API Spec 20B PDF
This specification identifies requirements for the forging manufacturer qualification, production, marking, and documentation of open die shaped forgings for use in the petroleum and natural gas industries when referenced by an applicable equipment standard or otherwise specified as a requirement for compliance.
This specification is applicable to equipment used in the oil and natural gas industries where service conditions warrant the use of individually shaped open die forgings, including rolled rings. Examples include pressure-containing or load-bearing components. Forged bars, rolled bars, and forgings from which multiple parts are removed are beyond the scope of this specification.
This specification establishes requirements for four forging specification levels (FSL). These four FSL designations define different levels of forged product technical, quality, and qualification requirements.