> Square corners are more flexible than
> flanged corners.
?????
Cold formed square corners are wonderful stress risers and a good source of early failure. My book says the outer radius of the flange should be at least four times the plate thickness.

lamontdc@adelphia.net

Consider: isn't a riveted seam a lot like a perforated piece of paper, designed to be torn along the dotted line?
Answer: No

Hi Everyone:

Mr.Kurilecz is correct, the object of the Form 4 is to reestablish the boiler's structural integrity in its current (80 year old) condition. There is a lot more to this than just "filling in the blanks" and some degree of engineering analysis is not only desirable, but should be required. His methods are the same ones I use and are the foundation to filling out the summary Form 4 as a true affidavit that can be signed by the operator/owner with some degree of confidence they won't end up in jail.

The joint under discussion on the California Western is, in my mind, not a true butt joint, but is a full penetration fillet weld on a corner joint. If the surrounding stayed surfaces are operating within the proper stress ranges then the resulting strain will not fatigue the joint any faster than if it was a flanged, true butt welded joint.

The real consideration is the condition of the old wrapper sheet material (is it safely weldable?), how carefully the repair was designed and how well the design's audit trail goes back to accepted practices for this type of construction.

Also, it is probably easier to obtain good radiographic proof of weld integrity on a straight, true butt weld (flanged sheets) than on a fillet weld with a complex geometry (square corners). It has been noted elsewhere that the reliability of welded structural joints is only as good as the ability to prove them with NDE methods after they have cooled. It is probably safe to say though that the hidden flaws lurking in many old boiler plates probably ensures that good welds probably have better metallurgy than flawed areas of old plates

It is my opinion that most boiler repair firms are not qualified to design this type of structural repair. A qualified, experienced engineer should design, draw and specify the repair and the procedure. Then a qualified, financially responsible boiler repair firm should take a contract to implement the repair.

This is not really new ground. Silverwood 2-6-2 #12 has a square corner boiler that has been kicking around since the 1980's. I don't know where this engine is now. Personally, I like flanged corners better, but there is no inherent reason the other way shouldn't work.

Bill Petitjean

> 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


petitinc@nwlink.com

Hi Again:

I always think of something after I post, so here goes again.

You can only repair so long, then some things just need replacing. The work at the California Western sounds like it represents toggling over from continually working on an old, worn out section to just replacing it wholesale. The real question is: Did they stop replacing at the right place? Only a careful survey of the boiler and analysis coupled with careful engineering review can answer that question. There is a lot more to surveying old boilers than simply looking at thicknesses. Chemical, mechanical and metallurgical considerations are also critical. The CW #45 is a classic case where sheet thicknesses may have been adequate -- it just wouldn't quit cracking. A history of cracking is the surest evidence all is not well with the boiler's original ductility and ability to withstand the stresses of everyday operation.

One consideration that is not always taken into account is the fact that locomotive boilers are mobile devices that sustain multiple G effects when making hard couplings or derailing (perish the thought). Also the erratic load characteristics and continual "fire up/shut down" cycles take their toll. Boiler design and construction must take these factors into effect, mostly by experience so the boiler has some extra structural ability to withstand these rather indefinite forces along with the basic chore of remaining static under working pressure loads.

The high cost of the repair is a function of the owner's ability to "shop" for bids when looking for a contractor to perform the repairs. In this respect it is better to separate the engineering and design phase from the repair phase. It is more difficult, in my mind, to find a qualified engineering firm that will adequately survey the existing boiler, develop a repair scenario and design, draw and specify the repair and procedure than it is to find a qualified repair firm. Nonetheless, they are out there. I talked with the CW several years ago and suggested exactly what they finally did -- replacement, but was not well received at the time.

Once an engineerng firm has been chosen they should be able to produce documentation that will enable a pool of potential repair firms to accurately bid the repair implementation. It is probably a good idea to retain the engineering firm to assist with contractor selection so everybody is in the loop if something goes sideways.

The above process allows good control over the project and is relatively straightforward in terms of establishing limits of responsibility. Of course, this all requires the owner/operator to have a project manager that is looking after the locomotive's best interests first and the other parties interests later.

$350,000 sounds a little steep to me, but if the CW ordered the repair on a "P.O. and a prayer" they left themselves wide open to whatever the contractor saw fit. However, in defense of the contractor, he may have had to accept total liability for the whole job. This degree of exposure on an 80 year old boiler probably caused his insurance underwriter to have several apopalectic fits and you might discover the actual job cost $50,000 and the insurance adder premium cost $300,000. Caveat Emptor!

Bill Petitjean

> 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


petitinc@nwlink.com

> The CW #45 is a classic case where
> sheet thicknesses may have been adequate --
> it just wouldn't quit cracking. A history of
> cracking is the surest evidence all is not
> well with the boiler's original ductility
> and ability to withstand the stresses of
> everyday operation.

> Bill Petitjean

If you are planning a rebuild and have stock available it should be sent out for analysis. Chemical and physical test results will certainly add to your engineering knowledge. "Alloy" boiler cracking has reared its ugly head while stress and chemical corrosion is alway a possibility with older, well used materials.

lamontdc@adelphia.net

My understanding was that the repair was done by an independant contractor from out west, and was not done by a boiler repair firm per se. It is unknown whether there was an "R" stamp (sometimes not neccessarily a guarentee of competance) or insurance involved.

Remember, this was a pretty run of the mill straight shell boiler, no wagon top courses, and the only real tricky fabrication would have been the reverse curves of the firebox where it 'necks down' to the frame. Even taking size into consideration, 350 would have gone a long way toward a new boiler.

lorija799@aol.com

> The high cost of the repair is a function of
> the owner's ability to "shop" for
> bids when looking for a contractor to
> perform the repairs. In this respect it is
> better to separate the engineering and
> design phase from the repair phase. It is
> more difficult, in my mind, to find a
> qualified engineering firm that will
> adequately survey the existing boiler,
> develop a repair scenario and design, draw
> and specify the repair and procedure than it
> is to find a qualified repair firm.

An excellent point!

The division of the determination of the repairs necessary and the execution of these repairs is
one of the best things that a locomotive owner can do.

If the firm performing the evaluation has no interest in the actual repairs, this firm is able to concentrate on what repairs are actually needed for the desired MAWP. Also consider, that the firm performing this review can work with the client to provide guidance to a client with limited resources.

For example, if some component would limit the boiler to 175 psi rather than the previous MAWP of 200 psi, would the client still have the performance out of the boiler for the application in which the locomotive is used. The ability of the client to make such informed decisions can help the client work within their limited budgets. Consider a locomotive that rarely operates at more than half throttle, would a reduction of 10% to 15% in MAWP significantly affect the performance?

If an organization knows exactly what repairs are needed to the boiler to maintain a certain MAWP, it is much easier to obtain realistic quotes. Any time a fabricator, or consultant, is faced with unknowns in the scope of work, the bid price goes way up. Or even worse, the potential client is told time and materials.

The fee that an engineering firm would charge for their services up front to determine the necessary repairs may sound expensive, but the overall project cost may be significantly less.

None of us like to see a locomotive taken apart and not returned to service. But wouldn't it be well worth it to spend $5K to $20K to find out realistically what is required, rather than to spend $100k, $200K, etc., only to still have a locomotive that is not considered operable.

Cheers;

PKurilecz

pkurilecz@yahoo.com