Standards of Welded Steel Pipes

The welded steel pipe is welded by crimping of the steel plates or steel strips. The welded steel pipe has the advantages of simple production process, high production efficiency, many varieties and specifications and less equipment investment. However, its general strength is lower than that of seamless steel pipes.

Since the 1930s, with the rapid development of high quality strip rolling production, the progress of welding and inspection technology, the quality of welding seam has been continuously improved, and the varieties and specifications of welded steel pipes are increasing day by day. It has replaced seamless steel pipes in more and more fields. The welded steel pipe can be divided into straight welded pipes and spiral welded pipes according to the form of welding seams. A straight seam welded pipe has the advantages of simple production technology, high production efficiency, low cost and rapid development. The strength of spiral welded pipes is generally higher than that of straight welded pipes. Therefore, larger diameter welded pipes can be produced from narrower billets, and different diameter welded pipes can be produced from billets of the same width. However, compared with the same length of straight seam pipes, the welded length is increased by 30~ 100% and the production speed is lower. Therefore, as for welded pipes with small diameters, the straight seam welding is mostly used, and the spiral welding is mostly used for welded pipes with large diameters.
 
1. Welded steel pipes for low pressure fluid transportation (GB/T3092-1993):
It is also known as general welded pipes or black pipes. It is used for conveying water, gas, air, oil, heating steam and other general low pressure fluid. The wall thickness of the steel pipe is divided into ordinary steel pipes and thickened steel pipes. The form of the noose end is divided into non-rebar steel pipes (light pipes) and rebar steel pipes. The specification of steel pipes is expressed in nominal caliber (mm), which is an approximation of the inside diameter. The inch unit is commonly used, like 11/2 Inch. Welded steel pipes for low pressure fluid conveying are also widely used as the original pipes of galvanized welded steel pipes for low pressure fluid conveying.
 
2. Galvanized welded steel pipes for low pressure fluid transportation (GB/T3091-1993):
It is known as galvanized electrowelding steel pipes, which are commonly known as white pipes. It is used for conveying water, gas, air, oil, heating steam, warm water and other general low pressure fluid or hot dip galvanized welded steel pipes for other purposes (furnace welding or electric welding). The wall thickness of steel pipes can be divided into ordinary galvanized steel pipes and thickened galvanized steel pipes. The nozzle end form is divided into galvanized steel pipes without threads and galvanized steel pipes with threads. The specification of steel pipes is expressed in nominal caliber (mm), which is an approximation of the inside diameter. Inches are commonly used, such as 11/2 Inch.

3. Ordinary carbon steel wire casing pipes (GB3640-88):
It is the steel pipe used to protect electric wires in industrial and civil construction, installation of machinery and equipment and other electrical installation projects.
 
4. The straight seam welded steel pipes (YB242-63):
It is a steel pipe whose weld is longitudinal parallel to the steel pipe. It is usually divided into metric welded steel pipes, thin-walled welded pipes, transformer-cooling tubing and so on.
 
5. Spiral seam submerged arc welded steel pipes for pressure fluid conveying (SY5036-83):
It is a spiral seam steel pipe used for pressure fluid conveying. The pipe billets are made from hot rolled steel strips. It is often shaped in warm spiral forming and welded by double-side submerged arc welding method. The steel pipe has strong pressure bearing capacity and good welding performance. It is safe and reliable. What’s more, it can be used after all kinds of strict scientific inspection and testing. The diameter of the steel pipe is large. The transmission efficiency is high, and it can save the investment in laying pipeline. It is mainly used to transport oil and natural gas.

6. Spiral seam high-frequency welded steel pipes for pressure fluid conveying (SY5038-83):
It is a spiral seam high-frequency welded steel pipe used for pressure fluid conveying. Its pipe billets are made from hot rolled steel strips. It is often shaped in heated spiral forming and welded by high-frequency lap welding method. The steel pipe has strong pressure bearing capacity, good plasticity, and it is easy to weld and process. Through a variety of strict and scientific inspections and tests, it is safe and reliable. The diameter of the steel pipe is also large. The transmission efficiency is also high, and it can save the investment in laying pipeline. It is mainly used to transport oil and natural gas.
 
7. Spiral seam submerged arc welded steel pipes for general low pressure fluid conveying (SY5037-83):
The pipe billets are made from hot rolled steel strips. It is often shaped in a warm spiral forming. It is made by double-sided automatic submerged arc welding or single-side welding method for water, gas, air and steam and other general low pressure fluid conveying.
 
8. High-frequency spiral seam welded steel pipes for general low-pressure fluid transportation (SY5039-83):
Its pipe billets are made from hot rolled steel strips. It is often formed by warm spiral, and welded by high frequency lap welding method for general low-pressure fluid transportation.
 
9. Spiral welded steel pipes for pile (SY5040-83):
Its pipe billets are made from hot rolled steel strips. It is often formed by a warm spiral. It is made by double-side submerged arc welding or high-frequency welding. It is used for foundation piles of civil construction structures, wharf, bridges and so on.