Sealing Threaded joints with P.T.F.E.

[Grizzly]

I was recently fitting some PRV,s (Changing single to dual style manifolds)
and decided to use ptfe instead of loctite as it is more forgiving.
Meaning the slightest movement when changing a prv and you have a leaking manifold. ( which is a gas out job!)
Something in the back of my mind says that there are certain refrigerants that it's not recommended.
To use ptfe does anyone know whether this is true?
And if so which ones are a no no!
Grizzly

[monkey spanners]

I think its HFCs and the blends containing them, but thats only something i remember reading on here. I think some of the refrigerant bottles still use ptfe on the valves so maybe it is ok?

I have been using that 'trublue' paste or whatever its called from rpw and not had any problems with i so far.

So i'm not much help

Jon

[Brian_UK]

BOC are against using PTFE on any threads but in particular Oxygen because PTFE contains an oil based substance.
Safe Under Pressure from BOC:- (might be handy for your gas storage question elsewhere Grizzly)

https://b2.boc.com/gases/BOCInfo.nsf/webgenpres/F9D8B56CFB97F5A7802568A4005D6ACA/$file/SAFEUNDE.PDF

(I had Firefox highlight this site because of a site certification problem but I accepted it and haven't had any problems.)

Also, Safety Data Sheet for PTFE
http://msds.chem.ox.ac.uk/PO/polytet...oethylene.html
State - Incompatible with molten alkali metals, fluorine and other halogens, strong oxidizing agents.

[al]

Grizz

Don't use it on 404a, only loctite is acceptable, every joint we used to do leaked until we switched to loctite, eventually wholesalers got confirmation especially when fitting PRV's!! Not sure about 134a though, could be acceptable.

al

[Magoo]

I had some expensive experiences with PTFE tape and R22, great for a while then all started leaking.
Went back to loctite. Currently using loctite 577, [ I think ] yellow looking stuff, on ammonia, good for sealing and does not go rock hard, easier to change when ever required .
magoo

[lowcool]

i used loctite 567 on everything,good for thread seal against moisture,after reading a bit more into data sheet i am now not so sure as it displays a thread tape property.thought i sussed it years ago.anyone got something that works everywhere.no leaks that i know of.spose we gotta solder in a tube bush then solder in ball valve tail,then pray that ball valve holds up,any laws about isolation valve before relief device

[littleyapper]

i am with al on this copeland will only recommend loctite ... r404a will react with ptfe in time ..

[Grizzly]

Thank you my friends for the helpful advise.
I will return the favour whenever I can!
Well the afore mentioned job was on a 407c system.
Time will tell as to if I have boobed or not.
Let's hope not as it has over 80 KGS of refrigerant in it!!!
Cheers Grizzly

[GHAZ]

IHello guys i thought the ester oil eats the ptfe tape

[Entropie]

I would recommend Loctite 577 especially on larger bond gaps. It is important to use the original Loctite cleaner not any other solvent. You should take care not to pressurize the system to early, especially at low ambient temperatures.

[lowcool]

i thought 577 was prone to moisture and have found when using on tx valve outlet it breaks down.

[Magoo]

Lowcool. The only type of valve before a safety relief is a double action valve with two safety valves, where one or the other is open to vessel at all times. This is covered in AS/NZS standards, for vessel design. And safety reliefs are to be tested and re-certified, or replaced every four years.
magoo

[lowcool]

cheers magoo,thought their was something regarding this

[nike123]

I use Leak Lock paste successfully on all refrigerants and oils. No leaks so far!
http://www.highsidechem.com/lklcksp.html

It is also part of Refco delivery program.

[Quality]

I use Leak Lock paste successfully on all refrigerants and oils. No leaks so far!
http://www.highsidechem.com/lklcksp.html

It is also part of Refco delivery program.

Ive used this and seems ok its available from Javac in the UK

[Magoo]

Hi Nike 123, thanks for referal to leak lock site.
magoo

[lowcool]

i used to use that stuff years ago,steered away from it because is it not user friendly.it hardens very well,is brittle and remains in threads,if someones been over zealous with the stuff before you and used it it in the wrong places its a female dog.if you want to do a quick tev change in a freezer to reduce ingress of moisture forget it.using to seal a removable fitting in a pressure vessel the stuff breaks apart and falls in,as is the usual case things dont fall out.think ill stick with loctite 567 and crank the hell out of the fitting.been doing it long enough now,as i said earlier i do not know of any leakage.

[Andy]

Thank you my friends for the helpful advise.
I will return the favour whenever I can!
Well the afore mentioned job was on a 407c system.
Time will tell as to if I have boobed or not.
Let's hope not as it has over 80 KGS of refrigerant in it!!!
Cheers Grizzly

Hello Grizzly

what about using lock tight along with the PTFE tape, the tape allows you to locate the PRV then the locktight sets and makes a permament seal.

Kind Regards Andy

[Slatts]

Andy, if you're using locktite and PTFE tape, you're still using PTFE tape.
With all of the disadvantages exposed in this thread.
So I'd say no.

Does anyone still use litharge and glycerine?
Or tin the thread with soft solder?
I'm talking BSPT threads of course, not flares.
For flares, I'd only use refrigeration oil.

[lowcool]

ya gotta seal yea thread were da nut goes on da valve udderwise yon nut wood split from da ice.

oh well

[Slatts]

ya gotta seal yea thread were da nut goes on da valve udderwise yon nut wood split from da ice.

oh well

Have you been giving those white cans a nudge lowcool?
I can't understand your post.
Are you one of those blokes who insist on putting thread tape on the thread of your flares?
I've been doing this for over 30 years and never used thread tape on a flare on a TX valve and never had one crack.
I did go through a phase a few years ago where I'd smear a film of Leaklock on the face of a flare, but I got over that.

What was that awful beer that used to come out of your area? Southwark or some such name? I still shudder when I think of the QLD beer strike back in 1979.

[lowcool]

Have you been giving those white cans a nudge lowcool?
I can't understand your post.
Are you one of those blokes who insist on putting thread tape on the thread of your flares?
I've been doing this for over 30 years and never used thread tape on a flare on a TX valve and never had one crack.
I did go through a phase a few years ago where I'd smear a film of Leaklock on the face of a flare, but I got over that.

What was that awful beer that used to come out of your area? Southwark or some such name? I still shudder when I think of the QLD beer strike back in 1979.

gday slatts havent seen a white can around for a while,me nudge,heavens no i was just comparing the taste difference over 14 or 15 cans with irish whiskey and amaretto to keep the pallatte clean,woke up bit funny though less amaretto next time.definitely seal tx valve outlet "thread" everytime and would kick apprentice bum for not doing so,apart from ice splitting the nut there is also a tendency for the nut to loosen,southwark desperate times call for desperate measures,not a favourite of mine after travelling our wonderful country,can only suggest mixing it with coke.god should forbid beer strikes if he really loves us.

[Slatts]

Each to their own low. I'm happy with a tape free thread on my valves. I do insist on the copper being soft when I flare it and if it's old, I anneal it first.
The problems I've had with these flares are mostly due to valves being changed and the copper having hardened.
If in doubt, cut it out, anneal it and re-flare it.


When I lived in the Territory I moved between blue, green and white cans. Of course now my best drinking days are behind me and my kids remain mostly in ignorance of my past...