Bolt standards
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Colleagues, what standards do you usually refer to when ordering bolt spare parts? For steel pipe flanges, we use the standards HG/T20592-20635 for flange gaskets and fasteners. However, we’ve found that these standards are not detailed enough, and they also rely on other standards; moreover, the pitch of the threads as well as the nuts used are not standardized
The standard for the relevant bolts referenced on the specification index
The main difference between specialty-grade studs and commercial-grade ones lies in the material, I guess
If your flanges are of the HG type, it is recommended to select fasteners in accordance with HG/T 20614-2009. Other standards, such as GB/T 9125-2010, require different fastener selections; the pressure-temperature limits specified in these standards are different from those of HG, being lower. The correct procedure is to determine the material using HG/T 20614-2009; this determines whether to use hex bolts according to GB/T 5782, double-headed studs according to GB/T 901 (accompanied by Type I hex nuts with coarse threads per GB/T 6170 and Type I hex nuts with fine threads per GB/T 6171), or fully threaded studs according to HG/T 20614 (accompanied by Type 2 hex nuts with coarse threads per GB/T 6175 and Type 2 hex nuts with fine threads per GB/T 6176). Then use HG/T 20614-2009 to determine the bolt model, and specify the exact model when submitting the material information. If only HG/T20592-20635 is specified, manufacturers are unlikely to go to the trouble of verifying each model for you, and some experienced workers will assume that a certain model is suitable; as a result, the products you receive will not be consistent.
The answer on floor 5 was very detailed; I used to file my declarations in the same way!
The manufacturer won’t help you verify it; you need to clarify your requirements on your own and include all the standard numbers