Low Temperature grease lead to seals leaking?

[davejc]

I have experienced the use of a -20deg lithium based grease at low temperatures (about -15deg). The grease is used to lubricate some seawater seals and these were found to be passing. On inspection there was evidence of solidification and crytals present. Does anyone know if the grease expands or contracts at lower temperatures?
I am trying to establish if the grease has contributed to the passing of the seals

The grease properties are as follows:

Drop point 180degC
Base Oil Viscosity 150cSt @ 40degC
Penetration 265-295 (N.L.G.No.2)

 

[MikeHalloran]

It might be more illuminative to find out if the seals are flexible at -15deg.



Mike Halloran
Pembroke Pines, FL, USA

 

[B3188]

Can you provide the specifics as to Manufacturer and
product name/number. Also environment used in specifically temperature.

 

[davejc]

The manufacturer was Millers Oils Delta EP2 Lithium based grease.
The ambient environment temperature was in the order of -15 deg C.
The seals were not reported to be hard but there was a leak detected.

 

[B3188]

Millers Oils is not one of our (Mil) supplier.
His lubes don't go through aerospace fuels test lab.
Ergo I don't have specific test data back to this batch
or mfr..
Grease Lab folk provide the following as it had a similar
situation a year or so back.

Data supplied is very close to Mil PRF 81322.
General purpose Lithium grease.
There were a couple of batches that showed 'speckles'
caused by something that got into the batches at
packaging time. Government pulled those batches,
no problems occured except with those batches.

Prime maker hereis BP in Texas. Lots of folks repackage it
or make similar.

None should show the crystals or speckles unless something
got into the batch along the line.

As to temperature. That grade should be fine at the temperature range you mention.

Therefore, grease (type and grade) may be fine and
you have a bad batch.
They are equating your 'crystals' to their "speckles".

Supposed to have more data on the way. Will post it when it arrives.

 

[B3188]

Follow up.
The NATO code G-395 wide temp range grease
is rated at Temp from -54 to 177 Deg C.

Lab thinks it is similar to your grease.

Lab folk asked if the "crystals" are
salt?

 

[davejc]

The manufacturer spec states the grease operating temp is only down to -20degC. The ambient temp was around -15degC. The manufacturer has suggested a lower temp grease as the would not recommend using at the lower end of the spec as the norm.
The temperature may have previously been lower (-30degC) and the seals/grease may not have recovered.

I have this information second hand and the engineer only mentioned crystals. I don't think I would be able to determine if it was salt.

 

[B3188]

Good deal look like your on the right track.

 

[powerjunx]

Better consult NLGI (National Lubricating Grease Institute)