Washers on flanged connections?
Washers on flanged connections?
(OP)
Are washers are allowed between the nut and flange of a bolted, flanged connection?
I can't find anything in ASME B16.5 except one clause (6.6) that says the bolt bearing surfaces must be parallel within 1 deg. And I searched the forum without success.
Also, if washers are allowed, what materials would be allowed?
thanks!
-Mark
I can't find anything in ASME B16.5 except one clause (6.6) that says the bolt bearing surfaces must be parallel within 1 deg. And I searched the forum without success.
Also, if washers are allowed, what materials would be allowed?
thanks!
-Mark





RE: Washers on flanged connections?
B16.8 includes lots of stuff including the Bearing Surface issues. Bearing surface shall be flat and washer faced. Diameter of washer face shall be equal to the maximum width across flats within a tolerance of minus 10%.
Also search the web for hydraulic tensioners.
RE: Washers on flanged connections?
I phoned ASME and they said B16.8 is obsolete. They're phoning me back to let me know why its obsolete and what superceded it.
Anyone else have some info that'll help?
RE: Washers on flanged connections?
Check your piping code. If your piping code is ASME B31.3, paragraph 309 says "Bolting includes bolts, bolt studs, studs, cap screws, nuts, and washers."
What are you flange and nut materials? I normally see hardened steel washers specified on CS flanges with SA-194-2H nuts to reduce friction.
RE: Washers on flanged connections?
ASME PCC-1, Pressure Boundary Bolted Joint Assembly explicitly states that the use of washers is optional. htt
jt
RE: Washers on flanged connections?
RE: Washers on flanged connections?
Although there are exceptions, most of the flanged joints I have encountered in power plants and process plants do not use washers.
The carbon steel/stainless steel flange noted above is an exception.
-MJC
RE: Washers on flanged connections?
Washers are sometimes considered to be superfluous. However, if the fasteners are "torqued", washers can be very useful: Not only is "torquing" a fastener highly inaccurate, the process also chews-up spotfaces like there's no tomorrow. The use of washers, although not eliminating it, tends to reduce this effect.
When "bolt tensioners" are used, washers become redundant because the tensioner applies an axial rather than a torsional load onto a fastener. To retain the load prior to the hydraulic being released, the nut is simply turned down to the spotface "finger-tight" - preventing any potential galling.
This well-recognzed method of controlled bolting provides as elegant solution to some of the myriad problems associated with "torque"!
* One should be careful that if a flange that has been torque-tightened in the past but is now being converted to tension-tightened (simply by using longer studs), most manufacturer's standard bolt tensioners may be obstructed if the washers stay in place.
Ciao,
HevïGuy
www.heviitech.com