The 5 Types of Carbon Steel Round Tube

Round Tube

There are 5 different types of carbon steel round tubes that have a variety of different applications which include architectural, furniture and machine parts. Carbon Steel Round Tubes are hollow metal cylinders that are measured by its outside diameter and the wall thickness and can be manufactured in the following ways:

  • Electric Resistance Welding (ERW)
  • Cold Drawn Seamless (CDS)
  • Drawn-Over-Mandrel (DOM)
  • Hydraulic
  • Hot Finished

Electric Resistance Welding (ERW)

Electric Resistance Welding requires cold forming metal coil to form it into round, cylindrical shapes. There are various ways to make the weld, however all welds are made through heating the joint via electrical resistance.

ERW tube is commonly welded using an automated process which results in a low manufacturing cost, and resistance welding typically allows for a high weld quality creating strong joins.

The uses for ERW pipe are wide ranging and include the manufacturing of axels and chassis in the automotive industry, general supports and stands, and internal machine components.

Cold Drawn Seamless (CDS)

Cold Drawn Seamless round tube is manufactured by piercing hot metal billets to create a tube that is then further rolled to elongate and reduce the diameter. The tubes are then cooled and refined to the required dimensions.

CDS tubing can have tight tolerances so the dimensions are accurate, they can have a thicker wall dimension allowing for a stronger tube and have an excellent aesthetic for the finished product.

CDS tubing can be used where the final product’s aesthetic is important such as roll cages and shafts in the automotive industry. Further uses include high speed/high pressure pumping applications, hydraulic cylinders, and infrastructure columns.

Drawn-Over-Mandrel (DOM)

Drawn-Over-Mandrel tubes are manufactured by cutting metal coil to the required width and cold rolling into a tube shape. The edges are welded together using electric resistance while under pressure to secure the final shape. The tubing can then be cut to the desired length before being drawn over mandrels to reduce the tube diameter and thins the walls to the required specifications.

Drawing the tube over a mandrel improves the strength, hardness and machinability of the tube and allows for very high tolerances and excellent consistency in the final product.

DOM tubing is typically used in hydraulic components including pumps and cylinders and are used extensively in the automotive industry for parts such as dampeners, shock absorbers, seat frames and gas springs.


Hydraulic round tube is produced to meet the requirements of hydraulic lines and where bending or flaring is required. Hydraulic tube can be manufactured by welding flat rolled metal or by rolling and piecing bar stock, which creates a seamless tube. Both methods require carefully controlled finishing stages, either through normalizing in a controlled atmosphere or through annealing, to meet the hydraulic standards.

Hydraulic tube has a very bright and clean finish which is aesthetically pleasing, the material is chemically controlled to ensure consistency and has a high degree of workability.

Hydraulic tubes are used in any application where fluid is pumped or where bending and flaring is important.

Hot Finished

Hot Finished tubing is manufactured by piercing a solid piece of hot metal as it rotates creating a seamless tube. The tube is then passed through various mills to reduce the diameter and wall thickness.

Hot Finished tubes are versatile and easily machined while being a cost-effective option for metal tubing. Due to the nature of the hot piercing, tolerances are not as tight, and the finish is not as aesthetically pleasing as the other tubing types. Hot Finished tubes are typically only used where tolerances and finish are not the primary focus or where further machining is planned. Applications include construction equipment such as supports and drilling equipment, machined parts, rolls and pillars.

Looking for Round Tube for your next project? Metal Supermarkets offers a variety of metal types, and sizes, cut to the size you need. Shop Now.

Metal Supermarkets

Metal Supermarkets is the world’s largest small-quantity metal supplier with over 125 brick-and-mortar stores across the US, Canada, and United Kingdom. We are metal experts and have been providing quality customer service and products since 1985.

At Metal Supermarkets, we supply a wide range of metals for a variety of applications. Our stock includes: mild steel, stainless steel, aluminum, tool steel, alloy steel, brass, bronze and copper.

We stock a wide range of shapes including: bars, tubes, sheets, plates and more. And we can cut metal to your exact specifications.

Visit one of our 125+ locations across North America today.

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