As two major categories in the steel pipe market, welded steel pipe and seamless steel pipe exhibit significant differences in production technology, application areas, and performance characteristics.

Differences in Production Technology
The production process for welded steel pipe is relatively simple and straightforward. It primarily involves rolling a steel plate or strip into a cylindrical shape and then welding the seams together to form the pipe. In this process, the weld is a notable feature of the straight seam welded pipe and one of the main differences between it and the seamless pipe. According to different welding methods, straight seam welded pipes can be divided into many types, such as arc welded pipes, high-frequency or low-frequency resistance welded pipes, gas welded pipes, and furnace welded pipes. Among them, high-frequency electric resistance welded pipes are widely used due to their high production efficiency and low cost.
The production process for seamless steel pipe is more complex. Seamless pipes are usually made from solid pipe billets (such as round steel) through processes such as piercing, hot rolling, cold rolling or cold drawing. These processes ensure that no welds are produced during the manufacturing process of seamless pipes, giving them higher integrity and strength. The production of seamless steel pipes has high requirements on raw material quality, process control and equipment precision, so its production cost is relatively high.

Performance Comparison: Seamless steel pipes, due to their weld-free design, offer superior pressure resistance and strength. When the diameter and wall thickness are equal, the pressure and strength of seamless pipes are much greater than those of straight seam welded pipes. This characteristic makes seamless pipes safer and more reliable in harsh environments such as high pressure, high temperature, and high corrosion. Therefore, in the oil, natural gas, chemical, electric power and other industries, seamless steel pipes are widely used in key components such as transmission pipelines, boiler tubes, and heat exchangers.

Although welded steel pipes have welds during the production process, modern welding technology can ensure that the quality of the welds reaches a higher standard. However, since the mechanical properties of the weld are lower than those of the base material, the use of welded steel pipes under extreme conditions such as high pressure and high temperature is subject to certain restrictions. However, straight seam welded pipes have the advantages of high production efficiency, low cost, and a wide variety of specifications, which give them broad application prospects in low pressure, room temperature, and general corrosive environments. For example, in the fields of construction, agriculture, machinery manufacturing, etc., welded steel pipes are used as scaffolding pipes, greenhouse pipes, fluid conveying pipes, etc.

Production Process
The production processes for seamless steel pipe (stock pipe) and expanded pipe differ significantly. The original pipe refers to the primary steel pipe of seamless steel pipe produced by using various steel billets as raw materials and undergoing processing and heat treatment. The production of raw pipes requires multiple processing steps, including billet pretreatment, piercing, hot rolling or cold drawing and other thermal processing processes. The production process of raw steel pipes is relatively complicated and difficult to process, but the seamless steel pipes produced have high quality and strength and are an important material widely used in various mechanical and structural equipment. Seamless steel pipes are widely used in the manufacturing of machinery and structural equipment, primarily in the manufacture of high-pressure boilers, oil and gas transmission pipelines, automotive engines, and mechanical parts.

Pipe expansion is the process of increasing the size of existing seamless steel pipes. Its production process is relatively simple, and there are two main methods: one is rolling or stretching; the other is extrusion. The production process of pipe expansion requires the use of special processing equipment and molds. During the pipe expansion process, the steel pipe will be subjected to greater pressure and force. Although the processing difficulty is not as good as the original pipe, the processing accuracy requirements are higher, because the product after pipe expansion needs to ensure surface finish and dimensional accuracy to ensure its application effect. Expanded pipe is primarily used in applications such as steel pipe joints, signal brackets, and pressure vessels.

Processing Methods
The processing methods for seamless steel pipe stock and expanded pipe also differ significantly. The production of seamless steel pipe raw pipes requires a series of thermal processing processes. If any quality problems occur during the production process, the quality of the final product will also be affected.

Pipe expansion is a process performed on existing seamless steel pipes, which greatly reduces the process difficulty and processing costs. After expansion, the steel pipe undergoes heat treatment and other processing processes to increase its strength and ensure its corrosion resistance.

The two types of steel pipe products have different application fields, and due to the difference in use, the required performance parameters are also different.

Color-coated coils are made from cold-rolled steel strip. Galvanized steel strip is made from galvanized steel sheets (electrogalvanized or hot-dip galvanized). After surface pretreatment (degreasing and chemical treatment), one or more layers of organic coating are applied by roller coating, followed by baking and cooling.

Improper storage of color-coated steel coils can lead to defects such as scratches, dents, and rust, which can even cause serious consequences. To ensure the quality of color-coated steel coils, careful storage is essential.

Store them indoors in a clean, dry, and well-ventilated environment. Avoid outdoor storage or locations prone to condensation or temperature fluctuations. The storage surface must be flat, free of hard objects, and have sufficient load-bearing capacity. Coils should be placed upright on rubber mats, wooden pads, or supports, with the buckles facing upward. Thick plates and coils should be stored properly for easy access and to minimize unnecessary movement. Stacking is strictly prohibited to prevent damage, and stacking height must be strictly limited.