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ASME B31.3-2016 <br /> of discharge,they shall meet the requirements of(a)and 322.6.3 Pressure-Relieving Devices <br /> either (b) or (c),below. (a) Pressure-relieving devices required by <br /> (a) A full-area stop valve may be installed on the inlet para. 301.2.2(a) shall be in accordance with the BPV <br /> side of a pressure-relieving device.A full area stop valve Code, Section VIII, Division 1, UG-125(c), UG-126, <br /> may be placed on the discharge side of a pressure- UG-127, and UG-132 through UG-136, excluding <br /> relieving device when its discharge is connected to a UG-135(e) and UG-136(c). The terms design pressure10 <br /> common header with other discharge lines from other and piping system shall be substituted for maximum <br /> pressure-relieving devices. Stop valves of less than full allowable working pressure and vessel,respectively,in these <br /> area may be used on both the inlet side and discharge paragraphs. The required relieving capacity of any <br /> side of pressure-relieving devices as outlined herein if pressure-relieving device shall include consideration of <br /> the stop valves are of such type and size that the increase all piping systems that it protects. <br /> in pressure drop will not reduce the relieving capacity (b) Relief set pressurell shall be in accordance with <br /> below that required, nor adversely affect the proper Section VIII, Division 1, with the exceptions stated in <br /> operation of the pressure-relieving device. alternatives (1) and (2),below. <br /> (b) Stop valves to be used in pressure relief piping (1) With the owner's approval the set pressure may <br /> shall be so constructed or positively controlled that the exceed the limits in Section VIII, Division 1, provided <br /> closing of the maximum number of block valves possible that the limit on maximum relieving pressure stated in <br /> at one time will not reduce the pressure-relieving capac- (c) below will not be exceeded. <br /> ity provided by the unaffected relieving devices below (2) For a liquid thermal expansion relief device that <br /> the required relieving capacity. protects only a blocked-in portion of a piping system, <br /> (c) As an alternative to (b) above, stop valves shall the set pressure shall not exceed the lesser of the system <br /> be so constructed and arranged that they can be locked test pressure or 120/o of design pressure. <br /> 12 <br /> or sealed in either the open or closed position. See (c) The maximum relieving pressure shall be in <br /> accordance with Section VIII,Division 1,with the excep- <br /> tion that the allowances in para.302.2.4(f)are permitted, <br /> 322.6.2 Pressure Relief Discharge Piping. Discharge provided that all other requirements of para. 302.2.4 are <br /> lines from pressure-relieving safety devices shall be also met. <br /> designed to facilitate drainage. When discharging 10 The design pressure for pressure relief is the maximum design <br /> directly to the atmosphere,discharge shall not impinge pressure permitted, considering all components in the piping <br /> on other piping or equipment and shall be directed away system. <br /> from platforms and other areas used by personnel.Reac- 11 Set pressure is the pressure at which the device begins to relieve, <br /> tions on the piping stem due to actuation of safety e.g.,lift pressure of a spring-actuated relief valve,bursting pressure <br /> p p g system y of a rupture disk,or breaking pressure of a breaking pin device. <br /> relief devices shall be considered,and adequate strength 12 Maximum relieving pressure is the maximum system pressure <br /> shall be provided to withstand these reactions. during a pressure relieving event. <br />