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Welding of 00Cr18Ni10 stainless steel pipe

Welding of 00Cr18Ni10 stainless steel pipe

Time:2022-03-17 Source:China Wuxi JiaNuo Special Steel Co.

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Paper manufacturing equipment . Stainless steel welding is becoming more and more widespread, especially the alkali recovery workshop, corrosion-resistant equipment, corrosion-resistant equipment, process pipelines are mostly stainless steel pipe, stainless steel pipe installation and maintenance is very important, the process operation method is as follows.

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1 Construction preparation

1.1 Material requirements

00Cr18Ni10 stainless steel pipe 60X3.5, carbon content <0.035% ultra-low carbon stainless steel, storage should be placed in accordance with the provisions;

Welding wire selection H00Gr21Ni10, must have a quality certificate or material certificate of conformity.

1.2 when the requirements of nitrogen

The purity of argon gas used must be guaranteed ≥ 99.99%.

1.3 Machine requirements

Welding equipment selected inverter type welding machine ZX7-400;

Welders used welding wire cylinder, stainless steel hammer, stainless steel wire brush;

Welders observe the root of the formation of the spotlight small flashlight, weld inspection ruler, contact thermometer.

1. 4 operating conditions

Welders must hold the material qualification certificate for the project to meet the welding requirements;

Prefabricated on site, installed on site, indoor work, without wind-blocking measures.

2 Welding

Bevel production:Before welding should be polished with a grinder, cleaned up with a stainless steel brush, bevel form and size according to the figure.

Grouping requirements: grouping the wrong side of the inner wall should be ≤ 0.5 mm.

Grouping before the bevel on both sides of the 20mm range with acetone scrub clean (oil and dirt spoils).

3 Welding method

All the welding mouth using tungsten argon arc welding seal bottom, cover surface. All welds are formed on both sides by single-sided welding.

4 Spot welding

Spot welding quality requirements are the same as normal welding.

5 Welding process

Welding power supply using DC positive connection, welding process parameters such as Table 1.

6 operation points

TIG welding when the welding machine and the workpiece angle 75-80 degrees, the angle between the wire and the workpiece 20-30 degrees to reduce the workpiece heat, increase the arc blowing force, the root of the weld port is well integrated;

TIG welding nozzle diameter 10mm, tungsten electrode extension length 34mm, nozzle and 00Cr18Ni10 stainless steel tube distance between 8mm;

The tube is protected by nitrogen gas before welding;

The intermittent wire feeding method is used, and the wire is fed drop by drop to the root of the molten pool within the protection of the beneficial gas;

The interlayer temperature is controlled at 100℃;

After the weld is completed, the weld port is cooled and marked with a marker at 50 mm from the weld with the welder’s stamp, weld port number and pipe line number.

7 Operation process

Position the weld seam 10-15mm. pre-polish the welded joint into a slope.

The bottom left welding method, the right end of the positioning weld on the arc, using a longer arc in the bevel preheating 4-5s, positioning the left end of the weld to form a molten pool and melt hole after the start of the wire feed for normal welding, using a smaller current and a smaller welding inclination. It is required that the wire is fed evenly and the welder moves smoothly and at the same speed. According to the size of the molten pool, adjust the angle of the welding machine; joint, release the welding machine button switch, stop wire feeding, welding current decay stop arc, the welding machine is still aligned with the molten pool for protection, to be cooled and then remove the welding machine. Check the quality of the arc pit before jointing, if there are defects such as oxides, they need to be repaired, and then make a slope, start the arc at 15-20mm on the right side of the arc pit, move slowly to the left, wait until the arc pit starts to melt to form a molten pool and molten hole, then continue to fill the wire welding. Weld to the end of the weld, reduce the welding machine and 00Cr18Ni10 stainless steel pipe angle, so that the heat is concentrated in the wire, increase the amount of melting wire to fill the arc pit. After cutting off the power supply, the welding current gradually decreases, the melt pool also decreases, the wire is withdrawn from the arc, the arc is stopped and the argon gas is delayed off. The welding of the bottom layer is over. The weld channel should be 1.0-1.5mm lower than the surface of the weld.

Cover welding, adjust the welding parameters, operation and priming layer is basically the same, increase the welding machine swing to ensure that both sides of the molten pool over the edge of the bevel 0.5-1.0mm, rest arc when filling the arc pit.

8 welding note healing matters and requirements

After each replacement of argon gas bottle or gas belt, must check the purity of argon gas; argon gas used gas belt must be kept dry to ensure the purity of argon gas.

9 weld rework

Weld rework should be licensed welders or by the corresponding qualified welders; rework before the analysis of the nature of the defect, defect length, width, confirm the location of the defect according to the negative; eliminate defects using grinding wheel machine grinding, root rework parts for bevel repair; rework welding process and formal welding the same.

10 color inspection

Root welding is completed, light color to light blue indicates that the weld is not well protected by argon filling, has been oxidized, silver-white indicates good protection.

11 Conclusion

After inspection,100% X flaw detection, a pass rate of 98% or more, good economic benefits, with certain promotional significance. Through technology, equipment and welding methods and process progress and innovation, welding electrode arc welding method welding stainless steel pipe gradually eliminated, the current tungsten arc welding method is widely used in Jiamusi paper mill, and bring good economic and technical benefits.

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