OldNuc wrote:I suspect that RTV of any of the multiple types would be a poor choice. If it was my boiler I would examine the failed pieces carefully and determine the cause of failure before doing anything. If it was determined the boiler metal shell was structurally sound I would probably silver solder on a replacement proper nozzle fitting. Back yard repairs on pressure vessels is a high risk undertaking right up there with welding on tire rims with the tire mounted on the rim or welding on gas tanks.

This is kind of what I was looking for. Through all my engineering classes I was always taught "just don't mess with pressure vessels."

Now I'm not sure what the working pressure of an espresso boiler is, and using a bulkhead fitting would hold up to the pressure, I'm just not sure what sealing method would work going down that route.

I would prefer to braze on a new fitting, I just don't know where to find the part to braze on.

Fair enough assessment. It is indeed prudent to scrutinize the integrity of the area that sheared off. The bulkhead fitting can hold good pressure (as evident on my aged machine), but the strength of bulk head fitting would depend on how strong the area is where it's mounted upon. A RTV glue bead is likely not up to the job as well. I was thinking along the line of a proper gasket cut from a flat solid sheet of teflon or food safe gasket material (Klingersil etc).

Looking closely, you still have part of the sheared off piece brazed in there. If part of it had sheared off so easily, what hope do we have to assume the residual part is intact. Even if you are attaching a new nozzle, it may be worth removing the old one and start anew, probably something easy for an experienced metal worker?

To do a proper repair all of the failed part must be removed. Generally on a low pressure boiler the fitting is only braised to the exterior surface and IF that is the case clean-up is relatively simple. A cold hydro test pressure would be 1.5 times the OPV setpoint as a good value to use. Some of these boilers have a tag on them that lists all of this info but most do not as they are officially exempt from almost all pressure vessel codes. On a flat surface a bulkhead fitting would be fine but on a thin curved shell it is not the best choice.

As a guess I would suspect the failure was the result of severe repeated over torquing of the drain bolt. The trick is to find someone who can make the repair.

samuellaw178 wrote:Fair enough assessment. It is indeed prudent to scrutinize the integrity of the area that sheared off. The bulkhead fitting can hold good pressure (as evident on my aged machine), but the strength of bulk head fitting would depend on how strong the area is where it's mounted upon. A RTV glue bead is likely not up to the job as well. I was thinking along the line of a proper gasket cut from a flat solid sheet of teflon or food safe gasket material (Klingersil etc).

Looking closely, you still have part of the sheared off piece brazed in there. If part of it had sheared off so easily, what hope do we have to assume the residual part is intact. Even if you are attaching a new nozzle, it may be worth removing the old one and start anew, probably something easy for an experienced metal worker?

Thanks.

Yeah I looked up all of the food-safe RTVs out there, and the ones that I could find are all acetic acid based. Bad news for copper, as it corrodes copper. Teflon would work, or making a proper gasket would likely work as well.

As far as thread locking goes, does anyone have experience with using the Loxeal stuff that Steffano sells? I couldn't find any other food grade high temp thread sealant out there that wasn't acetic acid based.

OldNuc wrote:To do a proper repair all of the failed part must be removed. Generally on a low pressure boiler the fitting is only braised to the exterior surface and IF that is the case clean-up is relatively simple. A cold hydro test pressure would be 1.5 times the OPV setpoint as a good value to use. Some of these boilers have a tag on them that lists all of this info but most do not as they are officially exempt from almost all pressure vessel codes. On a flat surface a bulkhead fitting would be fine but on a thin curved shell it is not the best choice.

As a guess I would suspect the failure was the result of severe repeated over torquing of the drain bolt. The trick is to find someone who can make the repair.

I know how to braze copper, and I've experience with silver solder (used to make copper jewelry long ago). I would just need to find the nut to go on the end, and I don't know where to find that.

Do you happen to know the pressure that these boilers are usually under? Or what pressure the relief valves open up on?

Firstly, typical boiler pressure is AROUND 1.00 bar = ~14.5 psig.

Secondly, why not try to remove the remains of the drain plug with an easy-out or, at worst, get a machine shop to either remove it or drill/tap new threading. It is likely 1/4" BSPP but if you measure the OD of the new part that screws into the boiler, it would be easy to identify.

man2112 wrote:I know how to braze copper, and I've experience with silver solder (used to make copper jewelry long ago). I would just need to find the nut to go on the end, and I don't know where to find that.

Do you happen to know the pressure that these boilers are usually under? Or what pressure the relief valves open up on?

Nominal boiler pressure is 15psi and the OPV should be about 18 - 19 psi. As far as a replacement fitting you can figure out the tread of the closure bolt and then obtain a matching nut or pipe coupling and file the back side to fit closely to the boiler. Or just obtain a standard 1/4 or 3/8 iron pipe plug and coupling in brass and make it all fit.

I've used Loxeal. It's fine, but pricey. Why not use PTFE plumber's tape?

Been busy for the past week or so so the machine has been on the side. I finally got the part in that I'm going to braze to the boiler to add the plug back in. Attached are a few pictures. But now I have a new problem... VFA Expres hearing coil MELTED?

Soldered in the plug today. I need to brush up on my soldering skills, so please ignore the messy joint, but this should hold just fine.