When buying a pipe you have probably noticed the inscription SCH, this word means “schedule” and is derived from the English “Schedule”, which represents the internal diameter, the dimensions and the tolerance in a calculation, that is, the measurement of the thickness from the walls of a pipe.
This information allows us to correctly select our pipe once we know the plant, installation, fluid, temperature, concentration requirements, to say some basic data, to make a correct calculation of the appropriate pipe.
What is the difference between SCH and NPS?
NPS (Nominal Pipe Size) is the nominal diameter of the pipe. It is related to the inside diameter of the SCH STD or pipe schedule. Although they are linked concepts, it may be that in some sizes they coincide, but it is not a constant.
How many SCH are there?
In the most commercial use we find three different types: STD (standard), XS (extra strong), XXS (double extra strong). For the thicknesses we find a wide variety of schedules, these are in accordance with the ASME 63.10 and ASME 63.19 standards, and are: SCH10, SCH20, SCH30, SCH40, SCH60, SCH80, SCH100, SCH120, SCH140, SCH160, SCH180 and so on (the larger the card, the greater the thickness). Complies for Carbon Steel and Forged Steel pipes.
Some factors to consider when calculating the identity card are:
- Internal pressure of the Pipe.
- Allowable stress of the material at the operating temperature (resistance suffered by the material to deformation or rupture).
- Allowable corrosion.
- Tolerance of manufacturing design and different regulations.
Important: SCH40 stainless steel pipes have a smaller wall thickness than SCH40 carbon steel pipes due to the different superiority of the two steel pipes.