Issues related to fasteners in pressure pipeline design
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What are the selection principles for fine-thread and coarse-thread in the field of pressure pipelines? Are washers not required for pressure pipeline fasteners? HGT 20592~20635-2009 does not specify standards for gaskets in steel pipe flanges, gaskets, and fasteners
I’ve run into this problem too~ I’m not sure when washers are needed and when they’re not. Is there any relevant standard? I couldn’t find it in the Chinese standards, and neither does the American standard 16.5 mention anything about washers. If the bolts don’t have washers and rust, could that cause the flanges to rust as well?
And for fasteners, how to choose between coarse-thread and fine-thread threads?
This post was last edited by FMSD on 2017-3-16 at 14:46
It’s because you didn’t read the book carefully yourself. 1. M36 starts with fine threads, with a pitch of 3 ； Use coarse threads below M33. 2. It can be added or omitted; it’s not mandatory. Personally, I think it’s better to use a washer. Double-headed studs are generally added. 3. The flat washers are in Appendix A, which has over 200 pages (I can’t remember exactly).
I saw this; it only specifies the standard dimensions of the washers that go with the bolts, without stating under what circumstances they are needed and under what circumstances they aren’t
I see the washer. Where are the regulations regarding coarse and fine threads that you mentioned?
It’s necessary; washers are rarely used in the field of mechanical design
Your question isn’t really a question at all; it’s written in the book. You’re just too lazy to read it carefully. Read the book a few times and you’ll naturally understand it. Chapter 3, Section 1 of HG/T20592-2009.
This post was last edited by FMSD on 2017-3-17 at 13:40. You’re wrong; it should be Part 3 of HG/T 20613 – coarse-threaded bolts GB/T 5782. In fact, the diameter of such bolts can reach 64. Then why does HG/T 20613 stipulate that bolts with a diameter greater than 33 should follow the standard for fine-threaded threads, namely GB/T 5785?