As Hopper, nozzle too small, look for the 1" plus one that came with the torch and screw the regulator in to get a decent flame. Looks like it took too long to get the job up to temp and your flux was burned / beads indicate temp not high enough probably the rod melted by the torch rather than by heat of the job so it didn't flow. Make sure your home made fire bricks are not absorbing heat but are reflecting it back to the job.

If you can find a commercial lagging company see if you can bag some off cuts of the white mineral high temp insulation mat (various trade names). You need a company that insulates steam pipes, exhaust pipes etc. Stuff comes on a roll in boxes about an inch thick, quite expensive to buy but on lagging jobs there are always trimmings of reasonable sizes. Price of a pint to the lads will get you plenty. Lasts well and it's really effective.

Paul.

Also looks like you have totally exhauste dthe flux or did not use any as there is no sign of it on the workpiece. You will need HT5 or Tenacity No5, big burner, 4bar regulator and be prepared to wait for it to warm up.

Don't know what your blocks are made from but I doubt they are reflecting much if any heat back into the job. You also have the air holes of the burner down inside the blocks which will mean they don't draw in plenty of fresh air and may even cause the burner to go out.

Edited By JasonB on 25/01/2020 07:31:23

Wrong set up.no air getting to burner,gas burner too small, work laid flat on brick does not heat up. So have one fire brick laid flat and another upright so it looks like an angleplate, a propane burner about 32 minimum diameter with high pressure regulator ,and prop the work so that its above the surface of the bottom flat brick, I use some bits of broken firebrick,if the work is flat on the brick it does not heat up easily ,a bit up in the air and the flame gets around the work. buy a good burner mine is a Calor I bought 50 years ago with a selection of burners,since then I bought a large dia Sievert abd made an adapter as the threads are different,mostly used for getting black iron to red heat for bending. Calor no longer make their own burners so Sievert is a good alternative. I have a sheet metal hearth with white firebricks which I bought from an autojumble, another source of fire brick is my local woodburner stove supplier,they cut the insulating "brick" from large sheets to replace the stove linings,when I needed some for my stove i scrounged some offcuts

I'm a little suspicious of the firebricks. While Vermiculite is a good insulator, I not sure Ciment Fondu is. It's a refractory cement, tough, strong and very temperature resistant. Could be your bricks are thermally only middling efficient. I use the soft white bricks made to line Pottery furnaces. Although mechanically weak, and unable to withstand the high temperatures Ciment Fondu is good for, they're excellent insulators. Under a direct flame the surface goes white hot almost instantly.

Dave

Its nice to have CUP on our side in their ever helpful self.

so you need loads of heat from a reliable source, but what has not been mentioned is the need to use a flux that can last the distance. You didnt mention what flux you tried using. We all have easy flow 2 in our toolkits, but it probably doent last long enough for this job