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# Swing joints. How do they work?

Member Posts: 8,004
I'm sorry if this is a dumb question but I'm trying to understand swing joints better.

Does the piping actually turn inside the fittings or is it to align piping in a way that it can flex and the actual threading inside the fitting doesn't move?

I'm having a hard time understanding if the piping actually turns inside the fitting how doesn't this create leaks?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

Steam system pictures
https://goo.gl/photos/ZgpNUTyckkmiEdAf9
Central air project pictures
https://goo.gl/photos/4JjnLStEq42sWsQo8

• Member Posts: 7,265
Swing Joints:

The alignment of any fitting depends on the other fitting being in the ALMOST exact same plane. Some number that is divided by 90 degrees. With one ell, you can only operate through 90 degrees. With two, one plane will be within 90 degrees, the other plane can be anything. If you add a third, you can swing throughout any plane. With four ells, there is no plane that you can not swing through. You can make a swing joint with two ells when connected to a stationary point. Like an oil tank where two ells will give you any offset but you need a third to get back plumb.

It comes into play when you are rising from the vertical and you have to go to the horizontal and need to travel with pitch at say 1/4" per foot. Unless you use a crooked thread on the start of the horizontal, you will need two ells to go from the horizontal. If you do not use two ells on the end of the pitched horizontal run, it will not be 90 degrees plumb. You need another ell. Unless you have a crooked thread.

If that makes any sense to you.
• Member Posts: 8,004
Swinging

So if I'm understanding correctly "swing joint" is a standard piping term in regards to when you use an elbow  so the pipe can "swing" to a different angle?

My assumption was it was a term only used in steam piping.
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

Steam system pictures
https://goo.gl/photos/ZgpNUTyckkmiEdAf9
Central air project pictures
https://goo.gl/photos/4JjnLStEq42sWsQo8
• Member Posts: 1,139
hot water risers

we also use a six elbow swing on hot water risers on high risers.My friend an incredible plumber showed me how but due to my computer inadaquacies or spelling I cant draw it out for you.It is beautiful though
• Member Posts: 6,476
Piping geometry

A happy, and informative time can be had at the hardware store, trying out different combinations of 90's, and 45's to get an idea of how stiff piping can be made to go between 2 points without using a single straight line.

Ice, why not go the hardware store, and put some joints together, and take a picture of them so we can see what your friend showed you.--NBC
• Member Posts: 5,552
Not just a steam term, but….

Swing joints are critical for the longevity of a piping system with extremely long runs. If left to its own action/reaction, a piping system can tear itself apart at the joints due to uncontrolled expansion AND contraction. I have seen long runs of PEX used for snowmelt system that literally tore itself out of the plastic supports due to contraction, a condition that no one anticipates on the start up of an extremely cold slab.

A properly installed expansion compensation system will have the ability for the pipes to move without causing undue wear on the pipes (slides and or guides) and is anchored such that the growth/contraction is directed towards the expansion compensator, and is virtually silent in operation.

Expansion joints (other than near boiler piping on steam boilers) can be comprised of 4 elbows arranged in a large U shape (there are actually required leg lengths based on anticipated growth) or in the case of copper or plastic, a large (again, calculated) circular loop, or a telescopic device sealed with O rings.

Again, even though it may be installed, if improperly blocked and supported, they may be useless if the expansion and contraction are not being directed towards the compensation device. In the case of contraction, the initial setting would be half way between compressed and relaxed to compensate for contraction. If used for heating only, they would be set in a contracted mode to allow for expansion.

This required anchoring is a detail that is typically overlooked by the design engineer, the inspector and the contractor and the expansion joints can be a waste of time if improperly applied and controlled.

Residentially, long runs of PEX, if improperly applied and controlled, can equate to a very noisy piping distribution system. In my opinion, "Comfort", does NOT include any noises associated with the operation of the system. Control is as simple as blocking and locking the tubing on the far ends, having an expansion joint in the middle of the run, and supporting the tubing with glides that will allow for a smooth movement of tubing without creating ticking and clicking.

This is one major reason I am not a fan of suspended tube, a.k.a. staple up tubing for RFH applications. When the tubing cools to room temperature,and then is heated up due to call for heat, it sounds like a herd of crickets running through the floor joist…

Got questions ?
It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
• Member Posts: 7,265
Expansion/Contraction:

Expansion is one thing. It grows and just compresses upon itself.

Contraction is a different animal, If in the act of expansion, it resolves its position in life and takes a new set, and then contracts, the same rules that apply to expansion, apply to contraction. But it can rip itself out of a fitting if it can't stretch anymore.

With copper tube, buried under a floor in screened sand, it will expand and push sand away, to fill in behind. Then, when it contracts, it will rip copper tube out of a copper fitting and leak.

Never underestimate the power of contraction.
• Member Posts: 7,265

Do The Google and put in the term "piping  swing joint". you will end up knowing more than you ever want to know.
• Member Posts: 8,004