Valve pressure testing

Pressure testing should be carried out; the factory inspection tests for valves are often unreliable, so it is advisable to conduct pressure testing once more as a precaution

Pressure testing shall be carried out in accordance with the specifications, especially for some key main valves.

We carry out suppression through proportional sampling; suppressing everything would be quite troublesome.

Whether a valve needs to be pressure-tested depends not on its nominal diameter, but mainly on its nominal pressure, the temperature of the medium, and the physicochemical properties of the medium. In accordance with the requirements of GB50235-97, the following valves must be pressure-tested individually; those that fail the test shall not be used: 1. Valves used for transporting highly toxic fluids, toxic fluids, or flammable fluids ； 2. Pipeline valves for non-flammable, non-toxic fluids with a design pressure greater than 1 MPa, or a design pressure of 1 MPa or less and a design temperature of less than -29 degrees Celsius or greater than 186 degrees Celsius. For valves used for transporting non-flammable, non-toxic fluids with a design pressure of less than or equal to 1 MPa and a design temperature ranging from -29 to 186 degrees Celsius, 10% of each batch shall be sampled, with a minimum of 1 valve per batch, to undergo tests for shell strength and sealing performance. Valves that cannot be pressure-tested individually can be tested together with the pipelines.

In petrochemical enterprises, ordinary valves are typically subject to pressure testing, whereas low-pressure valves that are neither flammable nor toxic usually do not need to be tested again within six months of leaving the factory. High-pressure water injection valves used in oil fields are usually not pressure-tested on-site; they are installed directly after being tested by the manufacturer prior to leaving the factory.

There are standards set by the Ministry of Chemical Industry and those set by the Ministry of Machinery for pressure testing; the main difference lies in the pressure level. Check the specifications and you’ll know!

The standards require random sampling on a proportional basis, regardless of size； In fact, many owners require 100% valve pressure testing to ensure quality.

There is a batch of stainless steel valves manufactured abroad that are of CL1500 standard (American standard), and the client has requested pressure testing to be carried out. After verification, it should be PN26; the experimental pressure of the component after conversion is 39 Mpa, while the experimental pressure indicated at the time of manufacture is 31.1 Mpa. What pressure should be used for testing?

For shell tests, use 1.5 times the maximum operating pressure of the valve at 38°C together with the maximum value of 26 MPa (39 cannot be used)； If the sealing test uses 1.1 times the operating pressure of the valve at 38°C.

We apply a 20% sampling rate for suppression.

It must be carried out in accordance with the specified requirements; it’s not the case that valves of any size do not need to undergo pressure testing – rather, the decision is based on factors such as pressure and the type of medium used. Some valves require full pressure testing, while others only need to be tested randomly.

We are required to have 100% pressure testing

Regardless of the type of valve, pressure rating, medium, or installation location, it should be pressure-tested, and all of them should be tested.

All pressure tests are carried out during the insurance period; that’s what we do.

No, it seems that pressure testing guarantees are something taken into consideration by their manufacturer

Whether pressure testing is necessary depends on the nominal pressure of the valve, as well as the nature of the medium inside the valve and its structural design. As required by regulations, valves used for fluids that are high-pressure, highly toxic, toxic, or flammable must undergo pressure testing. For valves made of ordinary materials as well, 10% of them should be selected from each delivery batch for pressure testing, in order to verify the strength and tightness of the valve body. Valves that cannot be pressure-tested separately can be tested together as part of the pipeline system pressure test.

During the project construction process, once the valves arrive, pressure testing is an essential step; generally, the test pressure is 1.5 times the design pressure

1 Pipeline components and pipe supports must be accompanied by a quality certificate issued by the manufacturer, and their quality must not be lower than the requirements of **current standards. 2 The material, specifications, models, and quality of pipeline components and pipe supports must comply with the provisions in the design documents; they must also undergo visual inspection in accordance with **current standards, and those that do not meet these requirements shall not be used. 3 For alloy steel pipeline components, the material should be rechecked using spectral analysis or other methods, and markings should be applied. The material of the internal components of alloy steel valves should be inspected randomly; for each batch (those from the same manufacturer, with the same specifications, model, and delivered at the same time), the number of samples inspected should be no less than 1. The quality of the corrosion-resistant lining in pipes must comply with the provisions of the current standard, “Specifications for the Construction and Acceptance of Corrosion Protection Works for Industrial Equipment and Pipes”. The following pipe valves must undergo pressure tests and sealing tests one by one; those that fail these tests shall not be used: (1) Valves for pipes transporting highly toxic fluids, hazardous fluids, or flammable fluids; (2) Valves for pipes transporting non-flammable, non-toxic fluids, where the design pressure is greater than 1 MPa, or where the design pressure is 1 MPa or less and the design temperature is less than -290°C or greater than 186°C. For valves used in pipes transporting non-flammable, non-toxic fluids with a design pressure of 1 MPa or less and a design temperature ranging from -29 to 186°C, 10% of the valves in each batch should be inspected randomly, with a minimum of 1 valve per batch, in order to conduct shell pressure tests and sealing tests. If they fail the inspection, additional random checks should be conducted; if they still fail, those valves shall not be used. 7 The test pressure for the valve housing shall be not less than 1.5 times the operating pressure, and the test duration shall be no less than 5 minutes; the test is considered successful if there is no leakage from the housing gasket ； The sealing test should be conducted at the nominal pressure, and it is considered successful if there is no leakage from the valve disc sealing surface. 8 Valves that have passed the tests should have any water accumulated inside them drained promptly and dried out. Except for the method that requires degreasing. The sealing surface should be coated with rust preventive oil. The valve should be closed, the inlet and outlet should be sealed off, and clear markings should be made. Additionally, the “Valve Testing Record” should be filled out in the format specified in Article A.0.1 of Appendix A to these specifications. For gate valves whose operating pressure is less than 1 Mpa and whose diameter is 600 mm or greater, it is not necessary to conduct separate tests for the shell pressure and the gate seal. The shell pressure test should be conducted at the test pressure of the piping system during the system pressure testing; the gate seal test can be verified using methods such as color marking, and the color marks on the joint surfaces should be continuous for 10 units. The safety mechanism should be adjusted according to the opening pressure specified in the design documents. The pressure should remain stable during pressure regulation; each safety valve must be tested for opening and closing at least 3 times. After the adjustment, the \"Initial Safety Valve Adjustment Record\" should be filled out in the format specified in Article A.0.2 of Appendix A of these specifications. 11 Valves with neat jackets shall be pressure-tested at a pressure equal to 1.5 times the normal operating pressure of the jacket. 12 For materials for which low-temperature impact toughness tests are required in the design documents, the supplier shall provide documentation showing the results of such tests, with the values meeting or exceeding those specified in the design documents. 13 For stainless steel pipes and fittings for which intergranular corrosion testing is required in the design documents, the supplier shall provide documents showing the results of such tests, with the criteria meeting or exceeding those specified in the design documents. 14 Pipeline components and pipe supports shall be properly protected during construction to prevent confusion or damage; their color codes or markings must be clearly visible. Pipeline components and pipe supports made of stainless steel or non-ferrous metals shall not come into contact with carbon steel during storage. Pipes that cannot be installed temporarily should have their openings sealed. The above excerpt is taken from Section 3 \"Pipeline assembly and inspection of pipeline supports\" of GB50235-97 \"Code for construction and acceptance of industrial metal piping projects\"