Copper Pipes and Boiler Base Plates

Hi, nice to have such a lucid question asked.
I'd say make the plate out of similar material to the boiler, presumably steel.
OK you are going to end up connecting dissimilar metals at some point, but hopefully some chemical inhibitor will take care of that, and the boiler connection is where the most heat is, so I'd try to keep to similar material.

Steel also wins on cost and ease of fabrication.
(I've disscounted wood which is often my preferred material)

Del

As Del says Go with the steel. Much easier to fabricate. The only other thing I would consider would be to thread the plate to connect the copper to the steel. With a good pipe dope it should seal well and help in the problem of corrosion.

We also recently learned that over-fluxing, and not cleaning the excess flux from the copper, will cause premature failure due to excessive copper corrosion at that joint.

Perhaps this is why the 'new' connection failed first.

Thanks, gentlemen. I now have some ideas I did not have before. Threading the plate is a possibility, but by the time I get someone to cut the plate, bore it and thread it, it may end up being more cost effective to go with my original thought. If I went that way, is TIG welding the best way to attach the copper pipe to the steel plate? I could bore the the hole with a drill press (Don't laugh guys, I'm a woodworker!) Even if it's a bit off, file it carefully till the pipe slides in. There is a (union?), about 8' away from the furnace to allow a permanent joint at the furnace. With the pump, the water temp does not exceed 240 degrees Fahrenheit, at about 65psi. Considering both gauges look like they may have come over on the Mayflower, those readings are subject to debate.

I didn't think you could weld dissimilar metals...but it's not my firld of expertise.
Surely the different melting points would make it impossible?

Del

Bronze and brazing but pictures would be excellent

Braze it do not go for welding. For your application (pressure, temp etc) I feel it will withstand. Steel to cu brazing is common.

If you can get some body, you can get the tubes expanded too.

Braze or high temperature silver solder would be preferable to TIG welding, but I would suggest tapping the hole with a pipe tap and using either a union or a soft solder socket. The plate can be made from mild steel, or a piece of 303-304 series stainless steel. 303 would be easier to machine, 304 would have better corrosion resistance.

you could tig weld threaded coupler on to the plate. then you would have way thread a dielectric union onto it. the coupler could be regular black iron. but i suggest you check about that.

I've had the same type of problem on hot water tanks. You can use a steel plate and thread it and use a brass tee. Then go with sweat fittings. If you use an extra heavy steel fitting they make a copper to galvanized tee with a plastic insert. I've found these need changed more frequently. Use teflon tape on the threads. Use a thick rubber gasket on the plate. They make steel flanges you can buy that are pressure certified depending on the pressure which you didn't state.

If I am not wrong, OP has a steel plate on which the cu tubes had been fixed, The steel plate has rusted - causing the leakage.

If that is the case, the cu tubes can not be possibly threaded. (the wall thickness will be too low)

Thats why I still suggest the usage of any alloy steel plate (SS could be advisable, but costly. Even materials like wrought iron may be used.

Cost wise

best option is to go for soldering the tubes to the plate

Second Best option is to drill&Ream holes and expand them - but quality wise best.

Third option is to press the tubes with small rubber O rings (if the temperature of water is not too high) or fix the tubes in hole with sealant (I propose RTV 732 or 736 silicone sealant of Dow approx 250-300 deg C ) and it has a good adhesive, sealing and pressure withstanding capacity. Also being silicone will not easily degrade.

And the costliest will be to tap the holes and fix with connectors.

I figure I've spent more time reading possible solutions to this problem than it would have taken to fix it. Therefore, I'm offering to fabricate a replacement for Guest at no charge. If he/she sends me the defective plate, I will make a new one and ship it back at no cost. I'm located in the Greater Boston area.

Geeeh.. That sounds like some galvanic effect trouble there. Probably by apply some good dielectric base paint to those connections areas and or by jumper it out by a piece of wire clamp it up at these connections areas it will retard the corrosive effect of such galvanic reaction and in order to prevent futures leaks here and there around such joints as preventive measure. And or better yet a dielectric joint connectors if available will also help take care of it. But so far everything sounds good as pointed out by the guys here at CR-4 so far to me, not bad at all! Allrigth Buddy you have the technology! Hahaha heee hiiiii hehehe, Oh Brotherrrrrrrr!

Piping Time,

MC

Excellent reason make plate of bronze