PAO Oil and Leaks

Hi Bruce,

I would use SS tubing and SS fittings. The brass ferrules in the brass compression fittings won't bite into the harder steel or SS tubing enough to effect a good seal.

Swagelok tubing and fittings are great. See here:

http://www.swagelok.com/search/find_products_home.aspx?SEARCH=/id-10000007/type-1

For the threaded fittings, I would select a pipe-thread sealant that is compatible with the type of oil you're using.

I recently built a hot-oil system. For the threaded fittings, I used LA-CO Pipetite Paste I got from McMaster-Carr. The fittings and tubing are 1/2" SS Swagelok type. I've had it working for at least 40 hrs and it's working very well! No leaks.

Mike

I would join in Mikeys advise. There are different (steel) piping fitting systems available working with a conical compression ring (bite in the pipes surface and providing a mechanical lock and tight fit this way. The connection between the fitting and the pipe then is made as a conical fit. More sophisticated fitting systems have rubber-like O-rings integrated in this conical fit - this is the most reliable design (see for instance the PARKER groupes PARKER-ERMETO System.

Please note: PAO lubricants within a certain degree can be mixed up with conventional petroleum based oils (mineralic oils). Nevertheless, the additives for PAO lubricants often are of different chemical nature as useful for mineral oils. From those differences some chemical incompatibility with materials in the lubrication circuit are possible. Avoid all common rubber seals (NBR), instead using VITON replacements. This is important when applying fittings with integrated rubber seals (choose the versions with Viton seals!).

Thanks for the suggestions. The Swagelock fittings look good. FAE says they do not leak with 5000 psi of hydrogen. That should hold a couple of psi of oil.

I'll be careful with O-ring materials too.

Thanks,

Bruce

Great advice so far.I wish to add that often a single to two carefully applied wraps of 1/2-3/4 teflon thread sealing tape centered on the ferrel will often seal a problem fitting.This also works on flared fittings.

Whether steam,solvents,oil or water under the kitchen sink.This often works.I have had to first redo it 4 -6 times in a row to get a seal at times,so do not give up too soon.Once it seals,it stays for years.I worked in steam traced lines for years.This will often seal one that has been cut by steam.

CAREFUL!Make sure none of the Teflon tape is over or in your tubing to get into your system if such will plug or damage something.

This has worked on Nuclear Submarines,Chemical Plants,home and farm for over 40 years now.It works far more often than not and has often lasted 20+ years and still going strong.I am 62 and retired from maintenance in a chemical plant.