Reasons for damage to the safety valve diaphragm

First, determine whether the bellows is included with the safety valve or was installed separately, and check if there is any certification for it. Second, it seems that the wall thickness of this bellows is not very substantial; it’s necessary to see if it can withstand the working pressure at the location where the safety valve is installed. Finally, based on personal experience, it appears that the bellows in this position may be used for buffering purposes, but other methods could also be employed for that purpose

The main function of a safety valve with a bellows is to address the issue of corrosion protection. Under normal conditions, a bellows for discharge is subjected only to external pressure, not internal pressure. But the ripples in the photo are likely caused by internal pressure; therefore, it is necessary to check for any leaks and to find out how gas or liquid gets inside the bellows.

Analysis based on the diagram is as follows: 1. It is a design issue with the valve; the bellows should be in close contact with the bellows cover to provide guidance and protection； 2. Is there overpressure, caused by the failure to release internal chacking phenomena? For reference.

The reasons for damage to the safety valve diaphragm may include the following: 1. Fatigue failure. Cause: Frequent pressure fluctuations or cyclic loads lead to fatigue of the diaphragm material. Performance: Cracks or fractures appear. 2. Corrosion: Cause – Corrosive substances in the medium erode the bellows material. Appearance: Surface corrosion, pitting, or perforation. 3. Overheating: Cause – The operating temperature is too high, exceeding the material’s tolerance limit. Behavior: The material softens, deforms, or melts. 4. Mechanical damage: Causes include improper installation or maintenance, and collision with external objects. Appearance: Surface scratches, dents, or cracks. 5. Material defects: Cause: Defects in the material during the manufacturing process. Appearance: Local weakness or cracks. 6. Vibration: System vibration causes the bellows to experience additional stress. Manifestation: Cracks or fractures. 7. Improper design: Reason: The design does not meet the requirements of actual operating conditions. Performance: Premature damage or failure. 8. Improper installation: Reason: The installation was not carried out in accordance with the specifications. Manifestation: Stress concentration or deformation. 9. Medium contamination: Cause – Impurities in the medium wear out the bellows. Appearance: Surface wear or perforation. 10. Aging: Cause: Material aging due to long-term use. Performance: decreased elasticity, embrittlement, or cracking. Preventive measures: Regular inspections: to identify and address issues promptly. Correct material selection: Choose appropriate materials based on the operating conditions. Proper installation: Ensure that the installation meets the requirements. Control conditions: Avoid abnormal situations such as overpressure and overheating. Through these measures, the risk of bellows damage can be effectively reduced.

Have you found the reason? Same problem solving

The strength clearly fails to meet the design requirements; either no calculations were carried out or the calculations showed that the requirements are not satisfied.

The manufacturing unit here has a very deep understanding of the properties of the materials used by the design unit; since the design unit deemed 4mm to be sufficient, they used 4mm for pressing, but the final thickness turned out to be only 1.5mm – without taking into account factors such as machining allowance and corrosion margin at all.