Suspect Pistons?

[pgmuza]

hie guys
I am new to this forum and this is my fisrt posting.I am a qualified ref mech in with four years post appy.been working on an ammonia ice cream manufactufing plant with six Sabroe SMC112 compressors(12 cylinders) .Three are low stage,two are high stage and one is a swing.I have changed all pistons on two of the low stage comps recently.Problem is one of them broke 2 consecutive pistons counting from the pump end some 4 weeks later.I checked for probable causes but could not find any so i replaced the broken pistons putting thicker gaskets below cylinder liners to eliminate posiblity of pistons hiting dischage vales.And it happened again,same pistons,after about six weeks this time.Puzzling! the other comp is perfectly fine.

Anybody experienced something like this before, or did my employer buy fake pistons?

[Lowrider]

How about oil? All pistons are lubracated enough?

[taz24]

it happened again,same pistons,after about six weeks this time.Puzzling! the other comp is perfectly fine.

Anybody experienced something like this before, or did my employer buy fake pistons?

Hi ya.

Have you checked the oil ways through the crank.
Is the oil reaching the big end and little end bearing.

Cheers taz.

[GHAZ]

Hello pgmuza i built one smc with cheap spares and it dumped 20 litres of very expensive oil in the plant room.Since then i always use original spares, these compressors are built like tanks, they take a lot of battering. when the compressor is fully loaded do those banks get very hot compare to the rest of them, if so change the discharge valve seat.Because the heat will cause the small end of rod to sieze and damage the piston,

[pgmuza]

Sandert,GHAZ and taz24,thanks guys. So you are saying overheating due to leaking discharge valves and lack of lubrication may be the cause. You must be right cause the bank which was affected is the last in terms of receiving oil through the crank oil ways.I will check lubrication system again and the valves.Will be back soon.

Regards