What is the suitable pressure for welded steel pipe?

The suitable pressure for welded steel pipe depends on the specific application. Generally speaking, the suitable pressure for ordinary welded steel pipe should be below 1.6 MPa and is suitable for steam, condensate, and hot water pipes with temperatures below 200°C. For applications requiring higher pressures and temperatures, such as steam or hot water pipes exceeding 200°C, seamless steel pipes with higher pressure ratings may be required.

1. Suitable Pressure Range for Welded Steel Pipes
Welded steel pipe is a commonly used fluid and gas transport pipeline. Its suitable pressure range is determined by the specific application. Generally speaking, the suitable pressure for ordinary welded steel pipe should be below 1.6 MPa, primarily for steam, condensate, and hot water pipes with temperatures below 200°C. This pressure range ensures safe pipeline operation while meeting fluid transport requirements.

However, in certain special applications, such as high-temperature steam or high-pressure hot water pipes, steel pipes capable of withstanding higher pressures and temperatures are required. In this case, seamless steel pipes are often a better choice, with suitable pressures typically exceeding 1.0 MPa and even higher pressure ratings.

2. The Impact of Welding Pressure on Weld Quality

In addition to considering the operating pressure of the steel pipe, the welding pressure during the welding process is also a key factor affecting weld quality. The welding pressure directly affects the strength and toughness of the weld. If the welding pressure is too low, the weld edges will not be fully compressed, and non-metallic inclusions and metal oxides may remain in the weld, reducing weld strength and increasing the risk of cracking. Conversely, if the welding pressure is too high, the metal will be over-compressed, which not only reduces weld strength but may also cause defects such as excessive internal and external burrs or overlays.

3. How to Adjust Welding Pressure

In practice, adjusting welding pressure is a skill. Welders need to comprehensively assess and adjust welding pressure based on factors such as the width and thickness of the pipe blank, as well as the welding temperature and speed. Generally, the amount of compression is controlled by adjusting the distance between the squeeze rollers or the pipe diameter before and after the squeeze rollers to achieve optimal welding results.

4. Pressure Ranges of Welded Steel Pipes of Different Materials and Specifications

Ordinary welded steel pipes: These pipes have a relatively low pressure tolerance, generally below 1.6 MPa. They are primarily used in low-pressure steam pipelines, condensate, and hot water pipelines.

Seamless steel pipes: Compared to ordinary welded steel pipes, seamless steel pipes have a higher pressure tolerance. They are typically used in steam pipelines with pressures exceeding 1.0 MPa or hot water pipelines with pressures exceeding 1.6 MPa and temperatures below 180°C.

Special material welded steel pipes: These pipes, such as stainless steel and alloy steel, have excellent corrosion resistance and high-temperature performance, and therefore can withstand higher pressures. Stainless steel pipes can generally withstand pressures around 10 MPa, while alloy steel pipes can withstand pressures exceeding 20 MPa. These special material pipes are widely used in high-pressure, high-temperature applications such as the petroleum, chemical, and power industries.

In short, when selecting the appropriate pressure for a welded steel pipe, we need to consider multiple factors, including the application scenario, pipe material, and welding process. Only in this way can the safe operation of the pipeline and the effective transportation of the fluid be ensured.

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