<div dir="ltr"><div>In some of my work I use NPT fittings and swagelok. Swagelok is a compression fitting that is designed to be metal to metal on the connection and does a great job as long as there is nothing but the fitting in there (teflon bad, bare metal seal good...). On the other end of that fitting may be NPT and we use it for vacuum systems in semiconductor type applications. The NPT fittings get 4-6 wraps of teflon tape (Dad worked as a boiler plant operator and found this to work for steam applications) with some uncovered thread at the end of the fitting. We assemble and leak check with a helium leak detector for proper sealing (key ingredient... test method).</div><div><br></div><div>Leaks are common if the threads are cut manually. The threading taps leave a step where they stop cutting and I see this cause leaks. On most of the equipment we use parts that are thread-cut with a mill (a continuous cut) and there is no step. These only leak if they aren't tight and don't have a couple wraps of teflon. The hand-tapped parts leak much more frequently but the 6-wrap treatment usually puts that to rest (except on small threads like 1/8" NPT where 6 wraps may prevent thread engagement and we use 4). </div><div><br></div><div>Our chambers are welded 6061 aluminum and fittings can be brass or stainless steel. We avoid China-built fittings if possible but overall the issue has been with the care taken on the threads and garbage fittings come from all over the place. With the brass fittings, one has to be careful not to overtorque as the teflon will lubricate during assembly and it's easy to break the fittings if it's low-pressure brass.<br></div><div>For hydraulic fittings I tend to look pretty closely at the manufacturer's recommendations if it's not NPT, then go with the teflon tape treatment if it is. I need to look into the Blue Monster version to see what that is (thanks Cecil). I've seen teflon get loose from careless installation and it can be a real menace (don't get it in an automatic transmission valve body for example). <br></div><div><br></div><div>Tired iron can be forgiving, but some applications definitely aren't. Think of the consequences and choose wisely. <br></div><div><br></div><div>Hope this helps</div><div><br></div><div>Ken in AZ<br></div><div><br></div><div><br></div><div> <br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Dec 14, 2020 at 7:54 AM Cecil Bearden <<a href="mailto:crbearden@copper.net">crbearden@copper.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF">
<p>I have had so many leaks on hydraulic fittings the last 5 years
that I have no choice but to use the tape. I make sure that if I
remove a hose or fitting I clean out the port or the threads and
use new tape.. I even bought some blue teflon hydraulic paste
that was supposed to seal 10K psi. It still leaked. I converted
most of my loader hose fittings to NPT so I could use a universal
hose. I only keep NPT hose fittings to crimp on hoses when I make
my own hose. Most of the time I purchase a hose for the loaders
as I don't trust my crimping where I might have myself or anyone
under a lift... I try to never have anyone under a loader, but
crap happens. The closest scare I had was when a factory New
Holland top link broke while connected to a 3pt disk we were
working on. It broke the swivel end off at the tractor just as my
helper moved his foot from under a disk blade... <br>
</p>
<p>Cecil<br>
</p>
<div>On 12/14/2020 7:52 AM, Stephen Offiler
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Some outfit, probably Permatex, used to run ads in
trade magazines like Machine Design for its thread sealant
compound, featuring images of hydraulic systems full of wispy
white shreds of teflon tape, gumming up orifices and filters.
<div><br>
</div>
<div>SO</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Dec 14, 2020 at 2:30
AM Brian VanDragt <<a href="mailto:bvandragt@comcast.net" target="_blank">bvandragt@comcast.net</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="auto">It is not recommended. Little pieces can break
off and plug something up.
<div dir="auto"><br>
</div>
<div dir="auto">Brian </div>
<div><br>
</div>
<div dir="auto" style="font-size:100%;color:rgb(0,0,0)" align="left">
<div>-------- Original message --------</div>
<div>From: Mike M <<a href="mailto:meulenms@gmx.com" target="_blank">meulenms@gmx.com</a>>
</div>
<div>Date: 12/14/20 1:48 AM (GMT-05:00) </div>
<div>To: Antique tractor email discussion group <<a href="mailto:at@lists.antique-tractor.com" target="_blank">at@lists.antique-tractor.com</a>>
</div>
<div>Subject: [AT] Teflon tape hydraulic system?? </div>
<div><br>
</div>
</div>
Hi all, was wondering if was OK to use Teflon tape on a
hydraulic fitting?<br>
<br>
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