Must stainless steel flanges be connected with stainless steel bolts?

304, 316 stainless steel bolts as low-strength bolts is only used for CL150/CL300 flange matching.

The reason is low strength bolts can only withstand a limited preload. High pressure grade stiffness of the flange or hardness of the semi-metal and metal gasket in the supporting use of stainless steel bolts may be not achieve the sealing effect.
Alloy steel bolts will be used for flange connection under severe circulation conditions. The so-called severe circulation condition refers to the internal stress alternating changes on the pipeline very large, such as reciprocating compressor pipe, PSA separation, if not the use of high-strength alloy steel bolts instead of stainless steel low-strength bolts, due to the low strength of stainless steel bolts, the increase in the magnitude of alternating stress corresponding to the number of allowable. Long-term use can lead to significant hazards. In addition, alloy steel bolts at the time of delivery with rust resistant oil can be isolated from the stainless steel flange direct contact. The weak corrosion caused by the contact between alloy steel bolts and stainless steel flanges does not have any effect on their performance.