Re: Impact test temperature

From: <Gordon.Reddek@Alcan.com>
Date: Wed May 05 2004 - 03:12:00 EDT

Sajit,

GOOD question. I believe the answer is an error in the DEP. -50F is in fact -45.6C. I have a book that lists ASTM333-gr6 as requiring an impact test of -50F or -46C. The same book lists the impact testing requirement of A350 LF2 as -50F or -45.6C. So it appears as though you could have tested that flange at -45.6C. Brittle fracture is nasty stuff. It would obviously always be safer to test at a lower temperature. It would be interesting to know if that flange survives at -45.6C.

Regards,

Gordon Reddek

Sajit Viswan <sviswan@tebodin.co.om> 05/05/2004 01:45 PM
Please respond to PipingDesign

         To:     "PipingDesign. com (E-mail)" <pipingdesign@yahoogroups.com>
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         Subject:        [PipingDesign] Impact test temperature

The Shell DEP on "Metallic materials - Prevention of brittle fracture" states that,

For a lower design temperature between -50 °C and 0 °C, impact tested carbon steel (e.g., for piping, ASTM A 333-gr 6) shall be used, with the impact testing having been performed at -46 °C with an average impact value of 27J.

Can anyone clarify why it is enough to impact test at -46 deg C than at the -50 deg C design. Though the difference of 4 deg C may not any appreciable significance.

Can the same be applied to ASTM A350 Gr LF2 flange.

To qualify a WPS for the welding of a A350 Gr LF2 flange an impact test was done at -50 deg C. The test, I believe was done in accordance to that specified in the ASTM specification. The test resulted in a failure.

Sajit

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[Non-text portions of this message have been removed] Received on Wed May 05 03:12:00 2004