Hardness Test of Welded Pipe

Welded pipe is made of steel plate or steel strip after bending and then welding. According to the form of weld seam, it is divided into straight seam welded pipe and spiral welded pipe.

According to the purpose, it is divided into general welded pipe, galvanized welded pipe, oxygen-blown welded pipe, wire casing, metric welded pipe, roller pipe, deep well pump pipe, automobile pipe, transformer pipe, electric welded thin-walled pipe, electric welded special-shaped pipe and spiral welded pipe.

General welded pipe: General welded pipe is used to transport low-pressure fluid. Made of Q195A, Q215A, Q235A steel. It can also be made of other soft steel that is easy to weld. Steel pipes must undergo water pressure, bending, flattening and other tests, and have certain requirements for surface quality. The delivery length is usually 4-10m, and fixed length (or multiple length) delivery is often required.

The specifications of welded pipes are expressed in nominal diameter (mm or inches). The nominal diameter is different from the actual diameter. According to the specified wall thickness, welded pipes are divided into ordinary steel pipes and thickened steel pipes. Steel pipes are divided into threaded and non-threaded according to the form of pipe ends.

The following briefly introduces the application of several welded pipes

1. General welded pipes are used for the transportation of generally low-pressure fluids such as water, gas, air, oil and heating steam.

2. Ordinary carbon steel wire casing (GB3640-88) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil buildings, installation of machinery and equipment.

3. Straight seam electric welded pipe (YB242-63) is a steel pipe with the weld parallel to the longitudinal direction of the steel pipe. It is usually divided into metric electric welded pipes, electric welded thin-walled pipes, transformer cooling oil pipes, etc.

4. Spiral seam submerged arc welded pipe for pressure fluid transportation (SY5036-83) is made of hot-rolled steel strip coil as pipe blank, spirally formed at room temperature, welded by double-sided submerged arc welding, and used for pressure fluid transportation.

The steel pipe has strong pressure bearing capacity and good welding performance. It has undergone various rigorous scientific inspections and tests and is safe and reliable to use. The steel pipe has a large diameter, high transportation efficiency, and can save investment in laying pipelines. It is mainly used for pipelines for transporting oil and natural gas.

5. Spiral seam high-frequency welded pipe for pressure fluid transportation (SY5038-83) is made of hot-rolled steel strip coil as pipe blank, spirally formed at room temperature, and welded by high-frequency lap welding. It is a spiral seam high-frequency welded steel pipe for pressure fluid transportation.

The steel pipe has strong pressure bearing capacity, good plasticity, and is easy to weld and process; it has undergone various rigorous and scientific inspections and tests, is safe and reliable to use, has a large diameter, high transportation efficiency, and can save investment in laying pipelines. It is mainly used for laying pipelines for transporting oil, natural gas, etc.

6. Spiral seam submerged arc welded steel pipe for general low-pressure fluid transportation (SY5037-83) is made of hot-rolled steel strip coil as pipe blank, spirally formed at room temperature, and made by double-sided automatic submerged arc welding or single-sided welding. It is used for general low-pressure fluid transportation such as water, gas, air and steam.

Welded pipes can be tested by three hardness test methods: Brinell, Rockwell and Vickers to determine HB, HRB (or HRC) and HV hardness values. Only one of the three hardness values ​​needs to be measured.