Please note that the API Monogram Program effective date for the this document's next edition is April 2021. Until then, this edition will still be considered active and not historical.This API standard specifies requirements for the qualification and production of closed die forgings for use in API service components in the petroleum and natural gas industries when referenced by an applicable equipment standard or otherwise specified as a requirement for compliance.This standard is applicable to equipment used in the oil and natural gas industries where service conditions warrant the use of closed die forgings. Examples include pressure-containing or load-bearing components.This standard establishes requirements for four different forging specification levels (FSL). These FSL designations define different levels of forged product technical, quality and qualification requirements.