Tubes are hollow products with a circular cross-section used to transport media. The term PIPE is distinguished from the term TUBE because it is primarily used in pipelines and piping systems. The main standards for tubes are: ASME B36.10 welded and seamless wrought and rolled steel tubes and ASME B36.19 stainless steel tubes.
The difference between PIPE and TUBE
In piping systems, the term PIPE is mainly used. PIPE usually uses NPS to indicate size. Wall thickness is distinguished using SCH. TUBE is usually described using OD and wall thickness WT (using Birmingham wire gauge or 1/1000 inch). Example.
Pipe NPS 1/2 Sch40 means: Pipe OD is 21.3mm, wall thickness is 2.77mm.
Tube 1/2 × 1.5 means: the outside diameter of the tube is 12.7mm, the wall thickness is 1.56mm.
The term Tube is mainly used for heat exchangers, instrumentation tubes and micro interconnect systems such as compressors, boilers, etc.
Tube materials
Piping engineering companies have in-house material engineers. The material engineer determines the material to be used for the piping system. The most commonly used materials are carbon steel materials (depending on the service conditions), which are usually manufactured according to different ASTM standards.
Carbon steel materials have the proper strength, plasticity, weldability, machinability, durability, and lower cost than other materials. Carbon steel materials are preferred if they meet pressure, temperature, corrosion resistance, and sanitary requirements.
Other alloy materials added with copper, lead, nickel, aluminum and other components and a variety of stainless steel materials. These materials are more expensive and they are chosen mainly for their exceptional corrosion resistance, excellent heat transfer or tensile strength at high temperatures. Copper and copper alloy tubes are traditionally used as instrument tubes, tubes for food processing and heat transfer tubes. Today, stainless steel tubes are increasingly used in these fields.
Lined Tubes
Some pipes are used in combination with a lining material.
For example, carbon steel pipe may need to be lined with a material such as polyethylene to resist chemical corrosion. Other lining materials include: glass, various plastics, cement, etc. and exterior coating materials such as: epoxy materials, asphalt, zinc, and other materials that can protect the lined pipe.
Many factors can influence the choice of material. Some of the most important factors include: pressure, temperature, type of finished product, pipe system size, budget cost, etc.