[AT] Hydraulic hoses

[Stephen Offiler]

I prefer a dope to tape, and I prefer anything over dry threads, and I
*have* seen tape shards permeate a system.  Long story and not
precisely related to old tractors but I'll go ahead and tell it.

Fresh out of engineering school, I went to work for a company that
assigned me to work with an engineering technician also fresh out of
school.  A good farm boy and extremely capable and practical, but
nonetheless he (and I) still had a lot to learn.  We were working on
an automotive air-conditioning component that required assembly of an
entire working system on a test buck.  He employed quite a bit of
conventional plumbing fittings, allowing us to tap at various points
in the system.  And he used teflon tape on those fittings.  And we had
to rebuild the entire system after it began to fail (exact failure
mode is lost in my memory, but it was probably a plugged expansion
valve or something like that).  We found tiny teflon tape shards
permeated the system.  Actual quantity was pretty minute but it's a
case where a little bit goes a LONG way.

Don't use teflon tape on hydraulic systems, and if you MUST, be
diligent with the advice Mike provided, and keep the tape well back
from the tip of the fitting.

SO



On Thu, Aug 13, 2009 at 6:12 AM, Mike Sloane<mikesloane at verizon.net> wrote:
> Here is my position on that issue: NPT threads are tapered and should
> not require any kind of pipe dope or tape. But, if your threads are old
> or you just want to make sure, start the tape at least two threads back
> from the end. That way, the is very little chance of tape pieces getting
> into the system. I have found old pieces of O rings gaskets, and other
> trash in the filters of hydraulic systems, but never Teflon tape. My
> take is that the potential for the tape being a problem is considerably
> less than some people claim.
>