Section 20.12 - Welding - Qualification and Nondestructive Testing(1) All welding must be performed by qualified welders employing qualified welding procedures, in accordance with the American Welding Society Standard Welding Procedure Specifications.(2) Welds subjected to temperatures over 350EF (175EC) on pipe over six inches in diameter shall be subject to nondestructive testing by radiographic inspection in accordance with 220 CMR 20.12(3) and (4).(3) All underground buried field welds greater than 21/2 inches in diameter in new Main and Service Piping installations and all prefabricated shop welds shall be nondestructively tested prior to being placed in service.(4) Each Steam Distribution Company shall establish a program of random, unannounced, nondestructive testing for new accessible field welds made on existing Main and Service Piping, to assess the quality of welding and the work of each welder. The required minimum testing rate shall be 10% of all welds made during a calendar month. If 10% or more of the welds tested in a calendar month are found to be unacceptable, the test rate shall increase by 5% for the ensuing calendar month. If fewer than 10% of the welds are found to be unacceptable in a calendar month where the required test rate was greater than 10%, the test rate may be decreased by 5% for the ensuing calendar month.Amended by Mass Register Issue 1468, eff. 4/29/2022.Amended by Mass Register Issue 1470, eff. 4/29/2022.