Repairing Tarm water jacket

[Yukontools]

One of the "soft plugs" as I refer them to on the side of the boiler tore through the outer side of the jacket. Tarm calls them something like expansion plugs. The boiler overheated after the circulating pump failed do to excess solder in the system. Tarm said it is carbon steel. What might some of you suggest for welding techniques(rod type, MIG, braze). Round or square patch. Tests will have to be above 30 psi to ensure safety. +37 in Galena today.

 

[maple1]

I think I would call Tarm & ask them - but I have no experience with that kind of thing.

Hope you get it back up & running - hope you also make changes so it won't happen again. A PRV should have stopped that from happening? And a dump zone?

 

[Bad Wolf]

It doesn't make sense that it would only be an expansion plug. I count at least 20 there and you should have had a pressure relief valve in the back. Those look more structural, like maybe tying the inner and outer walls together. I would talk directly to TARM.

If it is mild steel then Mig or stick should work. I think I would try to fill in the hole then weld a patch over it.

I have a TARM Excel 2000 which looks like what you have. I once started a fire and opened the damper and lower door but hadn't turned on the blower yet and then forgot it. The overheat dump valve still had power so it didn't open. When I went back downstairs I had steam allover from the pressure relief valve. I quickly turned on the fan/circ pumps and everything settled down.

8 below in Colchester last night, TARM running full tilt...

Good luck

 

[DaveBP]

I believe those "expansion plugs" are actually structural stays, rods welded between the inner and outer jackets of the boiler. They keep the rectangular walls from becoming cylinders. Looks from the photos as yours is part way there. And the one to the left of the failed one may be cracked judging from the way it is 'cratered'.

Definitely time to consult with your dealer.

Most folks use a pressure relief valve to prevent this. Some use 2. Just in case. They've been known to corrode shut.

 

[ewdudley]

I believe those "expansion plugs" are actually structural stays, rods welded between the inner and outer jackets of the boiler. They keep the rectangular walls from becoming cylinders. Looks from the photos as yours is part way there. And the one to the left of the failed one may be cracked judging from the way it is 'cratered'.

Definitely time to consult with your dealer.

Most folks use a pressure relief valve to prevent this. Some use 2. Just in case. They've been known to corrode shut.

This. Yikes.

Should be no problem to pound it all back and re-weld, be sure to back-up on the inside with heavy sledge or whatever.

But as all agree there should have been no way for the system to get into this state to begin with. Either you're missing a pressure relief or the one you have has failed to perform.

 

[maple1]

Yes, looking a bit closer looks like the one to the left is about to pop too.

Yikes indeed. Better unskin the whole thing & do a thorough inspection of all those stay welds, and all other welds - along with making the necessary other fixes/additions to ensure it doesn't happen again. Would be really curious what the pressure got to to cause it.

 

[Fred61]

Nice to know that this will happen without serious injury or loss of your home. I always assumed that this situation resulted in a big BOOM. I'm not able to access the situation from here but my first thought would b to drill and tap the stay in order to crank the expanded wall back into shape with a u-block before re-welding. Will do much less damage than an 11 pound sledge hammer.

 

[CrufflerJJ]

Pressure relief valves are a GOOD THING. Many moons ago, when I was working as an engineer in the automotive adhesives/sealants business, I heard a story out of one of our Canadian plants. Another person (luckily not me!) was making a trial batch of product in a newly installed water jacketed production mixer. They had charged the initial raw materials to the mixer, then turned on the water to the mixer's cooling jacket. Shortly thereafter came the sound of crunching/popping. There was no pressure relief valve installed (oops!) and the inner & outer walls of the steel jacketed mixer were pushed apart by the excessively high water pressure from the chiller. As this happened, the mixer's legs were yanked free from the bolts securing them to the concrete floor (the "popping" noise).

Not sure whatever ended up happening to the mixer....probably trashed, as the result of a simple pressure relief valve having been omitted.

Oopsie!

 

[Yukontools]

Pressure relief valves are a GOOD THING. Many moons ago, when I was working as an engineer in the automotive adhesives/sealants business, I heard a story out of one of our Canadian plants. Another person (luckily not me!) was making a trial batch of product in a newly installed water jacketed production mixer. They had charged the initial raw materials to the mixer, then turned on the water to the mixer's cooling jacket. Shortly thereafter came the sound of crunching/popping. There was no pressure relief valve installed (oops!) and the inner & outer walls of the steel jacketed mixer were pushed apart by the excessively high water pressure from the chiller. As this happened, the mixer's legs were yanked free from the bolts securing them to the concrete floor (the "popping" noise).

Not sure whatever ended up happening to the mixer....probably trashed, as the result of a simple pressure relief valve having been omitted.

Oopsie!

There was a PRV valve in the house on the oil boiler. The idea here is the two boilers become static in pressure as they support one another. The problem lies without a properly functioning or functioning circ pump for that matter the built up pressure has no way to mix with the oil boiler in the house. If I can repair this a PRV will be installed. Not sure how to do a dump zone, though I know what they are for. Understand that the guy that did the original install has since passed and taken all his secrets with him. There is no pressurized or non-pressurized storage in the system though the new owners would like t have one installed. I'm a dangerous handy man learning on the fly most of the time but not super thrilled about jumping into this one. Not a lot of options for welders here in the village.

 

[maple1]

An operating circ pump is not needed for the pressure to equalize in the system, it will do it on its own - there was something fundamentally wrong here. Maybe the oil boiler where the PRV is was valved off from the rest of the system?

 

[Hydronics]

I would consult with Tarm, depending what they recommend - weld up the end of that stay then pressure test to 30 psi (relief pressure). I wouldn't start hammering on the jackets, this won't negate whatever stress has occurred. Probably have to weld, pressure test it and hope for the best at this point. I'd inspect the stays on the other side also.
The over pressure came from heat and not enough expansion capacity (bad expansion tank), or bad make-up PRV. The relief should have been a safeguard for either -assuming there is one.
You'll want to be sure there are functioning relief valves on both boilers. You can set up a dump zone with an automag valve and aquastat, they are normally open so they don't need power to open. If the boiler is below the zone it will thermosiphon (colder water is more dense so it will drop, pushing warmer water back up). Put it on the largest zone.
The circ between boilers will help boiler temps to equalize depending on flow and heat loads, pressure will equalize within the system at all times as it's a closed loop -unless valves are closed. A circ will move heat energy but will create very little pressure differential.

 

[maple1]

This was a recent happening a few hours from me:

http://atlantic.ctvnews.ca/overheat...-explosion-at-n-s-home-fire-marshal-1.2250799

I would really like to hear more details, but haven't yet. They call it a furnace, but from the sounds of it I would guess it was a boiler, and that a situation occured very similar to what happened in this thread. Except that it didn't have stay welds to pop, and instead a huge explosion occured - huge enough to move the house off its foundation. These people were very lucky - there was an adult & 3 kids (I think) downstairs when it happened.

 

[mustash29]

One gallon of hot water under pressure = 1600 gallons of steam at atmospheric pressure.

 

[peakbagger]

Mythbusters has had some great shows on blowing up hot water heaters by plugging the relief valves.

 

[cityboy172]

I have a feeling that the pressure relief valve was isolated from the wood boiler. Scary stuff you have going on there.

 

[Buzz Saw]

If you do weld it MIG or TIG. I would stay away from stick unless you are really skilled. Push the panel back to the stay and burn it in. After it's burned it I would then put a patch on it to reinforce the metal around the area.

BUT, do call Tarm first to get a better understanding of the machine.

 

[peakbagger]

I have a suspicion that Tarm will be very hesitant to make any recommendations due to liability. They don't have control of the repair or the competency of the welder.

 

[Yukontools]

If you do weld it MIG or TIG. I would stay away from stick unless you are really skilled. Push the panel back to the stay and burn it in. After it's burned it I would then put a patch on it to reinforce the metal around the area.

BUT, do call Tarm first to get a better understanding of the machine.

That's my plan. I just need to get a portable welder with gen set as I don't have any close access to 220. TIG offers greater control for sure.

 

[Yukontools]

I have a suspicion that Tarm will be very hesitant to make any recommendations due to liability. They don't have control of the repair or the competency of the welder.

Correct.............one of the techs said no problem and Scott, the boss said no way. I can see his point. Sad thing is there were 3 Solo Innovas at an elders center that I was going to buy for $2,500 after the flood of 13 but they never drain the system and it froze and did the same thing to all 3.

 

[DaveBP]

Did the refractory cement pieces at the bottom of, and under, the floor of the firebox crack from movement of the boiler walls? I believe you'll need to remove all the refractory stuff to inspect in there, too. Most, if not all, of the stays are blind-welded (not coming through like the ones on the outside) to that inside wall and may not be east to assess. If any popped off the inside wall you may not be able to tell and would be next to impossible to repair.

I don't mean to cast a death sentence on your boiler but repairing it will be tedious and a bit of a gamble. You'll need to strip everything off the outside. I'd take the 2 doors off also; get all the blue painted stuff off the outside to check every one of the stays, bottom included. It may not be as bad as that one visibly broken weld makes it appear. The first weld to pop would have immediately released the pressure. When you've got everything welded, fill it with water and run the pressure up to 30 psi with a garden hose, NOT compressed air. No leaks? Then reassemble. Tedious, but not necessarily very expensive. And you would have to live with a bit of uncertainty.

And if you put a new pressure relief valve (perhaps even 2) on the boiler, with no valves in the circuit from the supply fitting on the boiler to the relief vent at the floor, there wouldn't be any danger involved.

 

[peakbagger]

hey never drain the system and it froze and did the same thing to all 3.

Bummer, a freeze failure is something I would consider repairing over an overheating/overpressurization event