In principle, the drying parameters of welding rods shall be in accordance with the parameters provided in the manufacturer’s instructions.
When the ambient temperature is lower than – 20 ℃, thermal insulation measures must be taken.
3.5 preheating.
Welding rods of different grades shall not be stored in the welding rod barrel, and the storage time of welding rods in the insulation barrel shall not exceed 4 hours.
The detection instrument shall be within the calibration cycle and meet the measurement requirements in the pressure pipeline quality assurance manual.
2.2 requirements for machines and tools: 2.2.1 the welding machine is a DC welding machine.
5.1.
5.3 the arc shall be well controlled during backing, and the arc operation and wire feeding shall be uniform to ensure good fusion at the root of the weld.
When the environmental conditions do not meet the above requirements, effective protective measures such as wind and rain protection must be taken.
For other requirements of heat treatment, see 5 welding precautions and requirements in general construction process for post weld heat treatment of industrial pipeline.
The welding machine shall be intact, reliable, sensitive and within the calibration cycle.
The tack welding method is full penetration, the number of welding points is 2 ~ 5, the length of tack welding is 10-15mm, the height is 2-4mm, and shall not exceed 2 / 3 of the wall thickness.
2.2.3 the welding rod insulation cylinder, planer hammer and steel wire brush used by the welder are complete.
2.3.2 environmental conditions: before welding, confirm that the environment meets the following requirements: a) wind speed: less than 8m / s for manual arc welding; less than 2m / s for argon arc welding; b) relative humidity: less than 90%.
2 construction preparation 2.1 material requirements: 2.1.1 the construction site shall be equipped with qualified fixed electrode warehouse or mobile electrode warehouse.
After meeting the quality standard, the pipeline number, weld number and welder code shall be marked 20 ~ 50mm away from the weld.
The storage, drying, distribution and recycling of welding materials shall be in strict accordance with the relevant provisions in the pressure pipeline installation quality assurance manual.
3.1 welding construction procedure: * when required.
4.
Tack weld the fixed pipe or rotating pipe at least three places.
5.4 the welding joints between layers shall be staggered, and the slag between layers shall be removed thoroughly..
The temperature measurement method can be temperature pen or surface thermometer.
2.2.2 the equipment for preheating and heat treatment shall be in good condition and reliable performance.
2) when the welding of welded junction with preheating requirements is interrupted, the welded junction shall be kept warm and cooled slowly immediately, and it shall be preheated again according to the original requirements before re welding.
4) socket welding must be formed twice; 5) after welding, the weld surface shall be cleaned in time, and the weld appearance shall be inspected.
Pipes requiring preheating before welding shall be preheated after the weld junction is assembled and inspected to be qualified.
When spot welding saddle mouth, spot weld two sharp corners first.
3.3 welding method: 1) argon arc welding shall be used for pipe diameter less than or equal to 2 “; 2) argon arc backing and manual arc welding covering shall be adopted for pipes with diameter greater than 2 “; 3) socket or fillet welds shall be welded by manual arc welding; 4) argon arc backing and manual welding of cover surface shall be adopted for nozzle welds with penetration requirements, and manual welding shall be adopted for non penetration nozzle welds.
When the pipe diameter is less than 57mm, spot weld two places.
The tack welding sequence shall be staggered from top to bottom.
The preheating range shall be no less than 100mm on both sides of the groove.
General construction process for carbon steel welding of industrial pipeline 1 scope of application this process is applicable to the welding construction of non low temperature pipes such as medium carbon steel and 16Mn steel by argon arc welding and manual arc welding.
The preheating method shall be electric heating.
3.4.
2.1.3 remove grease, rust and other sundries on the surface of welding wire before use.
Heat treatment.
5.2 it is forbidden to strike arc at non welding parts and scratch the pipe surface by arc.
The processing requirements of pipes and fittings with different wall thicknesses are as follows: (3) before assembly, polish the groove and oil stain and rust within 20mm on both sides until the metallic luster is exposed.
3.2 – groove – 1) see the attached table welding process instruction for size requirements – 2) assembly quality requirements: – when assembling pipe components with the same wall thickness, the inner wall shall be flush, and the misalignment shall not exceed the following provisions: 10% of the wall thickness of Sha grade pipeline and no more than 0.5mm; 10% of the wall thickness of SHB pipeline and no more than 1mm; Other pipes shall be 10% of the wall thickness and no more than 1.5mm– When assembling pipe components with different wall thickness, when the wall thickness difference is greater than the following values, it shall be processed according to the requirements of the following figure: the inner wall difference of Sha grade pipe is 0.5mm, or the outer wall difference is 2mm; The inner wall difference of SHB pipe is 1mm, or the outer wall difference is 2mm; The inner wall difference of other pipes is 1.5mm, or the outer wall difference is 2mm.
2.3 operation conditions 2.3.1 personnel qualification: the welder must hold the boiler and pressure vessel welder certificate or GB50236 certificate or other certificates specified in the design, and its material, diameter, thickness and position shall meet the engineering welding requirements.
3) for welded junctions with preheating requirements, the interpass temperature shall be kept within the preheating temperature range during welding.
2.1.4 the performance of thermal insulation materials shall meet the requirements of preheating and heat treatment.
The heat treatment parameters of various steels are as follows: steel type or steel grade wall thickness (mm), heat treatment temperature (℃) 10, 20 ≥ 30600-650.
The tack welding process and welding materials shall be the same as the formal welding.
The preheating temperature of various steels is shown in the following table: steel type or steel grade wall thickness (mm) preheating temperature (℃) 10, 20 ≥ 26100-2003.6 see the attached table welding process instruction 3.7 welding points: 1) each welded junction must be welded continuously at one time.
If not, they shall be in accordance with the parameters given in the welding process instructions.
C) ambient temperature: when the ambient humidity is less than 0o, the non preheated pipeline shall be preheated for more than 15 ℃ within 100mm of the initial welding position before welding.
2.1.2 welding materials must be provided with quality certificate or material certificate.
