Understand the 12 significant differences between steel tube and steel pipe in detail from the industry experts. Resolve the tube vs. pipe confusion.
Ever wondered what to call a cylindrical section? A pipe or is it a tube?
Confusing, isn’t it?
Both the tools appear to be working on the same hollow cylindrical concept. Regardless of how similar they appear, tube and pipe have dramatically different characteristics.
What exactly is the actual difference between pipe and tube?
Let’s hunt pipe vs tube down!
The difference is in the details!
1. Diameter
While determining the actual size, tubes and pipes are measured differently.
A tube is measured with the help of exact outside diameter (OD) with a set range of wall thickness. The wall thickness is vital as the tube’s strength is dependent on it.
On the other hand, we measure a pipe by using a nominal outside diameter. The most important property is the capacity or the inside dimension (ID). [1]
Pipes accommodate larger applications with sizes that range from a half-inch to several feet. Tubes are generally used in applications that require smaller diameters. While a 10-inch pipe is common, it is rare that you will find a 10-inch tube.
2. Wall Thickness
The wall thickness is an important factor while differentiating between pipes and tubes. [2]
The thickness of a tubing is often specified by a gauge for thinner thickness and for thicker tubing it is indicated by fractions of an inch or millimeter. The normal range of tubing is 20 gauge, which is 0.035 inch up to a thickness of 2 inches.
The wall thickness of a pipe is referred to as a pipe schedule thickness. The most common pipe schedules are:
• SCH20,
• SCH40,
• and SCH80.
SCH40 is the most common and SCH80 is quite heavy.
3. Structure
A tube’s structure does not have to be round always. It can be square or rectangular too. They are usually seam welded. [3]
Pipe, on the other hand, is always round and rigid. It cannot be shaped easily without the use of a special equipment. Pipes are usually seamless and pressure rated to avoid leakages as they usually carry liquids or gases.
4. Tolerance
Comparing the tolerance of both tubes and pipes, the tolerance for pipes is looser than tubes. Pipes are usually used for transporting or distributing, therefore the properties of pressure, straightness, or roundness are strictly specified. [4]
5. Manufacturing Process
The materials and the manufacturing techniques of both pipes and tubes differ.
Tubes require a higher level of processes, tests, inspection. As a result, the delivery period is longer too. The yield of tubes is comparatively much lower than the pipes.
Instead, the manufacturing process of a pipe is easier in comparison to tubes and more often undergoes mass production. [4]
6. Cost
The manufacturing of tubes utilizes much more labor, energy, and material. Therefore, in case of same material, the production cost of tubes is usually higher than pipes.
The manufacturing process of pipes is easier and they are always manufactured in large lots. This lead to a cutting in the cost of pipes. [3]
7. Uses
Pipes are used mainly for transportation of fluids and gases like water, oil, gas, propane etc. Therefore, the outside and inside diameter is the key measurement and pressure rating is important.
At the opposite, the main use for tubes is for structural purposes such as scaffolding. They are often put to use in applications that call for precise outside diameters. Therefore, the outside diameter is vital as it indicates how much the tube can hold.
8. Material
Pipes are usually made of carbon steel or low alloy steel.
Tubes instead are made of mild steel, aluminum, brass, copper, chrome, stainless steel, etc.
The difference in materials is also a reason for the difference in the cost and applications. [4]
Some widely used steel pipe standards or piping classes are:
• The API range – now ISO 3183. E.g.: API 5L Grade B – now ISO L245 where the number indicates yield strength in MPa
• ASME SA106 Grade B (Seamless carbon steel pipe for high temperature service)
• ASTM A312 (Seamless and welded austenitic stainless steel pipe)
• ASTM A36 (Carbon steel pipe for structural or low pressure use)
• ASTM A795 (Steel pipe specifically for fire sprinkler systems)
9. Mechanical and Chemical Properties
The pressure rating, yield strength, ductility properties are more important for pipes. However, for tubes, the hardness, tensile strength, and high precision is the key to high quality.
Carbon, Manganese, Sulphur, Phosphorus, and Silicon are the main chemical elements for pipes. While for tubing, the microelements are very important to the quality and process.
10. Surface Finishing
Pipes need to be painted or coated to anti corrosion or oxidation for outdoor field transporting or underground transporting.
Tubes often go through sour cleaning or special polish treatment for their particular field uses.
11. Connection
Connecting one pipe to another is much more of a labor intensive process as it requires welding, threading, or flanges along with its relevant equipment.
On the contrary, tubes can be joined quickly and effortlessly with flaring, brazing, or coupling. Tube assemblies can also take place through tube fittings where high standards of construction are needed. [3]
Pipe welding is safer that tube joining.
12. The Ends
Pipe ends are usually in a plain or beveled form. Whereas, tubes generally come with coupling ends or special end finishes like irregular ends, special screw thread etc.
