【SeaChuan Safety Discussion】Hidden Dangers Around Us – Flange bolts used in natural gas systems not selected according to requirements
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Walk every day, and you need not fear thousands of miles； Do it often, and you won’t fear a thousand things. Learn one safety in production knowledge point every day, continuously strengthen memory, and improve professional skills in safety in production. As a worker, the more vigilant you are, the greater your chances of survival ； As a business manager, more strictness means less risk. Only by treating every detail with professionalism can the safety goal of \"zero accidents\" be truly achieved. Safety is never a \"choice question\" but a \"must-answer question.\" There is no such thing as “more or less” when it comes to safety; there is only “100%”. A little more careful inspection today means fewer risks of accidents tomorrow. Security management is never a matter of focusing on the big issues while ignoring the small ones. The significance of identifying potential hazards lies in turning \"invisible risks\" into \"visible actions for correction.\" We firmly believe that every improvement in safety awareness and every enhancement in protective capabilities serves to build a stronger shield for lives and ensure safety for businesses. Keep hidden dangers in sight and have safety by your side at all times! --------------------------------------------------------------------- All marine enthusiasts are welcome to participate in the discussion and share their insights on this thread: [HaiChuan Safety Discussion] – A compilation of potential hazards around us. https://bbs.hcbbs.com/thread-5705518-1-1.html HaiChuan becomes even better with you all ------------------------------------------------------------------------------------------------------
Basis: 1. GBT43079.1-2023, \"Specifications for the selection of steel pipe flanges, gaskets, and fasteners – Part 1: PN series\", 6.2.3 Hex head bolts are suitable for applications with a nominal pressure of less than or equal to PN16 (1.6 Mpa), where the medium is non-toxic, non-flammable, not subject to severe cycling conditions, and metal-free flat gaskets are used. 6.2.4 Equal-length double-headed studs are suitable for nominal pressures of less than or equal to PN40 (4.0 Mpa), where the medium is non-toxic, non-flammable, and under conditions of no severe cycling. 6.2.5 Fully threaded studs are suitable for all nominal pressure classes, media, operating conditions, and gasket types. 6.2.6 Type 1 nuts are suitable for use with hex head bolts as well as equal-length double-headed studs. 6.2.7 The nuts used in conjunction with fully threaded studs shall be type 2 nuts designed specifically for pipe flanges. 6.2.8 Fasteners shall meet the sealing requirements of flange joints under pre-tensioning and operating conditions. II. Specifications for the Selection of Steel Pipe Flanges, Gaskets, and Fasteners – Part 2: Class Series GBT43079.2-2023 6.2.3 Hex head bolts are suitable only for applications with a nominal pressure of less than or equal to Class300 (5 Mpa), where the medium is non-toxic, non-flammable, not subject to severe cycling conditions, and metal-free flat gaskets are used. 6.2.4 Type 1 nuts are suitable only for applications with a nominal pressure of less than or equal to Class 300, and are used in conjunction with hex head bolts. 6.2.5 Fully threaded studs are suitable for all nominal pressure classes, media, operating conditions, and gasket types. 6.2.6 The nuts used in conjunction with fully threaded studs shall be type 2 nuts designed specifically for pipe flanges. 6.2.7 Fasteners shall meet the sealing requirements of flange joints under pre-tensioning and operating conditions. III. \"Fasteners for Steel Pipe Flanges (PN Series)\\" HGT20613-2009 5.0.1 The operating conditions for commercial-grade hex head bolts and type 1 hex nuts shall meet the following requirements: 1. The nominal pressure class shall be less than or equal to PN16. 2. Non-toxic, non-flammable media and applications without severe cycling. 3. Use non-metallic flat gaskets. 5.0.2 The operating conditions for commercial-grade double-ended studs and Type 1 hex nuts shall meet the following requirements: 1. The nominal pressure class shall be less than or equal to PN40. 2. Non-toxic, non-flammable media and applications without severe cycling. 5.0.3 Except as specified in paragraphs 5.0.1 and 5.0.2, special-grade fully threaded studs and type 2 hex nuts shall be used. Conclusion: Regarding the selection of flange bolts for pressure transmitters at the compressor outlet (with a design pressure of 10 MPa and natural gas as the medium), in order to prevent safety incidents caused by leaks at the flange sealing surfaces, it is necessary to carefully select the appropriate type of fasteners by taking into account key factors such as operating conditions, the properties of the fastener materials, the corrosion characteristics of the medium, stress loads, and high-temperature relaxation effects, in strict accordance with relevant standards and specifications.
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