Coverage This specification specifies requirements for the manufacture of two product specification levels (PSL 1 and PSL 2) of seamless and welded steel pipe for use in pipeline transportation systems in the petroleum and natural gas industries. This specification is not applicable to cast pipe. Application of the API Monogram If the product is manufactured at a facility licensed by the American Petroleum Institute (API) and is intended to be supplied bearing the API Monogram@ the requirements of Annex A apply.