What The Heck is a "Flexible" Staybolt?

Now I know, amazing what you can learn from this great forum.

Great visual. You could probably type several paragraphs and still not be as clear as the image.

Before I clicked on your post I thought - are you kidding me, looks who's asking the question!?

I thought I would answer the question to the best of my ability and then I actually saw your post.  Great visual by the way!!

Great info Rich!  

Excellent picture!

Uh oh! The boss is tryin' to educate us foamers so we can converse with correct terminology and stuff. .....

 Thank you for posting this!! It helps to understand how this stuff works. I always saw like a million caps on that box and didn't know what they were for. I didn't have the guts to ask.

 If they break off at the wall, do they get removed from inside the firebox?? Sounds like a maintenance nightmare.

Yep...you get out the smoke wrench (an acetylene torch for those of you in Rio Linda) and cut the bolt out from both ends. Then you use that long staybolt tap that John showed in the video to cut new threads and run in a new bolt.

If the firemen have treated the boiler well during the operating season, there will be very few if any broken bolts found at the end of the year. I don't think we had any broken bolts in the 765 this year.

Great topic, Rich. I've been following the NMSLRHS restoration of 2926 in Albuquerque. They had to replace like 400 of the shells on the flexible staybolt caps welded on the boiler.  When they replaced a side sheet on the boiler last year, they did not put staybolts in the side sheets, they used what they called "stayrod" and welded it in from both sides. It was round bar stock with no threads.Have you ever heard of this?

Thanks,

Dave

No, I have not heard of "stayrods" before. But I'm not an expert on boiler repairs.

Rich,

It's better to learn in one's later years. One problem, I won't remember it tomorrow.

It's time for my nap . Rich, your tid-bits of information are appreciated more than you realize. The inner-workings of a steam locomotive were the major expense that doomed the beautiful machines. IMHO

God Bless,

"Pappy"

RE: "Stayrods"

I've also heard of these referred to as ''staypins''. Not too sure as to their widespread use (legality?) in locomotive boilers in our country, but was told by the well-respected CMO at a well-known tourist road that regular Chinese practice is to seal-weld both ends of the bolt at the wrapper (or outer side) sheet and the firebox side sheet. However, I've also heard that a another road with an all new, welded boiler replaces broken welded stays with a built up (welded up) hole, then reamed and tapped for a regular threaded bolt. Hope to see others join in this discussion!

DV

Rich,

How many of these staybolts are used or(needed) in a boiler?

 Fred

How do you keep a fire lit with the tell tale hole blowing water into the firebox?

I've seen pictures of steam engines in use at the end of steam days with steam leaks on the outside of the fire box due to a broken stay bolt... how did the fireman keep the fire box going?

The Baldwin 0-6-0, #26  Steamtown National Historic Site had the boiler/fire box on display for many years in different stages of repair/rebuild.  At least twelve hundred  stay bolts.   The asymmetrical fire box requires the majority of the stay bolts.

Crown Sheet to Roof sheet 0-6-0

 The inherent design of a round boiler usually allows for more material in the outer sheet/shell. So the expansion of more material causes lateral movement compared to a smaller inside shell.  The flexible stay bolt has a ball and socket assembly outer shell that allows for the movement.

This roof sheet was part of Boston and Maine 3713 at Steamtown.  Note the sockets. Stay bolts and Cap are missing.

 Each time maintenance is done Stay bolts may be replaced, if broken or they leak. This requires a larger diameter bolt to be installed with new threads and machining. Eventually as the bolts become too large the sheets are replaced with new. Lots of work for lots of skilled workmen.  Welding stay bolts that leaked was a quick fix.  If you look closely, on old steam that is displayed, you should see some of the quick fix welding.

Larger boilers will have stay rods associated with the front boiler sheet and the rear door sheet to inhibit lateral movement.  These rods are usually attached to the top of the boiler and installed at an angle to the front and back sheets.

Note the long rods with the clevis end that will attach to the top of the front boiler tube sheet. You may see stay rods with turn buckles for tightening.

My guess is drafting is to the front of the boiler via the smoke box/stack, all fire box gases exit to the front, most of the time.  The catastrophic failure of the steam locomotive at Gettysburg several years ago saw steam exit the rear of the fire box via the fire box door, injuring the engineer and two firemen. Low water crown sheet failure.

A leaking staybolt doesn't create a stream of water big enough to put out the fire and the pressure loss is minimal.  Most if not all would evaporate before it reached the fire.  You have a red/white hot fire going in the firebox and it would take a lot of water to put it out quickly.  Just look how much water is needed to put out a burning building.  As for steam loss, the turbo-generator uses more steam than what's lost though a leaking bolt.

Rusty

Interesting, so you could have a few of these go and it would not even phase you.

That is one heck of a fire...

Very cool!  Thanks Rich!  I do love learning new things like this!

Mike CT,

Thanks for the your answer,1200,I never thought that there would be so many staybolts,,That is a lot of work putting all those in,Must be a very time consuming job.

Thanks

Fred

The telltale holes are very small--maybe 1/8 inch? And water wouldn't be spraying on the fire--steam would (water at a temperature well above the boiling point inside a boiler turns to steam when it hits the atmosphere). A squirt of steam from a 1/8 inch orifice onto a 1800 degree fire filling literally hundreds of cubic feet of firebox probably isn't even noticeable.

The telltales on the engine I work on are only on the outside of the firebox--the holes don't go all the way through.

The 765's firebox is 90 square feet. That's a 9' x 10' room with a 4" to 6" thick bed of coal fire on the floor. That is a huge amount of thermal inertia.

A tiny little stream of water from a broken staybolt is less than 1/4" in diameter. It will have no discernible effect on the fire at all.

Are you sure about them only being on the outside? That would be very unusual and I'm not sure it is even up to code. I think tell-tales are required on BOTH ends of the bolt.

Pretty sure--but now you're making me want to check!

EDIT: Most of them only have telltale holes on the outside. There are a couple on either side of the throat sheet that go all the way through. Remember though--our engine was built in 1941 and carries a MAWP of 190. Staybolts that didn't have the telltale go all the way through weren't uncommon.

I'm sure our FRA inspector would have told us already if we weren't up to code.

And this is why:

§ 230.38 Telltale holes. 

(a) Staybolts less than 8 inches long. All staybolts shorter than 8 inches, except flexible bolts, shall have telltale holes 3/16 inch to 7/32 inch diameter and at least 1 1⁄4 inches deep in the outer end. 

Emphasis added. Our engine can fit inside your tender!

1200 Staybolts for the 0-6-0. The 765 has about 3,600. The N&W 611 has about 4,200. And the Mighty Allegheny was pushing approx. 6,000. Telltale holes are 7/32" diameter and required by the FRA Rules to be cleared with a 3/16" bit to open the hole for the annual hydrostatic test.

I don't think the code requires that they be drilled to any specific diameter; it just requires that they be "kept open at all times."

According to the CFR Part 230 for Steam Locomotive Inspection and  Maintenance Standards, all rigid staybolts less than 8 inches must have a 3/16-7/32'' telltale hole drilled at least 1 1/4'' at the outer end OR the entire length of the bolt. 

What section of part 230 says it needs to be "drilled?"

I think you are referring to Section 230.38, which I quoted three posts above yours.

Gary Bensman is grossly mis-interpreting the code if he thinks they need to be cleared only for the annual inspection.

Were the staybolts torque wrench tightened, or just hammered in with an impact gun/hammer wrench?

If they were tightened with a torque wrench how would you like to keep up with that sequence!

Was there a retighten after heat up/cool down, or just a one shot deal?........Brandy!

Other than an annual, why else would one desire to go to all that trouble of drilling out the tell-tail holes?

Because the code says so.

OK, please site/quote THAT portion of the FRA regulation, as neither the UP, nor the SP 4449, crews have ever "drilled out" the tell-tail holes at a time OTHER than an annual hydro.

I quoted it in one of my posts above. Hence the quote marks. 

Here it is again. Sec. 230.38 (c): Telltale holes kept open. All telltale holes, except as provided for in §230.41, must be kept open at all times. 

Do you mean the statement you quoted that did NOT include flexible staybolts LONGER than 8"? All the flexible staybolts generally have the telltail holes filled with a fireclay inside the firebox anyway

Well Hot Water, it took me a couple of readings to try to understand but I think I see where smd4 gets his perspective. His loco only has telltales on the outer ends of it's staybolts - so he thinks the rule that says telltales must be kept clear at all times pertains to ALL telltales. It only applies to the outer ends of bolts with telltales.

Of course we ALL maintain our boilers with the outer ends of all telltales kept clear at all times.  smd4 didn't understand my post about clearing the telltale for an annual hydro because I was referring to ALL the TELLTALES on the inner end of the bolts.