Tube vs Pipe» What is Tube?
» What is Pipe?
» What's the difference between Tube and Pipe?
» Types of Tube and Pipe
What is Tube?
A common debate featured in off road forums and general questions asked by builders of roll over protection structures (roll cages) are: what is the difference between tube and pipe and which one is better?
Firstly the definition of tube.
Tube:
A tube refers to cylindrical, square, rectangular or any shape of hollow material of uniform thickness measured by two dimensions, the outside diameter (OD) and wall thickness (t or w). Tubing types available are structural, mechanical and pressure.
• Tubing types available are structural, mechanical and pressure. Structural and Mechanical tube are used for roll over protection structures (roll cages) but it is the specifications; the grade of the steel and process used to form the tubing that is important.
• Tubing (such as copper tube) is used to carry fluids and gases in pneumatic, hydraulic, or process applications.
• Tubing differs from pipe in that it's outside diameter / size is controlled and used for its designation. Pipes inside diameter are controlled.
What is Pipe?
The definition of pipe is somewhat different than tube. Historically, the general term for pipe was that it was primarily used for carrying gas or liquid.
Let's have a look at the definition of pipe.
Pipe:
Pipe is specified for the containment of liquids and gasses as opposed to structural or mechanical purposes. Circular Hollow Sections, the outside diameter and wall thickness (described by the term "schedule") of which are identified by one of the pipe specification systems, such as IPS; which usually carries a liquid or gas.
• Pipe is generally more rigid than tube, and is usually produced in heavier wall thicknesses.
• The importance of tensile strength in pipe is focused on internal pressure. The burst test is used to measure resistance in hydrostatic pressure (the force caused by fluid under pressure).
• Pipe is specified by a nominal dimension which bears little or no resemblance to the actual dimensions of the pipe. 1" Schedule 40 pipe, for instance, has an actual OD of 1.32", a wall of 0.133", and an inner diameter of 1.049". Tube dimensions are actual dimensions.
What's the difference between Tube and Pipe?
The general term for pipe was that it was primarily used for carrying gas or liquid. It was not intended for structural use because the dimensions used in describing pipe was not dimensionally accurate. Measurement was referred to its inside diameter and wall thickness. The inside diameter was a true dimension, but over the years had become "nominal" (in name only) so that when pipe size was referred to, it was an approximate inside diameter measurement with the thickness described by the term "schedule".
• Pipe is generally more rigid than tube, and is usually produced in heavier wall thicknesses.
• Pipe is specified by a nominal dimension which bears little or no resemblance to the actual dimensions of the pipe. 1" Schedule 40 pipe, for instance, has an actual OD of 1.32", a wall of 0.133", and an inner diameter of 1.049". Tube dimensions are actual dimensions.
• Pipe fittings are sized to meet pipe sizes, but not tube sizes. A 1" schedule 40 nipple will fit correctly on a 1" schedule 40 pipe, but not on a 1" OD tube.
Tube refers to round, square, rectangular or any shape of hollow material of uniform thickness which is defined by the outside diameter and wall thickness dimensions. It is the grade of the metals and how tube is produced and processed that is important.
• Structural Tube is generally produced using the ERW (Electric Resistance Welded) process. Identified under the Circular Hollow Section (CHS) or Hollow Structural Sections (HSS) class. Some steel mills specifically develop structural tube for roll over protective structures.
• Mechanical Tubing is usually produced as seamless, as-welded or DOM (Drawn Over Mandrel) tube.
Types of Tube and Pipe
Structural Tube - high strength welded steel tubing
Mechanical Tube - seamless, as-welded and drawn over mandrel
Stainless Tubing and Pipe - several seamless and welding processes requiring resistance to corrosive materials
Standard Pipe - several seamless or electric weld process, carries liquid or gas
