Analysis of fasteners for pressure materials

The design neglects the addition of the insulating filler to the insulating layer which hinders the free thermal expansion of the small tube. The device does not have to be used for a long time to generate cracks and penetrate the wall thickness. The design of the insulation layer is not under pressure, so the rupture disc is placed at the top of the insulation layer. The gas pressure leaking into the heat insulating layer causes the rupture disc to blast, but the rupture disc has a small diameter, which is insufficient to quickly release the pressure, so that the pressure of the heat insulating layer is further increased, thereby causing the carbon steel insulating layer shell to blast. The mode of blasting is also very characteristic. The top is a brittle fracture and gradually transforms into a ductile tear because the tip temperature is lower than the carbon steel plastic transition temperature and the lower shell temperature is the ambient temperature.

Another material problem with pressurized equipment is the quality assurance of the bolt material. At present, most bolts are produced in specialized chemical plants, but different enterprises have uneven quality control, and poor quality control is likely to cause safety hazards. At the 2009 British Pressure Vessel Symposium, the quality of the Chinese bolt manufacturer registered as SUN was introduced. The bolt material certificate stated that the strength meets the requirements of BS4882B7, but the installer will tighten the bolts when assembling the flange. At first, I thought it was too much force, but I found that the bolts had serious defects, and the defects were almost through the entire section, but the outer surface inspection looked intact. Later, the investigation found that this was caused by the pulling of the bar when it was pulled too fast. According to the requirements of British Standard BS4882B7, such bolts should be subjected to tensile and impact tests every 680kg. It can be seen that the bolt manufacturer may not have a tensile test, so there will be problems when pulling. Fortunately, this problem was discovered earlier, otherwise it is very likely that a big accident will occur. Therefore, the fasteners for pressure vessels must have a mechanical strength performance warranty written in batches and meet the requirements of bolt-specific standards.