Nickel is one alloy family where weave beads are a definite "no-no." Look who’s saying not use weave beads!

The oxide on the surface is very tenacious and must be removed by abrading each bead with a grinding disk, clean file, or carbide rotary file before depositing weld over the previous weld bead.

Do not use preheat and maintain a low interpass temperature. Surfaces should be dry, but allow to cool until warm to the touch if you need to warm the surfaces to dry moisture before welding. 

Clean the inside of the pipe to remove oxides (use an abrasive wheel or carbide rotary file) and wipe down with solvent soaked rags. Cleaning should extend at least 1 inch from the toe of the weld. Tape all joints until you are ready to weld and then peel the tape just before welding. Don’t leave the tape on small diameter pipe (4 inch or less).  Scorched tape will produce CO and CO2 that will contaminate the weld pool. The purge gas should be argon and the flow sufficient to reduce the oxygen and nitrogen to less than ½ percent. The system must be free of moisture as well. Heavy oxide deposits on the root surfaces are a sure indication of insufficient purge. The root surfaces should be silver if the purge is performed properly.

Use clean rags and clean acetone or MEK (you can still get MEK, right?) to wipe the joints before welding. Sulfur, phosphorus, lead, zirconium, and boron will result in cracking problems. Do not use “rent- a-rags” for cleaning. The solvents used by the cleaning company may contain harmful chemicals that will cause the nickel alloys to crack.

The weld pool is very sluggish and does not wet in. It can be described as like welding with toothpaste. You have to put the weld where you want it.

Best regards - Al