New Guy from Wis

[bug_hunter]

We may need to move this to Boilers questions and answers forum?

I concur. Once I am well along on the engine, I will start a post on that forum. Thanks for all the insight.

Greg

 

[Richard Carlstedt]

Welcome Bug-hunter
Are you close to Green Bay ?

Rich

 

[bug_hunter]

Are you close to Green Bay ?

Milwaukeeish!

 

[wce4]

I concur. Once I am well along on the engine, I will start a post on that forum. Thanks for all the insight.

Greg

Glad to be of assistance. looking forward to see your first engine.

 

[Steamchick]

Just a comment on the PM Research boilers. They say they provide "Silver Solder and flux" with their kits. I assume this means high temperature silver solder and flux - that works around 630~650 degrees C for the lowest melting point SILVER SOLDERS that I have seen listed. Maybe I m missing something here, but they do not state the Normal Working pressure for their boilers... and supply a Safety relief valve but no pressure gauge. I GUESS these are for less than about 15psi use (domestic pressure cookers and coffee machines work below this pressure to minimise pressure vessel legislation - I think?).
Toy boilers and engines in the UK work at such low pressures.
But I should advise that (IMHO) ONLY high temperature Silver solders should be used for any boiler over 15 psi, as the "soft" solders containing tin lose too much strength at the temperature of steam at 15psi.
K2

 

[Steamchick]

Wig-Wag engine. A proprietary name for a Single Acting Oscillating engine.
Now I understand.
First guess is that a 2 inch diameter spirit fired horizontal boiler, about 6 inches long will suffice, running less than 15psi.
I need to spend a half-hour doing sums though... (later?).
K2

 

[wce4]

Just a comment on the PM Research boilers. They say they provide "Silver Solder and flux" with their kits. I assume this means high temperature silver solder and flux - that works around 630~650 degrees C for the lowest melting point SILVER SOLDERS that I have seen listed. Maybe I m missing something here, but they do not state the Normal Working pressure for their boilers... and supply a Safety relief valve but no pressure gauge. I GUESS these are for less than about 15psi use (domestic pressure cookers and coffee machines work below this pressure to minimise pressure vessel legislation - I think?).
Toy boilers and engines in the UK work at such low pressures.
But I should advise that (IMHO) ONLY high temperature Silver solders should be used for any boiler over 15 psi, as the "soft" solders containing tin lose too much strength at the temperature of steam at 15psi.
K2

"Maybe I m missing something here, but they do not state the Normal Working pressure for their boilers..."

On PM site: Saftey Valve SV-1 use a stainless steel ball and spring in a brass body. They are set to blow at approximately 60psi. Threaded 5/16-27 Female (1/16 NPT).

""Silver Solder and flux" with their kits. I assume this means high temperature silver solder and flux - that works around 630~650 degrees C"
You know what they say about assuming.
"one should not make assumptions because they may turn out to be wrong and make those involved appear foolish"

Product Description​

1 ounce of 4% silver-tin alloy solder and flux. Excellent on copper, brass, bronze, and stainless steel. Melting point 430°F. (430 deg F = 221. 111 deg C) This is the solder we provide in our model boiler kits.
Please visit there site here for more info!
https://pmmodelengines.com/solder-flux/

"Toy boilers and engines in the UK work at such low pressures."
"Any suggestions for reasonable priced silver solder/flux domestically would also be appreciated."'
He lives on other side of the pond Wisconsin USA.
"But I should advise that (IMHO) ONLY high temperature Silver solders should be used for any boiler over 15 psi, as the "soft" solders containing tin lose too much strength at the temperature of steam at 15psi. "

I have personally built PM Research boiler #1 back in 2000 and PM Research boiler #2 in 2008 and to this date they have not failed. (hydrostatic tested each year to a pressure of 120 psi / 8.27371 bar steamed at 50 psi / 3.44738 bar ) # 1 boiler is 23 years old # 2 is 15 years old.
No problems as of today's date.
They have been selling these kits for years, As to date I have not heard or read about any of there boilers failing do to the Silver Solder and flux supplied with the boiler kits.
PM Research, Inc. has been doing business since 1973

I'm wondering if anyone on here have any problems with PM Research 4% silver-tin alloy solder and flux. on their boilers.

The term "Silver Solder" means two different things on either sides of the big pond.
In the UK Silver Solder means joining metals together using a Silver (Ag) based metal, a borax based flux and high temperature flame. AKA "Hard Solder".

Here in the USA term applies to joining metals together using a low temperature flame. AKA (UK) term "Soft Solder"

Hard Solder / Silver Solder UK = Brazing in USA (IMHO)

 

[Schutzie]

...
Add on question: When performing a hydrostatic test on the boiler, where might I find a small, manual pump to generate the required 120-180 psi? More of a do-it-yourself kind of guy, so the $75-$100 test kits on Ebay don't really interest me.

I made one from a motorcycle brake master cylinder. I added a check valve at the boiler. Works great!

 

[wce4]

I made one from a motorcycle brake master cylinder. I added a check valve at the boiler. Works great!

Good Idea I had never thought of that one. I have to give it a try.

 

[Steamchick]

I am aware that ASME Regulations for copper boilers only permit Silver soldered assemblies. I was not aware of 4% silver tin with this low temperature being permitted. I know lead has been banned... so maybe this Ar-Sn alloy is the alternative?
For a Pressure relief at 60 psi the design NWP must be 58psi.? (ASME State pressure relief must prevent over-pressure of 4%).
So the solder must still be strong at the temperature of steam at 60psi. (I thought tin solders were only good for 15psi. But not permitted at all in USA, for ASME Regulations?).
Thankyou for the advice.
I shall stick to high temp silver solders for my boilers, as I know they meet National Regs and Standards. (UK).
K2

 

[wce4]

"I know lead has been banned..."
The 1986 Safe Drinking Water Act Lead Ban required the use of “lead-free” pipe, solder, and flux in the installation or repair of any public water system or any plumbing in a residential or non-residential facility providing water for human consumption.

Steam at 15psi is around 249 deg F.
Steam at 60psi is around 307 deg F.
See attach steam table file

"For a Pressure relief at 60 psi the design NWP must be 58psi.? (ASME State pressure relief must prevent over-pressure of 4%)."

I have personally built PM Research boiler #1 back in 2000 and PM Research boiler #2 in 2008 and to this date they have not failed. (hydrostatic tested each year to a pressure of 120 psi / 8.27371 bar steamed at 50 psi / 3.44738 bar )

ASME Code is not considered law, it was established by manufacturer of the product. It is one of several recognized Codes and Standards that provide requirements for design and fabrication of boilers and pressure vessels for safe operation. If a design code is adopted within a Jurisdiction or municipality then it becomes a law.

"I shall stick to high temp silver solders for my boilers"
It is better to be safe than sorry .

 

[Richard Carlstedt]

Not sure of what solder they PM use or offer, but suspect it is a Stay Brite Product ? ( No Lead)
Rich

https://ch-delivery.lincolnelectric...t/e521e75f45b741e58940da1988c2976d?v=a156575a

 

[Steamchick]

In the UK, I can't get a boiler tested with any "soft solder" (low temperature alloy).
60/40 electrical solder is quoted as:
60-40 Soft Solder (60 Sn-40Pb) - ASTM B 32 Grade Sn60

Tensile Strength

12.4 MPa @Temperature 150 °C

1800 psi @Temperature 302 °F

30.9 MPa @Temperature 100 °C

4480 psi @Temperature 212 °F

Just found "4% Silver-tin" solder. (Harris do not quote the tensile strength). I found this Technical Data Sheet from Canfield: 96% TIN/4% SILVER
Canfield’s 96/4 solder is cadmium free and lead free. This alloy has a bright finish, is a perfect colour match to stainless steel, and meets high strength requirements.
TECHNICAL DATA:
Temperature Range:
430deg.F. (Solid to Liquid)
Shear Strength: 11,200 PSI (Room Temperature)
Tensile Strength: 15,000 PS (Room Temperature)

Not found it in the UK though... Any idea of tensile strength at 367deg. F? - Assuming metal can get 60deg.F above the Steam temp of 307deg.F at 60psi?
Another:
Kapp product is quoted with a tensile strength of 14000psi... and:
Applications

• Hand soldering Copper wires and tabs when the application could require more time to position the item being soldered
• Electrical and electronic applications
• Applying thin Copper and Stainless Steel wires to circuit boards
• Typical uses include:
• Electronics
• Fabrication
• Ducting
• Food containers
• Storage bins
• Instruments
• Copper plumbing pipe
• Cooling coils for refrigerators
• Paired with Kapp Comet™ Flux

It does NOT mention any application like the temperature of the steam boiler. The nearest may be "copper plumbing pipe" - the hottest may be 212deg. F? (Not stated, so who knows?).
But then one hopes (expects) that there is a proper Engineer at PM Research that warrants the boilers with this solder, for 60psi (307deg.F. steam temperature).
The thing I like about ASME... is that it is recommendations from scientists and Engineers. Not politicians. (as far as I know?). So if it works for them, it should be safe for me.
On this site, or any other public forum, it would be wrong for me to propose, condone or say anything that is below the standards I know to be "safe". Hence I quote ASME. If I am wrong there are plenty to correct me.
In the UK I am not bound by ASME, but just the laws of physics and BS. (That is the "British Standards" - not the "Brown Smelly" BS...).
Thanks,
K2

 

[Steamchick]

Just checked my 2015 copy of ASME... (may be out-of date? - Can anyone correct this?).
It describes brazing for boilers as:
"Definition of Brazing. A group of welding
processes that produces coalescence of materials by heating them to the brazing temperature in the presence of a filler metal having liquidus above 840°F (450°C) and below the solidus of the base metal."
It doesn't include the silver with 4% tin as per the PM Solder.
But I am sure PM are allowed to sell anything. I just can't use it in the UK on boilers that need insurance, because I display in public places. I guess the same applies in the US? - if you want a boiler certified (for insurance and/or public display?). Do PM provide some information for certification inspectors?
I am only curious, because I have been told I can't use it to make boilers for certification, by my inspector. I don't think I shall even try to change his rules!
K2

 

[Steamchick]

Hi again.
Just threw some numbers into my spreadsheet for boiler material/design strength to ASME.
(I know a lot of you Pooh-poo ASME. - please bear with me a moment - or ignore me and find something you like).
First: WCE4 has come up with some nice (simple?) designs.
But my analysis has found a couple of issues.

• The 2 inch dia horizontal boiler is a nice simple design - I guess it could be quite adequate for the Wig-Wag engine, just free-running, or maybe a tiny dynamo and LED? The drawing states 30psi working pressure, 60psi max pressure. Regulations vary, but the designed working pressure (NWP) should have a safety relief valve set at anything from 104% (ASME) to 110% (BS) of NWP. So I should set the relief at 32psi - or something.
• This 2 in boiler, says it has a max pressure of 60psi. Good idea. I used a graph developed from ASME to judge the end plate and boiler stay design. For the stated end plate thickness of 18 gauge, I reckon it is OK for 50psi, but not 60psi. If you need 60psi the end plate should be 16gauge.. But if you reset the Safety relief to anything below 55psi 18SWG end plates are OK... But that is just my interpretation of ASME...
• If you want to make a bigger more powerful boiler, to suit the next engine(s), then the 3 inch vertical boiler by Sandy C, Argyll (drawn by A.F. Campbell) is a better job. But personally I would not make a boiler with cross tubes in the flue. I found a similar design of horizontal boiler with many failures, as the user had been driving a boat with the boiler (and engine) and needed higher pressure than the cross-tube design could take.. There had been many repairs (very difficult with this design) and when I did some sums that explained the failures. The "45psi" boiler would fail at that, due to the large tube being in compression from boiler pressure. The stress concentration at the cross tubes caused at least 5 repairs in 8 cross tubes! So I suggest a different design without cross-tubes. They are OK and reliable if you don't work the boiler hard, as the cross-tube to flue joints are by far the weakest link. I estimate the SAFE (max) working pressure of this arrangement on the drawing to be around 30psi, not 90psi as stated on the drawing. At 30 psi you have a Factor of safety of just over 8, whereas at 90psi it is only 2.1!! Barely enough not to fail at an hydraulic test. Or at least that is what the sums tell me.. I suspect that Messrs Campbell and Sandy C have calculated shell pressures, but not considered the flue tube, with stress concentrations at cross-tubes. I am not saying the 3in. vertical boiler WILL fail at 90psi, but do you want to risk spoiling all that work in making something that is of high risk of failing? - Incidentally, looking at the burner, I have a 3in. vertical boiler, that just makes 45psi with no steam demand with a 2 3/4in ceramic burner. With a 2in diameter burner you may not make 30psi, especially when you demand steam from the boiler.

I suggest a different design of Horizontal boiler, so you can have double the size of ceramic burner beneath the boiler.
This one is a good boiler to make, and with a ceramic the full length of the underside is a good steamer!
K2

 

[wce4]

In the UK, I can't get a boiler tested with any "soft solder" (low temperature alloy).
60/40 electrical solder is quoted as:
60-40 Soft Solder (60 Sn-40Pb) - ASTM B 32 Grade Sn60

Tensile Strength

12.4 MPa @Temperature 150 °C

1800 psi @Temperature 302 °F

30.9 MPa @Temperature 100 °C

4480 psi @Temperature 212 °F

Just found "4% Silver-tin" solder. (Harris do not quote the tensile strength). I found this Technical Data Sheet from Canfield: 96% TIN/4% SILVER
Canfield’s 96/4 solder is cadmium free and lead free. This alloy has a bright finish, is a perfect colour match to stainless steel, and meets high strength requirements.
TECHNICAL DATA:
Temperature Range:
430deg.F. (Solid to Liquid)
Shear Strength: 11,200 PSI (Room Temperature)
Tensile Strength: 15,000 PS (Room Temperature)

Not found it in the UK though... Any idea of tensile strength at 367deg. F? - Assuming metal can get 60deg.F above the Steam temp of 307deg.F at 60psi?
Another:
Kapp product is quoted with a tensile strength of 14000psi... and:
Applications

• Hand soldering Copper wires and tabs when the application could require more time to position the item being soldered
• Electrical and electronic applications
• Applying thin Copper and Stainless Steel wires to circuit boards
• Typical uses include:
• Electronics
• Fabrication
• Ducting
• Food containers
• Storage bins
• Instruments
• Copper plumbing pipe
• Cooling coils for refrigerators
• Paired with Kapp Comet™ Flux

It does NOT mention any application like the temperature of the steam boiler. The nearest may be "copper plumbing pipe" - the hottest may be 212deg. F? (Not stated, so who knows?).
But then one hopes (expects) that there is a proper Engineer at PM Research that warrants the boilers with this solder, for 60psi (307deg.F. steam temperature).
The thing I like about ASME... is that it is recommendations from scientists and Engineers. Not politicians. (as far as I know?). So if it works for them, it should be safe for me.
On this site, or any other public forum, it would be wrong for me to propose, condone or say anything that is below the standards I know to be "safe". Hence I quote ASME. If I am wrong there are plenty to correct me.
In the UK I am not bound by ASME, but just the laws of physics and BS. (That is the "British Standards" - not the "Brown Smelly" BS...).
Thanks,
K2

"How to make a mountain out of a molehill." ask K2 aka Steamchick

#1 OP Does not live in the uk!
#2 OP Did not state or give any hint he was going to use boiler in the uk!
#3 uk laws are not binding here in the USA!
#4 Here in the USA each state has a design code or regulations that is adopted within a Jurisdiction or municipality that it lies in. Not the uk or ASME.
#5 Here in the USA A code tells you what you need to do, and a standard tells you how to do it.
#6 A state boiler inspector can only legally enforce what the code law says and that law may be more stringent or less stringent than the ASME.
#7 Is ASME a code or standard?
ASME is the leading international developer of codes and standards, here after referred to as standards, associated with the art, science, and practice of mechanical engineering. ASME cannot force any manufacturer, inspector, or installer to follow ASME standards. Their use is voluntary. Standards become mandatory when they have been incorporated into a business contract or incorporated into regulations by local or state authorities who have jurisdiction over.
Bottom line When in doubt contact your local building code department not someone who is pretentious !!!
In most cases, state and local governments here in the USA have exemption for model steam boilers under a given size.
**** OP please do not be put off by someone with a doctorate degree in ? ****
We learn by asking ,receiving a reply in the simplest way one can, not in a ^confusion book like way to answer the OP simple question
"I am looking for some guidelines and plans for a small model steam boiler for the Wig Wag."

I may be wrong and if I am, I stand corrected and apologize ( Administrator If I am wrong please remove this post and inform me) but I do not think the op request for "some guidelines" means a course in uk and or asme standards and specifications.
But a simple guide on how and where to start in this fine HOBBY and not how to be scared away with non existence codes in the USA.

Quote from Dan Rowe on Model Engine Maker Forum (Apr 17, 2019) :
"As far as I know the only countries to have a Model Boiler Code is the UK and Australia.
I actually hope that some one can prove that statement wrong." (As far as I know to this date no one has)
"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."

Reply from PM Research about their 4% silver-tin alloy solder and flux used with their boilers.

 

[Steamchick]

Hi wce4.
Sorry if I have upset you, that was not my intention. Take a big breath, remind yourself that I am "just ----- who doesn't know what you are about", and lets's discuss this calmly.
I was hoping this alloy was something with enough silver that I could use it on a boiler that needs a modification, before my Boiler Test Engineer will test it for certification. (His requirement is simply "Silver Solder). So I was looking for something from various manufacturers of this solder in case someone stated "OK at 200C" or "tensile strength at 150C" or Max. temp (whatever)...", or something?
But only to have a boiler maker say he has "not had a problem in the US" did not fit what I need, as I am in the UK. Actual technical data would have been good (internationally recognised). But there doesn't seem to be any readily available so I'll just have to use the big Blowlamp and use my regular Silver solder at around 650C to make the mods.
Once again, Sorry I upset you.
K2

 

[wce4]

Hi wce4.
Sorry if I have upset you, that was not my intention. Take a big breath, remind yourself that I am "just ----- who doesn't know what you are about", and lets's discuss this calmly.
I was hoping this alloy was something with enough silver that I could use it on a boiler that needs a modification, before my Boiler Test Engineer will test it for certification. (His requirement is simply "Silver Solder). So I was looking for something from various manufacturers of this solder in case someone stated "OK at 200C" or "tensile strength at 150C" or Max. temp (whatever)...", or something?
But only to have a boiler maker say he has "not had a problem in the US" did not fit what I need, as I am in the UK. Actual technical data would have been good (internationally recognised). But there doesn't seem to be any readily available so I'll just have to use the big Blowlamp and use my regular Silver solder at around 650C to make the mods.
Once again, Sorry I upset you.
K2

"Sorry if I have upset you, that was not my intention."
I agree it was not your intention. Your intention is to prove
you are a pretentious person. In my humble opinion you have.

"I was hoping this alloy was something with enough silver that I
could use it on a boiler that needs a modification, before my Boiler
Test Engineer will test it for certification."

Then one would simple ask one for a cut sheet / data sheet of said product.
Not give a course on UK and ASME standards.

example: That product sounds interesting I am wondering if the product would fit my needs. Do you have more information / data that I can review.
Not:
In the UK, I can't get a boiler tested with any "soft solder" (low temperature alloy).
60/40 electrical solder is quoted as:
60-40 Soft Solder (60 Sn-40Pb) - ASTM B 32 Grade Sn60 ................

What does that have to do with OP questions?

Well that's my two cents worth have a good day. Sorry if I ruffle a few feathers. but I am tired of seeing people turn away from the hobby because some have to drown newcomers in technical mumble jumble to prove/scare there point across.

Oh well no harm no foul all good here have a safe and happy hobby day, week, year. Time to move on.

Edit: Read GreenTwin Reply below he gets to the point without all technical mumble jumble.

 

[GreenTwin]

Boiler threads are some of the most contentious posts that I have ever seen.

I recall some very high spirited boiler posts in the past.

There does not seem to be much middle ground in thoughts about boilers and boiler safety.

I don't think soft solder should be used on any boiler, just because if you are not paying attention, and let the water level get a bit low, then the boiler will fail. I have personally failed a boiler this way and almost been blinded.

My dad built boilers; I have built boilers, and I plan on building more boilers.
I won't discuss how I build or have built them, other than to say I felt comfortable with operating them at 100 psi and less.

The biggest problem I am aware of is corrosion on the end plates of steel boilers, and that is a very real problem that can fail a boiler over time.

I saw someone decide to build a boiler from stainless steel, and I have seen enough information to convince me that a stainless boiler should not be built.

Silver-soldered boilers (with high-temp silver solder) seem to be the norm for many, with copper construction.
The problem with silver soldered boilers is getting all the joints perfect, and getting one joint done without affecting a nearby joint.
I have seen folks online totally botch the silver soldering process on small copper boilers.
I am good at silver soldering copper, but at this point I would not attempt to silver solder a copper boiler.
One of the problems I have seen is you can overheat the flux on an adjacent joint, and thus one joint is good, and the adjacent joint is not because the flux overheated and burned away. High-temperature flux helps with this.

I saw a steam bike with a boiler that operated at 1,200 psi, and the water tubes were square on the end.
Extremely scary build, and not safe by any measure to use flat ends on piping or anything that is not well supported, especially in a high pressure boiler.
I don't think any hobby boiler should operate around the general public at more than 100 psi, and I would personally not operate a hobby boiler above 50 psi.

I have seen TIG welded copper boilers, and I know that is a viable method if done correctly, with a TIG machine that had sufficient current to overcome the heat dissipation of the copper.

I have seem much discussion about using a safety valve with enough area to relieve a boiler that is in an overpressure condition.
This is very important.

I have seen safe boiler builds that were copied by other in an extremely unsafe way, with no safety valve, and no water sight gauge.
That is why I don't post boiler designs online.

And I have seen posts of certified fire tube boilers, and they have very thick end plates, some very careful welding, and the correct fittings in all places.

And laws about boilers in general, and boilers at engine shows, vary by country, and by state.

And I know of folks being killed by steam tractor boilers exploding at shows, and thus the push to tighten up on safety of boilers, especially old boilers that may have hidden internal corrosion.

I get the safety aspect of it, and so in general, I would recommend that if you build a boiler, stay within your skill level, and stick with a design that is used by others and proven to be an effective and safe design.

One of the better boiler references I have found is The Steamboating Forum, where they build full size boilers of all types, and use them to power boats.
They have a lot of experience about which boilers work well, and which don't, and they can explain what works well over time, and what does not.

I have built fire-tube boilers in the past, but I am looking at a Yarrow-style boiler with coiled copper tubes, and this seems to be a pretty cost effective way to build a boiler. I have seen this style in use on a steamboat, and so I know it is a viable boiler if the right design is used.

Good luck to all, and be safe.

Edit:
And one last note, if you operate a boiler at a public show, you should be especially cautious about the design, and the operation, since this involves not only your safety, but the safety of those nearby attending the show.

 

[wce4]

Boiler threads are some of the most contentious posts that I have ever seen.

I recall some very high spirited boiler posts in the past.

There does not seem to be much middle ground in thoughts about boilers and boiler safety.

I don't think soft solder should be used on any boiler, just because if you are not paying attention, and let the water level get a bit low, then the boiler will fail. I have personally failed a boiler this way and almost been blinded.

My dad built boilers; I have built boilers, and I plan on building more boilers.
I won't discuss how I build or have built them, other than to say I felt comfortable with operating them at 100 psi and less.

The biggest problem I am aware of is corrosion on the end plates, and that is a very real problem that can fail a boiler over time.

I saw someone decide to build a boiler from stainless steel, and I have seen enough information to convince me that a stainless boiler should not be built.

Silver-soldered boilers (with high-temp silver solder) seem to be the norm for many, with copper construction.
The problem with silver soldered boilers is getting all the joints perfect, and getting one joint done without affecting a nearby joint.
I have seen folks online totally botch the silver soldering process on small copper boilers.

I saw a steam bike with a boiler that operated at 1,200 psi, and the water tubes were square on the end.
Extremely scary build, and not safe by any measure to use flat ends on piping or anything that is not well supported, especially in a high pressure boiler.
I don't think any hobby boiler should operate around the general public at more than 100 psi, and I would personally not operate a hobby boiler above 50 psi.

I have seen TIG welded copper boilers, and I know that is a viable method if done correctly, with a TIG machine that had sufficient current to overcome the heat dissipation of the copper.

I have seem much discussion about using a safety valve with enough area to relieve a boiler that is in an overpressure condition.
This is very important.

I have seen safe boiler builds that were copied by other in an extremely unsafe way, with no safety valve, and no water sight gauge.
That is why I don't post boiler designs online.

And I have seen posts of certified fire tube boilers, and they have very thick end plates, some very careful welding, and the correct fittings in all places.

And laws about boilers in general, and boilers at engine shows, vary by country, and by state.

And I know of folks being killed by steam tractor boilers exploding at shows, and thus the push to tighten up on safety of boilers, especially old boilers that may have hidden internal corrosion.

I get the safety aspect of it, and so in general, I would recommend that if you build a boiler, stay within your skill level, and stick with a design that is used by others and proven to be an effective and safe design.

One of the better boiler references I have found is The Steamboating Forum, where they build full size boilers of all types, and use them to power boats.
They have a lot of experience about which boilers work well, and which don't, and they can explain what works well over time, and what does not.

Good luck to all, and be safe.

.

For myself and plus I have the equipment, I now TIG welded my copper boilers. But my first and second boiler I used PM Research 4%, still holding strong, still do a hydo test every year tho. Better to be safe than sorry.
A good book to read in my opinion is model boilers and boilermaking by Karl Noble Harris and making small gas-fired boilers for steam models by Alex Weiss