Recent steam up on this now-isolated line in California.

http://www.trainorders.com/discussion/read.php?f=10&i=9869&t=9869
ryarger@rypn.org

> Recent steam up on this now-isolated line in
> California.

Talked with someone last week who was expressing some reservation about the style of boiler repair to the backhead of this engine. I understand that the backhead was renewed by simple butt welding the new sheet onto the shell, without flanging of anysort. To compensate of for the loss of structural integrity, addtional staying was applied. I also was told that this repair was in the neighborhood of 350K.

Am I wrong to express misgivings about this type of repair? I know that the FRA is giving many operators fits about "theoretical" weaknesses in steam domes and lids, going so far leading investigations into modifying the original dome design (note that there is no problem with corrosion loss, ect., just that the 'engineer' in charge found a problem with Philidelphia's practice.

Would not butt welding the backhead directly to the wrapper be an alteration by any definition?

I am all for the utilization of modern methods, but I am concerned some out there lack an appreciation for the reasons for some "outmoded" practices (flanging, riviting) and may be given to reinventing the wheel for no good reason.



lorija799@aol.com

Oh boy, just done some backhead brace calcs so fresh in my mind. Without having any specific information about this particular situation:

The area of backhead which needs to be stayed by internal bracing is partly dependent on the radius of the flange. Essentially, it doesn't include the flanged area. A flat square corner has no flanged area, so many more square inches of surface to be stayed will be added to the equasion as a result. More area under pressure means more stress to be supported by stays which could require more stays to prevent any stay from being stressed beyond permissible PSI.

How to figure the area to be stayed and the maximum load a stay can support are explained in ASME and other documents for anybody interested.

I have seen modern welded boilers made with no flanged components whatsoever, and also seen a flanged backhead butt welded onto the wrapper sheet. Again, consult ASME and other such sources for welding design and execution requirements and specs.

It is a brave new world out there, and more than about time for us to be permitted to safely use the same welding practices the rest of the pressure vessel world has had available for decades. Consider: isn't a riveted seam a lot like a perforated piece of paper, designed to be torn along the dotted line?

dave



irondave@bellsouth.net

Consider: isn't a
> riveted seam a lot like a perforated piece
> of paper, designed to be torn along the
> dotted line?

> dave

NO, IT IS NOT. A rivited seam is not designed to be torn apart, it is designed to be held together by mechanical means working not only internally inside the hole(sort of "pinning"the seam together), but also to the friction and embedding of the rivit heads in the surface of the sheet.

We are only just now approaching the same level of understanding of welded seam dynamics that late 19th Century engineers had as regards rivited seams.

As one who has had to deal with boiler inspectors and other official nit wits who just couldn't understand that a rivited boiler can safely hold steam and erroniously felt that welded construction had replaced riviting ALTOGETHER, making the operation of a rivited vessel prohibited, thoughtless, false analogies comparing boilers to paper tear strips could lead the ignorant to believe that a rivited boiler is inherently destined for an "unanticipated, uncontrolled evaorative event."

Flanging introduces a self supporting radius into a structure, which is why many welded boilers have used them. My concern was not for the welding used to install the head, but the redesign of the weld structure.

I too, am happy we are free to use autogenous welding techniques in boiler repair, but I am real concerned about a bunch of possible Jack Legs welding in wholestructures without a nod to practices established by 150 years of everyday experience.

lorija799@aol.com

Hello All:

Interesting thoughts ....

As far as riveted vs. welded seams are concerned, it is not all that long that a designer has been able to use a 100% joint efficiency on welded seams. In comparison, on riveted longitudinal seams, it is possible for a well designed joint to aproach 98% efficiency.

If you look at older boiler construction, one will find welding in longitudinal seams. This welding though was used for sealing the joint and not necessarily for strength.

It was quite some time before radiography developed as a means for inspecting welds. As a result, riveted connections were still preferred as there are numerical methods to determine the strength of the joint. Without radiography, it is not possible to determing the strength of a weld.

Consider what PR-15 says about joint efficiency:

"In case of a riveted joint this is determined by calculating the breaking strength of a unit section of the joint, considering each possible mode of failure seperately, and dividing the lowest result by the breaking strength of the solid plate of a length equal to that of the section considered."

What would concern me the most about the repairs discussed would be the ability to obtain an interpretable radiograph on the welds. Without an interpretable radiograph, the allowable stress on the weld drops considerably.

Also, even though the material is likely to be a P1 material, I would be concerned about stress relieving after the weld is completed.

Any way, my $0.02.

PKurilecz


pkurilecz@yahoo.com

Right Jim, I communicated ineffectively. I had meant to make sure it was understood it was the paper not the boiler that was designed to come apart at the perforations. Mea culpa.

Having run calcs on longitudinal seams recently, and several times in the past on Baldwin, Lima, Alco, Glover and Union Iron Works products it has been my experience that the seams are weakest by tearing between the rivet holes in the outermost row in every double strapped butt seam I have figured so far. My comment was meant to reflect that reality.

This isn't meant to imply there are no safe riveted seams - the whole point of the calculations is to prove otherwise. Anybody who doesn't understand that shouldn't have any position of authority over pressure vessels.

Welded seams are no better than the materials and techniques used - materials specs are easy, welding skills are the more critical factor. Thankfully, we have documented standards and practices to follow and qualifications programs for welders to assure safety and high quality of work.

On the old industrial goats I work with, riveted seams are of rather low efficiency, which can prove beneficial in that there is much margin to be lost in the non-seam areas before critical loss of material is reached. Also, many of these were designed with a safety factor of 5 rather than 4 as FRA requires. More margin. Yeah, I like riveted seams from that POV but if I were to do substantial overhaul and replacement, I would want to weld. Hard to beat 100%, and I am just too old to buck rivets any more.

dave

irondave@bellsouth.net

Did a little bit of reading on this subject in between posts. Marks' Mechanical Engineering Handbook (a summary at best) 1941 edition has a series on rivet calculations. Their calculations are based on safety factors of 4.5 to 5, only go to 200psi and list efficencies of 75%. They talk about punched holes vs. drilled and slippage. As I thought, the shank of a rivet shrinks on cooling and is not a tight fit, the rivet strength depending on the clamping action of the heads ... so I don't know how you can expect efficencies in the 90's ???

By the same token I have witnessed Submerged Arc welding of nuclear waste containers that were 12" deep and 5" wide at the surface. These are x-rayed and needless to say must meet strict criteria. These huge weldments did not always pass the test either. A small number had to be machined out and rewelded and retested.

As experience has shown both methods will provide a pressure vessel capable of meeting design standards so the choice is till up to the customer.


lamontdc@adelphia.net

> Did a little bit of reading on this subject
> in between posts. Marks' Mechanical
> Engineering Handbook (a summary at best)
> 1941 edition has a series on rivet
> calculations. Their calculations are based
> on safety factors of 4.5 to 5, only go to
> 200psi and list efficencies of 75%. They
> talk about punched holes vs. drilled and
> slippage. As I thought, the shank of a rivet
> shrinks on cooling and is not a tight fit,
> the rivet strength depending on the clamping
> action of the heads ... so I don't know how
> you can expect efficencies in the 90's ???

Generally, the standard practice on rivet holes is to drill then ream to finished size. Punching holes is not advised due to possible cracking around the perimeter of the hole. For longitudinal seams, the load on rivets is in shear. The clamping force is more important with respect to being able to properly calk the joint. Rivet spacing adjacent to the plate edge can affect the calkability of the plate edge.

The ability to obtain joint efficiencies in the high 90's is very possible with sawtooth designs and with quintuple rivet designs. I obtained this information from a literature search on riveted joint design aimed specifically at locomotive boilers. The general efficiency of any riveted joint of maximum efficiency is given by:

E = (nC)/(nC+T)

n = number of rivets in a unit section
C = Crushing strength of the plate
T = Tensile strength of the plate

Calculating the efficiency of a riveted joint is very tedious.

> By the same token I have witnessed Submerged
> Arc welding of nuclear waste containers that
> were 12" deep and 5" wide at the
> surface. These are x-rayed and needless to
> say must meet strict criteria. These huge
> weldments did not always pass the test
> either. A small number had to be machined
> out and rewelded and retested.

So true, so true ... what is especially scary is telling a contractor that he can't "repair a repair" and the part has to be junked if the repair doesn't pass NDE.

> As experience has shown both methods will
> provide a pressure vessel capable of meeting
> design standards so the choice is till up to
> the customer.


pkurilecz@yahoo.com

Ah, the brains we have on this board.....and a substantive discussion of relevance to us all.

Here's an idea for a new thread - apart from ASME, what standards and practices do you guys have documented out there? For example, I have a book by Kleinhans on boiler design, the Little River Baldwin, Alco and Lima reprints, and a couple old home study course pamphlets. FRA allows us to use "industry standards" if documented, so pooling our resources could help us all.

BTW, calcs are tedious but even with my decades old high school algebra and a pocket calculator, with some occasional advice from MEs, I can do them and correctly build a new Form 4. It isn't anything to be scared of. You will pull out a lot of hair and eat a lot of antacid, but the result is a proven safe boiler and a personal understanding of how boilers react and handle mechanical stresses.

Dave

irondave@bellsouth.net

> Ah, the brains we have on this board.....and
> a substantive discussion of relevance to us
> all.

> Here's an idea for a new thread - apart from
> ASME, what standards and practices do you
> guys have documented out there? For example,
> I have a book by Kleinhans on boiler design,
> the Little River Baldwin, Alco and Lima
> reprints, and a couple old home study course
> pamphlets. FRA allows us to use
> "industry standards" if
> documented, so pooling our resources could
> help us all.

> BTW, calcs are tedious but even with my
> decades old high school algebra and a pocket
> calculator, with some occasional advice from
> MEs, I can do them and correctly build a new
> Form 4. It isn't anything to be scared of.
> You will pull out a lot of hair and eat a
> lot of antacid, but the result is a proven
> safe boiler and a personal understanding of
> how boilers react and handle mechanical
> stresses.

> Dave

As a PE, I take a different philosophical view towards the FRA Form 4. Instead of just filling out what the form requires, I review the boiler design according to code requirements. This means looking at current ASME Code requirements, historically contemporaneous Code requirements for the boiler in question; and, finally, current FRA requirements; then, selecting the most restrictive requirements of all as applicable. When I finish this review then I fill out the form. I have found that there are a lot of items that are not addressed by the FRA Form 4, but are addressed by Code requirements.

For example, under certain circumstances in ASME Section 1, an angle stay may have a stress not to exceed 10,400 psi. Yet 49 CFR Part 230 limits all angle stays, except in the firebox, to 9,000 psi.

For example, Part 230 Form 4 doesn't address knuckle radii.

As far as my reference libray for this work, I have assembled reference works which primarily address design and fabrication practices.

As I use spreadsheet programs, finite element analysis programs and software such as mathcad, I am impressed by the numerical and graphical methods that were developed by designers in the days where the most advanced computing machines were a slide rule; and, a pencil and piece of paper. BTW, the slide rule that I used in college has been enshrined in a shadow box with the sign: "In event of computer crash - break glass."

Cheers;

PKurilecz

pkurilecz@yahoo.com

........but back when we were trying to get a certain nameless southwestern state to inspect traction engine boilers 20 years ago, we were flatly told that rivited boilers were outlawed. Well, come to find out, the ASME/National Board hadn't revised rivited procedure guide lines since the sixties, so our local guy just thought they were defacto outlawed. This was also the same time that Pennsylvania's boiler inspecting guru was agitating to take ALL rivited boilers out of service and any boiler over 50 years old, regardless of actual condition. I have, buried somewhere, an article penned by this guy where he marvelled at miracle that there had been so few failures of rivited construction.

Any how, a rivited boiler still has to get what is called a "Special" number from the chief inspector due to the exoticness of rivits.

The only advantage that welding really has over riviting is speed and cost: welding is the cheaper way to fix something.

I was just concerned really about a lack of flanging on the back head of the 45, and also how such a repair could concievably cost $350,000.

You know what we really need? Use the best and most applicable techniques from around the world and develope a truly international set of historic boiler repair disciplines so that when we are confronted with questions about 'established practice' there is a stack of them to show them.

lorija799@aol.com

> I was just concerned really about a lack of
> flanging on the back head of the 45, and
> also how such a repair could concievably
> cost $350,000.

I too have concern about the lack of flanging - this discussion went off onto rivetting vs welding as a jointing method, but surely the real concern is the nasty rigid right angle joint(s) around the firebox. They may be perfectly fine for a pressure vessel running at constant pressure and load for months on end - but a loco boiler, especially one used on short trips the way we do now is anything but constant.Why else are flexible stays fitted (have you ever seen flexible stays in a boilerhouse?)

Look at the kriegloks and the QJs - nice flanged corners to allow flexing and simple butt jointing onto the side sheets - all very easy to get at to weld and Xray. Welding this way would seem to be a perfect way of building boilers

Does anyone have long term experience of the square joints? It's a fact that many boilers crack on the flanged corners, what's the betting that these ones will crack at the change of section/heat affected zone down each side of the weld?

FWIW, Tallylyn Railway in the UK built such a boiler about 1975, I'd be interested if anyone knows their experience. And I'm told that the Queensland Rail AC16 (Macarthur type) has such joints on the inner firebox.

No sweat Jim, I am not known for communications skills. Surprised Hume prints the crap I write, but then again, he needs contributions badly (nudge nudge).

350K does seem like the cost for a whole new boiler to me. Anybody out there from Texas State who can comment on the cost of the new boilers built there very recently?

OTOH, repairs can be made to cost whatever the purchaser can be persuaded to pay. Virtually everything of consequence done to steam locomotives is custom skilled craftsmanship these days which isn't inexpensive. Compliance with regulatory and record keeping costs, as does liability coverage.

I am now working on trying to help out a fine gentleman who wants to build something for his community and has spent over 150K on his steam locomotive restoration in the past 12 - 13 years. Virtually 80 - 85% of his investment is worthless now due to the new regulations and various noncompliant repairs made a decade back by a previous contractor. While I am doing the best I can to do a good job I want to keep it as cost effective as possible. Not everybody shares that philosophy.

Dave

irondave@bellsouth.net

> I too have concern about the lack of
> flanging - this discussion went off onto
> rivetting vs welding as a jointing method,
> but surely the real concern is the nasty
> rigid right angle joint(s) around the
> firebox. They may be perfectly fine for a
> pressure vessel running at constant pressure
> and load for months on end - but a loco
> boiler, especially one used on short trips
> the way we do now is anything but
> constant.Why else are flexible stays fitted
> (have you ever seen flexible stays in a
> boilerhouse?)

> Look at the kriegloks and the QJs - nice
> flanged corners to allow flexing and simple
> butt jointing onto the side sheets - all
> very easy to get at to weld and Xray.
> Welding this way would seem to be a perfect
> way of building boilers

> Does anyone have long term experience of the
> square joints? It's a fact that many boilers
> crack on the flanged corners, what's the
> betting that these ones will crack at the
> change of section/heat affected zone down
> each side of the weld?

> FWIW, Tallylyn Railway in the UK built such
> a boiler about 1975, I'd be interested if
> anyone knows their experience. And I'm told
> that the Queensland Rail AC16 (Macarthur
> type) has such joints on the inner firebox.
Can anyone tell me the best place to get GOOD rivets these days?btw I have seen flexies on old mannings and wet back boilers in power plants. If you want to know how square joints work out on locos that work hard and are up and down. Call the mt. washington clog rr. regards bb

staybolt2@netscape.net

Square corners are more flexible than flanged corners.