How to prevent weld defects from occurring in welded pipes in the construction industry

To prevent weld defects in stainless steel welded pipes in the construction industry, corresponding measures can be taken in the aspects of pre-weld preparation, welding process control, and post-weld treatment. The details are as follows:

Pre-weld Preparation

Selection of pipe materials and welding materials: Based on the specific requirements of the construction project, choose qualified stainless steel welded pipes and matching welding materials such as welding rods and welding wires that meet the standards in terms of chemical composition and mechanical properties. Ensure that the storage conditions of the welding materials are good to avoid the influence of moisture and rust on the welding quality.

Surface treatment of the welded pipe: Before welding, thoroughly clean the surface of the welded pipe of oil, rust, oxide scale, etc. Methods such as mechanical grinding and chemical cleaning can be used to ensure the stability of the arc during welding and the fusion quality of the weld seam.

Processing of welding bevels: According to the wall thickness of the welded pipe and the welding process requirements, process appropriate welding bevels. The angle, backing, gap, etc. of the bevels should comply with relevant standards and welding process regulations to ensure that the weld can be fully fused and avoid defects such as incomplete penetration.

Welding equipment inspection: Conduct a comprehensive inspection and calibration of the welding equipment to ensure that the equipment performance is good and the parameters are set accurately. For example, check the output stability of the welding power supply, the reliability of the wire feeding mechanism, etc., to ensure that the welding process can proceed smoothly.

Welding Process Control

Selection of welding process parameters: Based on the material, wall thickness, and welding position of the stainless steel welded pipe, reasonably select welding process parameters such as welding current, voltage, welding speed, gas flow rate, etc. During the welding process, strictly control these parameters to avoid weld defects such as pores, slag inclusion, and incomplete fusion due to improper parameters.

Welding operation skills: Welding personnel should have proficient operation skills and rich experience, and master the correct welding techniques and postures. During the welding process, maintain a stable welding speed and uniform oscillation amplitude to ensure a good weld seam formation. When welding in multiple layers and multiple passes, pay attention to the cleaning between layers and the welding sequence to avoid defects such as incomplete fusion between layers.

Gas protection: For welding processes using gas protection, ensure that the purity and flow rate of the protective gas meet the requirements. The protective gas should effectively protect the welding area and prevent air intrusion to avoid defects such as pores in the weld seam. At the same time, pay attention to the cleaning and integrity of the gas nozzle to ensure the protection effect.

Environmental control: Try to create a good welding environment and avoid welding operations in harsh conditions such as strong wind, humidity, and low temperature. When the environmental conditions do not meet the requirements, take corresponding protective measures, such as setting up wind shelters or heating the welded parts, to ensure the welding quality.

Post-weld Treatment

Weld seam appearance inspection: After welding, promptly inspect the weld seam for conformity with requirements regarding the formation, overhang, width, etc., and check for surface pores, cracks, undercut, etc. If any problems are found, they should be repaired or reworked in time.

Non-destructive testing of weld seams: According to the requirements of the construction project and relevant standards, conduct non-destructive testing of the weld seams, such as ultrasonic testing, radiographic testing, magnetic particle testing, etc., to check for defects such as incomplete penetration, slag inclusion, cracks, etc. in the weld seam. For detected defects, analyze the causes and take corresponding measures for handling.

Weld seam heat treatment: For some important welded structures of stainless steel welded pipes, heat treatment after welding may be necessary to eliminate welding residual stress, improve the microstructure and properties of the weld seam, and enhance the crack resistance and corrosion resistance of the weld seam. The process parameters for heat treatment should be reasonably selected based on the material and characteristics of the welding structure.

In addition, it is necessary to strengthen the training and management of welding personnel, enhance their quality awareness and operation skills, establish a complete quality management system, conduct full-process monitoring and recording of the welding process, and ensure that the quality of each weld seam meets the requirements.