In the oil and gas pipeline corrosion in the construction process, LSAW steel pipe anti-corrosion surface treatment is to determine the life of one of the key factors, it is ERW steel pipe coating with the premise of whether the combined firm.

In accordance with the different processes of production, seamless steel pipe is parallel to the longitudinal weld steel pipe steel pipe, usually divided into metric welded steel pipe, welding thin-walled tube, transformer cooling tubing.

When steel pipe yield is to a certain extent, due to the internal grain rearrange its ability to resist deformation increased, although at this time deformation developed rapidly, but it can only be increased as the stress increased, until the stress reaches the maximum value.

SMAW (shielded metal arc welding) is the most widely used in industrial production welding method, it is the use of an arc discharge (commonly known as the arc burning) heat generated melts the electrode and the workpiece with each other and form a weld after condensation, thereby obtaining a solid welded joints process. SMAW electrodes are manipulated by hand welding work can be welding, vertical welding, horizontal and overhead welding and other welding position welding.

The main energy parameters that determine the weld size are welding current, voltage and welding speed.

Preheating before welding and heat treatment after welding have great influence on welding quality. Preheating before welding is required for important components.

The main disadvantage of CO2 gas shielded welding is welding spatter, which mainly adopts the following measures:

Welding heat treatment residual stress refers to the residual stress of the workpiece after heat treatment, which has a very important impact on the shape, size and performance of the workpiece. When the material yield strength exceeds, it will cause deformation. When the strength limit of welding material exceeds, it will produce cracks, which should be reduced and eliminated.

Generally, forging cracks will be formed at high temperature. Due to the expansion of the cracks and contact with air, under the microscope, the cracks are full of oxide skin and decarburized on both sides. The cracks are relatively thick, without detailed tips, relatively round and pure. Sometimes some forging cracks are relatively fine, and the cracks are semi decarburized rather than full decarburized.

Crater on weld surface is a common weld surface defect in submerged arc welding, which refers to the defect that the weld surface is partially lower than the normal weld surface.

Seamless ( CARBON SMLS) Steel Pipe is made from a solid round steel ‘billet’ which is heated and pushed or pulled over a form until the steel is shaped into a hollow tube. The seamless pipe is then finished to dimensional and wall thickness specifications in sizes from 1/8 inch to 34 inch OD.

Carbon steel pipe as a product must have a certain performance to meet the needs of the usage conditions. Improving the performance of the steel is two ways, First, adjusting the chemical composition of the steel alloying; the other is the heat treatment, heat treatment and shaping deformation combination of approaches. In the field of modern industrial technology, heat treatment to improve the performance of the steel still occupy a dominant position.