ASME PTC 25:2001 pdf free download – Pressure Relief Devices
2.1 PURPOSE
The purpose of this Section is to define pressure- relief devices, their functional and operational char- acteristics, and to standardize the terminology cov- ering such devices, their characteristics, and testing methods. It also includes a description of terms and symbols used in this Code. These definitions and terms shall take precedence should there be any discrepancy with the referenced material.
2.2 General
bench testing: testing of a pressure relief device on a test stand using an external pressure source with or without an auxiliary lift device to determine some or all of its operating characteristics. flow capacity testing: testing of a pressure relief device to determine its operating characteristics in- cluding measured relieving capacity. in-place testing: testing of a pressure relief device installed on but not protecting a system, using an external pressure source, with or without an auxiliary lift device to determine some or all of its operating characteristics. in-service testing: testing of a pressure relief device installed on and protecting a system, using system pressure or an external pressure source, with or without an auxiliary lift device to determine some or all of its operating characteristics. pressure reliefdevice: a device designed to prevent pressure or vacuum from exceeding a predetermined value in a pressure vessel by the transfer of fluid during emergency or abnormal conditions.
design types:
(a) rupture disk device: a device that contains a disk which ruptures when the static differential pres- sure between the upstream and downstream side of the disk reaches a predetermined value. A rupture disk device includes a rupture disk and may include rupture disk holder.
(b) breaking pin device: a device actuated by static differential or static inlet pressure and designed to function by the breakage of a load-carrying section of a pin which supports a pressure-containing member.
(c) buckling pin device: a device actuated by static differential or static inlet pressure and designed to function by the buckling of an axially-loaded compressive pin which supports a pressure-con- taining member.
(d) shear pin device: a device actuated by static differential or static inlet pressure and designed to function by the shearing of a load-carrying member which supports a pressure containing-member.
(e) fusible plug device: a device designed to function by the yielding or melting of a plug, at a predetermined temperature, which supports a pres- sure-containing member or contains pressure by itself.
(f) frangible disk device: see rupture disk device.
(g) bursting disk device: see rupture disk device.
(h) direct spring-loaded device: a device actuated by static differential pressure or static inlet pressure in which the disk is held closed by a spring. Upon actuation, the disk is held open by a latching mech- anism.
(i) pilot-operated device: a device in which the disk is held closed by system pressure and the holding pressure is controlled by a pilot actuated by system pressure. The pilot may consist of one of the devices listed above.