It is my understanding that only an "R" certificate holder may perform routine repairs, repairs and alterations.
2011 NBIC Part 3 states;
3.3.2 Routine Repairs
a) Routine repairs are repairs for which the requiremnts for in porcess involvement by the Inspector and stamping by the "R" Certificate Holder may be waived as determined appropriate by the Jusirdiction and the Inspector. All other applicable requirements of this Code shall be met. Prior to performing routine repairs, the "R" Certificate Holder should deterine that routine repairs are acceptable to the Jurisdication where the pressure retaining item is installed;
b) The Inspector, with the knowledge and understanding of the jurisdicational requirements, shall be responsible for meeting jurisdiction requirements and the requirements of this Code.
c) The "R" Certificate Holder's Quality System Program shall describe the process for identifying, controlling, and implementing routine repairs. Routine repairs shall be documented on For R-1 with this statement.
Further information describes the categories that may be considered routine.
My advice would be to contact the National Board Member in that jurisdiction which would be Michael Graham for Oregon, Luis Ponce for Texas however I see in the OP's profile he is from Egypt and am unfamiliar with jurisdication there.