Standard practice for common pipe connection methods2

1. Welding connection

➤ Weld groove

According to the requirements of the specification, the groove is generally V-shaped, the groove angle is 60-75°, and the pairing gap is 2-3mm.

➤ Weld seam pair

The number of staggered edges on the inner wall should not exceed 10% of the wall thickness and ≯2mm; the number of staggered edges on the outer wall should not exceed 3mm.

➤ Welding

1) The inside of the stainless steel pipe welding is filled with argon protection, and the weld and the heat-affected zone are pickled and passivated after welding;

2) The brazing of red copper pipes must not be overheated (650-750°C). After welding, remove the residual slag and other debris at the welded joint;

3) Weld appearance inspection has no defects such as meat biting, slag inclusion, cracks, splashing, etc.

common problem

The brazing seam of the copper pipe is not cleaned

Untreated stainless steel pipe weld

Undercut, the width of the weld is narrow, and the reinforcement is different

2. Groove connection

➤ Groove processing

1) Check the size, roundness, and manufacturing quality of the nozzle to meet the requirements of groove production;

2) Process the grooves in stages according to the specified time, and re-measure the groove depth and other dimensions;

3) Groove processing shall not damage the galvanized layer and inner coating of the pipe.

➤ Groove assembly

1) Clean the pipe ends, put on rubber seals, install clamps, and tighten bolts;

2) The centerline of the pipeline at the two ends of the groove is the same, and the groove installation direction (fastening bolt position) is the same;

3) Rigid joints should be adopted for straight pipe sections, and a flexible joint should be arranged between every 4-5 continuous rigid joints on the pipe section.

common problem

The groove joint direction is not uniform

The pipes at both ends of the groove are not straight

3 Compression connection

Clean the insertion port and mark the insertion depth. Insert the tube to the specified depth, keeping the axis vertical. Use a special pressing tool to press the connector, and check whether the press size is in place with a gauge after pressing.

4. Hot melt connection

Clean the hot-melt part and the marked hot-melt depth of the socket connection. Use a special hot melt machine to heat the connection part according to the specified heating time. After heating, the joint is fused according to the specified pressure and time, and a uniform welding ring is formed at the joint.

5. Socket connection

Before the cast iron pipe is connected, clean up the debris that affects the tightness of the interface, and correctly put in the rubber sealing ring. Insert and maintain the verticality of the two pipe sections according to the depth required by the construction standard.

common problem

Two pipe sections are not straight