Issues regarding orificed tees in high-pressure natural gas pipelines
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Dear experts, I have a question: Can open-hole tees be used in high-pressure natural gas pipelines? Operating environment: The medium is a natural gas pipeline under a pressure of 10.8 MPa; the methane content is 98%, the mineralization degree of gas field water is 160,000 mg/L, the chloride ion concentration is 80,000 mg/L, and it contains a small amount of carbon dioxide. The construction party provided a reduced-diameter tee with dimensions of DN100*DN80; flanges were welded to both ends of the main pipe, and there were weld inspection reports available. The branch pipe was connected to the main pipe by welding after making holes in the main pipe, so it was not possible to conduct weld inspections on that connection. Are there any regulations regarding the use of tees that are welded with openings? What are the requirements for welding with openings? The construction deadline is tight; I urgently need an answer. Thank you!
Let’s check the calculation? It’s fine as long as the strength is sufficient. Also, regarding the medium, I’m not exactly sure.
Reference can be made to Clause 5.1.7 of GB/T 20801.3-2006 and Clause 5.4.4 of GB 50316-2000 (2008 edition); tees with welded openings can be used, but proof of their pressure-bearing capacity being at least equal to the design pressure of the pipeline, or a calculation document showing the reinforcement required due to the openings, must be provided. In design, whenever a standard tee is an option, it is generally chosen; otherwise, calculations are required.
1. A calculation report for reinforcement of the openings is required. 2. Non-destructive testing is necessary, and the welding must be thorough; at least 100% magnetic particle testing should be carried out, and 100% UT testing can be added as an extra precaution