Difference Between Pipe and Tube

Pipe Vs Tube

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We are going to compare the pipes and tubes that are used in the Oil & Gas and Shipbuilding industries:

Let us know what are pipes and tubes?

A pipe is usually a hollow cylinder of circular cross-section, used mainly to convey substances which can flow such as liquids and gases (fluids), powders, slurry, and masses of small solids.

Whereas pipe is a round cross-section, tubes can come in different shapes such as square, rectangular and cylindrical cross-section, which is also used mainly to convey substances which can flow such as liquids and gases (fluids), powders, slurry and masses of small solids.

Let us compare the engineering aspects of the circular cross-sections:

Size:  

# The pipe size is generally specified by a nominal diameter or nominal bore.

# The tube size is specified by its OD.

Wall Thickness: 

# The pipes wall thickness is defined by schedule number.

# The tubes wall thickness is measured in millimeters or inches.

Outside Diameter: 

# The OD of the pipe up to size 12” are numerically larger than corresponding pipe size

# The OD of the tube is numerically equal to the corresponding size.

Selection:

# In oil and gas or shipbuilding industries, the selection of the pipe depends upon the ID because it varies for each Schedule. 

# In oil and gas or shipbuilding industries, the selection of the tube can go with its OD due to its thinner wall thickness.  

From the below table, we are going to see some major differences between pipe and tube:

Pipe Verses Tube		Pipe	Tube
1	Key Dimensions (Pipe and Tube Size Chart)	The most important dimension for a pipe is the inside diameter (ID), expressed in NPS (nominal pipe size) or DN (nominal diameter), which defines its fluid conveyance capacity. The NPS does not match with its inside diameter, it is a rough measurement.	The most important dimensions for a tube are the outside diameter (OD) and the wall thickness (WT). These parameters are expressed in inches or millimeters and the OD of the tube is numerically equal to the corresponding size.
2	Wall Thickness	The thickness of a pipe is designated with a “Schedule” value (the most common are Sch. 40, Sch. 80 and Sch. 160). Two pipes of different NPS and same schedule have different wall thicknesses in inches or millimeters.	The wall thickness of a tube is expressed in inches or millimeters. For tubing, the wall thickness is measured also with a wire gauge nomenclature (Birmingham Wire Gauge, Stubs Iron Wire Gauge).
3	Cross Section of Pipes and Tubes	Circular in Cross-Sections.	Circular, rectangular, square and oval in Cross-Sections.
4	Production range	Extensive (up to 80 inches and above).	A narrower range for tubing (up to 5 inches), larger for steel tubes for mechanical applications.
5	Tolerances (straightness, dimensions, roundness, etc) and Pipe verses Tube strength	Tolerances are set, but rather loose. Strength is not the major concern.	Tubes are produced to very strict tolerances. Tubes undergo several dimensional quality checks, such as straightness, roundness, wall thickness, surface, during the manufacturing process. Mechanical strength is a major concern for tubes.
6	Production Process	Pipes are generally made to stock with highly automated and efficient processes, i.e. pipe mills produce continuously and feed distributors stock around the world.	The tubing requires many more production operations to make a finished product. It is normally of a lot higher quality than the pipe, resulting in increased testing and inspections. Pipe production far outweighs tubing production.
7	Delivery time	Can be deliverable in short period.	In common, delivery takes a long period from the date of order placed.
8	Market price	Relatively lower price per ton than the tubes.	Higher due to lower mills productivity per hour, and due to the stricter requirements in terms of tolerances and inspections.
9	Materials	A wide range of materials is available.	Tubing is available in carbon steel, low-alloy steel, stainless steel, and nickel-alloys and Steel tubes for mechanical applications are mostly of carbon steel.
10	End Connections	Pipes are typically connected by threading the ends and screwing together with couplings, T’s, or elbows. Another common way of connecting pipes is welding them together or to other components, such as flanges.	Tubes can be connected by flaring, brazing, tube couplings, or welding.  Pressures within the tube normally dictate the type of coupling used.