Welded Threaded Pipe Fittings

Precautions for repairing Welded Threaded Pipe Fittings：

Welding repair

Pre weld cleaning:Thoroughly clean the welding area and its surrounding areas of impurities such as rust,oil,moisture,and oxide scale to ensure welding quality.Tools and materials such as sandpaper,wire brush,acetone,etc.can be used for cleaning.

Welding process selection:Choose the appropriate welding process based on factors such as the material,thickness,and welding position of the pipe fittings,such as manual arc welding,gas shielded welding,etc.At the same time,it is necessary to strictly follow the welding process specifications and control parameters such as welding current,voltage,and welding speed.

Preheating and post heating(if necessary):For some materials with poor weldability or thick pipe fittings,preheating is required before welding to reduce welding stress and avoid cracking.Post weld heat treatment may be necessary to eliminate residual stresses and improve the microstructure and properties of the weld seam.

Multi layer and multi pass welding:If the welding thickness is large,multi-layer and multi pass welding is required.After each layer of welding is completed,the welding slag should be cleaned up in a timely manner,and the quality of the weld seam should be checked.If there are defects,they should be dealt with in a timely manner before proceeding to the next layer of welding.

Thread repair

Repair damaged threads:If there is slight damage to the threads,a tap or die can be used for repair to restore the accuracy and fit performance of the threads.When repairing,pay attention to the operation method to avoid further damage to the thread.

Replace threaded parts(if necessary):If the thread damage is severe and cannot be repaired,consider replacing the pipe fittings with threaded parts.When replacing,ensure that the thread specifications of the new pipe fittings are consistent with the original ones,and install and tighten them correctly.

Sealing treatment

Cleaning the sealing surface:During the maintenance process,the sealing surface of the pipe fittings should be cleaned to remove dirt,rust,and old sealing materials,ensuring that the sealing surface is flat and smooth.

Choose the appropriate sealing material:Based on the working medium,pressure,and temperature conditions of the pipe fittings,choose the appropriate sealing material,such as polytetrafluoroethylene(PTFE)sealing tape,sealant,rubber gasket,etc.

Correct installation of sealing material:Install the sealing material correctly according to the instructions for its use.For example,when using PTFE sealing tape,it should be wrapped around the thread in the correct direction and number of turns;When using sealant,apply it evenly.

Post repair inspection

Appearance inspection:After the repair is completed,conduct a visual inspection of the pipe fittings to check whether the welds are flat,smooth,and whether there are defects such as cracks,pores,and slag inclusions;Whether the threaded connection is firm and the sealing surface is good.

Dimensional inspection:Use measuring tools to measure the key dimensions of the pipe fittings to ensure that the dimensions of the repaired pipe fittings meet the requirements,especially the size and accuracy of the threads,as well as the length,diameter,etc.of the pipe fittings.

Pressure test:Conduct a pressure test on the pipeline system where the repaired fittings are located to check for any leaks.The testing pressure should comply with relevant standards and design requirements,and be maintained for a certain period of time to observe whether the pressure is stable.

Record and report:Record relevant information during the repair process,such as repair time,repair methods,materials and tools used,etc.At the same time,write maintenance reports to summarize the repair situation and provide reference for future maintenance and management.