Table of Pipe Schedules

Pipe schedule changes wall thickness, inside diameter, and how your weld joint behaves.

The Problem

If you do not know the pipe schedule, it is easy to misjudge fit-up, bevel prep, and heat input.

That can lead to poor penetration, bad fit, or wasted time in prep.

The Straight Answer

Higher schedule numbers mean thicker walls and smaller inside diameters.

You need the correct schedule before you cut, prep, or weld.

What Is a Pipe Schedule?

Pipe schedule is the wall thickness of the pipe.

As the schedule goes up, the wall gets thicker and the inside diameter gets smaller.

• Schedule 40 is thicker than Schedule 10
• Schedule 80 is thicker than Schedule 40
• 5s and 10s are common in stainless tube and pipe work

Why It Matters

Wall thickness affects more than just pipe strength.

• Heat input during welding
• Bevel preparation
• Fit-up and penetration
• Pressure capability
• Inside diameter for purge tools and fit checks

Knowing the correct schedule helps you prep the joint correctly and choose the right setup before welding.

Common Pipe Schedules

This reference covers common schedule sizes including 5s, 10s, 40s, and 80s.

These are some of the most common schedules used in fabrication, maintenance, and process piping work.

Shop Tip

Do not assume two pipes with the same nominal size have the same wall thickness.

Always verify the schedule before fit-up, especially when working with purge equipment, bevel prep, or replacement sections.

Bottom Line

Pipe schedule tells you how thick the wall is and how much inside diameter you really have.

That affects how the joint fits, how it welds, and how much prep it needs.

Know the schedule first, and the rest of the job gets easier.