What is the difference between welded and threaded pipes?

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TIANJIN YUANTAI DERUN STEEL PIPE MANUFACTURING GROUP CO., LTD.

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Welded joints are generally stronger than other jointing methods. In situations where lateral forces are present, such as tidal currents or wave actions, threaded joints may be weaker. It is best to use 'continuously welded' pipe.

Welded pipes and threaded pipes are two common types of metal pipes. The main differences between them lie in manufacturing process, connection method, application scenarios and performance characteristics.

Manufacturing process

Welded pipes

Definition Pipes that are formed by curling steel plates or steel strips and connecting seams through welding processes.

Manufacturing process 1. Roll the steel plate into a cylindrical shape;

2. High frequency electric resistance welding (ERW), submerged arc welding (SAW) or laser welding the seam;

3. Cooling, sizing and cutting.

Threaded Pipe

Pipes with threads processed on the pipe ends or pipe body through cutting, rolling and other processes.

1. The pipe is directly cast or welded;

2. The pipe end is threaded or rolled;

3. Surface treatment such as galvanizing may be performed.

2. Comparison of main features

Welded pipe

Seam type There is a longitudinal weld (straight seam weld) or a spiral weld (spiral welded pipe).

Connection method Usually connected by welding, flange or clamp.

Strength There may be weak points in the weld area, and the overall strength depends on the quality of the weld.

Sealing: Good sealing after welding, suitable for high pressure system.

Cost: High material utilization, suitable for mass production, and low cost.

Threaded pipe

No joints or only welded joints, but the pipe ends are threaded.

Tightly connected to other pipe fittings through threads (such as NPT, BSPT standards).

The strength of the threaded connection is low, and it is necessary to avoid over-tightening to cause thread damage.

Sealing tape or gasket is required, otherwise it is easy to leak.

Thread processing increases costs and is suitable for small batches or special needs.

3. Application Scenarios

Welded pipes

1. Fluid transportation (water, oil, gas);

2. Structural support (buildings, bridges);

3. Machinery manufacturing (equipment frame).

- Oil and gas pipelines;

- Building scaffolding steel pipes;

- Automobile exhaust pipes.

Threaded pipes

1. Pipe systems that require frequent disassembly;

2. Low-pressure fluid delivery;

3. Small equipment or household pipes.

- Household galvanized water pipes (threaded connection);

- Fire hydrant interface;

- Hydraulic system detachable pipes.