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 Received on Tue May 04 23:45:00 2004