HOW TO DEFINE THE TORQUE FOR A193B7 STUDBOLTS CONSIDERING GASKET COMPRESSIBILITY? 1

[lgracio]

Hi,

Someone can help me to find out how to define/calculate the tighten torque of studbolts A193-B7 considering the flanged joints as per ASME B16.5 and in between there is one gasket subject to compression?

Any place/handbook where I can find some assembly guides of such bolted flanges?

Thanks.

Luís Grácio
Mechanical Engineer (Engineering Solutions)
Portugal-Setúbal

 

[racookpe1978]

What kind of gasket?
Standard pipe flange designs and sizes?

 

[lgracio]

Hi,

Material Selection:
- Flange ASME B16.5, Welding Neck Flange, 6", 150# SCH40, SA-105
- Gasket ASMEB16.20, Spiral Wound Gasket - "CG" Flexitallic Style 6", 150#, Carbon Steel Rings with flexicarb filler
- Stud Bolts ASME B16.5, Stud Bolt 6"x150# Flange, 3/4", 4" LG (Set of 8), SA-193-B7.

Luís Grácio
Mechanical Engineer (Engineering Solutions)
Portugal-Setúbal

 

[gasketguru]

For a 6"-150 spiral-wound gasket I usually start at something like 4.5 or 5 tonnes per bolt or above if possible. You don't give the actual temperature pressure or media, but this is a fair starting point at ambient - it would only be around 35ksi on the root of the bolt, so OK with B7 and a lot of people would aim at perhaps 40-50% yield - thus even 6 tonnes per bolt could be thought reasonable. Torque of course can vary considerably as friction on threads, washers etc. can be unreliable - you are perhaps looking at around 135-165 ft-lbs / 180-225 Nm or thereabouts. (Note that gaskets with inner and outer rings tend to perform better than those with just the outer ring.)

It would be worth consulting your local supplier - check out the members of the European Sealing Association (europeansealing.com), as most major gasket manufacturers will offer advice such as above - the ESA has guidebooks on fitting and on safe seal usage which are translated into various languages and which you may find useful.

 

[ricklts]

Pull up either Flexitallic or Lamons gasket handbooks. All of your questions are answered therein.

 

[lgracio]

Greats to all of you. It was a good help. Thanks a lot.

Merry Christmas.

Luís Grácio
Mechanical Engineer (Engineering Solutions)
Portugal-Setúbal