Tighted flange with deformed flat washer
Tighted flange with deformed flat washer
(OP)
Hi,
I have a question, when I tighten the bolts of flange casuse the washer deformation, I don't know if the washer deformation will influence the bolts tighten force.
Does anyone can advise me how to calculate and approve deformation is acceptable.
Steven
I have a question, when I tighten the bolts of flange casuse the washer deformation, I don't know if the washer deformation will influence the bolts tighten force.
Does anyone can advise me how to calculate and approve deformation is acceptable.
Steven





RE: Tighted flange with deformed flat washer
Either way, washer deformation should not be acceptable.
RE: Tighted flange with deformed flat washer
Easy to deform washers when using undersize bolting. The holes in flanges are generously sized, to allow easier alignment for bolt-up. Thus the need [and Code requirement] for heavy-hex bolting.
RE: Tighted flange with deformed flat washer
Bolts material SA-193-B7, the vessel operating temperture at 300℃
During hydrostatic test @ 25℃ all washer no deformation but when we did hot tightening up at operating condition we found the washer outer rim was rising up
Should we need replace the washer to be more hardness one.
the wash dimemsion: 6t x 56 I.D. x 100 O.D. (mm)
Steven
RE: Tighted flange with deformed flat washer
What are you tightening the studs too? I guess a torque figure but you haven't stated it, I looked online and found this link below which talks about max bolt service temperature of 371 deg C for the material you stated however it also mentions a bolt tensile stress limit too.
I was just wondering whether you were over tightening the studs?
http://www.portlandbolt.com/technical/faqs/service...
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Tighted flange with deformed flat washer
Regards
r6155
RE: Tighted flange with deformed flat washer
Stevn23144 - a couple of questions"
1) Are you following a specific procedure for assembly? If so, who wrote it?
2) Why are you hot tightening?
3) Are your washers through-hardened?
RE: Tighted flange with deformed flat washer
TGS4 - See ASME PCC-1 "Washers are required only when torquing methods (versus use of hydraulic tensioners) are used for bolt tightening".
Regards
r6155
RE: Tighted flange with deformed flat washer
RE: Tighted flange with deformed flat washer
USAGE:The use of surface-hardened washers is not recommended since the soft interior material under direct compression will flow plastically, causing washer cupping and thinning with associated reduction in preload.
DIMENSIONS:The inside diameter of these washers was selected to enable their use under the nut. Use of these washers
under the head of a bolt may lead to interference with the bolt shank or underhead fillet.
INSTALATION :To avoid any concerns about the effect of washer markings on the performance of the washer to nut interface it is recommended that these washers be installed with the marked face towards the flange surface.
Regards
r6155
RE: Tighted flange with deformed flat washer
RE: Tighted flange with deformed flat washer
I agree with the posts which say washer deformation is not acceptable. At the least you need better washers or no washers. I've never liked washers because they are too easily made from incorrect material and often seem to fly under the radar when it comes to specification and testing. Neither B 16.5 nor MSS-SP-44 lists anything to do with washers (neither saying they should or shouldn't be used or providing any material specifications)
If you search under washers on this forum you will find a number of posts which list the requirements if you want to continue using them.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Tighted flange with deformed flat washer
Member TGS4 stated correctly that we have insufficient information to make a definitive judgment so unless the OP comes back I guess were screwed!
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Tighted flange with deformed flat washer
We're talking about TWO INCH diameter stud bolts here. Washers do absolutely nothing at this sort of size.
ASME B 16.5 or MSS SP 44 do not say a single thing about washers therefore they are not required.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Tighted flange with deformed flat washer
Hardened washers shall be provided under nuts for all bolts having diameters of 38 mm (11/2 in) or larger.
The washers shall be at least 6 mm (1/4 in) thick.
??????. Incredible !!!
Regards
r6155
RE: Tighted flange with deformed flat washer
However even this states that washers are optional....
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Tighted flange with deformed flat washer
However if you calculate the bearing area of a 2" nut it's approximately 3.95sq inches and a plain washer for that nut size as a bearing area of 12.35 sq inches, so in my book if that stud/nut is tightened to about 70% of the stud yield stress then the stress on the clamped part without the washer could be 3.15 times that of the joint fitted with a washer,which seems pretty significant to me.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Tighted flange with deformed flat washer
We had replaced all washer material into SA-540-B21,
Tighten the Bolts & Nuts with hydraulic bolt tensioning equipment,
eventually no deformation was found.
We guess that maybe the hardness of washer are insufficient or tighten method was incorrect.
I try to calculate the deformation as attachment for reference, you will find the deformation value are small.
RE: Tighted flange with deformed flat washer
Glad you got it sorted and thanks for letting us know.
There is no attachment with your post
Desertfox
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein