Thread sealer for 2600 psi?

ChrisJ

I'm replacing the unloader on my pressure washer and the parts appear to be npt brass and I used megaloc dope but after thinking about it is that the right stuff? 2600 psi is a tad higher than I've worked with. It had some kind of red sealer on the old parts.

ChrisJ

3/8" brass to be exact

BobC

I used to work on liquid CO2 cooling ovens in a environmental lab setting, those systems run at 1,000PSI. We used glyptol which is nothing more than enamel paint, it also worked well on vacuum systems down to 100 microns.

I'm sure there are better options but that worked well for us in that application.

Bob

ChrisJ

It looks like Megaloc is rated for up to 12000 PSI? wonder how true that is.

Paul48

I've never seen anything running that kind of pressure with a pipe thread. I certainly haven't seen everything though.

ChrisJ

Paul48 said:

I've never seen anything running that kind of pressure with a pipe thread. I certainly haven't seen everything though.

Best I can tell from it's looks, fit and description, it's 3/8" NPT.

deadmansghost

Loctite No: 545 refrigerant thread sealant , used it on everything.
Never failed to seal.

Paul48

Then again, look at the pressure rating of a typical brass valve. All the hydraulic stuff I deal with is steel. I don't know anything about pressure washers, except they use a gear pump, also.

SWEI

Most of the anaerobics, Loctite being the best-known brand. Can't find specifics on the datasheets for 565 or 567 (the two I'm most familiar with), but FPPI specs their PipeFit AS thusly:

10,000 PSI Fluids
3,000 PSI Gases
125 PSI Natural Gas

ChrisJ

Paul48 said:

Then again, look at the pressure rating of a typical brass valve. All the hydraulic stuff I deal with is steel. I don't know anything about pressure washers, except they use a gear pump, also.

Gear pump?
As far as I know mine uses a piston pump.

Seems to be commonly called a triplex pump, I guess because there's a 3 pistons. Not sure if it's staged, or what the deal is.

Paul48

See....I even proved I don't know crap about em....lol

Alan (California Radiant) Forbes

More to the point, what wouldn't work? And what happens to make the joint fail when it doesn't work? Does the pressure push the sealant out? If so, why not use something like ABS glue? (I've actually done that.)

Alan (California Radiant) Forbes

Plain old Rectorseal #5 is good for up to 12,000 psi (liquids) and 2,600 psi (gases).

http://www.rectorseal.com/pds-pdf/dsno5.pdf

FranklinD

Just finished replacing the hose, wand handle/trigger, and main pressure relief valve on our industrial pressure washer at work. Used standard Teflon tape with zero leaks or issues. The relief is rated to open at 3600 psi.

ChrisJ

I ended up using Megaloc and had no leaks.

jumper

Two questions are apropos for sealing. What are you sealing? Water in your pressure washer is much easier to seal than oil or freon. The second question has to do with thermal cycling.

ChrisJ

jumper said:

Two questions are apropos for sealing. What are you sealing? Water in your pressure washer is much easier to seal than oil or freon. The second question has to do with thermal cycling.

Huh?

Gordy

Teflon tape would have been plenty. Nothing wrong with going the extra mile though.

gennady

Threaded joint in essence is a weld joint. Conical IPS thread creates such a pressure in joining parts, it causes fusion of contacting metals. All you need is lubrication and polishing materials to remove unevenness in contacting materials so molecules can exchange in contacting metals. So, pro dope is all you need.

Alan (California Radiant) Forbes

That Gennady. What he says makes sense. I think he's a pipe whisperer.

ChrisJ

Yes except I've heard that as well as NPT having a spiral void that must be filled. Imo dope and tape both lubricate and fill that void.

gennady

ChrisJ said:

Yes except I've heard that as well as NPT having a spiral void that must be filled. Imo dope and tape both lubricate and fill that void.

Tread must be of a good quality. Worn dies make damaged thread. So fixing one problem with another will not produce good results. Also substandard fittings and nipples of poor quality will not make good joint. Quality tread will not need a glue to hold.

gennady

Hatterasguy said:

gennady said:

Tread must be of a good quality. Worn dies make damaged thread. So fixing one problem with another will not produce good results. Also substandard fittings and nipples of poor quality will not make good joint. Quality tread will not need a glue to hold.

Standard NPT pipe threads lockup across their pitch line. There is never an expectation that the major and minor diameters will also simultaneously contact. So, the need for dope is present on even the finest NPT threads cut from brand new tools.

NPTF threads, however, will seal across both major and minor diameters and have no requirement for dope. I have seen such threads available in brass fittings but not in iron.

Part of the practical exam for master plumber licence in NYC is to make so called triple offset. No sealant except pro dope allowed. Test at 100 psi air.
I had always done it this way. Never used anything except of pro dope on threaded joints. Just finished 3" and 4" gas line in the city. Pro dope only. It works. It does not leak.
It is important to make a threaded joint in one move. Fitting and pipe get hot from friction and expand. If you allow them to cool down, then they lock.

The idea of threaded joint is to create dynamic deformation of the joining parts. Some quality fittings even have stops built into the fitting to prevent over tightening of the joint.
That's my 2 cents.

ChrisJ

gennady said:

Hatterasguy said:

gennady said:

Tread must be of a good quality. Worn dies make damaged thread. So fixing one problem with another will not produce good results. Also substandard fittings and nipples of poor quality will not make good joint. Quality tread will not need a glue to hold.

Standard NPT pipe threads lockup across their pitch line. There is never an expectation that the major and minor diameters will also simultaneously contact. So, the need for dope is present on even the finest NPT threads cut from brand new tools.

NPTF threads, however, will seal across both major and minor diameters and have no requirement for dope. I have seen such threads available in brass fittings but not in iron.

Part of the practical exam for master plumber licence in NYC is to make so called triple offset. No sealant except pro dope allowed. Test at 100 psi air.
I had always done it this way. Never used anything except of pro dope on threaded joints. Just finished 3" and 4" gas line in the city. Pro dope only. It works. It does not leak.
It is important to make a threaded joint in one move. Fitting and pipe get hot from friction and expand. If you allow them to cool down, then they lock.

The idea of threaded joint is to create dynamic deformation of the joining parts. Some quality fittings even have stops built into the fitting to prevent over tightening of the joint.
That's my 2 cents.

Ok,
But you still used thread sealant.

Show me the same thing except use motor oil instead of dope. It'll lubricate the threads fine.

I'm an amateur and have no problems getting NPT to seal at 150 PSI with air using nothing more than blue monster tape. If the threads are questionable I'll smear a hint of megaloc on it to act as a lubricant.


What exactly does "making a threaded joint in one move" mean? How do you spin a pipe 6-8 full rotations without stopping? I think I'm just misunderstanding what you said.

gennady

ChrisJ said:

gennady said:

Hatterasguy said:

gennady said:

Tread must be of a good quality. Worn dies make damaged thread. So fixing one problem with another will not produce good results. Also substandard fittings and nipples of poor quality will not make good joint. Quality tread will not need a glue to hold.

Standard NPT pipe threads lockup across their pitch line. There is never an expectation that the major and minor diameters will also simultaneously contact. So, the need for dope is present on even the finest NPT threads cut from brand new tools.

NPTF threads, however, will seal across both major and minor diameters and have no requirement for dope. I have seen such threads available in brass fittings but not in iron.

Part of the practical exam for master plumber licence in NYC is to make so called triple offset. No sealant except pro dope allowed. Test at 100 psi air.
I had always done it this way. Never used anything except of pro dope on threaded joints. Just finished 3" and 4" gas line in the city. Pro dope only. It works. It does not leak.
It is important to make a threaded joint in one move. Fitting and pipe get hot from friction and expand. If you allow them to cool down, then they lock.

The idea of threaded joint is to create dynamic deformation of the joining parts. Some quality fittings even have stops built into the fitting to prevent over tightening of the joint.
That's my 2 cents.

Ok,
But you still used thread sealant.

Show me the same thing except use motor oil instead of dope. It'll lubricate the threads fine.

I'm an amateur and have no problems getting NPT to seal at 150 PSI with air using nothing more than blue monster tape. If the threads are questionable I'll smear a hint of megaloc on it to act as a lubricant.


What exactly does "making a threaded joint in one move" mean? How do you spin a pipe 6-8 full rotations without stopping? I think I'm just misunderstanding what you said.

In one move means do not stop to to let it cool down.

Pro dope is a mixture of 50%-60% Calcite (Calcium carbonate), the rest is Petroleum-based Lubricating Oil, Kaolin and Menhaden oil. So all there is in pro dope is a abrasive mineral, some clay and oil. I think in ideal situation, when tread well polished only oil would be needed to make quality joint.

Teflon tape, megalock and others to me just a filler to mask bad thread. If thread is bad, then good tread must be made.

ChrisJ

gennady said:

ChrisJ said:

gennady said:

Hatterasguy said:

gennady said:

Tread must be of a good quality. Worn dies make damaged thread. So fixing one problem with another will not produce good results. Also substandard fittings and nipples of poor quality will not make good joint. Quality tread will not need a glue to hold.

Standard NPT pipe threads lockup across their pitch line. There is never an expectation that the major and minor diameters will also simultaneously contact. So, the need for dope is present on even the finest NPT threads cut from brand new tools.

NPTF threads, however, will seal across both major and minor diameters and have no requirement for dope. I have seen such threads available in brass fittings but not in iron.

Part of the practical exam for master plumber licence in NYC is to make so called triple offset. No sealant except pro dope allowed. Test at 100 psi air.
I had always done it this way. Never used anything except of pro dope on threaded joints. Just finished 3" and 4" gas line in the city. Pro dope only. It works. It does not leak.
It is important to make a threaded joint in one move. Fitting and pipe get hot from friction and expand. If you allow them to cool down, then they lock.

The idea of threaded joint is to create dynamic deformation of the joining parts. Some quality fittings even have stops built into the fitting to prevent over tightening of the joint.
That's my 2 cents.

Ok,
But you still used thread sealant.

Show me the same thing except use motor oil instead of dope. It'll lubricate the threads fine.

I'm an amateur and have no problems getting NPT to seal at 150 PSI with air using nothing more than blue monster tape. If the threads are questionable I'll smear a hint of megaloc on it to act as a lubricant.


What exactly does "making a threaded joint in one move" mean? How do you spin a pipe 6-8 full rotations without stopping? I think I'm just misunderstanding what you said.

In one move means do not stop to to let it cool down.

Pro dope is a mixture of 50%-60% Calcite (Calcium carbonate), the rest is Petroleum-based Lubricating Oil, Kaolin and Menhaden oil. So all there is in pro dope is a abrasive mineral, some clay and oil. I think in ideal situation, when tread well polished only oil would be needed to make quality joint.

Teflon tape, megalock and others to me just a filler to mask bad thread. If thread is bad, then good tread must be made.

The taper on NPT threads allows them to form a seal when torqued as the flanks of the threads compress against each other, as opposed to parallel/straight thread fittings or compression fittings in which the threads merely hold the pieces together and do not provide the seal. However a clearance remains between the crests and roots of the threads, resulting in a leakage around this spiral. This means that NPT fittings must be made leak free with the aid of thread seal tape or a thread sealant compound. (The use of tape or sealant will also help to limit corrosion on the threads, which otherwise can make future disassembly nearly impossible.)






National pipe taper fuel (NPTF)[edit]
A semi-compatible variant called National Pipe Taper Fuel (NPTF), also called Dryseal American National Standard Taper Pipe Thread, defined by ASME B1.20.3, is designed to provide a more leak-free seal without the use of PTFE tape (often referred to by the popular brand name "Teflon") or other sealant compound. NPTF threads have the same basic shape but with crest and root heights adjusted for an interference fit, eliminating the spiral leakage path. Unfortunately, fittings made with these threads usually gall when attempting to unscrew them after they have been tightened for service. citation needed Galling generally ruins their ability to make a leak-tight seal and requires replacement of the fittings or subsequent seal welding or brazing in place to eliminate the leak path. Seal welding or brazing can be problematic if a lubricant or teflon tape was used on the thread when it was first made up.

You can think NPT threads don't have a spiral leakage path all you want, but they do and always will. I've heard thread sealer wasn't allowed on sprinkler systems so cast iron fittings were used to intentionally rust and fill in the gaps. Not sure how true that is or not.

ChrisJ

gennady

Quote from attachment: The threaded joint is still considered to be an excellent method of connecting pipe to fillings .

I re-read attached document 3 times from top to bottom and did not find any mention of glue need to make a tight joint. or some spiral thingie.

But I understand now confusion, NPT and NPTF ( dryseal). These are for different applications.
NPT is for mechanical or low pressure connections. They probably need sealant.
For critical applications NPTF must be used.

ChrisJ

gennady said:

Quote from attachment: The threaded joint is still considered to be an excellent method of connecting pipe to fillings .

I re-read attached document 3 times from top to bottom and did not find any mention of glue need to make a tight joint. or some spiral thingie.

But I understand now confusion, NPT and NPTF ( dryseal). These are for different applications.
NPT is for mechanical or low pressure connections. They probably need sealant.
For critical applications NPTF must be used.

Have you ever used NPTF for anything?
I've never seen it anywhere.

gennady

ChrisJ said:

gennady said:

Quote from attachment: The threaded joint is still considered to be an excellent method of connecting pipe to fillings .

I re-read attached document 3 times from top to bottom and did not find any mention of glue need to make a tight joint. or some spiral thingie.

But I understand now confusion, NPT and NPTF ( dryseal). These are for different applications.
NPT is for mechanical or low pressure connections. They probably need sealant.
For critical applications NPTF must be used.

Have you ever used NPTF for anything?
I've never seen it anywhere.

Not really. NPTF is fitting only. Pipe is same NPT. But anyway, pro dope works for me. And if inspector will see teflon tape or lampwick or any glue on gas line he will fail me. So I would stick to pro-dope. I still did not see any mention in american thread standard of necessity of the glue in threaded joint.

ChrisJ

gennady said:

ChrisJ said:

gennady said:

Quote from attachment: The threaded joint is still considered to be an excellent method of connecting pipe to fillings .

I re-read attached document 3 times from top to bottom and did not find any mention of glue need to make a tight joint. or some spiral thingie.

But I understand now confusion, NPT and NPTF ( dryseal). These are for different applications.
NPT is for mechanical or low pressure connections. They probably need sealant.
For critical applications NPTF must be used.

Have you ever used NPTF for anything?
I've never seen it anywhere.

Not really. NPTF is fitting only. Pipe is same NPT. But anyway, pro dope works for me. And if inspector will see teflon tape or lampwick or any glue on gas line he will fail me. So I would stick to pro-dope. I still did not see any mention in american thread standard of necessity of the glue in threaded joint.

No one said anything about glue?

Pipe dope and PTFE tape both work to fill in the spiral void.

There's no glue.

gennady

OK.

jumper

So what's with drain plug on our crankcase? Hardly any pressure. But the oil likes to creep and engine warms up and cools each day.

ChrisJ

jumper said:

So what's with drain plug on our crankcase? Hardly any pressure. But the oil likes to creep and engine warms up and cools each day.

Are you talking about the drain plug on a pressure washer crank case?

You need to be more specific, supply pictures if possible.
On mine I believe the dip stick on the pump crank case has a vent.

Abracadabra

ChrisJ said:

jumper said:

So what's with drain plug on our crankcase? Hardly any pressure. But the oil likes to creep and engine warms up and cools each day.

Are you talking about the drain plug on a pressure washer crank case?

You need to be more specific, supply pictures if possible.
On mine I believe the dip stick on the pump crank case has a vent.

Pretty sure he's talking about a car engine.

ChrisJ

I don't think I've had an NPT drain plug.
Most are straight threads with a gasket, either a rubber O ring or aluminum crush washer usually.