Standard specification for thin wall stainless steel water pipes

At present, the Water Supply and Drainage Products Standardization Committee of the Ministry of Construction has organized experts to review and pass two industry standards for thin-walled stainless steel water pipes and stainless steel compression pipe fittings, and the approval draft has been submitted to the Ministry of Construction. The key points of the above two standards are now introduced as follows:

1 “Thin-walled stainless steel water pipe”

1.1 This standard is based on the national standard GB/T12771-2000 “Stainless steel welded steel pipes for fluid transportation”, the European standard DINEN10312-1999 “Stainless steel pipes and fittings for liquid (including drinking water) transportation”, and the British standard BS4127-1994 “Main Thin-walled stainless steel pipes for water transportation” and Japanese standard JISG3448-1997 “Stainless steel pipes for general pipes”, and are formulated according to national conditions.

1.2 Range: DN≯150mm, working pressure≯1.6MPa. It can transport purified drinking water, domestic drinking water, hot water and high-temperature water with a temperature of ≯135℃.
1.6 Appearance The surface of the water pipe weld should be free of cracks, pores, undercuts, and slag inclusions. The inside and outside should be well processed, and there should be no scratches, pits, straightening marks and other defects that exceed the negative tolerance of the water pipe wall thickness. The fracture should be free of burrs. The rest should comply with the requirements of clause 5.7 in the GB/T12771-2000 standard.

Note: The medium-thick wall pipes in the wall thickness column in the table are for stainless steel compression fittings.

1.7.2 The allowable deviation of the wall thickness of water pipes is ±10% of the nominal wall thickness.

1.7.3 The length of the water pipe is a fixed length, generally 3000~6000mm. According to the requirements of the buyer and the agreement between the supplier and the buyer, other fixed lengths can also be provided, and the allowable deviation is mm. 1.7.4 The curvature of the water pipe shall not exceed 12mm for any length of 3000mm. 1.7.5 The ends of water pipes should be cut flat, and the bevel at the ends of water pipes should comply with the regulations.

1.8 Raw materials and manufacturing methods 1.8.1 The raw materials of water pipes are swiss machining stainless steel cold (hot) rolled steel strips, and their requirements should comply with the regulations of GB/T4239 and YB/T5090.

Stainless steel strips for water pipes are made by automatic argon arc welding or plasma welding on pipe making equipment, and generally no heat treatment is performed after welding.

1.9 Flattening performance When the water pipe is flattened for testing, the distance between the water pipe and the pressure plate should be 1/3 of the outer diameter of the water pipe. No cracks or damage should occur after flattening.

1.10 Expansion performance When conducting expansion tests on water pipes with a nominal diameter of no more than DN50mm, a 60° cone shall be used, with an expansion rate of 25%. The pipe wall shall not be cracked or damaged after expansion.

1.11 Bending performance When a water pipe with a nominal diameter of no more than DN25mm is subjected to a bending test, the bending radius is equal to 4 times the outer diameter of the water pipe. When the bending angle is 90°, there should be no cracks or wrinkles on the pipe wall.

1.12 Hydraulic pressure test and air tightness test

1.12.1 When a water pipe is subjected to a hydraulic test, the test pressure is 2.45MPa. Under this pressure, after 10 seconds, the water pipe should have no leakage or permanent deformation.

1.12.2 When water pipes undergo hydraulic gas medium or formal inspection, an air tightness test shall be carried out. The pressure for liquid medium is 0.6MPa, and the test pressure for gas medium is 1.7MPa. After the water pipe is completely immersed in water for 10 seconds, the water pipe shall No bubbles appear.

1.12.3 When water pipes are subjected to eddy current flaw detection, their artificial standard defects (drilling diameter) should comply with Level A in GB/T7735.

1.13 Hygiene requirements

When required by the user or during type inspection, the hygienic requirements for water pipes used for drinking purified water and domestic drinking water after immersion shall comply with GB/T17219

Provisions.

2 “Stainless Steel Pressure Fittings”

2.1 The pipe fitting structure type of this standard is equivalent to the extrusion type fitting part of the Japanese Waterworks Association standard JWWWA G 116-1982 “Stainless Steel Pipe Fittings for Waterways”. The process performance of this standard pipe fitting is not equivalent to the Japan stainless-steel-alloy-430-fr standard SAS 322-1995 “Performance Standard of Stainless Steel Pipe Fittings for General Piping”.

2.2 Range: DN≯65 mm, working pressure≯1.6MPa, can input drinking water, domestic drinking water, pure water, hot water and high temperature not exceeding 135℃.

2.3 The types, types and codes of pipe fittings are shown in Table 6.

2.4 The materials of pipe fittings are 0Cr18Ni9 (304) 0Cr17Ni12Mo2 (316) and Cr17Ni14o2 (316L). When extruded, the materials should comply with the regulations in CJ/T × × × × “Thin-walled Stainless Steel Water Pipes”. When using steel strip stamping, it should comply with the regulations in GB/T4239 and GB/T5059.

Note: 1. Both ends of Type A connector are sockets.

2. Type B interface has a socket at one end and a straight pipe at the other end.

2.5 The O-rings used in pipe fittings are generally made of butyl rubber. When the angle is greater than 80°, silicone rubber should be used. Its basic dimensions, technical requirements, experimental methods, inspection rules and markings, packaging, transportation, and storage are in accordance with Appendix A (the appendix of the standard).

2.6 The appearance of the pipe fittings should be clean and smooth. The weld surface should be free of cracks, pores, undercuts and other defects. Slight mold marks are allowed on the outer surface. Longitudinal scratches should not be greater than 10% of the nominal wall thickness.

2.7 The wall thickness of pipe fittings should not be less than the corresponding wall thickness negative deviation requirements specified in CJ/T × × × × “Thin-Walled stainless steel parts Water Pipes”.

2.8 Hydraulic performance

5% (no less than five) of each batch of products should be sampled for a hydraulic performance test. The test pressure is 2.45 MPa. Under this pressure, after 15 seconds, the pipe fittings should have no leakage or permanent deformation.

2.9 Air tightness

When pipe fittings are used for gas media or type inspection, an air tightness test should be carried out. The air tightness test pressure for liquid media is 0.6 MPa, and the air tightness test pressure for gas media is 1.7 MPa. After the pipe fittings are completely immersed in water for 10 seconds, the pipe fittings There should be no air bubbles.

2.10 Connection performance

When required by the user or during type inspection, a connection performance test should be carried out. The test pieces are equal-diameter butt joints at both ends and are clamped and connected to thin-walled stainless steel water pipes of appropriate length to form a set of samples for pressure test, pull-out test, Vibration test and pressure fluctuation test.

2.10.1 Withstand voltage test

When conducting the pressure test, the test pressure is 2.45 MPa. Under this pressure, after 2 minutes, there should be no leakage or falling off at the connection parts of the pipe fittings and pipes.

2.10.2 Pull-out test

When performing a pull-out test, stretch at a speed of 1-4mm/min until the pipe fitting is separated from the pipe. The tensile force at this time should be greater than the minimum tensile resistance. The minimum tensile resistance of the pipe fitting.

2.10.3 When conducting a vibration test, the test pressure is 1.75 MPa. Under this pressure, the number of vibrations continues for 100,000 times. There should be no leakage or falling off at the connection parts of the pipe fittings and pipes.

2.10.4 Pressure fluctuation test

When conducting pressure fluctuation tests, when required or when type testing, pipe fittings used to transport purified drinking water and domestic drinking water, the hygienic requirements after immersion should comply with the provisions of GB/T1721.