Expansion joints in steam risers

bob young

packless joints are available. fulton sylphon is one vendor, metaflex another

Sal_4

Expansion joints in steam risers

Hi all,
i met a customer who maintains a apartment building that has been having a problem with leaking expansion joints in the buildings steam risers. He said that he had repacked some of them(with grafite packing) and the hold for a "little while" but then start up again. I'm wondering if grafite is the right type of packing for the job considering the high temps. System is a two pipe, with down fed risers, 7/8 story building. Unit running at 2psi. I questiong why the 2psi building manager said middle floor had trouble heating if they went lower.
Any help would be appriciated.

Tony Conner

As Long...

... as the packing is rated for the service - 2 PSIG isn't very much - there are packed expansion joints on 300 PSIG steam systems that work just fine - it should be OK. Something else is wrong. Where there are expansion joints, there are guides and anchors. Are they still in place & OK?

Sal_4

Thanx for the response. You now i don't believe there were any guides or supports of any sort. i just saw risers and tee that went to an old capped off radiator. I would be willing to bet that who ever capped the rad. took out the supports. what do the support/ guides look like? fiction clamp looking device?

Sal

Tony Conner

Expansion Joints

Guides look like sleeves over the pipe, then the base of the sleeve is fastened to something structural - a beam, floor, wall, etc. These are normally a few of these where the expanding pipe moves into the joint. The pipe must be able to slide through them, but they need to be a close enough fit that they keep the line true to joint. Otherwise the expanding line can squirm in the hangers, and that can cause the expanding line to become cocked at the joint, and jam. Or if it's a bellows-style, unguided expansion can wreck the bellows one side gets squashed, and the other side arches out. The side that arches out usually sort of balloons and stays that way, even with it cools off. If that happens, it's wrecked, and needs to be replaced. On high pressure systems, they can blow out - very nasty. I'm not a big fan of bellows expansion joints. I prefer the slip style.

Also, the pipe with the expansion needs to be achored - usually at a 90 or tee at the far end of the expanding run. This means as the pipe heats up, and expands, it moves into the expansion joint.

It's kind of odd to see expansion joints on systems like the one your working on. It's not that hot, or very long. Not a whole lot of expansion to deal with.