Superheater pipe repair

[Colin ReedParticipant @colinreed51485]

My son has asked if I can repair the superheater pipe from his 3″ Atkinson steam lorry, which failed on a steam rally last weekend. I’ve attached some photos below.

It’s made out of thick walled copper and I’m assuming the two halves were joined at a tight angle due to the fairly narrow central tube the pipe goes down to the fire box.

I’m unsure how the pipe was originally joined. Where the halves broke away there are what look like gold coloured lumps of metal.

We’ve got access to silver soldering and tig welding equipment, so any suggestions on the most appropriate method of joining the bits back together would be very welcome.

Colin

 

[noel shelleyParticipant @noelshelley55608]

looks like someone tried to braze the joint with silver soldering heat and failed – miserably ! Either remake in stainless and tig weld or clean up the ends and re braze with sifbronze. You WILL need plenty of heat and brazing or HT5 flux. Good Luck, Noel.

[Clive Brown 1Participant @clivebrown1]

I’d think that the joint for the original construction was either brazed or a high mp silver solder. Perhaps not ideal for something directly exposed to an intense fire especially if and when there is no steam flow to give a cooling effect. Sifbronze at least seems required for repair. Tig would probably be better if possible but a good clean-up is needed. As said above stainless steel and tig would be best for the tube length actually in the firebox.

HTH

[bernard towersParticipant @bernardtowers37738]

Its amazing what things manage to get through a steam test as parts of that joint have never been joined by braze, must have been a good fit.

[duncan webster 1Participant @duncanwebster1]

If the superheater is downstream of the regulator it isn’t part of the system tested in either hydraulic or steam tests.

[ZanParticipant @zan]

Here is my Atkinson superheater, it’s out because of a damaged o ring and it leaked

the spear and Down tubes are both stainless, soldered with sifbronze which is of course very high temperature.     I added very large solder fillets th give a stronger and more reliable joint.  The top spiral tube is copper hence the junction block

irecently had the.
same problem, the spear was leaking it transpired that the original bronze block had partly melted ( or severely wasted).  It lasted  10 years     the problem here is that the superheater is upstream of the regulator and is thus always pressurised and has nothing to absorb the heat

because of the high temperatures involved I advise you not to use the jointing method

as shown in your original post  just not enough area to seal the joint   The heater is part of the pressure test

[FulmenParticipant @fulmen]

I’m no welder, and I have only tested TIG on copper out of curiosity. But if you’re proficient with a TIG welder I don’t see what could go wrong (famous last words).

[Colin ReedParticipant @colinreed51485]

Thanks for all of the suggestions. I’ll attempt the repair using tig.

Sifbronze 1 doesn’t look like it’s an appropriate filler for the tig process as it contains almost 40% zinc. Sif No. 8 or Sif 968 look more suitable. I’m leaning more towards the no. 8 as it looks the more useful general purpose tig brazing rod for any future projects.

Ultimately I think you’re all correct and I should remake in stainless steel, and I like the solution that @Zan used with the spear. That’s a future task though as we need the engine back up and running for another rally next weekend.

Colin

[noel shelleyParticipant @noelshelley55608]

Hi Colin, If you have oxy propane then this is a 10 min job with  normal sifbronze.  If your near me in N west Norfolk you can use my gear if thats any help. Noel.

[noel shelley]

On noel shelley Said:

Hi Colin, If you have oxy propane then this is a 10 min job with  normal sifbronze.  If your near me in N west Norfolk you can use my gear if thats any help. Noel.

I don’t have oxy propane. Thanks for the offer Noel, but I’m in the North East near Newcastle, so a bit far to travel unfortunately.

Colin

[FulmenParticipant @fulmen]

Is bronze filler really needed? I only did it for fun, but I successfully welded copper pipe with copper wire as filler. It wasn’t easy, but I managed to get some decent welds when I got the settings right.

[Fulmen]

On Fulmen Said:

Is bronze filler really needed? I only did it for fun, but I successfully welded copper pipe with copper wire as filler. It wasn’t easy, but I managed to get some decent welds when I got the settings right.

Probably not, but I was thinking ahead to when I remake in stainless steel.

[bernard towersParticipant @bernardtowers37738]

when tig welding copper doesnt the filler rod have to be oxygen free rod?

[bernard towers]

On bernard towers Said:

when tig welding copper doesnt the filler rod have to be oxygen free rod?

If the parts were actually being welded together with a high % copper rod then I think that’s the case, especially for electrical conductivity or if the part will be subject to high strain. For brazing this wouldn’t be as important.

[Author]

Posts