I saw this photo in a Facebook post. The poster, someone called "3985/844 Info" said that these are flexible stay bolt caps and were standard practice on the UP. I have seen photos of 844's firebox and have seen the more usual Flexi caps with the threaded plug. But since these look for all intents and purposes like rivet heads, they are new to me. Apparently the UP steam shop has fabricated a special tool for cutting these off.
Here's the link to the Facebook post.
https://www.facebook.com/10112103662175 ... =1&theater
Can anyone comment on these?

Greetings:
Those are Flannery style "MK" flexible staybolt caps.
Not rivets, see the fillet weld around each one.
The "MK" assemblage used a hollow, "K" head flexi bolt seated on the wrapper sheet itself (no sleeve) and then the "MK" cap was welded over it.
Flannery made special tools to make the seat in the wrapper and remove the cap as well as the electric testing device to test the hollow bolts without removing the "MK" cap.
A lot of large, modern locomotives had these, but I have seen them on 0-6-0 tank engines as well.
These days, folks use a standard weld on pipe cap similar in size to the "MK".
Be well,
J.David

Look what I found

http://users.fini.net/~bersano/english-anglais/Flannery_1938_stay_catalogue.pdf

I'm curious as to why they are being removed? Nothing in the regs requires that unless they are replacing the bolt.

The corrosive nature of the engine, of course.

(not my words, go read the facebook posts)

Keep in mind the facebook page is NON official.

The 'reasons' seem to waffle between that there is damaging under the cap and/or the staybolt is rusted beyond use, with a heaping helping of 'the last rebuilds were crap'

Not my words, don't jump on me. A lot of folks are angry etc about this, I'm pretty much to the "Aint nothing I can do gonna do squat and my wishes don't matter, just watch the circus and wait till the change happens" stage

And these caps must be removed every 5th annual inspection and each 1472 day inspection. Makes those threaded types seem a little more "restoration friendly."

Have any locomotives using this Flannery design been brought back from retirement or gone through a 1472 day inspection?

The MK caps do not have to be removed for flexible staybolt tests; that is what the electric test device is for.

I seem to recall seeing these caps on NKP 759. Other AMC power may have them as well.

Howard P.

The reason I am asking about these stays is that CFR49 Part 230.41 requires that "flexible stay bolts with caps shall have their caps removed for inspection..." Do these Flannery caps qualify as "caps"?

Even if there is an electrical device for inspecting these stays, Part 230.41 does not appear to allow any exceptions. Sounds like anyone with a locomotive sporting this style stay has a somewhat larger job ahead of them than otherwise.

.

Greetings:
One of the most prized and useful items in my library is my 1936 Flannery catalog.
Anyone out there who works on steam locomotives (or dreams of) should obtain a copy (available above) and study it. Most anything you'll ever need to know about staybolts is in there, including the tools needed to repair them.
In so far as inspection is concerned, it is true that they must be inspected every 5 years, but note that 49CFR Part 230.41(b) says that the cap need not be removed if it can be established that the bolt isn't broken. Hollow bolts are always used with MK caps.
Please note that not all hollow flexible bolts use MK caps. Our primary locomotive when I was with Steamtown in Vermont was No.1246 (now at Railroad Museum of New England), which had hollow bolts and a conventional sleeve and cap.
J.David

.

Thank you all for your able assistance. I now understand much more about the technology and the reasons that 230.41 was written as it was.

How often do these flexible bolts break or otherwise fail? I noticed that on the ATSF2926 they ended up replacing about 2 dozen of the hundreds of flexible stays.

Failure can be from a lot of different reasons, not just from being cracked or broken. Corrosion or wastage can be reason to replace. In the case of the 2926 this could be the case or perhaps when a portion of the sheet is replaced then the bolts are replaced.

.

The main reason why we replaced those stays was because the caps had mostly or completely eroded away due to water being trapped by the asbestos jacketing, and the upper portion of the stays were damaged as a result. Several other stays had eroded caps, but those stays hadn't been damaged enough (if at all) to require replacement, and the existing sleeves were ground down to permit installation of new caps. (SBRHS had a similar issue with 3751's flexible stays, except they had to replace many more caps and stays.) The remaining flexible stays were in very good condition. I don't know offhand what the failure rates for flexible stays vs. rigid stays are or might be, but flexible stays can fail just like any other part or component (or anything else made by human beings).