Plumbing Union/Coupling Question


Hello:
Have done a fair amount of home plumbing type of work, but, surprisingly, have never had need to use a "union".
Have to run a line from a washing machine water outlet to the machine, and for various reasons, before I get to the hose itself, I could use a Union in the rigid section to provide some angularity adjustment, as well as the removable advantage they provide.
Have looked at them at HD, and frankly they make me very nervous.
What's your experience with these things. e.g.,
Once you snug them up, do they tend to stay that way ?
Reason i'm asking is that there is no elasticity in the union coupling itself, so it seems to me that if the threads back off, even a very small amount, there will be leakage thru the ground and polished seat where the two pieces actually come together.
Any thoughts on this ? Safe to use ? Proven in practice pretty well ?
Are there any other types, or brands, besides the HD ones that are perhaps of better quality ?
Thanks, Bob
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They work. Never had a problem when installing a new one. Minor problems when re-using an elderly one. Even then in most cases nothing a little pipe dope would not solve.
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Robert11 wrote:

A union won't give you any angle adjustment. And the threads won't simply loosen on their own; the nuts get tightened with 2 big pipe wrenches.
Why don't you go into more detail with exactly what you're trying to do.
Does "washing machine water outlet" mean a threaded hose connector?
Would some form of hose quick-connect suit your needs?
Jim
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[...]
Unions are absolutely standard equipment in hooking up natural gas appliances (have a look at the line to a NG water heater, for example). Typical arrangement is supply pipe -- shutoff valve -- union -- short pipe -- appliance.
That good enough for ya?

Undoubtedly. The fittings sold at HD are IMO pretty much the bottom of the barrel, and you'll almost certainly find higher quality at a plumbing supply shop.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Robert11 wrote:

Union provides no more angular adjustment than a coupling. If you want adjustability, use several back-to-back 45 or 22 degree ells.
Best regards, Bob
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By angle adjustment, I think he meant that the pipes on each size can rotate with respect to each other.
Bill

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Unions are fine If you are going from Iron to copper you need a dielectric union. Also when installing one coat the threads with pipe dope if a non dielectric also coat the face, don't be afraid to tighten them. A union should always be accessible. What I like better is a Left/Right nipple witch also are made for dielectric use. Now if you want some flexibility buy a flex hose. Basically pipe threads on the end of a stainless hose, They also make a copper sweat flex. If this is going to be something you see disconnecting now and then start off with a ball valve.
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You can also go from iron/steel to copper with a brass valve eliminating the need for a dielectric union/nipple if that would be more appropriate.You can also purchase 3 piece valves so the valve itself acts as a union,valve,and dielectric connection.Would be hard to say without seeing the install location.
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They've been used for scores of years. With threaded iron plumbing, they were a must. Yes, they work. And yes, they stay seated. Can you imagine a water heater hooked up without them? Or a water softener? What a pain that would be.
--
Steve Barker



"Robert11" < snipped-for-privacy@notme.com> wrote in message
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Hello all,
Thanks for all the information, and time to help me out. Appreciate it.
Just one quick follow-up, please:
What type of Grease, or other lubricant, should the mating faces be lightly coated with prior to assembly ? Any reasons not to (water usage) ?
Thanks, Bob --------------------------

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I would use Rectorseal pipe dope it's just acting more like a lubricant . Were ever the metal rubes or threads you want to coat. If you get to much on it's just to wipe off after assembly. I don't know what the line is hooking to but before you install a valve or whatever run some water threw the line to get any debris out.
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Just my experience here. I don't know what the _official_ stance is on it.
I have _never_ applied any kind of pipe dope, lubricant or anything else to the mating faces. On the threads, yes. The mating faces do not slide across one another when intalling so don't need 'lubricant'. Sealer? Not in my experience. I have had leaks in just about any type joint normally found in a house but never in a union.
Harry K
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Agree. I'd just put some pipe dope on the threads.
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