What is the pipe schedule?
The Pipe Schedule (SCH) refers to the thickness of the walls of a steel pipe. Pipe schedules are denoted by a number, which is based on the thickness of the pipe's walls. The schedule number does not correspond directly to the pipe's actual wall thickness but rather to a set of standardized thicknesses. These standardized thicknesses were established by the American National Standards Institute (ANSI) and are based on a formula that takes into account the pipe's nominal size and its pressure rating.
"Schedule 40" and "Schedule 80" refer to reference charts published by the American National Standards Institute (ANSI).
When speaking about carbon steel tube, the different schedules refer to the size, thickness and maximum pressure of the pipe.
What is Schedule 40?
Schedule 40 (SCH 40) Pipe is a type of pipeline specification, which represents the wall thickness and pressure-bearing capacity of the pipeline. SCH is the abbreviation of Schedule, which represents the pressure-bearing capacity level of the pipeline. 40 represents the wall thickness of the pipe in 1/1000 of an inch.
The wall thickness of SCH 40 pipe is: 40×1/1000=0.040 inches=1.016 mm.
According to the American pipeline standard ANSI/ASME B36.10M, the specific specifications of SCH 40 steel pipe are:
Outside diameter: 1/8 inch ~ 30 inches, wide range, covering various pipeline applications.
Wall thickness: 0.040 inches, approximately 1.016 mm.
Nominal diameter ratio: 0.85 (D/t).
The minimum yield strength specified by the standard: 35000PSI or 240Mpa.
Standard working pressure: up to 700PSI, about 48.3Bar.
Therefore, the pipe specification SCH 40 represents:
1. The wall thickness of the pipe is 0.040 inches, which is relatively medium and has a certain strength without being too heavy.
2. The pipeline has a high pressure bearing capacity, with a maximum working pressure of up to 700 PSI, which can meet the pressure requirements of general industrial pipeline systems.
3. The strength of the pipeline also reaches a certain standard, with a minimum yield strength of 35,000 PSI, which can ensure the firmness of the pipeline.
4. The outer diameter range is wide, from 1/8 inch to 30 inches, which can meet the needs of different pipe diameters.
In short, SCH 40 is a more commonly used and universal pipe specification. The pipes it represents have medium wall thickness, high pressure bearing capacity and strength, and a wide range of outer diameter options, which can meet the requirements of most industrial piping systems. This is also The reason for its wide application.
What is Schedule 80?
Schedule 80 (SCH 80) Pipe is also a type of pipe specification, which represents a thicker wall thickness and higher pressure-bearing capacity of the pipe. SCH is the abbreviation of Schedule, which represents the pressure-bearing capacity level of the pipeline. 80 represents the wall thickness of the pipe in 1/1000 of an inch.
The wall thickness of SCH 80 pipe is 80×1/1000=0.080 inches=2.032 mm, which is twice as thick as that of SCH 40.
According to the American pipeline standard ANSI/ASME B36.10M, the specific specifications of SCH 80 steel pipe are:
Outer diameter: 1/8 inch ~ 30 inches, the range is the same as SCH40, but also wider.
Wall thickness: 0.080 inches, about 2.032 mm, 2 times that of SCH40.
Nominal diameter ratio: 0.43 (D/t).
The minimum yield strength specified by the standard: 35000PSI or 240Mpa, the same as SCH 40.
Standard working pressure: up to 3000PSI, about 207Bar, much higher than SCH 40.
Therefore, the pipe specification SCH 80 represents:
1. The wall thickness of the pipe is 0.080 inches, which is relatively thick and has high strength, but it will increase the weight of the pipe.
2. The pipeline has a very high pressure-bearing capacity, with a maximum working pressure of up to 3000 PSI, far exceeding SCH 40, and can meet the requirements of most high-pressure pipeline systems.
3. The strength of this pipe reaches the same standard as SCH 40, and it also has a high safety factor.
In addition, the outer diameter range is the same as SCH 40, which is also wider, covering different pipe diameter needs. In short, SCH 80 represents a pipe specification with a thicker wall and a much higher pressure bearing capacity than SCH 40. When the pressure of the pipeline system is high and pipes with thicker wall thickness and higher strength are required, the SCH 80 pipe specification will be selected. However, if the pipe wall is too thick, it will also bring the disadvantage of excessive weight of the pipe.
When it comes to cost, Schedule 40 plumbing parts are typically more affordable than those made with Schedule 80. The reason behind the price difference is that SCH 80 has a thicker sidewall than SCH 40, which requires more material to manufacture. Additionally, SCH 80 pipes often come with colorant added, which also increases production costs.
The major difference between schedule 40 and schedule 80 pipe is the wall thickness, inside diameter, and their weight. Schedule 80 will have a greater wall thickness, a smaller inside diameter and a higher weight than Schedule 40 pipe at a given nominal pipe size. Of course, all of these numbers will vary based on the nominal pipe size. There are also many other pipe schedule numbers as well. For these reasons, it is important to also reference a pipe schedule table to ensure that the proper pipe size is being selected.
Smaller schedule pipe tends to be less expensive than larger schedule pipe. Depending on the volume and pressure of material that needs to be moved with the pipe, the different schedules offer a choice in the cost of materials used. If a low-pressure drainage line is being installed, a Schedule 40 seamless pipe would be adequate and more cost effective than a Schedule 120 seamless tube.
