API RP 90-1

This document (formerly RP 90) covers the management of annular casing pressure in existing offshore wells to maintain integrity and manage risk. It covers a range of casing annuli pressures including thermal casing pressure, sustained casing pressure (SCP) and operator-imposed pressure.
This document also addresses monitoring, diagnostic testing, establishing maximum allowable wellhead operating pressure (MAWOP) and documentation of annular casing pressure for the various types of wells that occur offshore. Included is a discussion of risk assessment methodologies that can be used for the evaluation of individual well situations where the annular casing pressure is not within the MAWOP thresholds.
This document includes information regarding annular casing pressure that is applicable to various offshore well types to include fixed platform wells, subsea wells, hybrid wells and mudline suspension wells.