Material and Standard Classification of SSAW Steel Pipe

Material of SSAW steel pipe:

SSAW steel pipe (also called spiral welded pipe) is the steel pipe with spiral seam that using strip coil as raw material, extrusion forming under normal temperature, and welding by automatic Double wire double-sided submerged arc welding process. The material of it includes: Q235A, Q23b, 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, Q345, L245(B), L290(X42), L320(X46), L485(X70), L555(X80).

Standard classification of SSAW steel pipe:

1. Spiral welded pipe (SY5036-83) used for pressurized fluid transportation is mainly used for conveying oil and natural gas pipeline.
2. Spiral seam high-frequency welded steel pipe (SY5038-83) used for pressurized fluid transportation, it is welded with high-frequency welding method. The loading capacity of it is powerful, the plastic is good, and it is easy to weld and machine shaping.
3. Spiral welded pipe (SY5037-83) used for general low-pressure fluid transmission, it is welded with double-sided automatic submerged arc welding method or one-side welding method, it is mainly used for water, gas, air and steam and other general low-pressure fluid delivery.

Now general standards for SSAW steel pipe is generally divided into: SY/T5037-2000 (ministerial standard, also known as spiral submerged arc welded steel pipe for ordinary fluid transportation pipeline), GB/T9711.1-1997 (Chinese standard, also known as pipe for oil and gas industry transportation, API-5L (American Petroleum Institute, also known as pipeline steel pipe; which is divided into PSL1 and PSL2), SY/T5040-92 (spiral seam submerged arc welded pipe for pile).

Prime Steel Pipe as a excellent manufacturer and exporter of steel pipe, will provide the spiral welded pipe with highest quality and the most comprehensive service for our customer. If you are interested in our products, you can click the hyper-link to view details.

The Welding Quality of Welded Steel Pipe

Welding quality of welded steel pipe refers to the degree to which the welding product meets the design technical requirements. Welding quality not only affects the use performance and life of welding products, more importantly, affects personal and property safety. Welding quality is usually ensured by design quality, processing quality, quality inspection and post-weld treatment and other links of the product.

Design Quality

The type of joint used in the welding product and its calculated strength should meet the actual carrying capacity. Welding method should be suitable for the characteristics of components, and its economical efficiency should be good. The welding process should be able to minimize stress, deformation and stress concentration. Production labor and material consumption should be as small as possible, the convenience of flaw detection should also be taken into consideration when design the joint.

Processing Quality

The performance of adopted the base metal, wire, flux or welding electrodes and other welding materials should meet the design requirements. The performance of welder, auxiliary equipment and testing equipment should be good. Before welding, the welding material should be dried according to the provisions, the welding groove of workpiece should meet the requirements and remove the cutting residue, cracks and dirt.

Quality Inspection

Quality inspection runs through the whole production process from design to finished product, we must ensure that the test method used in the quality inspection process is rationality, the reliability of the testing instrument and inspection staff technical level. The properties of the joints, physical properties, mechanical properties, microstructure, chemical composition, corrosion resistance, appearance dimensions and welding defects of products after welding should be checked by means of various inspection methods.

Welding defects can be divided into external defects and internal defects. External defects include: excess height does not meet the requirements, welding tumor, undercut, crater, arc burns, surface pores, surface cracks, welding deformation and warping. Internal defects include: cracks, not penetration, not fused, slag and porosity. The most harmful in welding defects is the crack, the followed is lack of penetration, incomplete fusion and slag inclusion, pores and structure defect. Individual flaws are allowed to exist. The number and the nature of allowed defects are determined by the using conditions and the quality assessment criteria of the product. If the surplus height of welding line is too high, it is allowed for those products by the static load, but it is not allowed for those products by cyclic fatigue loading in high frequency, even the normal excess weld metal also has to be cut off. The presence of welding defects is related to the groove processing and assembly accuracy, the rigor degree of the welding process, the technology of the welder and other factors.

What is Welded Steel Pipe?

Welded steel pipe, also known as welded pipe, is the steel pipe that made of steel plate or steel strip after crimped and welded. The production process of welded steel pipe is simple, production efficiency is high, variety specifications are many, the investment of equipment is little, but its general strength is lower than the seamless steel pipe. Since the 1930s, with the rapid development of high-quality strip continuous rolling line and the improvement of welding and inspection technology, the quality of welding line has been increasing continuously, and the specifications of welded steel pipes have been increasing. And welded pipe have replaced the seamless steel pipe in more and more field. Sewing steel pipe. The welded steel pipe is divided into straight seam welded pipe(also called LSAW steel pipe) and spiral welded pipe(also called SSAW steel pipe) according to the form of welding line.

Production process of LSAW steel pipe is simple, production efficiency is high, cost is low, and it develops rapidly. The strength of the SSAW steel pipe is generally higher than that of the LSAW steel pipe, and the SSAW steel pipe with larger diameter can be produced with the narrow billet. And it also can use the billet with the same width to produce t SSAW steel pipe with different diameter. However, compared with the straight seam welded pipe in identical length, the length of welding line increased by 30 to 100%, and the production rate was low.

Therefore, pipe manufacturers usually use straight seam welding to produce the smaller diameter of the pipe, use spiral welding to produce large diameter welded pipe.

Connection Modes of Oil Pipelines

Several days ago, we introduced the types of tube that used in oil pipeline, today, we will share the connection modes of oil pipelines for people those interested in this aspect.

Oil pipeline must use a certain connection to form a complete system. Connection methods of pipeline are mainly three categories, including screw thread, welding and flange connection.

When the pressure is not high, the pipe with small diameter can be connected by using screw thread this method. This connection method is very convenient, but most of the diameter of oil pipelines are generally larger, so other two connection methods are used commonly.

The pipeline that DN≥50 basically uses welding method to connect. Welding has many advantages, such as convenient construction, strong, tight and saving steels. The general straight pipe or bends those parts do not need to tear down can use this method.

The connection of pipes and valves or other equipment (such as: pump) and the parts those need to disassemble of pipeline need to use flange to connect. In order to ensure the tightness of the flange connection, we also need to use a relatively soft flange grommet to assist on both sides of the flange. According to the production process, flange can be divided into flat welding, thread, butt welding, loose tube and blind plate and other types. Except blind plate flange, others are all used in interconnection between the pipeline. If you need to connect different diameters of the pipeline, you can use the adapter flange that two diameter corresponding. The blind plate flange is used to close the end of the pipe head. Therefore design of it make it can withstand greater bending stresses.

Pipe Application: Urban Gas Pipeline

There are two steel pipe mainly used for urban gas pipeline, including seamless steel pipe and welded steel pipe. The intensity of seamless steel pipe is high, but it is generally the small diameter below DN200 steel pipe as the constraints of production process and cost. There are more types of welded steel pipe, according to the welding method that can be divided into straight welded steel pipe and spiral welded steel pipe two categories. Among them, straight welded steel pipe includes Longitudinal Submerged Arc Welded pipe (LSAW steel pipe), Electric Resistance Welded pipe (ERW steel pipe) steel, and so on. For urban gas line installation, Prime Steel Pipe provides Seamless steel pipe, LSAW steel pipe, ERW steel pipe, Spiral steel pipe various types of steel pipes for selection.

According to the difference of gas pressure, city gas pipeline can be divided into low pressure (no higher than 0.01MPa), medium pressure (0.01 ~ 0.4MPa), secondary pressure (0.4 ~ 1.6MPa) and high pressure (1.6 ~ 4.0MPa). Different uses, different pressures and different diameter of the pipelines determine that urban gas pipelines have different materials and different processes.

In city gas pipeline network, high pressure pipelines, sub-high-pressure pipelines and gas transmission pipe generally select steel pipe, but there are also the problem of steel pipe type choice. In recent years, LSAW steel pipe has tended to gradually replace spiral tubes in higher pressure pipelines. At present, the price of ERW steel pipe is lower than the price of spiral welded pipe, and the quality of reliability is higher than the spiral welded steel pipe, the former has a good cost performance and its application is more and more widely. There is a way to take the pipe: when the diameter ¢ ≤ 406mm, choose ERW steel pipe, when the diameter ¢> 406mm, choose LSAW steel pipe.

In the low pressure and medium pressure pipeline, PE pipe has good flexibility, and it is corrosion-resistant, pipe wall of it is smooth and other advantages. But when the pipe diameter is larger, greater than the economic limit of PE pipe diameter, you should use steel pipe. For example, the medium-pressure pipe above DN200 is mainly using ERW steel pipe.

The Material of Natural Gas Pipeline and Its Characteristics

Natural gas pipeline refers to the pipeline that transports the natural gas (including the production of oil associated gas) from the mined land or processing plant to the city gas distribution center or industrial enterprise users, also known as gas line. In the world pipeline overall length, natural gas pipe accounts for about half.

The steel pipe is the main material of the natural gas pipeline. Modern gas gathering lines and gas line are made of steel pipes those connected by welding. There are various kinds of steel pipe, including seamless steel pipe, spiral welded pipe, longitudinal welded pipe. Seamless steel pipe be appropriate for natural gas pipe that the diameter is below 529mm, and spiral welded pipe and longitudinal welded pipe are suitable for large diameter pipe.

Features of natural gas pipeline:

(1) The gas line system is a continuous closed conveyor system.
(2) From the transport, storage to the user, natural gas is with high pressure.
(3) Due to the small proportion of transported natural gas, the influence of static pressure head is much smaller than that of liquid. In design, when the height difference is less than 200 meters, the static pressure head is negligible, and the line is almost without limited by the longitudinal terrain.
(4) There is no harms of water dashing of water pipeline.
(5) Once an accident occurs, natural gas pipe is very dangerous and extensively affected. Once the natural gas pipeline rupture, it will release plenty of energy, and its tear length is longer. If the discharge of natural gas meets open fire, also easy to lead to fire.

What type of tube is used in Oil pipeline?

The tube that used in Oil pipeline is mainly carbon steel pipe, according to its manufacturing process, it can be divided into seamless steel pipe and welded steel pipe.

Seamless steel pipe has the characteristics of high strength, specifications and more features, so it is applicable to transport strong corrosive oil or transport in the high temperature conditions. The technology of seamless steel pipe is divided into hot rolling and cold drawn. As the cold drawing process will cause the material hardening, it also needs to do the corresponding heat treatment based on the specific use of pipe.

Welded steel pipe can be divided into two kinds, straight seam steel pipes (LSAW steel pipe) and spiral welded pipe (SSAW steel pipe). The process characteristics of carbon steel pipe leds the steel pipe to tend to become brittle at low temperatures, so it is mainly applied to the normal temperature pipeline, the use of pipe temperature should not exceed 300 degrees Celsius. In general, the temperature of ordinary carbon steel pipe is between 0 to 300 degrees Celsius. If using the high-quality carbon steel pipe, the temperature range can be broadened from -40 to 450 degrees Celsius. The experimental pressure of the steel pipe is generally 1.5 times of the nominal pressure. When the temperature of the material delivered does not exceed 200 degrees Celsius, the working pressure is the nominal pressure. When the temperature exceeds 200 degrees Celsius, the working pressure should be correspondingly lower than the nominal pressure.