SCH 40 and SCH 40S are commonly used pipe schedules in construction, petrochemical, pharmaceutical, and general industrial applications. While they appear similar, they differ in material suitability, standards, and performance.
1. Material Applicability
SCH 40
SCH 40 represents a standard wall thickness primarily used for carbon steel pipes.
It is designed based on the mechanical properties of carbon steel and is widely applied in general industrial piping systems.
SCH 40S
SCH 40S is a pipe schedule specifically used for stainless steel pipes, most commonly 304 and 316 grades.
At the same schedule number, SCH 40S has a thinner wall than SCH 40 due to stainless steel’s higher allowable stress and better corrosion resistance.
The “S” stands for special, indicating suitability for harsh or corrosive environments.
2. Material Range
SCH 40 can be used for carbon steel, stainless steel, or alloy steel, depending on design needs.
SCH 40S applies only to stainless steel pipes.
Material choice will depend on required corrosion resistance, operating temperature, pressure, and service conditions.
3. Standard and Design Basis
SCH 40 generally follows ANSI/ASME B36.10, the standard for carbon steel pipes.
SCH 40S follows ASME B36.19, the standard dedicated to stainless steel pipes, with wall thickness based on the higher allowable stress of stainless steel materials.
4. Application Scenarios
SCH 40S stainless steel pipes are preferred in corrosive environments—such as systems containing chloride ions, chemical processing, and high-purity applications.
SCH 40 carbon steel pipes are more economical for low-pressure, non-corrosive, or budget-sensitive projects.
At the same schedule number:
SCH 40 → thicker wall → higher pressure/temperature tolerance
SCH 40S → thinner wall, but superior corrosion resistance
Both may be used in demanding industries such as chemical plants and energy systems, depending on the environment.
How to Choose Between SCH 40 and SCH 40S
Choose SCH 40S if the system requires corrosion resistance, hygiene, or durability (e.g., food processing, chemical manufacturing, marine environments).
Choose SCH 40 for general plumbing, structural use, low-pressure systems, or where cost efficiency is important.
Budget should also be considered—stainless steel (SCH 40S) is more expensive but provides longer service life in corrosive conditions.
For accurate selection, consult industry professionals or suppliers to match the pipe specification to the actual working environment.
