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What you need to know about welded steel pipes

Galvanized welded pipe

Galvanized welded pipe is a hollow circular cross-section light thin-walled steel pipe, also known as steel refrigeration bending profile. It is Q235 hot-rolled or cold-rolled strip or coil as the base material by cold bending process forming and then high-frequency welding made of square cross-sectional shape size of the section steel. Hot-rolled extra thick-walled galvanized welded pipes, in addition to the thickening of the wall, the corner dimensions and straightness of the edges are up to and even beyond the level of resistance welded cold-formed galvanized welded pipes.

The main welding process 

Welded galvanized welded pipes can be produced from a narrower billet with a larger diameter, or from a billet of the same width with a different diameter. However, the weld length increases by 30 to 100% compared to the same length of straight-seam galvanized welded pipe, and the production speed is lower.

Large or thicker diameter welded galvanized welded pipes are usually made directly from steel billets, while small welded thin-walled welded pipes are simply welded directly through the steel strip. Then after a simple polishing, drawing is done. Therefore, most of the smaller diameter welded pipes are straight seam welded, and most of the large diameter welded pipes are spiral welded. Comprehensive mechanical properties, weldability, cold, hot processing properties and corrosion resistance are good, with good low-temperature toughness.

The cut-off operation points to note.

(1) to cut off the place, please use a rag or soft cloth to galvanized welded pipe surface oil, debris or mud completely wipe clean.

(2) Be sure to choose stainless steel cut off special.

(3) cut off the location, with the construction drawings and site conditions, using a meter ruler or other measuring tools, draw a definite location and mark the cut-off line.

 (4) cut off, please use the vise and other galvanized welded pipe fixed apparatus, indeed fixed before cutting.

(5) The cutting surface of the galvanized welded pipe should be kept true round, and the cutting line should be at right angles to the axis of the galvanized welded pipe.

The beautiful process of welded galvanized welded pipe and rectangular pipe will keep moving forward with the development of science and technology to make the welded galvanized welded pipe process more perfect and produce better and more beautiful galvanized welded pipe products.

Hot-dip galvanized pipe

Production method

Hot-dip galvanized pipe is made by reacting molten metal with iron substrate to produce an alloy layer, thus combining both the substrate and the coating. Hot-dip galvanizing is done by pickling the steel pipe first, in order to remove the iron oxide on the surface of the pipe, after pickling, it is cleaned by ammonium chloride or zinc chloride aqueous solution or ammonium chloride and zinc chloride mixed aqueous solution bath, and then sent to the hot dip galvanizing bath.


Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. The hot-dip galvanized steel pipe substrate reacts with the molten plating solution in a complex physical and chemical reaction to form a corrosion-resistant, structurally compact zinc-iron alloy layer. The alloy layer is integrated with the pure zinc layer and the steel pipe substrate, so its corrosion resistance is strong.


Hot-dip galvanized steel pipes are widely used in construction, machinery, coal mining, chemical industry, electric power, railway vehicles, automobile industry, highways, bridges, containers, sports facilities, agricultural machinery, petroleum machinery, prospecting machinery, shed construction and other manufacturing industries.

What is the difference between galvanized steel pipe and welded steel pipe

Galvanized steel pipe is mainly hot-dip galvanized steel pipe. In the case of new houses, interior decoration, production and processing, many different types of pipes are usually used, and the more common ones are hot-dip galvanized and welded pipes.

Difference one: production method

As galvanized steel pipe is gradually dissolved, and welded steel pipe is immediately welded welding, so welded steel pipe is more convenient in the case of production, galvanized steel pipe is more time consuming, but it is precisely because of this difference between galvanized steel pipe and welded steel pipe, which caused them to be very different in other levels.

Difference two: appearance

Their production methods are very different, which immediately causes them to have a very big difference in appearance, the bright eye can immediately identify the difference between galvanized steel pipe and welded steel pipe, galvanized steel pipe usually has a layer of metal material layer on the surface, the overall very smooth and colorful, but the welded steel pipe because the production of the case is more immediately rude, so it does not look good, some people It is also called the black tube.

Difference three: price

As these two different tubes, in the production method and appearance are very different, resulting in a big difference in their prices, galvanized steel pipe is more beautiful, the production of time, so the same specifications of the model of the pipe, its price is much more expensive than the welded steel pipe. If you want to buy these two materials of decorative building materials, usually prefer galvanized steel pipe, welded steel pipe for the general home.