ASTM A320 B8M ASME VIII-1Max Temp Limit 1

[pipesvessels1]

All,

Does anyone know why ASME VIII-1 puts a max temperature limit of 100F (38^oC) on ASTM A320 B8M Class 1? Does this mean these bolts cannot be used in countries where temperatures can reach 40^oC or where the black bulb temperature can reach much higher values?

Any thoughts on the correct approach where these bolts are specified for nozzles attached to ASME B31.3 piping which does not have the same restriction on the bolting?

Any assistance is appreciated?

Kind regards,

pipes&vessels1

 

[metengr]

Because of stress relaxation over time (creep) for strain hardened material. The temperature limit means metal temperature.

 

[pipesvessels1]

Thanks metengr,

I understand it means metal temp but these metals can heat up significantly under a hot sun over the course of a day therefore rendering this material unuseable for a lot of countries. I don't understand as A320 B8M is often specified in Oil & Gas industry.

Anyone got any thoughts on the B31.3 question?

Rgds,

pipes&vessels1

 

[mrfailure]

The specification is for bolting intended for low temperature (below ambient) temperature service. I wonder if one can purchase B8M bolts that are certified to both A320 (well, technically ASME SA320) and (S)A 193? (S)A 193 are intended for elevated temperature service; such a dual certification would answer the problem presented if it is legal.

Aaron Tanzer

http://www.lehightesting.com

 

[metengr]

Dual certification is neither the issue nor concern because it boils down to specific rules and scope of application. There are many situations where Codes and Standards rules vary between different committees (B31.1, B31.3, Section VIII) because of specific applications, use and past experience. The case of SA 320 bolt material under B31.3 is one of many examples.

If you look at bolting materials under Appendix A in B31.3 there is dual certification between SA 193 and SA 320 in sharing stress lines. For B31.3 application, the maximum service temperature is well above 100 deg F for either of these bolting materials. However, read the Notes that describe cautions associated with use at higher temperatures. So, use of SA 320 above the permitted use on Section VIII, Div 1 is allowed in B31.3 provided proper evaluation is performed, like reducing stress to avoid leakage in service.