Valve inspection and test introduction
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November 27 08:08:09, 2022
Inspection, Inspection and Complementary Inspection of Valves 1. Inspection at the valve manufacturer The buyer will specify in the order to inspect the valve at the valve manufacturer and to witness the inspection and testing of the valve. During the execution of the purchase contract, the Buyer Inspector may enter any part of the manufacturing plant related to valve manufacture at any time. 2. Inspection outside the valve factory When the purchaser specifies that the inspection includes the parts of the housing manufactured outside the valve factory, these parts should be subject to inspection by the buyer at the place of manufacture. 3, valve inspection notice When the provisions of the inspection by the buyer, the valve manufacturer should carry out the required valve test and the provisions of the supplementary inspection or inspection 5 working days, according to the order listed in the notice of the buyer. If the factory inspection is needed, the valve manufacturer shall also notify the buyer at 5 days in advance when and where it can inspect the shell parts manufactured outside the valve factory. 4, the scope of the valve inspection scope of inspection can be specified in the order, unless otherwise stated, the inspection should be limited to the following a, the valve during the assembly process to ensure compliance with the provisions of the order. Inspection may include the use of prescribed non-destructive testing methods. b, witnessed on-site needs and provides for optional pressure test and inspection. C, witness any additional testing site. d, review processing records and non-destructive testing records (including the provisions of the ray inspection records). 5, the valve test 1. Valve manufacturer should all the body, bonnet and seal casting appearance inspection to ensure compliance with the provisions of the valve MSSSP-55. 2. The valve manufacturer shall verify each valve to ensure compliance with this standard and reference procurement specifications. 3. All inspections shall be conducted in accordance with written procedures prepared in accordance with the appropriate standards. 6, the valve to add a variety of additional testing test specified in the order, and only within the provisions of the range. Magnetic powder test, ray test, liquid penetrant test and ultrasonic test of cast steel or forgings shall comply with Chapter 8 of ASME Bl6.34 or buyer's own procedures and acceptance criteria, if any. These inspections should be carried out by the valve manufacturer in the presence of the buyer inspector. 7, the valve pressure test 1) test site pressure test valve manufacturer by the valve factory. 2) Test Equipment The equipment used by the valve manufacturer to perform the required pressure tests shall not apply external forces that affect the seat seal. If the end clamp test device is used, the valve manufacturer shall verify that the test device does not affect the sealing performance of the tested valve. End clamps are suitable for valves fitted between mating flanges, such as wafer-type check valves and wafer-type butterfly valves. 3) Required Tests ①Each valve shall be subjected to the pressure tests listed in Table 1-A or Table 1-B in accordance with written procedures prepared in accordance with this standard. ② Unless otherwise stated in the order, the valve with sealing performance on the seal test can be high pressure test or low pressure test by the manufacturer choice. ③ specifications less than or equal to NPS 4 pressure rating less than or equal to ASME 1500 pounds of valves and specifications greater than NP5 4 pressure ratings less than or equal to AsME 600 pounds class valve should be tested in Table l-A. ④ specifications of less than or equal to NPS 4 pressure rating greater than AsME 1500 pounds of valves and specifications greater than NPS 4 pressure rating greater than ASME 600 pounds of valves should be tested in Table 1 a B. 4) High Pressure Seal Tests As shown in Table 1-A and Table 1-B, there are several types of valves that require high pressure seal tests. For some types of valves, high pressure sealing tests are optional, as shown in Tables 1A-A and B-B. However, these valves are still required to pass the high pressure seal test as a design of the valve seal structure. 5) High pressure gas shell test When specified in the order, high pressure gas shell test shall be carried out. High-pressure gas shell test should be carried out after the hydraulic shell test, and have the appropriate safety precautions, gas shell test pressure should be 100 (30 ℃) 110% of the maximum allowable pressure or as specified in the order No visible leaks allowed. 8, the valve pressure test method 1) Overview ①For the valve with a structure that allows the emergency or replacement of the sealing surface or filler to inject sealing grease, the injection system should be empty and ineffective during the test, the oil seal Excluding plug valves. ② When the liquid as a test medium for testing, the valve should be basically no air. ③ required protective coating, such as paint, may cover the surface defects. No coatings of this type shall be applied to any surface prior to inspection and pressure testing (phosphating or similar chemical treatments are acceptable for protecting valve surfaces and may even be performed prior to testing as long as such treatments do not obscure defects such as porosity ). ④ When the gate valve, plug valve and ball valve seal test, the valve manufacturer should be used in this test method, the valve seat and the valve cover between the valve chamber filled with medium and pressurized. This ensures that no leakage of the sealing surface is not detected due to gradual filling of the media with the test site and pressurization. ⑤ When the valve seal test, the valve manufacturer's test method should be able to ensure that you do not use excessive force to close the valve. The applied closing force can be determined from the appropriate value of MSSSP - 91, but this force must not in any case exceed the valve manufacturer 's published value. 2) Shell Tests In addition to the conditions listed in 4.3.2, the shell test shall be to pressurize the fitted valve. At this point, the valve closed at both ends, the valve part of the open, in addition to the bellows sealed valve, the packing gland pressed enough to maintain the test pressure, which also tested the stuffing box. Non-adjustable shaft seals (O-rings, single washers, etc.) should be free from leakage in the shell test. 3) Upper seal test ①All the valves with the upper seal performance should be sealed on the test, except bellows sealed valves. The test should be to have been installed within the valve pressure, this time, the valve closed at both ends, gland packing loose. The upper seal test may be carried out immediately after the shell test. The upper seal test shall be followed by re-packing of the packing gland. Valve manufacturers should not seal the valve on the success of the test, as the recommended valve pressure can be loaded or replaced when filling. ② The buyer and the valve manufacturer, when using the volume meter to detect the leakage of the shell and the seal, the upper seal test and the shell test can be combined. In this test, the filler should be relaxed. The valve manufacturer is responsible for verifying that the valve is not leaking of packing at a rated pressure of 100T (38c). 4) Low pressure seal test ①Low pressure seal test, the sealing surface should be kept clean, no oil, no grease and sealing grease. To prevent scratches, apply a layer of oil film that is not heavier than kerosene on the sealing surface. The requirements of this section do not apply to valves that lubricate the primary seal (eg, oil-tight stopcocks). ② low-pressure seal test should be carried out by one of the following methods. a. For valves designed to be bi-directional, with the exception of a dual purpose discharge valve and a stop valve, pressurize at each end of the shut-off valve in turn and open to the atmosphere at the open end to check for leakage at the open end. For the cut-off valve, the valve should be pressurized under the pressure direction. Valves marked as such with wells designed to be unidirectional shall be pressurized only at the inlet. For check valve. Pressurize at the outlet. Any leaks behind the valve seat, seat ring or through the valve disc should be checked at the open end of the valve, sealed with water or smeared with soap and water or similar solution Sealing (valve flap, valve seat and seat ring behind) , Observe the bubbles that pop up from here. In addition, leak detection may be performed using a drain gassing unit, as determined by the purchaser and the manufacturer, provided that measurable leaks correspond to the values ​​given in Table s. Air bubbles may only be tested on valves larger than NPS 2 with the purchaser's consent. b. For interrupting a discharge valve, one end of the valve should be pressurized through the valve orifice. Leakage into the valve chamber between seats should be checked at the stuffing box (at this point, without packing) or through the discharge hole between the seats. Valve test, the stem should be in the vertical position. Leakage rate at the seal should not exceed Table 5. NOTE For wedge single-gate (rigid or flexible) gate valves, pressure-test air or gas is enclosed in the body cavity between the two sealing straps and then either sealed with water or smeared with soap and water or similar solution for leak detection, This low-pressure seal test method is not recognized. ③ If there is a vent on the valve body, the valve is to be tested according to Section 8.4.2, then press ASMEBl. 20.1 Joints shall not exceed NPS 1/2. Before the valve is shipped, plug the discharge fitting with a screw-on (equivalent to ASME B16.11) of the equivalent valve housing.