HOW DOES ASTM A574 COMPARE TO B7?

[DarkAce]

Can anyone tell me how A574 compares to B7 with regard to high temperature applications? My situation is that a B7 Socket Head Cap Screw (3/4"-10 X 3") was sheared during removal. Our vendor does not have any of these in B7, but assures me that A574 will perform just as well under my high temperature application. I can see that the A574 has higher Tensile Strength, Yield, And Hardness qualities, but I am still concerned about the temperature, which is nominal 800 Deg F. I have not been able to find any data to support the supposition that A574 will perform at this temperature range.

TIA

 

[metengr]

Yes, there are differences in allowable stress values. Your source for information is ASME B&PV Code, Section II, Table 3 - Maximum Allowable Stress Values for Bolting Materials.

The SA-574 AISI 4140 material is limited to 550 deg F. The SA 193 Grade B7 is suitable for a maximum service temp of 1000 deg F.