(1) Before alloy steel pipe welding, the weld groove and the two sides should be preheated to 250~350℃ within a range of not less than 3 times the thickness of the weldment, and during welding, the temperature of the parent material (inner and outer surfaces) within the preheating range should be not lower than the preheating temperature, and the interlayer temperature should be not lower than 250℃ and not higher than 350℃.

(2) Each weld must be welded once. If the welding work is interrupted during the welding process, the temperature of the weld groove and the two sides within a range of not less than 150mm should be not lower than the preheating temperature (250~350℃) until the welding work is restarted. It is necessary to ensure that the inner and outer surfaces of the weldment reach the specified preheating temperature.

(3) The welding rods used for welding must be dried strictly according to the requirements, and the storage time in the insulation barrel shall not exceed 4h. The remaining welding materials should be returned to the welding material drying box in time after getting off work, and are not allowed to be left in the insulation barrel.

(4) After each weld is completed, dehydrogenation heat treatment must be carried out immediately. The dehydrogenation heat treatment temperature is 250~350℃, and the insulation time is 30min. After the insulation work is completed, the part is wrapped with an aluminum silicate plate to take slow cooling measures.

(5) It is prohibited to strike the arc in the non-welding part of the weld. The arc pits and arc scars caused by arc scratches, and the weld scars left after cutting off the temporary attachments, should be polished smooth and 100% magnetic particle inspection should be carried out according to JB/T4730.4, and Class I qualified.

(6) The surface of the weld and heat-affected zone is not allowed to have defects such as undercuts, cracks, pores, arc pits, inclusions, etc. The slag on the weld joint and the spatter on both sides must be polished and removed.

(7) The repaired parts that failed the flaw detection should be preheated as required before root cleaning and repair welding. After the repair welding is completed, non-destructive testing should be carried out as required.