I've seen similar failures many times. In fact, in small hp field compressors that don't get much attention you see first stage suction valves fail every few months. It happens so often that most companies running small hp field compression simply don't investigate it, just replace the broken valves when found and get on with their lives. I've never thought about it much, but when I've had to think about it I just assumed that it was fatigue (they operate 800-1200 times/minute, a few months is a lot of cycles) and went on. I can't explain why one set of valves will last a decade and the next set will last a month.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

thanks zdas04
this valve is for suction second stage , we changed this valve after compressor overhaul and after 1 month it failed.
driver operating rpm is 600 rpm , suction pressure at 2nd stage is 3.81 Bara , discharge pressure is 5.44 bara.

The nut (310) obviously loosened and the excessive movement of the valve hammered until it broke. You can see the groove left by the alignment pin (430) which shows that the pin came out of its alignment hole. This could only happen if the nut loosened.

One of my clients has resorted to tack welding the nut to the stud on one suction valve in their facility. It is in a high speed compressor and the valve is in a nominal 1000 psig service. It solved the problem. They had experienced a few failures a year prior to resorting to tack welding. Now they are going over a year without failure.

I am not sure that this would have been the direction I would have taken, but they are happy.