There are small holes at the contact surface between the packing of the reciprocating machine and the piston rod
Thread Content
Since the start of operation, the recovery temperature for leaks at the packing at the second stage of the analyzer gas compressor in our plant’s PSA unit has remained high. Upon disassembly, it was found that there were discontinuous small holes on the contact surface between the packing ring and the piston rod (this issue also occurred during the maintenance on September 24, 2020)； The radial and axial wear of the piston rings, support rings, and packing rings is minimal ； Dimensional load requirements such as surface roughness and cylindricity of the piston rod at the contact point with the filler ； No foreign objects were found in the cylinder and the cup grooves of the packing box ； There are no significant differences between the medium components and the design parameters; the hydrogen sulfide content is <5 ppm (the designed value is 7 ppm). I would like to ask if anyone has encountered this situation – how do filler failures occur? Note: The packing is provided by COOK, and the inlet and outlet pressure and temperature ranges are 0.5/2.5 MPa ； 40/102°C. The recovery temperatures for secondary rear-stage and primary front/rear-stage air leakage are normal
Is there a problem with the quality of the packing ring, resulting in pores during compaction, molding, and sintering?
The density of the filler material is insufficient; in other words, it’s a quality issue with the filler.
I checked the production batch number on the packing, and found that the packing rings on all four cylinders of the unit belong to the same batch. If there is a problem with the manufacturing process of the packing, then it should be that all packing pieces from that batch are defective. But currently, only the packing in the second stage is leaking while the others are in good condition. How can this be explained? ? ? ? ? ? ?
I checked the production batch number on the packing, and found that the packing rings on all four cylinders of the unit belong to the same batch. If there is a problem with the manufacturing process of the packing, then it should be that all packing pieces from that batch are defective. But currently, only the packing in the second stage is leaking while the others are in good condition. How can this be explained? ? ? ? ? ? ?
Corrosion. The filler contains metal components, and pit formation occurs as the medium comes into contact with the filler particles.
Agree with the person above. Is it possible that, under specific temperature and pressure conditions, the metal fillers in the packing react with the medium? The original poster might want to try using a different material for the packing.
I have already contacted the packing supplier, and they confirmed that there are no metal components present~~~~~. At present, it seems that the leakage recovery temperature is high for cylinder number 2; it was only after disassembly that holes were found on the packing ring. The other cylinders have not been disassembled, so it is not known whether there are holes on their packing rings as well~~~
The composition of the filler is not clear, but based on the analysis of the medium’s components, it seems there are no corrosive substances present~~~
Please ask the original poster to explain the composition of the filler and the temperature at that location (during operation).
This post was last edited by Qingqiu_GGMfG on 2021-4-20 07:48. Reply to floor 10! ! ! The composition of the packing is unknown (the supplier does not provide this information either:()). As for the temperature at the location where the packing is in use, does it refer to the temperature of the piston rod in contact with the packing, or the temperature of the groove in the packing box? The side cover at runtime has never been opened, and the packing box does not have a temperature probe either; the temperature difference of the cooling water is normal. We determine whether there is a leak by detecting the temperature drop due to air leakage from the packing. The recovery temperature for leakage gas at the second stage rear is around 30°C, while that at the second stage front is generally around 50°C--