1. Key points of welding of Hastelloy alloy pipe

Ⅰ. Bottom, when welding groove on both sides of the paste of white tape should be reverse, otherwise, wash clean with acetone before welding.

II. Less wire energy shall be used for welding. The front end of the wire (the heated end) shall be in gas protection.Short arc welding should be used throughout the welding process to control the temperature between layers.The arc pit will be filled when the arc is closed, and the gas will be stopped with a delay of 30S to prevent thermal cracks from occurring.

III. The tungsten electrode shall avoid contact with the weld pool and welding wire, shorten the arc length as far as possible, and prevent the weld from being filled with tungsten.

IV. Ensure appropriate welding speed.Slow speed, large energy of weld metal line, resulting in more burning loss of weld metal alloy elements, overheated structure in the welding heat affected zone, so that the grain size is larger and the physical performance of the welded joint decreases.High speed, poor protection of molten pool, poor reaction of molten pool metal metallurgy, low weld temperature, poor weld edge fusion, easy to produce arc pit cracks.

2, welding construction management personnel should use special glove, set pair adopts fixed clamp, crater arc carefully when fill arc crater, prevent producing arc crater crack, welding position setting file wind, the wind plate weld width difference in 1 ~ 2 mm advisable, more high demand of 0 ~ 1.6 mm, the weld surface must not have crack, incomplete fusion bite edge, surface defects such as porosity, slag, weld on X-ray detector, fillet weld penetration.

3. Welding quality Situation The welding seam applied on site has been inspected by radiographic flaw detection, the first pass rate, and the weld surface quality inspection has reached the qualified requirements.