Over the past nine years that my son, Steve, and I have taken our steam traction engines to shows, we have spoken with many people about the new boilers we've built and installed in our tractors.
The September/October 2003 issue of Steam Traction carried my article 'Steaming Through Life,' in which I discussed my history in steam and my current steam projects, including building new boilers. We have received some really great feedback from that article, including many questions about making new boilers.
Looking back at the most commonly asked questions, there appear to be some myths and misconceptions about boiler facts. Possibly this is a result of information being passed down through generations of collectors, and of course there's the fact that standards have changed since most of our boilers were originally built. Manufacturing methods and materials have evolved a great deal since the days when everyone drove Model Ts.
I am retired, and I no longer build boilers or have any affiliation with any boiler shop. Even so, I'm often asked to recommend a good boiler shop, a question whose answer I can certainly appreciate. I would instead, however, like to give some sound information and facts to help people make their own decisions about who they hire to build a boiler.
The following information is documented in the American Society of Mechanical Engineers (ASME) Power Boilers Manual, a publication every certified boiler shop has to follow. Additionally, much of this follows the normal manufacturing standards, practices and requirements imposed by New York State Board of Labor Boiler Inspectors. For many readers this will be a very dry article, but if you are thinking of having a new boiler made, the information could be very beneficial.
A 60 HP Reeves engine and gearing assembly mounted on a partially completed boiler shell. This initial fitting was done to ensure that necessary studs were properly located and capped on the inside and to ensure that all the major parts and gearing were properly located and meshing correctly.
THIRTEEN STEPS TO A NEW BOILER
1. Contact your state boiler inspector. It is in your best interest to keep your inspector informed of your intentions before you do anything. Keep your inspector on your good side by keeping him up to date. Let him look everything over before you start calling him when the work is complete is the wrong approach. An inspector will not want to pass something without knowing what went into it.
2. The boiler has to be built to the latest ASME codes and have an 'S' stamp. For manufacture in New York State, it must also be stamped and registered with a national board number, check with your state inspector.
3. Thoroughly research the manufacturer or fabricator. Talk to someone who has had a boiler built by this company and see if they are happy with the results. See the work shop if possible and study their craftsmanship. Most manufacturers will allow this, as they want you to be happy with the finished product and send more work their way.
4. Make sure you have a signed, written contract stating all work to be done and the manner in which it should be completed. Your contract should mandate that you receive a copy of the boiler prints, proof of x-ray of the longitudinal seam of the barrel, heat treatment charts and the manufacturer data report. Having a boiler built is not like buying a car where everything is cut and dry. Cars are mass-produced: one is the same as the next, you know what you're buying. With a custom-manufactured boiler, the only proof you'll have is documentation.
5. The ballpark price for a mid-size boiler (60 HP steam tractor) should be around $25,000 to $30,000. If you get a quote much lower than this, there is most likely some corner-cutting involved and it could come back to haunt you later.
6. If a manufacturer claims they could save you money with a boiler they already made that will fit your tractor be suspicious, as this is highly unlikely. No two boilers were made the same: each one was individually handcrafted.
Contracted crews that worked side by side in the assembly bay in the factory built most traction engines. Each crew would start with a boiler from the boiler department and obtain all the partially finished parts from the machine shop, custom fitting, grinding and drilling the parts to fit the particular boiler they were working on. Mounting studs and pad locations were all unique. Each crew would come up with their own practices, resulting in minor differences between finished boilers.
You are now faced with the opposite task. You have all the finished parts already drilled and shaped. Now you need to make a boiler to fit those parts. For some designs this is not as bad as others. If you have a boiler that is frame mounted, like a Frick, you will only have to mate up a few key points. On the other hand, when we fitted our Minneapolis there were 150 taped studs that held the saddles and mounts onto the boiler. Every one of the mounting studs has to be capped or have a backing plate. If using straight thread studs, the holes cannot go all the way through into the boiler.
7. Do not buy a boiler that is stamped too much over the working pressure of the original engine. The boiler may be new, but the engine castings are still 80-year-old cast iron. A boiler made with modern materials to the design of the original boiler could possibly be manufactured and stamped for over 250 psi, and someone could then put a 250-psi safety valve on the boiler. The 'D' valve and piston were not designed for this much pressure and could blow apart. Another problem is the water-feed injectors will not function properly at this high a pressure.
8. Some manufacturers use pipe couplings and plugs for inspection openings and others use hand-hole covers. Both methods are acceptable, and both have their advantages and disadvantages.
Couplings and plugs are less expensive to install initially, and they don't require gasket replacement every year. The downside is that the threads will not last and eventually the couplings will have to be replaced. Further, the hole is smaller than a standard hand hole, making cleaning and inspection much more difficult.
Hand-hole covers are more difficult to install, they require gaskets that need periodic replacement, and there is always the chance of a gasket blowout. Code section PFT-43.4 calls for there to be seven inspection openings in locomotive fire-tube boilers: One in the rear head (smoke box) below the tubes; four in the lower corners of the water leg; one near the throat sheet (when possible); one in the front head (firebox end) at the line of the top of the crown sheet; and one in the shell (barrel).
9. One of the issues we questioned consultants and inspectors on was water feed inlets. Code section PG-61 states that if the feed supply is interrupted one such means of feeding water shall not be susceptible to the same interruption as the other, and each shall provide sufficient water to prevent damage to the boiler. I was assured that this meant two completely separate feed lines all the way into the boiler. Many original boilers have two feed lines that go into one inlet. This is no longer acceptable.
10. A vital issue with the boiler is the water level in the boiler in relationship to the gauge glass. Code section PG-60.1 states that the lowest visible part of the water gauge glass shall be at least two inches above the lowest permissible boiler water level, as determined by the boiler manufacturer.
11. Another important issue is to ensure there is a suitable, new, ASME-stamped fusible plug fitted at the highest point of the crown sheet. While you are looking at the fusible plug, take a good look around the firebox at the stays. Code section PW-19 states that the ends of the stays inserted through the sheet shall not project more than 3/8-inch beyond surfaces exposed to combustion. This is because stays can, over time, burn. Also, look at how the fire bars are going to be hung and the ash pan mounted. Will they be able to be removed in a practical manner for cleaning and inspection of the firebox?
12. Those of you wishing to preserve the original look of your boiler by riveting sections together should keep in mind that riveting has been excluded from the codebooks since 1971. Many inspectors view riveting as an obsolete practice, and any rivet work that is done has to follow the 1971 code. A good number of mechanical engineers and inspectors have been born after 1971.
13. When installing a new boiler the most underestimated job is refitting all the pipe work and accessories. Although the price tag for this part of the project varies from state to state, it can cost up to $3,000. In New York, everything has to be installed using schedule 80 pipe, and everything has to be rated for at least 1-1/2 times the Maximum Allowable Working Pressure (MAWP). Our boilers have a MAWP of 175 psi, which meant all of our valves, checks, gauges and fittings had to be rated for a minimum of 300 psi. Some expensive valves such as the main steam shut off, blow down and safety valve have to be purchased new. A new set of fire bars will probably have to be custom cast. Sandblasting and painting is going to be a time-consuming and costly item, and there are always parts that need to be built up and repaired.
IN THE END
While the foregoing discussion doesn't cover all the issues surrounding the manufacture of a boiler, the points I've addressed answer commonly asked questions. Getting a boiler made is not something to just jump into, as there are many issues to be considered. Be that as it may, the more informed you are, the more successful you will be in getting a good, new boiler made, which, of course, is the whole point.
The ASME and the 'S' Stamp
The American Society of Mechanical Engineers traces its roots back to 1880 when it was established to encourage uniformity in shop drawing symbols, pulleys and other mechanical elements used in manufacturing.
The ASME's Boiler and Pressure Vessel Code was first written in 1914 and has since been adopted by 49 states and Canada. Only South Carolina has yet to officially adopt the ASME code.
ASME certification stamps contain a letter (and in some cases an attendant number) categorizing the specific certification. The stamps are a stylized four-leaf clover with the letter (and number) contained within the clover's borders.
For owners and operators of historic boilers, the most commonly referenced ASME stamp is the 'S' Under ASME code, power boilers generating over 15-psi steam, 160-psi water and temperature exceeding 250 degrees F are required to carry the ASME's 'S' stamp.
Contact steam enthusiast Brian Harris at: 3939 Upper Mountain Road, Sanborn, NY 14132-9119.