Hydraulic tightening
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What are the requirements for hydraulic bolt tightening?
If the HG/T 21573-95 standard is adopted, the tightening procedure specified in that standard should be followed. However, I would like to ask how everyone calculates the preload – is it also using the calculation method in Appendix A of HG/T21573.1-95? It feels a bit?
It depends on the instructions. Generally, it needs to be tightened in three to four steps: the first step is 25%–30% of the final pressure, the second step is 60%, and the third and fourth steps are 100%.