Don’t high-pressure steam pipes in power plants need strength testing?
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Question: If the high-pressure steam pipes supplied by a power plant follow the electrical industry standards, is it possible to omit the strength testing? I have reviewed many regulations in the power industry, which specify that the pressure value for strength testing of pipes should be 1.25 times the design pressure plus the allowable stress correction factor. However, these regulations only require a leak test to be carried out at 1.5 times the design pressure; they do not mandate a strength test. Is it possible to omit the strength test? (The pressure for the tightness test of high-pressure steam pipes is much lower than the pressure for the strength test). Strength testing is required for industrial pipelines, and the test pressure value is: 1.5 times the design pressure × allowable stress correction factor.
100% radiographic and ultrasonic non-destructive testing of the welds can replace the strength test.
Hello, it seems that industry standards vary greatly; for industrial pipelines to be exempt from strength tests, many prerequisites must be met. So, may I ask if a tightness test is also not required after 100% non-destructive testing?
Process pipelines are used in situations where strength testing is not possible, with the consent of the owner and the designer; they are typically pipelines that cannot be pressurized and have few welds
The test values for this chemical plant and the power station differ significantly, especially for high-temperature pipelines
Strictly speaking, 100% non-destructive testing of welds simply involves testing the welds themselves, without checking the strength of other components such as the pipes themselves, elbows, tees, and other pipe fittings
These are two different things. Non-destructive testing of welds only checks the welded area; it does not cover other parts such as flanges, fittings, or the sealing quality of the sealing surfaces. A sealing test is still necessary
Yes, I agree with you, but that’s how the standards in the power industry are set. For example, Clause 12.3.3 of GB50764 stipulates that for large-diameter steam pipes, 100% non-destructive testing can be used as a substitute for integrity testing. Similar provisions are also found in DL/T 5054 and others.
This post was last edited by *exz on 2016-9-5 16:57. Power industry standards often conflate hydrostatic testing with integrity testing. The hydrostatic test mentioned for industrial pipelines generally refers to a strength test, while the leakage test in industry is equivalent to the tightness test in the power sector. But the test pressures vary significantly. However, the original industrial pipes have now been classified as process pipes, and together with power pipes and refrigeration pipes, they are referred to as industrial pipes.
Of course, industrial pipelines are classified as GC, while power plant steam pipelines are classified as GD. Standards for different industries are applied separately.
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