Drawn Over Mandrel Tubing (DOM) is made from fully annealed ERW pipe through a cold drawing process. The tube blank is pulled through the mold, with or without a mandrel inside the mold.
ERW pipe is a straight seam resistance welded pipe, English Electric Resistance Welding, abbreviated as ERW. It is used to transport vapor and liquid objects such as oil and natural gas. It can meet various requirements of high and low pressure and plays a decisive role in the field of transportation pipes in the world. status.
Technically, DOM is not a type of steel pipe, but the completion process of stainless steel pipes. It is considered a high quality tube. The first stage of manufacturing is the same as that used to make resistance welded pipe, but in the finishing stage the entire flash weld is removed and the pipe is cold drawn on a mandrel. The cold drawing process provides the tube with better dimensional tolerances, improved surface finish and the strongest achievable weld strength. DOM is often incorrectly referenced as "seamless steel pipe" when it actually does have a seam (albeit barely visible).
The main processes are forming, welding, sizing, cold rolling or cold drawing (with core rod or without core rod), or continuous cold drawing (i.e. electric welding-cold drawing combined production line).
Features: The production process is dispersed, the process flow and production cycle are long, the floor space is large, the product dimensional accuracy is good, the internal and external surfaces are smooth, and the mechanical properties and metallographic structure are good.
Seamless steel pipe
Seamless steel pipes are manufactured using a method called extrusion. In this process, a solid steel bar is passed through the center and a mold is used to convert the solid circle into a round tube.
Seamless pipes have the following performance characteristics:
1. The internal and external surfaces are smooth, the friction coefficient is small, and it has superior performance in transporting fluids, gases and oil and gas;
2. High tensile strength and strong pressure resistance;
3. It has high dimensional accuracy and can meet various complex processing requirements;
4. Outstanding characteristics such as corrosion resistance, high temperature resistance, and low temperature resistance.
Seamless pipes have a wide range of applications and are mainly used in fields such as transporting fluids, gases and oil and gas. In the petroleum, chemical, natural gas, pharmaceutical and other industries, seamless pipes are widely used in oil wells, chemical equipment, pressure vessels, boiler pipes and other fields. The application range of seamed pipes is also very wide, especially in some special environments, such as high temperature, high pressure and other conditions, the application range of seamed pipes is wider than that of seamless pipes. In industries such as electric power, shipbuilding, chemical industry, petroleum, and natural gas, seamed pipes are widely used in boilers, heat exchangers, chemical equipment, pressure vessels, and other fields.
There are basically two types of seamless pipes:
Cold Drawn Seamless (CDS), typically manufactured from SAE 1018, has precise tolerances and a good surface finish; Thermoformed Seamless (HFS), typically manufactured from SAE 1026, has less critical tolerances and scales, and is not as strong as CDS .
The advantages of Cold Drawn Seamless (CDS) are good surface finish, excellent workability, increased dimensional tolerance, high strength to weight ratio. Advantages of Seamless (HFS): Cost-effective material, good processability, wide range of sizes.