Our specification calls for line pipe API-5L X52QS PSL2 for sour service meeting ISO 15156/NACE MR0170. Due to small quantity for fabricating launchers/receivers, our fabricator proposes to utilize ex-stock line pipe of API-5L X52Q. In order to meet API-5L X52QS, they propose to conduct additional testings in accordance with Annex H and Annex K of API-5L.
Whilst it is technically feasible to ensure the material meet the intent with the additional tests, Standard API 5L, however, states following restriction in re-certification by another party other than the mill/manufacturer as follow :
11.4.2 The manufacturer is responsible for ensuring that the pipe conforms to the requirements of each of the certified grades. This allows pipe to be used as any of the grades individually.
11.4.4 After delivery of the pipe, no re-marking or re-certification of the pipe to a different grade or
different PSL level (PSL 1 to PSL 2) shall be permitted.
3.1.43 pipe grade is defined as Designation of pipe strength level. NOTE Chemical composition and/or heat treatment condition of a pipe grade may differ.
May I have your interpretation to the above restriction on
1) Whether X52Q and X52QS are treated as different grades though both grades carry same TS and YS ?
2) Whether another party other than the mill/manufacturer is allowed to perform additional tests to re-certify the material ?