Schedule Pipe: A Detailed Overview

Schedule Pipe refers to a standardized system used to denote the wall thickness of pipes. The schedule number is used to classify pipes based on their wall thickness, and this measurement varies according to the pipe’s nominal diameter. The concept of schedule pipe originates from the ASME (American Society of Mechanical Engineers) standards, but it is widely used globally, including in Europe and industries that follow EN standards.

The schedule number (SCH) is essential because it helps engineers and manufacturers determine the pressure-carrying capacity and structural integrity of a pipe under various conditions. As the schedule number increases, the wall thickness increases, which directly impacts the pipe’s ability to withstand internal pressure.

Key Aspects of Pipe Schedule

1. Nominal Pipe Size (NPS): Refers to the nominal diameter of the pipe, usually in inches, such as 1 inch, 2 inches, etc. It represents the approximate internal diameter.
2. Schedule Number: It is the identifier for pipe thickness, and common schedule numbers include SCH 5, SCH 10, SCH 40, SCH 80, and SCH 160. A higher schedule number indicates a thicker pipe wall for a given NPS.
3. Wall Thickness: The wall thickness increases as the schedule number increases. For example, a pipe with SCH 40 will have a thinner wall than a pipe with SCH 80, but both can have the same nominal size.
4. Pipe Material: Schedule pipes are available in different materials such as carbon steel, stainless steel, and various alloys. The material selection plays a key role in determining the pipe’s application and pressure rating.
5. Pressure Rating: Higher schedule pipes can handle more internal pressure due to their thicker walls. Hence, a SCH 80 pipe can handle more pressure than a SCH 40 pipe of the same nominal size.

Applications of Schedule Pipes

Schedule pipes are used in various industries based on the application’s pressure and temperature requirements. Some common applications include:

• Oil and Gas Pipelines: For high-pressure fluid transmission, schedule pipes are used to ensure the integrity and safety of oil, gas, and other industrial fluids.
• Water Supply Systems: Schedule pipes in SCH 40 and SCH 80 are often used in residential, commercial, and industrial water systems due to their durability and ability to handle different pressure levels.
• Power Plants: Pipes in power generation plants, especially for steam and hot water, require high pressure and temperature resistance. Schedule pipes of higher thickness (e.g., SCH 80, SCH 160) are typically used in these environments.
• Petrochemical Industry: High-pressure applications in refineries and petrochemical plants demand strong and reliable piping systems. Schedule pipes provide the necessary thickness and strength.
• Mechanical Systems: In HVAC (Heating, Ventilation, and Air Conditioning) and cooling systems, schedule pipes are used to manage fluid and gas distribution.

Table of Common Pipe Schedules

Here’s a summary of the most common schedules and the corresponding pipe thickness for a given nominal size:

Common Grades of Pipe Material

Depending on the application, pipes are manufactured from different materials to meet specific requirements such as corrosion resistance, pressure tolerance, or temperature resilience. Here are some common grades:

Common Pipe Schedule Abbreviations

• SCH 40: Also known as standard weight or STD, SCH 40 pipes are the most commonly used pipes in construction and general applications.
• SCH 80: Known as extra strong (XS), these pipes are used in high-pressure environments due to their thicker walls.
• SCH 160: Known as double extra strong (XXS), these pipes are used for the most demanding environments requiring extreme pressure and temperature resistance.