"This chapter presents a general description of the various types of automatic pressure-relieving devices commonly used in the oil and petrochemical industries. It is intended as a guide for the inspection and control of these devices in the user's plant to assure proper performance. Inspections and tests made at manufacturers' plants are usually covered by codes or purchase specifications and are not included in this text. Automatic devices such as spring-loaded pressure-relief valves (safety@ safety-relief@ and relief valves)@ spring-loaded pilot-operated valves@ and rupture disks are included; but such devices as ""weak"" seams or sections in tanks@ explosion doors@ fusible plugs@ devices depending on an external source of power (such as control valves) for operation@ and manually operated devices are not covered in this chapter. The information presented is not intended to supersede requirements established by regulatory bodies for the inspection and control of pressure-relieving devices."