The primary distinction between high frequency straight seam welded pipes and spiral welded pipes lies in their production process. The former is created by initially shaping a hot rolled coil into a cylindrical form with a smooth outer surface, followed by welding. This article delves into the specifics of these two types of pipes, their production processes, and their applications.
Welding involves the use of proximity or flux under the arc's burning and skin effect, heating the tube's edge to melt it. This is then cooled and molded under appropriate extrusion. The longitudinal submerged arc welded pipe and high frequency straight seam welded pipe differ in their tube edge melting method. The former generally uses arc melting and is referred to as a straight seam submerged arc welded pipe. In contrast, the latter employs high-frequency current melting.
The production process of spiral welded pipes involves rolling low-alloy structural steel and low-carbon carbon steel into a tube at an appropriate helix angle, followed by pipe forming through welding. The primary form of spiral welded pipes is the spiral submerged arc welded pipe. The most notable feature of spiral steel pipes is their ability to produce large diameter steel pipes from narrow billets. These pipes are extensively used in various industries for gas pipeline construction.
To prolong the lifespan of longitudinal seam welded pipes and minimize the impact of coating quality, layer types, and construction environment factors, regular rust removal is necessary. Four common derusting methods include pickling, cleaning, spraying rust, and tool derusting.
Pickling is a widely used derusting method that not only serves as a post-sandblasting and dehumidification re-treatment process but also completely removes rust, oxide, and deteriorated coating from the pipe's surface. Although this method meets standard cleanliness and roughness requirements, it is a chemical cleaning method and may potentially pollute the surrounding environment.
Cleaning high frequency straight seam steel pipes can only serve as an auxiliary means in anti-corrosion treatment. This method can only remove residual organic matter such as dust, grease, and lubricant from the steel surface and does not have an anti-corrosion effect.
Tool derusting involves professional and technical personnel using wire brushes and other cleaning tools to polish the workpiece's surface. This method can completely remove loose rust, welding slag, and oxide, but it cannot remove solid scaling attached to the steel surface, thus failing to achieve the standard anti-corrosion effect.
Spraying rust involves using high-quality abrasives like steel sand and steel balls to spray the straight seam steel pipe surface through a strong centrifugal force jet. This method can effectively remove surface dirt, rust, and oxide, and the roughness level can be achieved through the friction between the abrasive and the straight seam welded pipe.
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