How to Properly Execute Bolt Fastening for Heat Exchangers?

How is the correct bolt fastening sequence for heat exchanger tube boxes and tube plates achieved? Typically, diagonal and cross-bearing methods are used, and torque wrenches tighten the bolts to the specified torque value in the design.

Are the material grades of the fastening bolts and nuts for heat exchanger tube boxes and tube plates the same? No, they differ. The material grade of the fastening bolt is higher than that of the nut. The bolt material has higher hardness to avoid damaging the thread during installation, and lubricant or anti-seize agent is commonly applied.