesh and covered in cheap S/S wire wool. - This burner has been improved with the addition of a venturi air intake (I can give it "Excess air" so can now tune the mixture and gas pressure)
I studied Jan Eric Nystrom's burner, and tried to improve on it - and failed .... here are 3 stages of my development in the attempt.
Your Mongolian burner is a good approach for intense heat, but your description of a "ball of blue luminous gas" suggests it is choking from back pressure and not getting enough air to form a series of Blow-lamp - type flames from each hole in each nozzle. So you are venting a lot of fuel as Carbon Monoxide up the flue.... from the lack of air and combustion. I.E. too much gas and not enough air. Please don't breath the exhaust - it can kill!
K2


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## wazrus (Nov 30, 2021)

Looking at the very prolific US sites, many there have made, seemingly successfully, what they call 'pipe' burners, which seem, from pix, to be little more than a tube or pipe with slots cut across the body. My effort at one of those resulted in a most spectacular wall of orange flame. There wasn't enough air(?) but it _was not_ in a flue, but in free air. This of course led to experiments with various means of air 'induction'(!), (the venturis I touched upon) and also a wacky device which included an automotive type of butterfly arrangement. Success rate? Nil.
It seems as though I'll just have to wear the 'glow cones'. I do have a fair bit of stainless steel mesh. And I might also have to arrange the boiler to allow quick and easy replacement of the cones. Looking at your pix, the 'ball of flame' I mentioned was not at all unlike your P8272325, at least with its colours.
I'm certainly hanging in there with the 'burner in flue' approach and i do have some 38x1mm threading tackle, so I'll be messing around with removeable end caps carrying the burner assembly, whatever form that might take. For this, I'm planning to have the flue tubes(s) extend past the 'backhead' and thread the projecting end. Perhaps, too it might be easier to allow cone replacement from the 'other' (smokebox) end, as there'll be a convenient access door. A thought occurs that maybe, if hollow, longitudinal stays were used, extra draught from the engine exhaust, through the stays, could possibly augment the primary air supply. Then , that gets away from the inherent simplicity of the cylinder with two or three large flues. But there'll have to be stays anyway, so what the hell...
We used to be known as 'model and experimental engineers': I'm sort of re-incarnating the 'experimental'... yeah, right.....
Wazrus


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## wazrus (Nov 30, 2021)

Just finished a quickish look at Susan's design and that's almost the bee's knees, isn't it? Two things come to mind, the first is the burner head arrangement and jet size. I doubt if I'd include a feedwater heater. A shortcoming with my Sweet Pea boiler was what seemed to me to be a lack of steam space, so in my rebuild, I have added a dome, in which I'll house the regulator. Otherwise, though, I'll go with Susan's words and music and as you say, let's not re-invent the wheel. Between you and Susan, there isn't much room for any theoretical input from me, so it's over to the explosions department, but not right away. The medicos have intervened yet again.
Wazrus


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## Steamchick (Nov 30, 2021)

Hi Wazrus. Good luck with medicos. I've just finished a course of radiotherapy blasts! Now getting through the after effects, so body tired,  but brain glad for the stimulation you provided! Thanks. It makes sitting around more entertaining.
Explaining the burners in that pic. The side-stalks of mini-blow-lamp flames are good clean combustion with good concentrated heat. That is what you should get from the Mongolian burner. The balloon of blue CO combustion above the jets of flame is basically excess gas, due to insufficient air ingress at the jet.
In your vertical boiler firebox, the major issue is the cross-sectional area of the flues. Too little CSA means back-pressure, then that reduces the efficiency of the air taken in at the gas jets, so less air means Surplus CO with too little air for fast combustion, and the consequence is a balloon of poor combustion of CO gas that stops much of the heat flow into the boiler.
BUT, that may not be a problem as you managed to implode the firebox. (#  67). POSSIBLY you can recover the firebox with the imploded firebox wall, by deft use of hammer and drift after annealing the copper. To anneal, you just need to raise the copper so it develops black oxide but does not glow red at all. Otherwise you risk undoing all the silver soldering!
Having repaired a few boilers, it is much easier making from new!
Cheers!
K2


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## wazrus (Dec 1, 2021)

I've been called lots of things, but never stimulating! Like you, one needs something other than sitting around waiting for god.
The vertical boiler's flues were very much to the words and music. I don't recall and haven't looked at the number, but they were about 8mm dia and lots of 'em. I _do_ recall brazing them, as there was a bit of trepidation, but all went quite well and there's a good ring of solder around each. Yes I whacked the firebox wall to very small effect and then reasoned(!) that the 'implosion' might have work-hardened (AKA strengthened) the copper. At least to some extent.
Undoing silver solder isn't as easy as it sounds. My 'original' Sweet Pea boiler re-uses quite a bit of the platework and dismantling the thing was a real exercise in finding out just how tenacious silver solder is! The Pea boiler has, I reckon, one of the more awkward bits of flanging - albeit circular - being the throatplate, where the flange 'reverses' almost immediately. I had to make up a full steel flanging dolly. So maybe, just maybe, it was worth the dismantling problems.
As I said, I'll try to find some of the pikkies I've taken of the burners and other bits and pieces.
As for the medicos, I've had a couple of moles diagnosed as 'not very nice': not dangerous -yet - but worth watching, so I spent most of today at their behest and tomorrow I'm to be fitted with a sleep doover, by another clutch of medicos. Can't imagine sleeping - or trying to sleep - with the bloody thing!
Regards
Wazrus


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## cds4byu (Dec 1, 2021)

I got fitted for a CPAP machine a couple of years ago.  I diidn't think I needed it until I saw my oxygen levels during a sleep study.  So I reluctantly started using the CPAP.  Now I find that I sleep much better when I use it, even though I still hate the mask.  So for me, it's a net benefit.


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## Steamchick (Dec 1, 2021)

Hi Wazrus,
Does the vertical boiler still exist, or has it been "re-cycled"? 
My view on that design is that it was suitable for NWP = 12psi, before the failure you experienced. (I.E. it could fail at anything over 103psi.). Assuming you "Failed" it at 100psi, that relates to a factor of Safety of 8.3 - so in fact I would expect it to have failed, if not at the NWP = 100psi when the safety valve blows, but either at the 104psi Max. steam test pressure, or at the hydraulic test if you went much above 100psi. (The ASME test pressure for a NWP = 100psi boiler shall be 277psi !). But that is on Annealed copper, so if it failed at a higher pressure than 100psi, then it was likely that it was work hardened to some (unknown) degree.
It is often mis-understood that if a boiler can achieve the Hydraulic test, then it meets the Regulations. In fact, the hydraulic test for ASME only simulates 1.3 times the NWP, but the regulations require the design to withstand at least 8 times the NWP. (Based on stress calculations).
I reckon that there are quite a number of boilers that cannot withstand 8 times the NWP. In reality, this means there are some boilers being operated at a reduced factor of Safety. I simply ask anyone to think, and decide if they want to sit 3 feet away from a loco that contains more stored energy than a hand-grenade, and risk (through a catastrophic failure) scalding hot steam venting that will permanently damage humans and cause extreme pain.
As the Sweet Pea design is "well proven" by the number of examples that exist and have not failed, it appears to be "a good design". But, I would suggest you take the experience from your vertical boiler and get design calculations made of all the material thicknesses, and if required, increase any thicknesses to something at or above the calculated minimum. Much easier to do now, before you make the boiler!
I haven't read the Australian regs. (Don't appear to be on-line). but guess they are equivalent to the ASME regs for USA. Maybe you need to get a copy from AMBSC code, part 1, issue 7 copper boilers / Australian Miniature Boiler Safety Committee | National Library of Australia ?
I did read an interesting article that may help you?


			https://www.ndmes.org.au/wp-content/uploads/2020/07/July-Newsletter-2003-1.pdf
		


Cheers,
K2


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## wazrus (Dec 1, 2021)

G'day, Steamchick
The vertical boiler still exists, yes, but it's very much on my list of 'things to do' (endless list) which includes radial staying. As I said and we've discussed, bashing out the bulges ought to be, in some measure, possible, but....I'm prepared to risk the brazing coming undone. After that came the Sweet Pea boiler and it was thoroughly stayed, which made the construction just that much more difficult. Besides the longitudinal stays, I added radials as per AMBSC specs. There were no 
issues with firebox bulges. While it may be a 'well proven' design, the Pea boiler has no fans in Australia, at least none from the AMBSC and there is an alternative design, vaunted as 'essential'. After the vertical boiler, I began using only 4mm copper in all my creations, if nothing else, erring on the side of safety.
It wasn't the hydraulic test which caused the bulges, or at least that's my contention: the AMBSC stipulates an hydraulic test to 2x NWP and this is what I did. I do have copies of the AMBSC codes, copper and steel.
And for cds4byu, today is CPAP day, which for me, like getting older, has nothing to recommend it.


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## Steamchick (Dec 2, 2021)

Hi Wazrus. The 2 difficulties with "old fashioned" 2 x NWP for the hydraulic test is that: 

It does NOT consider the effect of temperature on the strength of Copper. If temperature deterioration of the strength of Copper is considered, you need to factor the pressure by 6700/3142 - I.E. you need 2.13 times the NWP just to get the same % of limiting stress in the boiler as it will see at NWP. So that hydraulic test would only simulate about 80 psi steam pressure. All you are doing with that test is satisfying the inspector that the boiler won't easily fall apart, and it doesn't leak. BUT when you do the steam test at 104% of the NWP (104psi) you are getting  to the stress level where you should still have a factor of 8 for Safety on the stress in the boiler. That boiler obviously did not as it buckled.
The service hydraulic test at 2 x NWP is superceded in ASME to consider permissable stress at steam temperatures. But this is still only a Service test. It is not intended to prove a design factor of safety of 8. To do that, you would need a test at 8 x NWP = 800psi. Susan Parker did that with her design. But for those of us "Innocent" of design parameters we follow the designs of old - which we assume will meet the regulations and service conditions that we will meet. Sadly, not all "old designs" are good enough for today's regulations, and Real Life - as you experienced. 
I think that as there are improvements to the Sweet Pea Boiler you will do well to adopt them.
But get the calculations done by your club engineer - or someone capable - and be sure your design is OK before you cut metal.

Cheers!
K2


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## Shopgeezer (Dec 2, 2021)

For the CPAP users you will probably need a humidifier if your unit doesn’t already have one built in. Mine didn’t and I had a raging dry throat in the morning. The humidifier was just a pan with a heater under it. Maybe you can use your vertical boiler. Plumb it in to the CPAP line with a heater under it. You could be truly steam powered.


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## kaolsen1728 (Dec 3, 2021)

I have attached a copy of the ASME info on doing a hydrostatic test on boilers. Note that it states to do the test at 1.5 or more above the NWP. Note also that this is what the code refers to for full size boilers. I am not sure but in the State of Washington, the NWP max that they allow is 100 psi. I believe that may also be noted in the ASME code for Model Boilers. I did not verify this however. I personally see no reason to go over 150 psi for a hydrostatic test. If there is a leak in a soldered joint, it will be obvious even before the 150 psi is reached. No reason to over stress as this can do more harm than good.


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## wazrus (Dec 4, 2021)

CPAP, BiPAP, EPAP, APAP. It's quite enough for some cynicism. Tonight, I catch up on a bit of the lost sleep. And their prices! Eye-watering stuff. Shopgeezer: cheeky bugger. And my (hired) blower has a humidifier.
The 'tried and true' maxims I have used and clearly, they've come up short. Extra stays in the Pea boiler didn't do any harm, as well as making it more interesting to dismantle. The gas revised type will certainly use stays in the firebox area. I'm not sure whether or not this post went earlier, but I am attempting to 'attach files' of pikkies of some of the aspects of my endeavours.
pic 002 shows one of the bell-shaped venturi sections being formed in the fly press
pic005 shows the final steel formers, male and female, for the venturis
pic007 a sort of completed venturi: needs a lot more work, but the intake is there...maybe...?
pic 0326 is a collection of jets, sizes varying between 0.4 and 0.8mm
pic0329 is one of the 'burner bars', the large circular sections have threaded seats for a pair of jets. I had envisaged one of the bars would be around 400 long, with eight? or so jets along its length. I have no idea whether the 
jet bar' thing will work at all. It's my hope that it may be an alternative to the 'glow cones'. 
pic 689 is the Pea boiler, with some new platework and a new dome. The old outer firebox shows some of the 'old' stay positions. patches of silver solder can be seen where they were.
pic 690 shows the pea boiler and my larger creation
pic 691  the two boilers side -by-side again, with a 12" square for scale
pic 696 is a variety of plates, for dome, tubeplate etc, with some strengthening rings, as required around the dome penetrations. The drilled steel rings are bolt pattern templates for drilling of the dome flanges.
The jets gave some heartaches and not only because of the tiny holes, but by the non-availability at least in Australia, of very small hex brass bar. However, on a  trip to Hong Kong, I found both 3 and 4mm A/F in shops in Reclamation Street, Kowloon. I would recommend that locality if you're shopping for the oddest of odds and ends. But maybe not in 2021!


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## Steamchick (Dec 4, 2021)

K A Olson (I guess that is your name?), thanks for that. The ASME regulation I refer to is the design regulation. The ASME limit of 100psi for silver soldered copper boilers is based on material properties which do not change by nation or state, so maybe it is good for us all to follow that limit (e.g. In the UK or anywhere else outside of USA).
The hydraulic test I found from ASME, based again on permissable stresses in annealed copper at elevated temperature.
To quote: UG-99: "The hydrostatic test pressure shall be at least 1.3 times the Maximum allowable working pressure multiplied by the lowest ratio of the stress value St for the test temperature for the design temperature." - In the case of a boiler for Max. 100psi (Max limit as required by ASME for Copper boilers) the ratio of St/Sd = 6700/3142 = 2.132: So the test pressure (Hydraulic at 70degrees F.: designed for 100psi = 338degrees F.) shall be 1.3 x 100 x 2.132 = 277psi.
My information source is a design document written by Kozo Hiraoka published in 2006, so I may be out-of-date by now?
The logic I expressed is based on sound engineering principles, of stress calculations and compensation for copper at elevated temperature, but if there is a Service test for in-service annual tests (as the UK test at 1.5 times the NWP) then that is accepted for that certification. But for new boilers there is usually a design hydraulic test - at least done by the designer or agent to prove the strength of the design is good for the simulated stress for 8 x NWP and factored for the material strength at the temperature of the NWP.
My recommendation to Wazrus was that if he had a boiler deform due to pressure, then that pressure should have been at least 8 times the NWP. So there was something wrong with the original design.
If you think being able to withstand 8 times the NWP is excessive for your boiler, then you misunderstand the purpose of the Regulations, in my opinion. It is the regulating authorities' decision that this is the level of safety required to prevent injury to people. So I have re-rated some of my boilers that were "inadequate" when I applied the ASME principles to the designs of those boilers. But I am just an engineer (following Kozo Hiraoki's explanation paper on ASME Boiler and Pressure vessel code and general engineering calculations for stress), with my opinion expressed on this site, so please check with your local test authority if you need your calculations or testing to be confirmed/ratified.
My prime interest is the safe operation of steam boilers by safe design. 
Happy ( and safe!) steaming!
K2


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## Steamchick (Dec 4, 2021)

Hi Wazrus, 

I am fascinated by the boiler design: Do you have any general arrangement drawings you can show so I can better understand the firebox and fire tubes planned? I have had a notion that "conventional flat-sided and stayed" fireboxes are appropriate only because they copy full size Locos. Cylindrical fireboxes are much easier to manufacture and "naturally stronger" than flat plate constructed fireboxes. (I have a "scrap" super Simplex boiler with possibilities of repair - but the stayed flat sides limit the pressure it can take - and leak madly!).
I am curious about your idea of the fire-tube burner. Have you lit it yet? What does it do in a fire-tube? Where does the "venturi" fit?
I have attached a copy of a USA Government design of venturi. The jet goes at the left-hand end. The air inlet (between jet and venturi - needs to have a cross-sectional area of 120% of the area of the opening into the venturi. The area of the opening into the venturi is critical: this needs to be at least 250 x the jet cross-sectional area. - then all other dimensions are scaled from that dimension. The drawing attached is suitable for a propane jet about 0.55mm. dia., mounted about 11mm. or 7/16" from the end of the hole, by my reckoning.... but the US government paper suggests "0.5 x D" which would be 0.7" or about 18mm from the end of the venturi. So some degree of adjustment should be made so you can tune the gap between the jet and the venturi to get the optimum flame in your fire tubes. 
Scale up or down as appropriate for your planned jets?
Of course, it is intended that the venturi blows the gas-air mixture into a burner - such as the burner that Susan Parker has  = a lot of slots in a long tube! But I reckon you will do better with a blow-lamp type burner anyway.
Have you estimated how much heat you need for the boiler to generate the steam you want for the Pea to run happily? - That is the key so you can decide how much gas you need to burn - and then that dictates the jet sizes, etc.

Cheers!
K2


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## wazrus (Dec 4, 2021)

G'day, Steamchick
Fascinated by the boiler design? As far as I'm aware, the design is almost public domain and I certainly agree with your remarks about the circular firebox. What I _have _ altered, though, is the _placement_ of the boiler 'cylinders' relative to each other. That doesn't sound clear, does it? The boiler, for _coal _firing, had the barrels of the firebox and the main barrel_ almost _in line at the top, to accommodate the firegrate, below which was, of course, the ashpan. The ash space was, in my opinion, far too small and certainly too small for the high ash coal I had on hand. The steam space above the firebox was reduced. My version has pretty much 'inverted' the boiler, so the firebox 'outer' (such as it now is) centreline is considerably _above _the barrel centre line. So all I've done is simply 'roll the boiler over' and dispensed with the firebox altogether. Other than the staying, the increased material thicknesses and the gas firing arrangements (flues), nothing else has changed. It's still pretty much a Sweet Pea ((Bagnall) style boiler, with dome and my larger flue tubes running from front to backhead, through what _was_ the coal-type firebox area. So the thing is just two cylinders, silver brazed at the circular throat joint and the 38mmx3mm flues go straight through. Why not make it a simple cylinder? Good point, but I had the barrel(s) and some flanged plates, so why change at this stage? I've also gained much needed steam space and, with the addition of a dome on the larger diameter part, a drier steam collection point. Priming was a problem with the original boiler.
I like your inverted commas used with my 'venturi'. Venturis had sort of been confined, in my private pantheon, to a mysterious black art, as had burners, and no I haven't had the burner 'stick' in a flue, so I'm still in the black art area. I had very little room for a venturi of any sort and looking at the pipe reducer types, it seemed that they might be made shorter, say along the lines of a carburettor intake, with the bell shape. The outlet is probably woefully undersized. You could say that it's all not much more than guesswork and you'd be right!
But I do really appreciate your input which has thrown a little light into the black places.
Note also that my larger flue tubes in the small Pea boiler, have been reduced to two tubes. I plan to use three in the larger boiler.


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## Steamchick (Dec 4, 2021)

Thanks Wazrus. I'll do a bit go digging and find the tube sizes of a regular pea boiler. Are your tubes bigger? And what wall thickness? I'll do a few sums on your fire tubes. I really think a blowlamp burner for each tube is probably best. You get very good control of each burner with screw-down taps, so you can "idle" the boiler by turning down the fires, then "Whack 'em open" when you want to pull away with a load. Blow-lamp makers spend a lot of time and money making their burners "the best" so why try and re-invent the technology? You can buy nozzles for the cost of the brass! (I made a steel burner, but much easier to buy a scrap blowlamp for the burner!).
Cheers!
K2


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## wazrus (Dec 5, 2021)

Steamchick/K2
I must apologise for a bit of a bollocks in the 'explanation'. What isn't clear is that there are _none of the usual firetubes at all _ in my 'revised' boiler. As in Kozo Hiraoka's Pennsy switcher, there will be just two or perhaps three larger (38mmx3mm copper tube) flues, in which I plan to place the 'burners'(!). The tubes (flues) themselves, seem to be OK as regards crushing. By the 'tubes' for a 'regular' Pea boiler do you mean the small fire tubes? If so, in the original, 20 are called up, 1/2" ODx20SWG. These have been eliminated. If you mean the outer barrel/tube, it is 5" ID. The firebox outer diameter isn't shown on the drawings (pages 102 and 103 of Jack Buckler's book)) , but mine is about 7" diameter     
Note that I have not used _tube,_ but have rolled the barrels myself and they have
been jointed using Alec Farmer's version of a castellated joint. This joint was debunked by some pundits here in Oz, so I doubled up and strapped it, to be sure. All platework/barrel etc is out of 4mm copper. During dismantling, the joint let go: not the castellated, but the strap, so a friend TIG welded all the legs of the castellations and I plan to strap over that, too. I used Jack Buckler's book 'Build Your Own Steam Locomotive', which is a blow-by-blow construction manual for a 5" Sweet Pea.
I plan to install some radial staying where possible. The large flue tubes will probably get in the way, so that's a work in progress. Longitudinal staying as per the words and music, referring to the AMBSC guidelines. I hope I've made my ideas a little clearer. The burners, as you say, shouldn't be a case of re-inventing the wheel, but I have reservations about whether a blowtorch flame will be long enough to reach the 'end' of my flues and what the characteristics of that flame might be. I know it's hot: I've been experimenting and have made a long lance-type burner, with air intake holes at the 'handle' end and a large head on the other, The result is a large, bushy roaring flame, which I use on household weeds! But the flame isn't very stable and I suspect there's not enough inducted air. For the head I copied a Bulgin burner, but located the air holes remotely. maybe the holes are simply too far away from the head for stability. it tends to be 'touchy' and inclined to self extinguish. I suppose the long 'wand' might be replicated in the boiler flues.....hmmmm.....
Again, many thanks for your input.
Wazrus


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## Steamchick (Dec 5, 2021)

Thanks Wazrus, I have a better understanding of what you are doing. Using my ready-reckoner (spreadsheet for calculations) I deduce that the 38mm OD x 3 mm wall copper tubes can withstand 100psi external pressure with a factor of safety of 11. - Good in my opinion!
This means you have a 32mm hole to put a blow-lamp into. Looking at manufacturer's data, a Bullfinch blow-lamp - dia 32mm (ref 1240) generates about 8.5kW of heat. As these burners are designed to draw-in maximum air - balanced to the max. gas through the jet - they are much more stable than my home-made equivalents, and this is as big as you'll get a burner in that hole. This is a good as it gets in a flue tube. The flame will progress 2/3rds of the way down the tube if not all the way, so you should get 75% of the heat before the hot flame/exhaust goes up the lum! If you can put a simple triangular tube of Stainless wire mesh inside the tube you'll increase this by at least another 10% so you'll get 85~90% of the heat into the boiler - by my reckoning. 
3 tubes like this at 85% efficiency will be ~21kW... which should pull the skin off a rice pudding... - But only if 2 tubes with burners you will keep the safety blowing-off when in the station, but run out of puff when you reach an incline! - Can you fit 4 or 5 fire-tubes and burners in the 5" boiler tube? - You'll need 19mm of metal between each tube and from tube to outer edge of the tube plate.
The biggest problem is lighting burners. This needs a clever and reliable arrangement of spark ignition, or a means of withdrawing burners for ignition.
Have fun!
K2


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## wazrus (Dec 7, 2021)

Steamchick/K2
Many thanks for your efforts and I _do _ like the idea of not making burners or jets, especially, as you suggest, the flame should blow about 2/3 of the way down the flues. That sounds pretty well OK by me! As you say, too, your efforts (and mine) building burners etc weren't too auspicious. I have ordered a couple of 'sets' of weed burners, which comprise handle and other bits and the only items of real interest are the burner heads themselves. The only issue is that the burner 'sets' come in 30mm, 40mm and 50 mm diameters. the 30mm is the one of most appeal, of course. Not quite the 32mm, but the set is priced at $A30, so I won't quibble too much: there shouldn't be too many issues adapting the 30mm job to the 32mm flue. like you, I think, I'd rather not mess around making the things, if it can be avoided!
Medical things have intervened yet again and it may be a while until I get sufficient time in the shed, especially now that the Southern hemisphere is entering summer and the stinking heat is on the way. I do hope, too that my Australian sense of humour hasn't been mistaken for insult, in calling Cds4byu a 'cheeky bugger'. That's Australian for a sort of endearment.
Wazrus


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## Steamchick (Dec 7, 2021)

Hi Wazrus,
I have no problem making jets down to 0.25mm drill. But without the boiler for tuning against back pressure, and cooling (which all changes the combustion pressures and air fuel ratio) the burner is cheaper and easier if a proprietary item. I have bought a few second-hand blowlamps for burners, gas- taps & gas connections. Then fitted them in my own applications. But I have made my own blowlamp style burners, with the trials and tribulations of the various boiler influences on the combustion. From experience, I have even re-worked old early attempts and made better burners. So it isn't quite as easy as one hopes!
 Maybe your 30mm burner in a 32mm ID tube will leave 2mm for a wire to the spark for an igniter.? Extracted from an old cigarette lighter? For the wire, I would use flame-proof wire from a scrap electric cooker. But then making the sparky end is a problem I have not yet tackled. There may be room inside the 30mm burner - where there is more space? - to insert a piece of ceramic tube, such as from a domestic fuse, with steel or copper wire up the middle to where a spark will light the burner? This wire takes the spark from the wire off the piezzo igniter. Bit of design thought needed.... Over too you?
K2


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## Steamchick (Dec 8, 2021)

I could use some of your Stinking Heat. 22 deg. C in summer - MAX. now 5 deg. C but feeling sub-zero. We may even get down to -2deg.C this winter if it is very cold... We have had snow for 2 days already this winter, but the roses and chrysanthemums are till in flower. The cold killed the dahlias though... Some spring plants are starting through... - they will die if we do get a week of freezing weather.. No wonder we Brits complain about the weather all the time!
K2


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