Weld Pipe
Welded steel pipe, also known as welded pipe, is made of steel plate or steel belt after crimping forming welded steel pipe. Welded steel pipe production technology is simple, high production efficiency, varieties, specifications, less equipment investment, but lower than general strength of seamless steel tube. Since the 1930 s, with the rapid development of high quality strip steel rolling production and the progress of welding and inspection technology, constantly improve the weld quality, increasing varieties of welded steel pipe specifications, and in the field of more and more instead of seamless steel tube.  Welded steel pipe is divided into straight seam welded pipe and spiral welded pipe according to the form of weld.

Straight seam welded pipe production process is simple, high production efficiency, low cost, rapid development. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe, and the welded pipe with larger diameter can be produced with a narrower blank, and the welded pipe with different diameter can also be produced with a blank of the same width. But compared with the straight seam pipe of the same length, the weld length increases by 30~100%, and the production speed is lower.
Therefore, small diameter welded pipe mostly use straight seam welding, large diameter welded pipe mostly use spiral welding.
1.Low pressure fluid transport welded steel pipe (GB/T3092-1993) is also known as general welded pipe, commonly known as black pipe. It is a welded steel pipe used for conveying water, gas, air, oil, heating steam and other general lower pressure fluids and other purposes.  The wall thickness of steel pipe is divided into ordinary steel pipe and thickened steel pipe.  Pipe end form is divided into non - rebar steel tube (light tube) and with rebar steel tube.  Steel tube specifications are indicated by nominal diameter (mm), which is an approximation of the inner diameter.  It is customary to use inches, such as 11/2.  The welded steel pipe used for low pressure fluid transportation is mainly used as the original pipe of galvanized welded steel pipe used for low pressure fluid transportation.
2.Galvanized welded steel pipe for low pressure fluid transportation (GB/T3091-1993) is also known as galvanized electric welded steel pipe, commonly known as white pipe. It is a Hot Dip Galvanized welded (furnace welding or electric welding) steel pipe used for conveying water, gas, air oil, heating steam, warm water and other general low pressure fluids or other purposes.  The wall thickness of steel pipe is divided into Ordinary Galvanized Steel Pipe and Thickened Galvanized Steel pipe. The end of the pipe is divided into galvanized steel pipe without thread and galvanized steel pipe with thread.
Steel tube specifications are indicated by nominal diameter (mm), which is an approximation of the inner diameter.It is customary to use inches, such as 11/2.
3.Common carbon steel wire bushing (GB3640-88) is used to protect the wire in industrial and civil buildings, installation machinery and equipment and other electrical installation projects.
4.Straight seam electric welded steel pipe (YB242-63) is a steel pipe with longitudinally parallel welds.It is usually divided into metric welded steel pipe, welded thin-wall pipe, transformer cooling tubing and so on.
5.Spiral seam submerged arc welded steel pipe (SY5036-83) for pressure fluid transportation is a spiral seam steel pipe, which is made of hot rolled steel strip as tube blank, often formed at warm temperature and welded by double-sided submerged arc welding method.  The steel pipe has strong bearing capacity and good welding performance. It is safe and reliable to use after all kinds of strict scientific inspection and testing.  The large diameter of steel pipe has high transmission efficiency and can save the investment of pipeline laying.  Mainly used for conveying oil and natural gas pipelines.
6.High frequency helical seam welded steel pipe (SY5038-3) used for pressure fluid transportation is made of hot rolled steel strip as tube blank, often warm spiral forming and welded by high frequency lap welding method.  The steel pipe has strong bearing capacity and good plasticity, which is convenient for welding and processing.  After all kinds of strict and scientific inspection and testing, the use of safe and reliable, large diameter steel pipe, high transmission efficiency, and can save the investment of pipeline laying.  It is mainly used for laying pipelines for conveying oil and natural gas.
7.Spiral seam submerged arc welded steel pipe (SY5037-83) for general low pressure fluid transportation is a kind of submerged arc welded steel pipe used for water, gas, air, steam and other general low pressure fluid transportation by double-sided automatic submerged arc welding or single-side welding method.