GB/T 20490-2006

This standard specifies the ultrasonic testing requirements for layered defects in seamless and welded (except submerged arc welding) steel pipes according to four acceptance grades. Acceptance grade B1 (see Table 1) is only applicable to seamless steel pipes used under certain harsh conditions, such as steam collectors. Note 1: For welded (except submerged arc welding) steel pipes, ultrasonic testing of layered defects in steel strips can also be performed before the steel pipes are formed. This standard applies to the inspection of steel pipes with a nominal outer diameter greater than 30 mm. There are no provisions for the minimum wall thickness of steel pipes. Note 2: For steel pipes with a nominal wall thickness of less than 5 mm, when it is difficult to detect and determine the size of layered defects using the methods specified in this standard, the detection methods and methods for determining the size of layered defects to be used shall be determined through consultation between the supplier and the buyer.