repairing a rusted pipe?

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  #1  
Old 08-03-14, 09:23 AM
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repairing a rusted pipe?

I will preface this by saying I anticipate trouble.

This past winter I noticed the rads seemed to be requiring more bleeding than usual. There is a rad at the top of the stairs that every couple of weeks, I'd give a little bleed to. Normally there would be nothing, but this past heating season, every time I'd bleed it, air would come out.

Then about 6 weeks ago my wife noticed the rusting pipe in the pic when she moved her sewing box.

Sometime in the past, before we arrived on the scene, someone either replaced or tried to replace the valve and instead opted for the tape around the top. I suspect the there was no pipe dope used when reconnected and now dissimilar corrosion has set in.

IIRC the fitting that connects to the radiator is a right hand thread, but I tried to break it loose, to no avail.

Any suggestions on how to proceed with this with doing more damage than is already there?

Terry
 
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  #2  
Old 08-03-14, 10:02 AM
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This is a hot-water system, not steam? Let's take off the tape, and see what things look like underneath. Do you have access to the piping below the floor? Are you noticing any water leakage? If your system is always pressurized to, say 12-15 psi, I don't see anything in the photo that would allow air to be injected into the system.

The purpose of pipe dope isn't to prevent dissimilar metal corrosion although it should help loosening of fittings.

You are using two pipe wrench on the RH fitting, right? What size wrenches?
 
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Old 08-03-14, 10:18 AM
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Does it appear that the leak is from the top of the valve, around the stem, rather than where it connects to the vertical riser pipe? That's what I see anyway... and the water runs down over the valve and is rusting the pipe below.

That being the case, I would first try to get the 'guts' out of the valve, leaving the valve in place, and replace the packing gland material.

You've got the system drained and de-pressurized, right?

Have you tried to get the top nut loose from the valve?
 
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Old 08-03-14, 11:17 AM
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I just loosened the nut on the valve and I hear water rushing into or out of the rad, its hard to tell. Initially I undid the bleeder valve, then opened the drain valve in the bottom of the boiler. I also turned off the make up water valve. Perhaps I did not drain enough water. This particular rad has always been cooler than the rest in the house. This rad is the furthest from the boiler and I suspect it has been throttled back somewhat. This is a hot water 2 pipe system.
 
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Old 08-03-14, 11:25 AM
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Have you cut the tape off yet?

Do that and take a picture and show us what you see.

Have you removed the 'guts' from the valve yet? When you loosened it, did any water leak out? If not, you may be safe to remove the guts and let us see that too with a pic.

What's the pressure gauge on the boiler show?
 
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Old 08-03-14, 01:18 PM
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So I cut the tape off and as trooper suggests, it looks as though the valve has been leaking down the pipe rusting it from the outside. They had a ton of teflon tape and it was a rubber, almost a shrink wrap around the outer.

Finally got enough water out ( I don't want to drain the entire system) The pipe looks OK on the inside, just some pimples of rust. Name:  20140803_155056.jpg
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Old 08-03-14, 01:44 PM
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OK... good...

That valve may in fact have been partly or fully closed, no way to really tell by looking at it since the handle was broken and missing.

There's typically an 'arrow' or some indicator on the handle to tell you when it's open / closed.

Obviously, that hole has to point toward the pipe to the radiator when it's open.

Wire brush or sand the stem of the valve and then using two wrenches, try to remove the nut directly below the stem. Under that you will find a 'packing material'. I'm sure it's all dried out and NFG anymore.

After that nut is off the stem, clean up the rest of the stem with wire brush or fine emery cloth to remove the corrosion.

Lowes or HD will have small packages of packing material, it's like a teflon string. You may be able to keep the original stuff in the nut and just add more, or you may be able to fill that nut with the new stuff. You don't need to gorilla tight that packing nut, just enough to keep it from leaking. In the future, keep an eye on it and if you see any seepage, just tighten it a bit more. That nut is not designed to go down all the way tight, it's purpose is only to compress the packing enough that there is no leak from the stem.

Does the stem still turn the valve? You might need to soak it with some PB Blaster to loosen it up so it will turn again.

File a notch, or otherwise mark the stem so you know which way the valve is OPEN after you reassemble.

I think that just refurbishing that stem part with new packing will do the trick.
 
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Old 08-03-14, 02:52 PM
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I got the valve apart and what was in there just crumbled and fell out.
I noticed the stopper just spins, with no stop to be had, no threads on the shaft?

I was always under the impression these valves were like a screw type shut off valve like you find on a water shut off.

Since this is on the second floor and there are 2 more rads, I think I should re do the others while I have the system open. One at the top of the stairs looks like it may in the early stage of a similar fate.

I'll check in with the lowes around the corner from here. If this works, my wife will be happy because this rad is in our bedroom and it was always the coldest in the house.

Thanks so much for the feedback, I really appreciate it.
 
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Old 08-03-14, 05:09 PM
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the stopper just spins, with no stop to be had, no threads on the shaft?
Correct. I don't know if there's an exact name for that type valve other than 'radiator valve', but it's closest cousin is called 'plug valve'.

The fact that it just spins and spins is all the more reason to somehow mark the position of the opening on the shaft so you know if it is in fact open or closed because there's really no other way to tell!

I think I should re do the others while I have the system open
Probably not a bad idea, but now that you know what's under there, unless the position is 'lost' (knobs missing, etc), there's no reason to have to take the whole thing apart, just the packing nut on the stem. That can be done easily with everything else still in place.

lowes around the corner
There are other types of packing material that actually might be better suited to the purpose. The original was probably a fibrous material, kinda like a 'washer' with a hole in the middle, I think they're impregnated with graphite or some such. If you have a REAL plumbing supply house in town, you might take that valve there and see if they have the 'real thing' that's actually made for the valve. The stuff they sell on the hooks at Lowes will work, but may not (or may) be as durable. You probably won't be operating the valve much if at all, so durability isn't really a big issue, you just need the leak stopped.

The original probably looked like this, if you can find this type that fits your valve, it's what I would go with:


image courtesy midlandhardware.com

The following item might be your next best bet, wrap enough around the stem so that it's compressed on the stem without the gland nut bottoming out to leave room for future tightening if necessary:

Shop Danco Graphite Packing at Lowes.com
 

Last edited by NJT; 08-03-14 at 06:11 PM.
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