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Detailed explanation of the surface treatment and processing methods of thick-walled steel pipes

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Thick-walled steel pipes have a wide variety of steel types and specifications, and their performance requirements are also various. All of these should be differentiated as user requirements or working conditions change. Generally, steel pipe products are classified according to cross-sectional shape, production method, pipe material, connection method, coating characteristics, application, etc. Thick-walled steel pipes can be divided into round steel pipes and special-shaped steel pipes according to the cross-sectional shape.


Special-shaped thick-walled steel pipes refer to steel pipes with various non-circular cross-sections, mainly including square pipes, rectangular pipes, elliptical pipes, flat elliptical pipes, semi-circular pipes, hexagonal pipes, hexagonal inner round pipes, unequal hexagonal pipes Tube, equilateral triangle tube, pentagonal plum blossom tube, octagonal tube, convex tube, biconvex tube. Double concave tube, multi-concave tube, melon seed tube, flat tube, diamond tube, star tube, parallelogram tube, ribbed tube, drop tube, inner fin tube, twisted tube, B-shaped tube, D Type tubes, and multi-layer tubes, etc.


Thick-walled steel pipes are divided into equal-section steel pipes and variable-section steel pipes according to the shape of the longitudinal section. The variable section (or variable section) steel pipe refers to the steel pipe with periodic or non-periodic changes in the section shape, inner and outer diameter, and wall thickness along the length of the pipe. The main ones are the outer tapered tube, inner tapered tube, outer stepped tube, inner stepped tube, periodic section tube, corrugated tube, spiral tube, steel tube with heat sink and gun barrel with a double line, etc.


To improve the service life of oil and gas pipelines, surface treatment is usually required to facilitate the firm combination of thick-walled steel pipes and anti-corrosion layers. Common treatment methods are cleaning, tool rust removal, pickling, shot blasting, and rust removal.

1. Surface pickling of straight seam steel pipe

Common pickling methods include chemical and electrolytic methods. However, the anticorrosion of the pipeline only adopt chemical pickling. Chemical pickling can achieve the cleanliness and roughness of the surface of the steel pipe, which is convenient for subsequent anchor lines. Usually, as a reprocessing after shot peening (sand).


2. Shot blasting to remove rust

The high-power motor drives the blades to rotate at a high speed so that abrasives such as steel grit, steel shot, iron wire, minerals, and other abrasives can spray and project the surface of the steel pipe under the action of centrifugal force. Under the action of the abrasive impact and friction, the required uniform roughness is achieved.


3. Thick-walled steel pipe cleaning

Grease, dust, lubricant, and organic matter adhering to the surface of thick-walled steel pipes are usually cleaned with solvents and emulsions. However, for the rust, oxygen reaction skin, and welding slag on the surface of the steel pipe, it is necessary to use other treatment methods.


4. Use tools to remove rust on straight seam steel pipes

Oxygen reaction skin, rust, and welding slag on the surface of the steel pipe can be cleaned and polished with a wire brush. The rust removal of tools is divided into two types: manual and power. The rust removal of manual tools can reach the Sa2 level, and the rust removal of power tools can reach the Sa3 level. If there is a particularly strong oxygen reaction skin attached to the surface of the steel pipe, it may not be able to be cleaned with the help of tools to remove rust, and other methods need to be found.


Among the four surface treatment methods of thick-walled steel pipes, shot blasting is the ideal treatment method for pipe derusting. Generally, shot blasting is mainly used for the inner surface treatment of steel pipes, and shot blasting is mainly used for the outer surface treatment of steel pipes. The main processing method of thick-walled steel pipe steel is rolling, which is the pressure processing of passing the steel metal billet through the gap (various shapes) of a pair of rotating rolls, reducing the cross-section of the material due to the compression of the rolls and increasing the length of the thick-walled steel pipe. Method, which is a common production method for producing steel, is mainly used to produce steel profiles, plates, and pipes. Cold-rolled and hot-rolled. Forged steel: A press working method that uses the reciprocating impact force of a forging hammer or the pressure of a press to change the billet into the shape and size we need. Generally divided into free forging and die forging seamless steel pipe, steel pipe is still an indispensable material for various conventional weapons, and the barrel, barrel, etc. must be made of steel pipe. Steel pipes can be divided into round pipes and special-shaped pipes according to the shape of the cross-sectional area. Because the area of the circle is large under the premise of the same perimeter, more fluids can be transported by a circular tube.


In addition, when the ring section of the thick-walled steel pipe is subjected to internal or external radial pressure, the force is relatively average. Therefore, most of the steel pipes of the thick-walled steel pipe are round pipes. The steel pipe has a hollow section and is widely used as a pipeline for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water, and certain solid materials. Compared with solid steel such as round steel, seamless steel pipe is lighter in weight when the bending and torsional strength is the same. Thick-walled steel pipe is economical section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobiles, etc. Drive shafts, bicycle racks, and steel scaffolding for building construction roofs, etc.


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