Please provide additional details, do you have any photos of damaged liner? Rubbed the liner is a very broad term, rubbed where in the liner? new liners? packing? any measurements taken on the liner to prove it is straight and not worn?

If the piston touched the liner, ring rides too deep in piston, egg shaped liner, worn piston holding pin, bent rod to name a few possible starting points

Dave

pawannlng posted:

We have Reciprocating type Dresser Rand make Natural Gas ( BOG)  compressor.. It is 2 stage 4 cylinder compressor.Recently we have done complete overhauling of the machine and replaced all piston ring and rider ring with new one. In HP NDE Cylinder Piston rubbed the liner after only 50 hrs of running hour. With same piston ring and rider ring we are getting more than 4500 running hour life. In one piston there is 2 Piston and 2 rider rings. Construction of rings is Rings Split type.

What are probable reason for failure??

dear sir

because of failure event after overhauling you should check all installing and assembly procedure .do you have any vibration condition monitoring data during 50 hrs?any protection like rod drop proximity sensor ?

are you sure about  operating process parameter during that time ?   

It is necesary to evaluate pictures and operational parameters. Probably was a assembly problem hiwever it is necessary to have more information.

Was the cylinder starved of processed gas? How about the end devices that was to shut down the unit for excessive vibration are they properly installed and working? from your explanation though not too clear- Rod reversal due to lubrication issues might be the root cause.

pawannlng posted:

We have Reciprocating type Dresser Rand make Natural Gas ( BOG)  compressor.. It is 2 stage 4 cylinder compressor.Recently we have done complete overhauling of the machine and replaced all piston ring and rider ring with new one. In HP NDE Cylinder Piston rubbed the liner after only 50 hrs of running hour. With same piston ring and rider ring we are getting more than 4500 running hour life. In one piston there is 2 Piston and 2 rider rings. Construction of rings is Rings Split type.

What are probable reason for failure??

dear sir

 have you n checked the suction and discharge valves  ? if you sure about  maintenance  of all components  and installation procedures ,you should looking for cause around operation after overhauling .for example be sure about condensate gas  or liquid drainage during operation. 

best regards    

Greetings Pawan,

Good case study. 

1. One thing is sure after overhaul and fitted the piston ring failed with in 2 days. 

2. Especially when lowering the piston into liner, the guide ring, if having any scratches or dents or when forcing the piston into the cylinder liner normally the bottom ring can stuck or break and continue to run the broken piece can damage the piston and liner. 

This failure occurs in Tandem compounding pistons. 

In Marine Industry we have faced this type of failures for 2nd stage piston rings. 

The best method we have derived to fix this 2nd stage piston rings successfully is " compress the piston rings and freeze upto -15*C and piston ring remains in complete compressed condition and before lowering just remove the compressing clamp and lower the piston and will move easily.

This type of problems need to have understanding during lowering the piston. Many people use to curse the compressor makers or spare parts suppliers etc.,

Best of luck

regards