Questions regarding fully threaded studs
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Are there full-threaded studs of grade 8.8? I might be a bit confused about the concept here; please advise.
You use it for pipe flanges, right? There isn’t any. For hex bolts and double-headed bolts, commercial-grade ones must be used; their quality is indicated by mechanical properties such as 5.6, 8, A2-70, and so on. For fully threaded studs, special-grade products must be used; these are usually designated by materials such as 35CrMo, 06Cr19Ni10, B8, and so on. Standards are not just for you to look up; you need to understand them deeply as well.
Is the questioner asking about hex head bolts? :Q The flange uses fully threaded double-headed bolts, without hex heads.
Thank you, they are fully threaded double-ended studs for flanges.
@Sammy_Wang: Hex heads can be used, but not for process pipelines; there are certain restrictions
Flange standards such as HG indeed do not specify 8.8 grade fully threaded studs; the explanation given on the second floor was quite clear. However, for DIN standard projects, the specifications and material lists provided by foreigners include 8.8 grade fully threaded studs for use at PN16 and below. So I think a 8.8 grade fully threaded stud of this specification is feasible; it’s just that we in China don’t use it for safety and reliability reasons.
8.8 grade fully threaded studs have been used, either galvanized or blackened.
It is generally selected with reference to double-headed studs.
This post was last edited by Chow Tai Fook on 2015-8-6 at 10:56. No, we are only responsible for placing orders for designs provided by foreign parties; the manufacturing factory also said there’s no problem, so they will use full-threaded studs of grade 8.8. After all, full-threaded studs can withstand greater stresses than double-headed studs, so we can’t lower the standards for them.