Hight Strength Flange Bolts

[engpes]

I have an ASME VIII low temperature / low pressure applications (275 psig @ 140 F). I have a custom flange design and the number of bolts and size is critical.

I am currently using 1/2" 193-B7 studs and am asking if their is any other ASME acceptable stud material with a higher strength (yield and tensile).

Thank you in advance for your help. This is something I would need in the very near future for this one-time application.

 

[SnTMan]

engpes, there are a number of stronger bolt materials permitted for Sec VIII, Div 1, Div 2, both ferrous and non-.

Do you have access to Sec II, Part D by chance? If so, see Table 3. You really need to select based on your service, any limitations noted in Table 3 and commercial considerations.

I have used SA-354 BD (150 ksi min tensile) once before.

Regards,

Mike

 

[RVDallas]

Go over section 8 Div 1, App. 2, which concerns flange design and goes over adequate bolt load for sealing.

At 275 psi, generally B7 bolts are suitable for a variety of flange and gasket combinations, especially for class 300 and above flanges, so I would look into off the shelf components to suit your needs.

 

[Cockroach]

ASTM A193-B7 Studs are not permitted under CSA Z245.15 as low thermal application flange bolting.

You should be using a Category II Standard fastener (i.e. Sweet application - Cold Temperature), something like ASTM A320 L7 Stud with ASTM A194 4/7-S4 Heavy Hex Nut.

The Category II NACE fastener is ASTM A320-L7M with ASTM A194 7M-S4 Heavy Hex Nut. You could theoretically use this low temperature NACE faster(s) for a low temperature standard application, BUT NOT the reverse.

Be careful with fastener selection, your initial choice is only good for a Standard Service Category I application, which is not low temperature. B7 studs are not Notch Toughness and therefore, restricted for use under the spirit of the code.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[CoryPad]

The following materials are in the ASME B&PV Code and have allowable stress higher than B7:

XM-19 (austenitic Fe-Cr-Ni-Mn alloy)
17-4 PH (martensitic Fe-Cr-Ni-Cu alloy)
B22 (4140 steel)
718 (nickel alloy)
SA 574 (4140 steel)