1、Seat Tightness of Pressure Relief ValvesAPI STANDARD 527 FOURTH EDITION, NOVEMBER 2014Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed.Neither API nor any of API
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4、do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss
5、or damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict.API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obvia
6、te the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices.Any manufacturer marking equipment or materials in confo
7、rmance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard.Users of this Standard should not rely
8、 exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein.All rights reserved. No part of this work may be reproduced, translated, stored in a retrieval system, or transmitted
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11、f letters patent.Shall: As used in a standard, “shall” denotes a minimum requirement in order to conform to the specification.Should: As used in a standard, “should” denotes a recommendation or that which is advised but not required in order to conform to the specification.This document was produced
12、 under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which t
13、his publication was developed should be directed in writing to the Director of Standards, American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director
14、.Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of AP
15、I publications and materials is published annually by API, 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . . . .
16、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Testing with Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、. 12.1 Test Apparatus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、. . . . . . . . . . . . . . . . . . . . . 22.3 Acceptance Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Testing with Steam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.1 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Acceptance Criteria. . . . . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Testing with Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.1 Procedure . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.2 Acceptance Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、. . . . . . 45 Testing with AirAnother Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.1 Type of Valve to be Tested . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . . . 45.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.3 Acceptance Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Figures1 Apparatus to Test Seat Tightness with Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Device to Relieve Body Pressure Caused by Accidental Popping of the Valve . . .
25、. . . . . . . . . . . . . . . . . . 2Table1 Maximum Seat Leakage Rates for Metal-Seated Pressure Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . 3v1Seat Tightness of Pressure Relief Valves1 ScopeThis standard describes methods of determining the seat tightness of metal- and soft-
26、seated pressure relief valves, including those of conventional, bellows, and pilot-operated designs.The maximum acceptable leakage rates are defined for pressure relief valves with set pressures from 103 kPa gauge (15 psig) to 41,379 kPa gauge (6000 psig). If greater seat tightness is required, the
27、purchaser shall specify it in the purchase order.The test medium for determining the seat tightnessair, steam, or watershall be the same as that used for determining the set pressure of the valve.For dual-service valves, the test mediumair, steam, or watershall be the same as the primary relieving m
28、edium.To ensure safety, the procedures outlined in this standard shall be performed by persons experienced in the use and functions of pressure relief valves.CautionWhen looking for leakage, the observer shall use a mirror or some other indirect means of observation so that the observers face is not
29、 in line with the outlet of the valve, in case the valve accidentally pops.2 Testing with Air2.1 Test ApparatusA test arrangement for determining seat tightness with air is shown in Figure 1. Leakage shall be measured using a tube with an outside diameter of 7.9 mm (5/16 in.) and a wall thickness of
30、 0.89 mm (0.035 in.). The tube end shall be cut square and smooth. The tube opening shall be 12.7 mm (1/2 in.) below the surface of the water. The tube shall be perpendicular to the surface of the water.Arrangement shall be made to safely relieve or contain body pressure in case the valve accidental
31、ly pops (see Figure 2). Figure 1Apparatus to Test Seat Tightness with AirRanged or threadedoutlet adapter forpressure relief valveTube with outside diameter of 7.9 mm (5/16 in.) and wall thickness of 0.89 mm (0.035 in.)12.7 mm (1/2 in.)WaterNOTE See Figure 2 for an example of a device to relieve bod
32、y pressure in case the valve accidentally pops.2 API STANDARD 5272.2 Procedure 12.2.1 Test MediumThe test medium shall be air (or nitrogen) near ambient temperature.2.2.2 Test ConfigurationThe valve shall be vertically mounted on the test stand, and the test apparatus shall be attached to the valve
33、outlet, as shown in Figure 1. All openingsincluding but not limited to caps, drain holes, vents, and outletsshall be closed. See Figure 2 for an example of a device to relieve body pressure in case the valve accidentally pops.2.2.3 Test PressureFor a valve whose set pressure is greater than 345 kPa
34、gauge (50 psig), the leakage rate in bubbles per minute shall be determined with the test pressure at the valve inlet held at 90 % of the set pressure. For a valve set at 345 kPa gauge (50 psig) or less, the test pressure shall be held at 34.5 kPa (5 psi) less than the set pressure.2.2.4 Leakage Tes
35、tBefore the leakage test, the set pressure shall be demonstrated, and all valve body joints and fittings should be checked with a suitable solution to ensure that all joints are tight.Before the bubble count, the test pressure shall be applied for at least one minute for a valve whose nominal pipe s
36、ize is 50 mm (2 in.) or smaller; two minutes for a valve whose nominal pipe size is 65 mm, 80 mm, or 100 mm (21/2 in., Figure 2Device to Relieve Body Pressure Caused by Accidental Popping of the Valve1Users of procedures should not rely exclusively on the information contained in this document. Soun
37、d business, scientific, engineering, and safety judgment should be used in employing the information contained herein. Where applicable, authorities having jurisdiction should be consulted.Soft rubber gasket attach to face of detector to prevent leakageCup weld todetectorC-clampAir pressureSafety va
38、lveMembrane seals during test and bursts if valve accidentally opens12.7 mm (1/2 in.)Outlet tube cut end smooth and squareWater level control hole-maintain 12.7 mm (1/2 in.) from bottom of tube to bottom of holeSEAT TIGHTNESS OF PRESSURE RELIEF VALVES 33 in., or 4 in.), and five minutes for a valve
39、whose nominal pipe size is 150 mm (6 in.) or larger. The valve shall then be observed for leakage for at least one minute.2.3 Acceptance CriteriaFor a valve with a metal seat, the leakage rate in bubbles per minute shall not exceed the appropriate value in Table 1. For a soft-seated valve, there sha
40、ll be no leakage for one minute (0 bubble/min). 3 Testing with Steam3.1 Procedure 23.1.1 Test MediumThe test medium shall be saturated steam.3.1.2 Test ConfigurationThe valve shall be vertically mounted on the steam test stand.3.1.3 Test PressureFor a valve whose set pressure is greater than 345 kPa
41、 gauge (50 psig), the seat tightness shall be determined with the test pressure at the valve inlet held at 90 % of the set pressure. For a valve set at 345 kPa gauge (50 psig) or less, the test pressure shall be held at 34.5 kPa (5 psi) less than the set pressure.3.1.4 Leakage TestBefore starting th
42、e seat tightness test, the set pressure shall be demonstrated, and the test pressure shall be held for at least three minutes. Any condensate in the body bowl shall be removed before the seat tightness test. Air (or nitrogen) may be used to dry condensate.Table 1Maximum Seat Leakage Rates for Metal-
43、Seated Pressure Relief ValvesSet Pressure at 15.6 C (60 F)kPa (psig)Orifice Diameter Less Than or Equal to 18 mm (0.700 in)Orifice Diameter Greater Than 18 mm (0.700 in)Leakage Rate(Bubbles/min)Approximate Leakage/24 hrStandard m3(ft3)Leakage Rate(Bubbles/min)Approximate Leakage/24 hrStandard m3(ft3
44、)13 to 6896 (15 to 1000) 40 0.017 (0.60) 20 0.0085 (0.30)10,300 (1500) 60 0.026 (0.90) 30 0.013 (0.45)13,800 (2000) 80 0.034 (1.20) 40 0.017 (0.60)17,200 (2500) 100 0.043 (1.50) 50 0.021 (0.75)20,700 (3000) 100 0.043 (1.50) 60 0.026 (0.90)27,600 (4000) 100 0.043 (1.50) 80 0.034 (1.20)34,400 (5000) 1
45、00 0.043 (1.50) 100 0.043 (1.50)41,400 (6000) 100 0.043 (1.50) 100 0.043 (1.50)2Users of procedures should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. Wh
46、ere applicable, authorities having jurisdiction should be consulted.4 API STANDARD 527After any condensate has been removed, the inlet pressure shall be increased to the test pressure. Tightness shall then be checked visually using a black background. The valve shall then be observed for leakage for
47、 at least one minute.3.2 Acceptance CriteriaFor both metal- and soft-seated valves, there shall be no audible or visible leakage for one minute.4 Testing with Water4.1 Procedure 34.1.1 Test MediumThe test medium shall be water near ambient temperature.4.1.2 Test ConfigurationThe valve shall be verti
48、cally mounted on the water test stand.4.1.3 Test PressureFor a valve whose set pressure is greater than 345 kPa gauge (50 psig), the seat tightness shall be determined with the test pressure at the valve inlet held at 90 % of the set pressure. For a valve set at 345 kPa gauge (50 psig) or less, the
49、test pressure shall be held at 34.5 kPa (5 psi) less than the set pressure.4.1.4 Leakage TestBefore starting the seat tightness test, the set pressure shall be demonstrated, and the outlet body bowl shall be filled with water, which shall be allowed to stabilize with no visible flow from the valve outlet. The inlet pressure shall then be increased to the test pressure. The valve shall then be observed for 1 minute at the test pressure.4.2 Acceptance CriteriaFor a metal-seated valve whose inlet has a nominal pipe size of 1 in. or larger, the leakage rate shall not exc
