Pipe strain check for reciprocating compressors
Pipe strain check for reciprocating compressors
(OP)
Guys,
While connecting the discharge and suction piping to the cylinders of reciprocating compressors,Which is right location to put dial indicator to see the strain coming from piping to the compressor? Some one told me to put dial indicator on the crank shaft coupling hub to see the piping strain coming to the compressor but makes no sense to me I don't think the forces due to suction/discharge piping strain is strong enough to move the crank case so that we can see deflection in crank shaft hub?
What do you think guys? Where to check the pipe strain effect Is it really on crank shaft hub?
While connecting the discharge and suction piping to the cylinders of reciprocating compressors,Which is right location to put dial indicator to see the strain coming from piping to the compressor? Some one told me to put dial indicator on the crank shaft coupling hub to see the piping strain coming to the compressor but makes no sense to me I don't think the forces due to suction/discharge piping strain is strong enough to move the crank case so that we can see deflection in crank shaft hub?
What do you think guys? Where to check the pipe strain effect Is it really on crank shaft hub?





RE: Pipe strain check for reciprocating compressors
Johnny Pellin
RE: Pipe strain check for reciprocating compressors
RE: Pipe strain check for reciprocating compressors
RE: Pipe strain check for reciprocating compressors
RE: Pipe strain check for reciprocating compressors
Measuring at the coupling hub may mask strains in the case which, over time, can cause damage other than just to the rotating element. Such as case cracking.
RE: Pipe strain check for reciprocating compressors
Johnny Pellin
RE: Pipe strain check for reciprocating compressors
Clause 4.8 Pipe Strain Measurement
4.8.7 Reciprocating compressor piston rod run out shall be measured before and after connection of process gas
piping to the compressor cylinders and/or pulsation vessels and compared to the compressor manufacturer’s
allowable run outs or API 618, as applicable.
I think it is good idea to check piston run out before and after connection of process piping , if there is strain coming to the cylinder then it will show up in piston run out ,
I believe that checking at the crank shaft coupling hub may not give the correct reading since the shaft rests in sleeve bearings & had clearances so it will mask the shaft deflection(if any due to pipe strain) while bolting up the piping to the cylinder.
What do you think Guys?
RE: Pipe strain check for reciprocating compressors
Johnny Pellin
RE: Pipe strain check for reciprocating compressors
After achieving the pipe alignment within specification ,when inserting and torquing the bolts do we still need to put some kind of dial indicator on the crank shaft to see the shaft deflection due to pipe strain?
RE: Pipe strain check for reciprocating compressors
Rod runout readings are important but out of spec readings can be caused by any number of other things such as x-head alignment or foundation issues.
RE: Pipe strain check for reciprocating compressors
I do not know why you are going through a dial indicator to know pipe strain.
I can comment on pulsation study though :-
There are parties who carries out pulsation study of recip machines by considering gas effects and vibrations.
For a reciprocating compressor, it is always a good practice to carry out pulsation study of the complete system after commissioning in the max load scenario and/or after any modifications done to the machine (For eg. changing to stepless capacity control system etc).
Piping modifications (if required) are easily identified and necessary corrections can be made well in advance.
Thanks,
Bhaskar5150