Regarding the pressure testing of pipelines at atmospheric pressure

Pipelines all need to be purged, pressure-tested, and leak-tested

To ensure the safe operation of pipelines, pressure testing and pipeline purging are generally required after the pipelines have been installed. The typical test pressure in our factory is 1 times the working pressure. 25~1. 5 times.

Atmospheric pressure pipelines must be leak-tested. During the leak test, pressure testing was also carried out, with the pressure kept at less than 1.5 times the specified value.

This post was last edited by summersch on 2010-10-18 09:19. Thank you all for your generous help. I’m sorry, does \"leak testing\" mentioned here refer to a leakiness test? If so, it’s a different concept. Pipe pressure resistance (strength) testing includes hydraulic and pneumatic tests. For pipes subjected to internal pressure, the test pressure is 1.5 times the design pressure (it’s important to consider whether there is a large difference between the design temperature and the test temperature; if so, the allowable stress at the design temperature must be taken into account). For pipes subjected to external pressure (such as vacuum tubes), a pressure of 0.2 MPa is generally used, though the difference between internal and external pressures also needs to be considered ； However, the test pressure for leakage tests is generally taken as the design pressure, and the test medium is usually air. I hope some experienced designers can give us some guidance. Both GB50316 and GB50235 stipulate that pipes subjected to pressure must undergo strength tests. SH3501 states that \"pipeline systems\" need to undergo strength tests, but this applies only to pipes carrying toxic or flammable media in the petrochemical industry. He doesn’t care whether he is under pressure or not.

First, the design pressure is determined. Each design agency has its own rules regarding the determination of this pressure; for example, the design pressure = operating pressure + 0.18 MPa. If the operating pressure for a pipeline under normal conditions is 0 MPa, then the design pressure is 0.18 MPa. According to the standards, the pressure used for pressure testing should be 1.5 times the design pressure, which is 0.27 MPa. If the medium inside the pipeline is toxic or flammable, an integrity test is also required, with the test pressure being equal to the design pressure.

The medium used for the strength testing of pipelines is usually liquid (water); pneumatic testing is employed as a substitute only when using liquids proves difficult. The strength test is primarily aimed at assessing the operational strength of the pipeline under simulated working conditions after it has been installed, as well as whether the support and hanger systems are properly installed (to ensure that excessive stress is not generated). On the other hand, the gas leakage test is carried out on pipelines carrying toxic or flammable substances, with the main purpose of preventing leaks of such substances from causing harm to people or leading to fire accidents. The SH3501 standard specifies that the \"piping system\" must undergo a gas leakage test, with the test pressure being the design pressure.

I’m sorry, but first of all I don’t understand why the design pressure of a pipeline with operating pressure at atmospheric pressure needs to be increased Secondly, you didn’t read my question carefully. I don’t understand why the specifications state that a strength test refers to pipes subjected to internal or external pressure; it’s clear that the decision regarding whether a strength test is necessary is not based on the design pressure. The design pressure is merely used to determine the test pressure for pipes that require a strength test.

Standards are also created by humans, and the so-called pressure-bearing pipes are a vague concept as well. For example, in the case of pipes operating at atmospheric pressure, if it can be ensured that such pipes remain at atmospheric pressure at all times and under all extreme conditions, then the design pressure can be set at atmospheric pressure; in such cases, no strength testing is required for these pipes ； Otherwise, the design pressure will not be 0, and a strength test will be required. (In fact, the design pressure is determined as the highest pressure resulting from the overall conditions of the pipeline; when the exact value cannot be determined and there is a risk of overpressure, it is possible to use the operating pressure plus a safety margin in accordance with the relevant standards.)

Pressures higher than normal pressure can also occur at atmospheric pressure; therefore, for safety reasons, it is highly necessary to conduct tests at pressures above normal pressure

Hello! Where in GB50235 is it specified that pressure pipelines need to undergo pressure testing?