(5) any piping beyond the rupture disk cannot be obstructed by the rupture disk or fragment;
(6) the system is designed to consider the adverse effects of any leakage through the pressure relief valve or through the outlet side rupture disk device, to ensure system performance and reliability.
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(7) the bonnet of a balancing bellows or diaphragm type pressure relief valve shall be vented to prevent accumulation of pressure in the bonnet.
(1) Breaking pin devices shall not be used as single devices but only in combination between the pressure relief valve and the vessel.
(2) The space between a breaking pin device and a pressure relief valve shall be provided with a pressure gage, a try cock, a free vent, or suitable telltale indicator. This arrangement permits detection of breaking pin device operation or leakage.
(3) Each breaking pin device shall have a rated pressure and temperature at which the pin will break. The breaking pin shall be identified to a lot number and shall be guaranteed by the Manufacturer to break when the rated pressure, within the following tolerances, is applied to the device:
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(4) The rated pressure of the breaking pin plus the tolerance in psi shall not exceed 105% of the maximum allowable working pressure of the vessel to which it is applied.
(5) The rated pressure at the specified temperature
58 shall be verified by breaking two or more sample breaking pins from each lot of the same material and the same size as those to be used. The lot size shall not exceed 25. The test shall be made in a device of the same form and pressure dimensions as that in which the breaking pin is to be used.
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(c) Spring Loaded Nonreclosing Pressure Relief Device
(1) A spring loaded nonreclosing pressure relief device, pressure actuated by means which permit the spring loaded portion of the device to open at the specified set pressure and remain open until manually reset, may be used provided the design of the spring loaded nonreclosing device is such that if the actuating means fail, the device will achieve full opening at or below its set pressure. Such a device may not be used in combination with any other pressure relief device. The tolerance on opening point shall not exceed ±5%.
(2) The calculated capacity rating of a spring loaded nonreclosing pressure relief device shall not exceed a value based on the applicable theoretical formula (see UG-131) for the various media, multiplied by: K = coefficient = 0.62.
The area A (square inches) in the theoretical formula shall be the flow area through the minimum opening of the spring loaded nonreclosing pressure relief device.
(3) In lieu of the method of capacity rating in (2) above, a Manufacturer may have the capacity of a spring loaded nonreclosing pressure relief device design certified in general accordance with the procedures of UG-131, as applicable.
UG-128 LIQUID PRESSURE RELIEF VALVES
Any liquid pressure relief valve used shall be at least NPS ½
(DN 15).
UG-129 MARKING
(a) Safety, Safety Relief, Relief, Liquid Pressure Relief, and Pilot Operated Pressure Relief Valves. Each safety, safety relief, relief, liquid pressure relief, and pilot operated pressure relief valve NPS ½ (DN 15) and larger shall be plainly marked by the Manufacturer or Assembler with the required data in such a way that the marking will not be obliterated in service. The marking may be placed on the valve or on a plate or plates that satisfy the requirements of UG-119:
(1) the name, or an acceptable abbreviation, of the Manufacturer and the Assembler;
(2) Manufacturer's design or type number;
(3) NPS size (DN) _____ (the nominal pipe size of the valve inlet);
(4) set pressure
_____ psi (kPa), and, if applicable per UG-136(d)(4), cold differential test pressure _____ psi (kPa);
(5) certified capacity (as applicable):
(a) lb/hr (kg/hr) of saturated steam at an overpressure of 10% or 3 psi (20 kPa), whichever is greater for valves certified on steam complying with UG-131 (b); or
(b) gal/min of water at 70°F (20°C) at an overpressure of 10% or 3 psi (20 kPa), whichever is greater for valves certified on water; or
(c) SCFM [standard cubic feet per minute at 60°F and 14.7 psia] (M3/min, cubic meters per minute at 20°C and 101 kPa), or lb/min (kg/min), of air at an overpressure of 10% or 3 psi (kPa), whichever is greater. Valves that are capacity certified in accordance with UG-131 (c) (2) shall be marked “at 20% overpressure."
(d) In addition to one of the fluids specified above, the Manufacturer may indicate the capacity in other fluids (see Appendix 11).
(6) year built, or alternatively, a coding may be marked on the valve such that the valve Manufacturer or Assembler can identify the year the valve was assembled or tested;
(7) ASME Symbol as shown in Fig. UG-129.1. The pilot of a pilot operated pressure relief valve shall be plainly marked by the Manufacturer or Assembler showing the name of the Manufacturer, the Manufacturer's design or type number, the set pressure in pounds per square inch (kPa), and the year built, or alternatively, a coding that the Manufacturer can use to identify the year built.
On valves smaller than NPS ½ (DN 15), the markings may be made on a metal tag attached by wire or adhesive meeting the requirements of UG-119 or other means suitable for the service conditions.
(8) Restricted lift _____ in. (mm) (For restricted lift valves only)
(b) Safety and safety relief valves certified for a steam discharging capacity under the provisions of Section I and bearing the official Code Symbol Stamp of Section I for safety valves may be used on pressure vessels. The rated capacity in terms of other fluids shall be determined by the method of conversion given in Appendix 11. [See UG- 13l(h).]
(c) Pressure Relief Valves in Combination With Rupture Disk Devices. Pressure relief valves in combination with rupture disk devices shall be marked with the capacity as established in accordance with UG-127(a)(3)(b)(2) (using 0.90 factor) or the combination capacity factor established by test in accordance with UG-132(a) or (b), in addition to the marking of UG-129(a) and (f) below. The marking may be placed on the pressure relief valve or rupture disk device or on a plate or plates that satisfy the requirements of UG-119. The marking shall include the following:
(1) name of Manufacturer of valve;
(2) design or type number of valve;
(3) name of Manufacturer of rupture disk device;
(4) design or type number of rupture disk device;
(5) capacity or combination capacity factor;
(6) name of organization responsible for this marking. This shall be either the vessel user, vessel Manufacturer, rupture disk Manufacturer, or pressure relief valve Manufacturer.
(d) Pressure Relief Valves in Combination With Breaking Pin Devices. Pressure relief valves in combination with pin devices shall be marked with the capacity as established in accordance with UG-127 (b) (3) (b) (2) (using 0.90 factor) or the combination capacity factor established by test in accordance with UG-132 (a) or (b), in addition to the marking of UG-129 (a) and (f) below. The marking may be placed on the pressure relief valve or pin device or on a plate or plates that satisfy the requirements of UG-119. The marking shall include the following:
(1) name of Manufacturer of valve.
(2) design or type number of valve.
(3) name of Manufacturer of pin device.
(4) design or type number of pin device.
(5) capacity or combination capacity factor.
(6) name of organization responsible for this marking.
This shall be either the vessel user, vessel Manufacturer, pin device Manufacturer, or pressure relief valve Manufacturer.
(e) Rupture Disk Devices. Every rupture disk shall be plainly marked by the Manufacturer in such a way that the marking will not be obliterated in service. The rupture disk marking may be placed on the flange of the disk or on a metal tab that satisfies the requirements of UG-119. The marking shall include the following:
(1) the name or identifying trademark of the Manufacturer;
(2) Manufacturer's design or type number;
(3) lot number;
(4) disk material;
(5) size _____ [NPS (DN) of rupture disk holder];
(6) marked burst pressure _____ psi (kPa);
(7) specified disk temperature _____ °F (°C);
(8) minimum net flow area _____sq in. (sq mm);
(9) certified flow resistance (one or more as applicable);
(a) KRG _____ for rupture disk certified on air or gases;
(b) KRL _____ for rupture disk certified on liquid;
(c) KRGL _____ for rupture disk certified on air or gases, and liquid;
(10) ASME symbol as shown in Fig. UG-129.2;
(11) year built, or alternatively, a coding may be marked on the rupture disk such that the rupture disk device Manufacturer can identify the year the rupture disk device was assembled and tested.
Items (1), (2), (5), (10), and (11) above and flow direction shall also be marked on the rupture disk holder.
(f) Pin Devices and Pin Actuated Pilot Operated Pressure Relief Devices. Pin devices shall be plainly marked by the Manufacturer with the required data in such a way that the marking will not be obliterated in service. The marking may be placed on the device housing or on a plate or plates that satisfies the requirements of UG-119. The marking shall include the following:
(1) the name, or an acceptable abbreviation of the Manufacturer
(2) Manufacturer's design or type number
(3) NPS (DN) size (the nominal pipe size of the device inlet)
(4) set pressure psi (kPa)
(5) flow direction
(6) pin to pin device identifier
(7) for capacity certified devices
(a) lb/hr of saturated steam at an overpressure 10% or 3 psi (20 kPa), whichever is greater for devices certified on steam complying with UG-131(b), or
(b) gal/min of water at 70°F (20°C) at an overpressure of 10% or 3 psi (20 kPa), whichever is greater for devices certified on water, or
(c) SCFM [standard cubic feet per minute at 60°F and 14.7 psia (20°C and 101 kPa)], or lb/min, of air at an overpressure of 10% or 3 psi, whichever is greater. Devices that are capacity certified in accordance with UG-131 (c) (2) shall be marked “at 20% overpressure."
(d) In addition to one of the fluids specified above, the Manufacturer may indicate the capacity in other fluids (see Appendix 11).
(8) for flow resistance certified devices:
(a) minimum net flow area _____ in2 (mm2)
(b) certified flow resistance (one or more as applicable)
(1) KRG _____ for pin devices certified on air or gases
(2) KRL _____ for pin devices certified on liquid
(3) KRGL _____ for pin devices certified on air or gases, and liquid
(9) ASME symbol as shown in Fig. UG-129.2
(10) year built, or alternatively, a coding may be marked on the device such that the device Manufacturer can identify the year the device was tested
(11) The pin shall be marked according to one of the following methods:
