assembling flanges with studbolts
assembling flanges with studbolts
(OP)
In appendix 2 of ASME VIII div 1 I see no mention of using studbolts (two side threaded wire + nut at each side); only bolt (screw + 1 nut). But in ASME B16.5 we can use studbolts.
Does ASME VIII div 1 allow using studbolts ? To avoid lossen at high temperature (differential straining) should we use nut and counter nut (in total 4 nuts) ? Should we use also spring washer to maintain adherance ?
Thanks for help
Does ASME VIII div 1 allow using studbolts ? To avoid lossen at high temperature (differential straining) should we use nut and counter nut (in total 4 nuts) ? Should we use also spring washer to maintain adherance ?
Thanks for help





RE: assembling flanges with studbolts
We use studs on all piping flanges up to 1250F. We never use bolts on piping flanges except on some water lines.
RE: assembling flanges with studbolts
316 SS bolting B8M/8M size 7/8"
graphite gasket 2 mm thickness
non standard dimension
temperature depending on application : sometimes 100°C, others till 450°C
some units intended to NACE
media : steam or hydrocarbon
RE: assembling flanges with studbolts
RE: assembling flanges with studbolts
what do you mean by "gauls" ? which problem did you face with such boltings ?
I think it's the standard bolting available in the market ? Do you an idea of other 316 SS bolting ?
Thanks
RE: assembling flanges with studbolts
Where are you located and where, in the world is this facility ?
-MJC
RE: assembling flanges with studbolts
ASME VIII allows you to use any stud bolt listed in B16.5, even if Table 2-5.2 in Appendix 2 shows the hex head of a bolt... Those stud bolts don't require double nuts or spring washer in standard piping or vessel applications. Some special cases with vibrations might require double nuts or other locking devices. Also, the softer stainless steel bolting could adhere / seize to the carbon steel flange due to the bolting tensions, makeng it difficult to remove or even to turn a nut on the bolt. It usually ends in damaging the bolts, flange and compromising the joint.
Cheers,
gr2vessels
RE: assembling flanges with studbolts
no washers are allowed. double nuts are permitted and used for locking purposes only,
genb
RE: assembling flanges with studbolts
And lately I've even seen the use of Bellville(sp?) washers on steam systems, to try cutting down on steam damages connections when the connection loosens up. They are a type of lock washer, but semi-pricey.
RE: assembling flanges with studbolts
Do your Appendix 2 calcs. to spec. your bolts. You may be surprised.
11echo:
I like B7 studs for steam service. If the gaskets scream before the line warms up your preload may be to low. You can also go to a sprial wound gasket.
RE: assembling flanges with studbolts
RE: assembling flanges with studbolts
I wish I could complain about retorquing piping flanges! I usually see exchangers torqued and piping flanges "torqued" to "two arm-grunts". Its amazing we don't deal with more piping flange leaks.
jt
RE: assembling flanges with studbolts
RE: assembling flanges with studbolts
I think if plants stopped using millwrights and electricians for their piping maintenance (and/or low-bid maintenance contractors), a lot of these problems would never come up for discussion because they wouldn't exist. Steamfitting/pipe fitting is a separate trade for a reason.
RE: assembling flanges with studbolts
We've none the go thru after start-up to do the snug-up on these flange studs, pretty standard practice. I was working with a company that was trying to generate a yearly procedure to re-torque and document this operation, but I don't think it took root. The bean counters back in the office didn't see a return on the effort. These steam systems are 2500# to 600#, alittle different then your low-pressure steam lines. What’s the old adage ...Never enough time to do it right, but always enough time to do it over!?? *G*
RE: assembling flanges with studbolts