The purpose of the IOGP S-612 specification documents is to define a minimum common set of requirements for the procurement of packaged, integrally geared centrifugal air compressors in accordance with API Standard 672, 5th Edition, August 2019, Packaged, Integrally Geared Centrifugal Air Compressors for Petroleum, Chemical and Gas Industry Services for application in petroleum and natural gas industries. The IOGP S-612 specification documents follow a common structure comprising a specification, also known as a technical requirements specification (TRS), a procurement data sheet (PDS), an information requirements specification (IRS) and a quality requirements specification (QRS). These four specification documents, together with the purchase order, define the overall technical specification for procurement.