Surface treatment of thick-walled straight seam steel pipes

The uniformity of the pipe wall of thick-walled straight seam steel pipes will directly affect the later processing parts. If the pipe wall of thick-walled straight seam steel pipes cannot be controlled, the overall steel pipe cannot be strictly controlled. Small and medium-sized steel, wire rods, steel bars, medium-caliber thick-walled steel pipes, steel wires and wire ropes, etc. can be stored in ventilated material sheds, but with thatch on top and padding on the bottom. Some small thick-walled steel pipes, thin steel plates, steel strips, silicon steel sheets, small-caliber or thin-walled thick-walled steel pipes, various cold-rolled, cold-drawn thick-walled straight seam steel pipes, and expensive and easily corroded metal products can be stored in warehouses. Choose a suitable site and warehouse to store thick-walled steel pipes. The site or warehouse should be clean and well-drained, away from factories and mines that produce harmful gases or dust. The warehouse should be selected according to geographical conditions. Generally, an ordinary closed warehouse is used, that is, a warehouse with a roof, walls, tight doors and windows, and ventilation devices. The warehouse requires ventilation on sunny days and moisture-proof on rainy days, and a suitable storage environment should be maintained at all times.

Thick-walled straight seam steel pipes are rolled from steel plates. After rolling, they need to be welded. Generally, three steps of welding are performed: pre-welding, external welding, and internal welding. After welding, flaw detection is required. Exported steel pipes need to be beveled, painted, and capped. Length processing is performed according to customer requirements. Generally, it is divided into fixed length and non-fixed length. The main implementation standards are GB/T3091, GB/T9711, and API. Among them, GB/T9711 is divided into three parts: steel, grade B steel, and grade C steel. Thick-walled straight seam steel pipe is a steel pipe for oil and gas pipelines with large consumption and high reliability. Submerged arc welding straight seam steel pipe unit, forming unit forms include UOE, RBE, JCOE, etc. The main production process is qualified steel plate-plate edge chamfering-plate edge pre-bending-forming-JCOE forming-continuous welding of steel pipe joints-arc welding of inner pipe joints-submerged arc welding of outer pipe joints-rounding and straightening-pipe end chamfering and flattening-weld wave inspection-unqualified weld repair-weld X-ray inspection-water pressure test-weld wave inspection-unqualified weld repair-pipe inner surface drying treatment-pipe inner surface rust removal treatment-pipe inner surface anti-rust coating treatment-pipe outer surface rust removal treatment-pipe outer surface anti-rust coating treatment-finished product.

The service life of a ship is generally about 20 years. There are many conventional systems, mainly bilge water, ballast, drainage, injection, domestic water, fire protection, domestic sewage, air, measurement, cargo oil, tank sweeping, ventilation, inert gas, heating, tank washing, foam fire extinguishing, water sprinkling, evaporative gas, liquid level telemetry, valve remote control, and other systems. Special ships also include special systems for transporting liquefied petroleum gas (LPG) and liquefied gas (LNG). The service life of straight seam steel pipes in marine engineering can reach at least 40 years. In addition to conventional systems, marine engineering also has special drilling and production equipment systems, crude oil, liquefied petroleum gas, and liquefied gas processing process systems. According to statistics, the annual consumption of large-diameter straight seam steel pipes for ships is 5 million tons, about 500,000 pipes, and its standards are GB, YB, and CB, of which 70% of steel pipes are connected. The steel pipes and pipe fittings used in a 300,000-ton ultra-large oil tanker alone can reach tens of kilometers. The amount of steel pipes (including) alone is about 1,000-1,500 tons, which is of course relatively limited compared to the amount of steel pipes used in the 40,000-ton hull structure. In addition, considering that the same type of ship needs to be built in multiple ships, there are many other ships. A 300,000-ton ultra-large FPSO has more than 40,000 pipes and a length of more than 100 kilometers, which is 3-4 times that of the same tonnage level. Therefore, the shipbuilding industry has become a major user of the steel pipe industry. In addition to the conventional and special systems mentioned above, many structures use straight seam steel pipes in marine engineering, such as conductor frames, underwater steel piles, watertight casings, mooring brackets, helicopter platforms, towers, etc.

This type of straight seam steel pipe has many specifications and high materials, with the same diameter, different diameters, different wall thicknesses, and a large number of Y, K, and T-shaped pipe nodes. For example, conductor frames, steel piles, wellhead watertight casings, etc. are mostly large-diameter straight seam steel pipes, which are generally rolled from steel plates. In addition to the size requirements of straight seam steel pipes, marine engineering also has high requirements for its performance. Since steel pipes are in contact with water and various media in water for a long time, the corrosion of steel pipes is very serious. Therefore, before using straight seam steel pipes, they must be treated with anti-corrosion technology. There were many tricks in the early days of the steel pipe industry, but now people are more proficient in this industry. If the wall thickness of the steel pipe is not enough, the gate means are used. The mouth of the steel pipe is hammered with a shield to make it look thicker, but it will be exposed when measured with instruments. Use straight seams as seamless steel pipes. There are relatively few straight seams, only one longitudinal weld. Use a machine to grind the entire steel pipe, commonly known as polishing, so that it looks seamless as if there is no gap.

Straight seam steel pipes need to use a product in the production process, that is, glass lubricant. Before using glass lubricant, it was produced with graphite. Because there was no such product in the market at that time, graphite could only be used as a lubricant. However, after long-term use, everyone will find some problems, that is, the heat transfer efficiency of graphite is very high, and the heat insulation effect is also very poor. This will cause the mold to heat up very quickly during work, which will easily cause the straight seam steel pipe to wear so that the product cannot be used for a long time. Therefore, manufacturers have been looking for a product that can replace graphite, that is, glass lubricant, but why use them? It is because the trolley furnace has many advantages. First of all, the heat transfer efficiency is relatively low, which can play a role in heat preservation and extend the use time of the equipment.