Silver soldering 3/4 inch pipe with MAPP gas

[emptybucketman]

I've read most of the threads on silver soldering and some suggest that it is possible to silver solder 3/4 inch pipe, but I'm still having problems getting enough heat into the fitting for the solder to flow. I'm attempting to join two 6m lengths of 3/4 inch type B copper pipe with a 8000 TS (from memory) MAPP gas torch. One of the pipes is mostly buried in the ground.

I can successfully join 1/2 inch pipe and I was wondering what I can do to get more heat into the joint?

[watson]

G'day,
Probably pushing the BTU limits, but maybe a bit of excavation around the buried pipe and some heat sinks around the area.....like fire bricks or similar. I know from experience that house bricks go bang when they get hot enough.
Lots of cleaning/good flux, and good luck

[Timmo]

I've read most of the threads on silver soldering and some suggest that it is possible to silver solder 3/4 inch pipe, but I'm still having problems getting enough heat into the fitting for the solder to flow. I'm attempting to join two 6m lengths of 3/4 inch type B copper pipe with a 8000 TS (from memory) MAPP gas torch. One of the pipes is mostly buried in the ground.

I can successfully join 1/2 inch pipe and I was wondering what I can do to get more heat into the joint?

Try and point the flame along the pipe not across it and not too close. you will see the tail of the flame start to change colour when it starts getting hot.

It might take a bit of practice to work out the best angle to hold it.

[Squirrel]

It can be done. I have just replace my hot water system. (this is what stopped me going to the woodworking show as it took all my spare cash )

I had to silver soldier one of the joints as it kept on leaking with soft soldier. I bought MAP just for the job and got it red hot and the silver soldier went straight on, with flux of course. Your problem maybe water in the pipe, if you can eliminate this you shouldn't have a problem.

Squirrel.

[emptybucketman]

Maybe I have the torch too close since the tip of the flame is nearly two inches from the nozzle. There was a little condensation in the buried pipe but it hasn't been used only buried.

Would a heat shield attachment make the difference?

Watson...Where can I get the fire bricks? I presume these are bricks for kilns and fireplaces.

[watson]

I reckon you can get firebricks at one of those Coonara places.

[Timmo]

A bit of fibre cement sheeting can be very useful as a heat shield.

No need for flux if joining clean copper but you need it if joining to brass etc.

[wonderplumb]

Cleanliness is next to godliness, use flux if necessary, make sure there is NO water in the pipe at all, dont use the tip of the mapp use the start of the flame and try a stick of 15% silver solder, youll be surprised.