Impact test temperature confusion in acceptance

[gkvengat]

Dear friends,
i facing one problem.I gave a job to sub-vendor,to make a spool for low temprature service(operating temp.-9 degree C).The sub vendor completed the job with already qualified WPS & PQR of material A333 with impact test temperature at -20 degree C.But our client requirement is A333 Gr.6,its imapct test requirement temperature is -45 degree C as per standard.

Now,is the spool is acceptable depon as per operating temp.-9 degree C.can i move futher to approach my client regarding the acceptance ofthis spool

 

[BigInch]

Normally an impact test at a temperature equal to, or less than, design temperature is necessary. There would be no reason to require an impact test at -45, if the pipe will never reach that temperature.

Your client's specs require impact testing at -45C temperature, because that is the lowest temperature that ASTM A333 Gr6 can be used. They obviously want to make sure that testing allows the entire temperature envelop to be used for that material.

I think it is somewhat unusual to be using ASTM A333 when your temperatures are above -20F, as low alloy carbon steel can generally be used down to -20F.

I would say it is OK, as the expected low temperature of -9 is greater than the test temperature of -20C. Ask your client to approve the material you used under a variance order issued for their typical specification.

Independent events are seldomly independent.

 

[LittleInch]

It all depends what the design temp is. Operating is useful info, but it's the design temp that matters most.

Even if this is the same as the test temp, you may be able to extrapolate the energy values down another 10 or 20 degrees and still meet the test requirment. A metalurgist will need to assess the tests and temperatures.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[gkvengat]

THANK U FRIENDS...........