Selection of bolt material for the connection flanges of low-temperature high-pressure towers
Thread Content
The existing tower is operated at a temperature of -62.7°C; its design temperature is -196°C, with a design pressure of 6.5 Mpa and a test pressure of 8.37 Mpa. The 32 (M70) bolts used at the flanges of the tower are made of 304 material. During the hydrostatic test, when the pressure reached 6.8 Mpa, abnormal noises were heard from those bolts – this is likely due to the low strength of the stainless steel bolts, which stretched under high pressure and thus produced noise. There are two possible solutions: using 30CrMoA studs and 30CrMoA nuts, or A193B8-2 studs and A194B8 nuts. The first option can only be used up to -100°C, while the second option’s maximum bolt size specified in the standards is M36, and its strength is not much higher than that of 304 material. Which expert can help? Is there no suitable bolt material for this operating condition at the moment?
For studs, only 304 or 316 can be chosen; stainless steel studs require strengthening treatment. Are your studs not up to standard?