NDT Dwell Times & AWS Codes

Date 03-27-2002 22:42

According to our Canadian Welding Code W47.1, “When NDT is specified the examination of welded joints subject to high restraint and/or joints of QT steels shall be delayed as long as practicable and preferably not less than 48 hours after completion of the welds.”

Is there a similar requirements in any of the AWS Codes for welded joints similar to high restraint? Our application is the fabrication of a replacement component off an industrial crane. I have found a similar requirement for air-hardenable material in AWS D14.1, but not specifically for highly restrained welded joints. Is there such a requirement for restrained welds in any of the AWS Codes? If anyone out there could point me out in the right direction it would be greatly appreciated.

-Sean

By R. Johnson (**)

Date 03-28-2002 15:34

AWS D1.1 has the same requirement for ASTM A514 and A517 (QT)steels, see section 6.11. But AWS seems to take a different approach on highly restrained joints to avoid cold cracking, 1) heat-affected zone hardness control and 2) hydrogen control. See Annex XI in AWS D1.1. They are mainly using preheat to avoid cracking and give recommendations for low, medium and high restraint.
From a practical point of view there would be an advantage in delaying inspection if delayed cracking is of concern. So even if the welding code does not address the delayed inspection, your contract specification could and should address your concern.