Tig Welding Stainless Steel Pipe

tig welding stainless steel pipe
1. Prepare the materials: Clean the stainless steel pipe thoroughly using a wire brush or grinder to remove any dirt, rust, or contaminants. Ensure that the ends of the pipes are clean and free of any burrs.
2. Set up the welding machine: Use a TIG welding machine with the appropriate settings for stainless steel. Select the correct type and size of tungsten electrode (usually thoriated or lanthanated) and install it properly. Set the gas flow rate to the recommended level (typically 10-20 cubic feet per hour) and adjust the amperage according to the pipe thickness.
3. Clamp the pipes: Securely clamp the stainless steel pipes in position, ensuring that they are aligned properly and held firmly in place. This will prevent any movement during the welding process.
4. Start the arc: Position the TIG torch at a 90-degree angle to the pipe joint, with the tungsten electrode close to the workpiece. Initiate the arc by touching the tungsten electrode to the pipe and quickly lifting it to create an arc. Maintain a short arc length (around 1/8 inch) throughout the welding process.
5. Weld the joint: Move the TIG torch along the joint in a controlled manner, applying the filler rod as needed. Use a weaving motion or a back-and-forth pattern to distribute the heat evenly and prevent overheating. Keep the torch at a slight angle (around 10-15 degrees) to direct the heat towards the weld pool.
6. Control the heat: Stainless steel has a low thermal conductivity, so it is important to control the heat input during welding. Avoid excessive heat buildup by using short bursts of welding and allowing the material to cool between passes. This will help reduce the risk of distortion and ensure a high-quality weld.
7. Finish the weld: Once the welding is complete, allow the welded joint to cool gradually. Use a wire brush or grinder to remove any slag or discoloration from the weld bead. Inspect the weld for any defects or imperfections, and make any necessary repairs if required.
Remember to always wear appropriate safety gear, such as welding gloves, helmet, and protective clothing, when TIG welding stainless steel pipes. Additionally, practice proper ventilation or use a welding fume extraction system to minimize exposure to welding fumes.

Hardness index

316L stainless steel welded pipe is a basic pipe, so it also has a lot of hard necessary indicators, including many aspects, the following we are going to talk about the hardness of 16L stainless steel welded pipe. According to the different test methods and the range of use, the hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. There are three kinds of Brinell, Rockwell and Vickers hardness commonly used for pipes.

1, Brinell hardness (HB with a certain diameter of steel ball or cemented carbide ball, to delimit the test force (F) pressed into the surface of the pattern, after delimit the holding time to remove the test force, measuring the indentation diameter of the specimen surface (L) Brinell hardness value is the test force divided by the indentation spherical surface area obtained by the business. Expressed in HBS(steel ball), the unit is N/mm2(MPa) and its calculation formula is as follows :F-- test force pressed into the surface of 316L stainless steel welded pipe sample, N, D-- test steel ball diameter, mmd-- uniform diameter of indentation, mm. The measurement of Brinell hardness is more correct and reliable, but generally HBS is only suitable for metal materials below 450N/mm2(MPa), and is not suitable for harder steel or thinner 316L stainless steel welded pipes. In the 316L stainless steel welded pipe scale, Brinell hardness is the most widely used, and the hardness of the material is often expressed by the indentation diameter d, which is both intuitive and convenient.

For example, 120HBS10/1000130 indicates that the Brinell hardness measured by a steel ball with a diameter of 10mm is 120N/mm2(MPa) at a test force of 1000Kgf(9.807KN) and held for 30s(seconds).

2, Rockwell hardness (HK) Rockwell hardness test, like Brinell hardness test, is an indentation test method. The difference is that it is to measure the depth of the indentation, that is, under the action of the test force (Fo) and the total test force (F), the indenter (steel cone or ball) is pressed into the surface of the sample, after the holding time is specified, the main test force is removed, and the hardness value is calculated with the measured residual indentation depth increment (e). Its value is an anonymous number, expressed by the symbol HR, and the ruler used has 9 rulers such as A, B, C, D, E, F, G, H, K. Among them, the scales commonly used for hardness test of 316L stainless steel welded pipes are generally A, B, C, that is, HRA, HRB, HRC. The hardness value is calculated by the following formula: HR=100-e when tested with A and C scales when tested with B scales, HR=130-e, e-- residual indentation depth increment, which is indicated by the delimiting unit 0.002mm, that is, when the axial displacement of the indenter is a unit (0.002mm), that is, it corresponds to the Rockwell hardness change of one number.

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