I didn't want to hijack the fundraising thread, but a post caught my eye so I have started a new thread to discuss these boilers. First the quote:



As has been reported on RYPN, the ASME Code, Section I as of the 2015 Edition contains Part PL, Requirements for Locomotive Boilers and as of the 2013 Edition has a modernized version of Part PR, Requirements for Boilers Fabricated by Riveting. I think it would be very useful, if those involved in the WW & F boilers are willing, to share how the rules in the two Parts are applied to these projects.

For example: Paragraph PR-2 deals with who has responsibility for riveters. Under certain conditions, Code shops can use riveters that are not in their employ as long as the quality control program of the Code shop addresses administrative and technical responsibility for the rivet work done. This would allow volunteers the Code shop deems capable of doing some of the rivet work.

I am not aware of any all riveted or partially riveted boilers built under the newest Code. It would be fascinating to see how an experienced Code shop interprets the new and modernized sections.

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Look towards the traction engine people. It is being done, and done well, with "S" stamp. Maybe not "L" stamp, but same animal. "R" stamp repairs w/rivets, too......

Over the years I have come to admire many who work in the industry. Kelly, Rick and Linn at the Burg as well as Paul in California for the work that they have done. My list of those I admire goes on and on....

As one who also builds boilers in the industry, I want to make a comment in response to Paul's original post and the general question that is being asked. In general the question is; "Will we ever see a FULLY riveted new boiler?"

It is clearly possible and legal and I recall one of the ASME meetings where the subject was discussed. If a group wants a "pure" no variation replica of what they have and money is of zero concern, I believe that yes, one day we will see a full riveted, zero variation new all riveted boiler.

The flip side is, like Kelly has shown and as we have done at Wasatch, I believe that most common will be the hybrid partial rivets partial welded boiler. What is under the jacket really need not be 100% original seamed boiler as generally nobody will ever see it. Beyond that, I believe that the preparation of a riveted seamed shell with rivets at every course is far more labor hours than prepping the shell with a V-groove and welding it. Even considering the x-ray time and post weld heat treatment, I still believe that there is great efficiency in welding the long seams and the circumferential seams.

Even if somebody came to us tomorrow and said, "We want as many rivets as possible," I would make a strong push for welding under the jacket and rivets where people can see it. Mechanically and from an engineering standpoint, clearly both have merit and both can be used. I really think the end result on any new boiler will come down to dollars and efficiency.

I believe that this discussion becomes more and more relevant each day. The reality is; boilers have a defined life span as do most mechanical items and boiler change outs are going to become more and more common and more and more cost effective.

The largest economic constraint in building an all riveted boiler is the cost of the labor. The man hours it takes to form the plate, drill and ream the rivet holes and drive the rivets is extremely high compared to all welded construction. I think this is the crux of John's point above, it's just not an economically viable method of construction. But what if you are a museum with a pool of talented volunteers willing to do the work under the supervision of a Code shop willing to take responsibility for the work? Well then it starts to make sense. Especially if it is important to the mission of the museum to incorporate the methods of construction used during the time period represented by the museum's collection. The modernized Part PR allows this type of cooperation to exist.

Moving on to other aspects of riveted construction, there are some other things to bare in mind. The factor of safety for riveted construction is 5, not 4 as the FRA requires or the ASME minimum of 3.5. If you look at the formulas in Part PR where S is a variable, the formulas require that S (the allowable stress found in the tables in Section II of the Code) be multiplied by .7. So if you want an ASME Code riveted boiler, even if it's in FRA service, the factor of safety is 5.

Lap seams are no longer allowed for any long seams in a boiler except for sheets supported by stays such as wrapper sheets or the long seam in a dome less than 24" diameter. In the case of a dome with a lap seam, the factor of safety for the seam increases to 8.

Thanks Paul - for clarity, the riveted FS of 5 - this is for new builds and not retroactively applied to existing old school riveted boilers isn't it? It would seem to run counter to current FRA FS regulations if I'm understanding it correctly otherwise. Of course, this applies to old locomotives in FRA regulated service only....... insular might be a different story.

This is for any riveted construction in an ASME Code boiler built to the 2013 Edition or later. Yes, this is for new construction only. It is also important to remember it only affects the riveted part of the boiler. If you wanted, for example, to weld a nozzle to the shell you could use a factor of safety of 4 for a boiler in FRA service or built to Part PL of the 2015 Edition or a factor of safety of 3.5 for other types of boilers built to the ASME Code.

So if a group was to be rebuilding a locomotive, and it needed a new boiler, would it be substantially less money to just have it welded and eliminate the rivets? To me, if I was trying to get a machine running, and not restore it to as delivered, museum quality condition, but make it safe and reliable, I would strongly consider going all welded. I personally don't care is I see rivets on the backhead. Smokebox, yes, because it is exposed for all to see. What is the percentage of cost difference between rivet/weld and all welded? If it is substantial enough, that could be the difference between a project being feasible or not.

Also, is there more benefits if the boiler is smaller (WW&F) versus larger (a Northern or beyond) for full weld or hybrid?

Good info here.

There's another way also - a welded boiler with fake rivet heads applied where it is visually noticeable. The only reason our predecessors riveted was because they didn't have reliable arc welding of pressure vessels yet.

In the case of #11, the locomotive will be a true reconstruction, seeking to recreate not only the appearance of the machine, but also the process by which it was created.

Choosing our construction method can be traced back to the importance of authenticity to the WW&F's identity. In addition, I have a personal interest in preserving the entire process of creating a riveted boiler in a historically accurate way. I feel that learning and understanding the process is one part of what makes visiting a living history museum special.

So, in the end, choosing to build a welded, partially-riveted, or fully-riveted boiler is , from my perspective, perhaps less a question of cost but more of a question of mission and interpretation. It may matter, or may not depending upon your circumstances.

Stephen

Can you elaborate on the reasoning for this change?

Check out this guy's riveting tools. I have visited and it is very cool:

https://www.youtube.com/user/blaxmith64

https://www.facebook.com/ballardforge/

Some Jurisdictions and the Historic Boiler section of the NBIC require a factor of safety of 5 for riveted butt-strap construction. So for the same reason the factor of safety in Part PL is 4 to be in line with the FRA requirement, the factor of safety in Part PR is 5 to be in line with the NBIC. I realize a newly constructed riveted boiler is not a historic boiler, but the Jurisdiction's rules don't always differentiate between historic and new riveted construction.

The design condition of 300psi remains the same, just the allowable stress of the material changes. This may mean that thicker material is necessary to accommodate the calculated minimum required thickness of the plate plus the corrosion allowance. A boiler built with 55,000psi tensile strength firebox plate will have an allowable stress of 13,750psi with a factor of safety of 4 and the same boiler built with SA-516-70 (70,000psi tensile strength) will have an allowable stress of 14,000psi with a factor of safety of 5. This assumes the design temperature is below 650° F.