EFM 520 Cut Thread

Purchased an used EFM 520. Thread on the top , one you hook up safety valve have cut thread as shown...

Is that suppose to be there? How does it seal against the safety valve?

http://imgur.com/YNFzqWQ

OUCH! That ain't good. That's a deep cut right through all the threads, that won't seal.

Options;
Drill to the next threaded pipe size?
Weld in a new bung.
Put tons of tape and sealer on and pray?

-Don

Someone really got carried away with a reciprocating saw.

Get a can of X-Pando pipe joint compound and use it to install a new nipple.

Had a radiator I was going to install and ended have to cut one fitting out, damaged the threads slightly but not anywhere near as deep as that. Sealed up fine with some pipe dope. Unfortunately it was cracked elsewhere <sigh>.

Something you might want to try is first wrap the threads with some string in the groove, pipe dope and hope it works.

Fill it with JB weld and re-tap it . when you fill it just don't fill the crack all the way to the top. leave room for the tap to get started in the old thread.

I can't tell from the photo. Is it a 3/4 inch opening or 1 inch?

blrman07 wrote:I can't tell from the photo. Is it a 3/4 inch opening or 1 inch?

PRV tapping on a 520 is 3/4".

For those that are not familiar with it, the X-pando compound I mentioned is a 2-part compound that expands as it sets. It is kind of like JB weld, but made for pipe threads. I heard about it from one of our factory maintenance guys, they used it on old steam pipes/fittings that had been damaged.

I've got 4 different repair suggestions in ascending order of cost.

The old school repair for this type of situation was to wrap the pipe or fitting threads going in the hole with small diameter lead wire and dope the hell out of it with the best dope you could get. Before the world went nuts about lead I used this method several times and it worked every time. You can still get lead wire at most of the big box hunting stores in the fishing department. Last time I bought lead wire I got it at Cabela's. The still carry it for under $5.00. Lead doesn't melt until over 600 degrees F so no worries with it melting out of the joint. If you hit 600 degrees with your boiler you have other more pressing problems!!!

If you don't want to use lead, a workable two part repair would be to take a short nipple with a 3/4 coupling and wrap the threads going into the boiler with several wraps of cotton sewing thread. Then apply the Expando pipe dope. Your local hardware store probably doesn't carry it and would have to order it. OR you can order it yourself on line. My research shows it's under $20 plus shipping. Follow the instructions and pay close attention to the working time. Also once it's in don't mess with it for at least 24 hours so the stuff can set up.

Also Helicoil makes a 3/4 inch pipe threaded insert coil but that is a last resort as it's EXPENSIVE. Permanent repair but its a couple hundred dollars or more for the kit you would need.

If all else fails horse in a 3/4 bushing and have a welder come in. To get a good weld he may need to grind the flats off the bushing. Have the welder seal weld it in place. A good bead of weld all the way around will hold it and seal it up.

I would braze the cut and retap.

I would just tap it out for the next size bigger. Even if you go past the size of the bung, the 5/16" thick metal still takes a tap pretty good. And there is a bunch of high quality weld backing it up. The weld materiel is harder than the boiler plate. Or just try some RTV.