Need Pipe Unions that don't leak

[ljhhontx]

I work in the natural gas industry and we use Ward fittings, the best unions are the insulated ones with black plastic mating surfaces for electrical isolation, they don't leak like a regular one does. I have no idea the cost but it might be worth it.

 

[The Cobbler]

seems that unions are real bad these days.
when I did plumbing in school they always referred to as ground joint unions, you weren't supposed to mix the halves

So how often is the tooling inspected/changed in plumbing fitting factories in India/China/Korea/Philippines ?

Hence my comment. Lapping compound and lap by hand !

I'm not suggesting they are well maintained, I'm pointing out that they used to be considered "precision, matched sets." It seems you took comment out of context

 

[Shortbread]

I am a toolmaker these days. I used to do plumbing work and pipe fitting. I obtained 2 of these copper unions ,cooper halfs and brass/bronze nut. Well to keep things short 6 tries later I took a pair to work and tested them. What I found...first test add air fittings and tested at 35 foot pounds torque and leaked. This was in a vice on a work bench. Disassembled the hall's and added spotting blue to one half. Torqued to 35 for, leaked 45fp leaked, 55fp and seamed to stop. Just temporary but it slowed greatly. Disassembled and the only seatting was on a line less than 1/32" and maybee not all the way around. So are 10# increments tightened and checked up to 100fp where the copper threads stripped and still no improvement in the seat. I took a second set(male and female) and set to test but first machined a precision seat to both male and female seats. Torqued to about 15fp and tested held for an hour. Retightened to 35fp and rechecked leak. Disassembled and near perfect seat seal. My conclusion is that unless the seats are machined that type fitting is useless.i ended up making solid connections much to my dislikes because the fittings I found were unmachined no matter the price or where they were made.

 

[nadogail]

I used to maintain the piping for steam heated molding presses that were heated with 250 pound steam pressure. We found ground joint unions were the only thing that worked for us.

 

[Busted_Knuckles]

Don't buy the big box store chinese unions, buy the ones at the plumbing supply house or online, the ones made in America

Figured this out, several years ago, same situation as the OP Chinese pipe parts and air, solution is Loctite 565 ( other than going and finding USA parts and pipe )

I tried EVERY last pipe compound / sealing product on the market, this actually CURES !

Now I dont leave home without a tube of this stuff !



https://www.henkel-adhesives.com/us/en/product/thread-sealants/loctite_565.html




White to off-white, 1-part, low strength, high viscosity, anaerobically-cured, methacrylate ester, acrylic thread sealant

LOCTITE® 565 is a white to off-white, 1-part, low strength, high viscosity, anaerobically-cured, methacrylate ester, acrylic thread sealant designed for the locking and sealing of metal pipes and fittings. The product cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration.

• Designed for the locking and sealing of metal pipes and fittings.
• Prevents loosening and leakage from shock and vibration

 

[Shortbread]

I used to maintain the piping for steam heated molding presses that were heated with 250 pound steam pressure. We found ground joint unions were the only thing that worked for us.

I build the molds for the presses usually these days and the ones I machined were almost as precise as a ground one would be...did steam piping as a pipe fitter, no room for bull doin that kinna stuff.

 

[LS6 Tommy]

Figured this out, several years ago, same situation as the OP Chinese pipe parts and air, solution is Loctite 565 ( other than going and finding USA parts and pipe )

I tried EVERY last pipe compound / sealing product on the market, this actually CURES !

Now I dont leave home without a tube of this stuff !



https://www.henkel-adhesives.com/us/en/product/thread-sealants/loctite_565.html




White to off-white, 1-part, low strength, high viscosity, anaerobically-cured, methacrylate ester, acrylic thread sealant

LOCTITE® 565 is a white to off-white, 1-part, low strength, high viscosity, anaerobically-cured, methacrylate ester, acrylic thread sealant designed for the locking and sealing of metal pipes and fittings. The product cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration.

• Designed for the locking and sealing of metal pipes and fittings.
• Prevents loosening and leakage from shock and vibration.

That stuff is pretty darn good, but keep in mind, the threads on a union (or flare) have nothing to do with the seal.

Tommy

 

[PoorUB]

I used to do a lot of gas piping at my job. We used Ward brand fittings. Once in a while I would get one that would not seal. I got into the habit of lubing the threads and the back side of the nut with some pipe dope. I could get a bit more torque on them with a bit of lube.
On gas, a good inspector wil jump your *** if he sees pipe dope on the sealing surfaces. Our inspector jumped me a couple times until I took the union apart and showed him what I did. Plus, in a few years if you ever have to take them a part the break loose so much easier!

 

[Shortbread]

That stuff is pretty darn good, but keep in mind, the threads on a union (or flare) have nothing to do with the seal.

Tommy

We all do what it takes to get a job done and right, well mostly. The problem in part for me was the best supply houses around were selling the same stuff and some were made here just the same as the imports and that sucked. I guess I am just old school what you buy for a job is supposed to work as expected. In this case you shouldn't need anything else to make it do so. Kinna like threads and I see a lot of this. Using standard self-seal tappered threads there should be no need for anything other than lubricants allow proper tightening. These days tho Lord help you if you try to assemble anything store bought without sealant of some sort.

 

[readhead]

Unless it needs regular service I would use a right-left coupling. If there is enough flex it can still be removed for service.

 

[andyvh1959]

Pipe unions seal in a manner similar to 37 degree flare, being a metal to metal cone to seat seal. 37 degree flare works best to make sure the seat to cone is fully aligned and seated before applying any tightening. Similar for pipe swivel seal, and the pipe seat to cone seal. Even within the design specs for any metal to metal seal are variances/tolerances, and the difference is obvious in cheap market products versus quality products (US products). Differences in metal, surface finish, especially plating, all affect the seal area, so stay with better quality products. Unless the material is stainless steel, no sealant should be applied onto the cone/seat interface. If the material IS stainless steel, then anti-sieze is needed on both parts in the threads and seat/cone.

 

[LS6 Tommy]

Pipe unions seal in a manner similar to 37 degree flare, being a metal to metal cone to seat seal

Unless the material is stainless steel, no sealant should be applied onto the cone/seat interface. If the material IS stainless steel, then anti-sieze is needed on both parts in the threads and seat/cone.

BTDT. Just replaced a bunch of SS unions with galled seats on a chemically free steam system last month. Someone opened the unions to service the humidifer wands and couldn't get the unions to seal again. Same person argued with me about using anti sieze during the original installation...

Tommy

 

[andyvh1959]

I was on a customer replumb project of a yacht lifting mobile crane. They called me in because no matter the torque/tightening applied they couldn't the SS flare connections to seal. We were able to get the connections apart, and they were dry. Instructed them to clean up the seats/cones, apply anti-seize to the threads and seat/cone, and everything tightened up completely and sealed at the right torque values.