Welded Steel Pipe VS. Seamless Steel Pipe

The main difference between seamless steel pipe and welded steel pipe are molding process. General welded steel pipes such as water pipes, is generally flat plate by bending and welded together after that you can find a seam in the above; coarse diameter is usually spiral weld. The molten steel seamless pipe is generally through an annular slit molten state and then by stretching out the backlog of processing molding process, so there is no seam. In performance, especially compared to welded steel has greatly improved the bearing capacity, it is often being used for high-voltage equipment. Hydraulic equipment such as piping connections. Welded steel pipe weld area is its weak link, weld quality is also a major factor in its overall performance impact. Welded steel pipe lived in the north generally have had water pipes or heating pipes burst in the winter cold experience explosive place are generally weld.

Seamless steel pipe is piercing round holes to produce steel. Welded steel pipe is rolled into a bucket and then weld. According to their method of manufacturing seamless steel pipe and welded steel pipe in two. Seamless steel pipe with high-quality carbon steel or alloy steel, hot-rolled, cold-rolled (pull) of the points. Welded steel pipe is rolled into a tube-shaped plate with the seam or spiral seam welded, in the manufacturing method, is divided into low pressure fluid welded pipe, spiral welded steel pipe, directly welded steel pipe, welded pipe. Seamless steel pipe can be used for a variety of liquids, gas pipelines. Welded pipes can be used for water pipes, gas pipes, heating pipes. Seamless steel pipes are used in important applications, uniform, high pressure tolerance, such as the barrel, the barrel and so on. Generally with high-quality steel, alloy steel and even. Welded steel are used in general purpose compression generally well tolerated, such as water pipes, gas pipes, etc., with ordinary steel.

Types of Welded Steel Pipes:

Carbon steel welded pipes can be divided into three types: Longitudinal submerged arc welded steel pipes (LSAW), Spiral welded steel pipes (SSAW), and Electric resistance welded Steel Pipe (ERW, also called high-frequency straight seam welded steel pipes ) according to the forming method of the weld seam.

1) LSAW steel pipe (Longitudinal submerged arc welded steel pipe)

Longitudinal submerged arc steel pipe is a steel pipe with a weld seam parallel to the longitudinal direction of the steel pipe. It is made of hot-rolled or cold-rolled steel plates or steel strips that are curled and welded. The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. Straight seam steel pipes are widely used in water supply projects, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction.

2) SSAW steel pipe (Spiral welded steel pipe)

Spiral welded steel pipe is made of strip steel coils as raw materials, rolled into tube blanks at a certain spiral angle, and then welded together. It can use narrow strip steel to produce large diameters. steel pipe. Spiral steel pipes are mainly used in drainage and water supply projects, fluid liquid, and solid transportation pipelines. It is widely used in urban construction and municipal engineering.

The strength of spiral welded pipes is generally higher than that of straight seam welded pipes. Welded pipes with larger diameters can be produced from narrower billets, and welded pipes with different diameters can also be produced from billets of the same width. However, compared with straight seam pipes of the same length, the weld length is increased by 30~100%, and the production speed is lower.

3) ERW steel pipe (Electric resistance welded steel pipe)

ERW steel pipe uses the skin effect and proximity effect of high-frequency current to heat and melt the edge of the pipe blank after the hot rolled coil is formed by a forming machine, and presses it under the action of a squeeze roller Welding to achieve production. ERW has the characteristics of high efficiency,low cost,material saving and easy automation,it is widely used in aviation, aerospace, energy, electronics, automotive, light industry and other industrial sectors, is an important link in the welding process.

What is SAW steel pipe?

SAW steel pipe (Submerged Arc Welding Steel Pipe), it can be classified into longitudinal submerged arc welding steel pipe (LSAW steel pipe) and spiral submerged arc welding steel pipe (SSAW steel pipe). SAW is a manufacturing process using submerged arc welding of steel,this process produces high current density, which prevents the flux layer from losing heat quickly and concentrates in the welding region. Commonly used standard is API 5L.

Submerged arc weld of high quality, high production efficiency, arc and smoke a few characteristics of submerged arc welded pipe is widely used in pressure vessels,pipe manufacturing, beams, low pressure fluid, steel works.

Welded Steel Pipe VS Seamless Steel Pipe

Method for identification of seamless and welded steel pipes:
 
Common steel pipe mainly has two forms of seamless steel pipe and welded steel pipe. In the process of engineering construction, appropriate steel pipes will be selected according to the specific construction situation, and the cost will be the primary factor.
 

1) Manufacturing process
Seamless steel pipe is mainly a solid tube billet or steel ingot for perforation, made of wool tube, and through hot rolling, cold rolling, cold drawing and other processing, and then formed seamless steel pipe. Since seamless steel tubes contain a members section, this hollow section can be used as a conduit for transporting fluids.
 
 A Welded steel pipe is generally a steel strip or steel plate under the action of external force, make it into a round or square, and then weld the surface joints, thus forming a welded steel pipe. The commonly used processes are arc welding, high or low frequency, cold rolling and so on, but the use of these processes for welding will lead to welded steel pipes. At present, according to the shape of welding seam can be divided into straight seam and spiral welded steel pipe, but the two use different technology. The spiral steel pipe is welded by submerged arc welding, which has the advantages of high welding efficiency and less dust. For high frequency or low frequency welding, mainly based on the principle of electromagnetic induction, due to the ac charge in the conductor will occur adjacent and turbine heat effect, can achieve the welding edge of steel to melt state, the final completion of welding.
 

2) Appearance difference
In appearance, the difference between seamless steel pipe and welded steel pipe is that the inner wall of the welded pipe has welding ribs, while seamless steel pipe does not. Seamless steel pipe pressure is higher, welded pipe is generally about 10 MPa. Seamless steel tube is formed once in rolling. Welded steel pipes need to be rolled and welded, generally spiral welding and direct welding. Performance seamless tube is better. Of course, the price is higher.

3) Wall thickness
The precision of seamless steel pipes is low and the wall thickness is relatively thick. The steel pipe of welded steel pipe has high precision and the wall thickness is usually thin.

4) Price
Seamless steel pipes are more expensive than welded steel pipes because the production process of seamless steel pipes is more complex and their costs are higher.

5) Performance characteristics
Seamless steel pipe: Because there are no welded joints, seamless steel pipe generally performs better in high temperature, high pressure, and corrosive environments. They are suitable for applications requiring high strength and high corrosion resistance, such as oil and gas transmission, chemical industry and high-pressure boilers. 

Welded steel pipe: The performance of welded steel pipe often depends on the quality of the weld. Although they can be used in many applications, welded joints can become a potential source of corrosion and weakness. However, with proper welding techniques and corrosion protection, the risk of these problems can be reduced. In terms of corrosion resistance, pressure bearing, high temperature resistance and other properties, seamless steel pipes are better than welded steel pipes.

6) Applicable fields
Seamless steel pipe: Due to their high-performance characteristics, seamless steel pipes are often used in applications that require a high degree of reliability and safety, such as nuclear power plants, high-temperature and high-pressure vessels, and chemical equipment.
Welded steel pipe: Welded steel pipe is suitable for some general engineering and low pressure applications such as building structures, hydraulic transmission and general piping systems. They are usually more affordable.

Seamless steel pipes and welded steel pipes each have advantages in different application areas. When selecting pipe materials, engineering needs, performance requirements, and cost factors need to be considered to determine which type of steel pipe is more suitable for a specific project.