Pipe Schedule Chart: Steel Pipe Dimensions and Wall Thickness

Use this steel pipe schedule chart to look up outside diameter and nominal wall thickness for a specified NPS. SCH 40 and SCH 80 do not have one fixed thickness: select the pipe size first. For the same NPS, SCH 80 has a thicker wall than SCH 40, but schedule alone does not define allowable working pressure.

Start with the common SCH 40 / SCH 80 sizes below, or scroll to the full schedule table. For definitions, inch-to-mm wall values and gauge notation, see the steel pipe wall thickness guide.

SCH 40 and SCH 80 Pipe Dimensions: Common Sizes

Nominal carbon steel pipe dimensions; not guaranteed inventory. SCH 80 must not be confused with XS or SCH 80S at NPS 10 and NPS 12. Confirm the governing ASME B36 dimensional standard and material specification.

For product selection, compare ASTM A106 seamless pipe and ERW steel pipe against the project-approved manufacturing route, grade and inspection scope.

Full Pipe Schedule Reference Table

Blank cells mean that no value is listed here. Do not interpolate a wall thickness or treat STD, XS and S-suffix schedules as universally interchangeable. Confirm non-listed and large-diameter dimensions against the governing standard and order.

What Is Pipe Schedule?

Pipe schedule, often shown as SCH, is a standardized way to indicate pipe wall thickness. For the same NPS, a higher Schedule generally indicates a thicker nominal wall. Schedule alone does not establish allowable working pressure; material, temperature, tolerances and the governing design code must also be checked. For example, SCH 80 pipe has a thicker wall than SCH 40 pipe for the same nominal pipe size.

Pipe schedule is widely used when selectingseamless steel pipefor pressure piping, boiler systems, oil and gas pipelines and industrial applications.

Pipe Schedule Chart

The pipe schedule chart usually includes nominal pipe size, outside diameter, wall thickness and different schedule values such as SCH 10, SCH 40, SCH 80, SCH 160, STD, XS and XXS. These values help users choose the correct pipe size for design, purchase and installation.

For water, gas and structural applications,ERW steel pipeis often selected according to the required outside diameter, wall thickness and pipe schedule.

Common Pipe Schedules

SCH 40 Pipe:
SCH 40 is one of the most commonly used pipe schedules. It is widely used for general fluid transmission, water pipelines, structural applications and low to medium pressure systems.

SCH 80 Pipe:
SCH 80 pipe has a thicker wall than SCH 40 pipe and is often used where higher pressure resistance is required.

SCH 160 Pipe:
SCH 160 pipe is used for high pressure service and demanding industrial applications.

STD, XS and XXS:
STD, XS and XXS are traditional wall thickness designations. They are still commonly used in steel pipe specifications and project documents.

How to Choose the Right Pipe Schedule

The right pipe schedule depends on pressure, temperature, fluid medium, pipe material, project standard and application environment. Engineers usually select the pipe schedule according to design codes, working pressure and safety requirements.

In oil and gas transmission projects, API 5L line pipe specifications usually define the required pipe size, grade and wall thickness for pipeline service.

Confirm nominal pipe size, outside diameter and nominal wall thickness from the same Schedule row. Inside diameter and weight are not tabulated here. For a purchase specification, verify NPS/DN/OD conversion, the actual wall-thickness requirement and single-length or total order mass separately.

Related Reading

• Steel Pipe Wall Thickness Chart: SCH, mm, Inch and Gauge Explained

Convert between Schedule, millimeter, inch and legacy gauge notation, and confirm the exact wall thickness before ordering.

• Steel Pipe Size Chart: NPS, DN, OD and OD-to-Inch Conversion Table

Compare nominal pipe size, DN and actual outside diameter before selecting a Schedule.

• Steel Pipe Weight Chart and Formula

Calculate theoretical pipe weight from outside diameter and wall thickness for quotation and shipping estimates.

• Steel Pipe Tolerance Guide: OD, WT, Ovality and Dimensional Inspection

Check how permitted OD and wall-thickness variation can affect acceptance, fit-up and inspection.

• Steel Pipe Length Guide for Global Buyers

Confirm random, fixed and mill lengths together with dimensional and shipment requirements.

References and Sources

The Schedule and dimensional relationships used in this chart are based on recognized pipe standards. The licensed standard edition and the governing project design code should take precedence over a general online chart.

• ASME B36.10M - Welded and Seamless Wrought Steel Pipe

Primary dimensional reference for NPS, outside diameter and wall-thickness Schedule series for welded and seamless wrought steel pipe.

• ASME B36.19M - Stainless Steel Pipe

Dimensional reference for wrought stainless steel pipe, including Schedule designations that use the “S” suffix.

• ASME B31.3 - Process Piping

Design-code context for selecting and applying piping materials, components and wall thickness in process piping systems.

• API Specification 5L - Line Pipe

Line-pipe specification context for dimensions, manufacturing, inspection, testing, marking and ordering requirements.

How to Read a Schedule Row Without Mis-Specifying Pipe

NPS identifies a nominal size, and Schedule identifies a wall series; neither one alone states every purchase dimension. Read across the same row, keep units consistent, and verify that the required combination exists under the product standard and manufacturing route.

Field	Use	Do not assume
NPS/DN	Nominal size reference	It equals measured OD in inches or millimetres
OD	Fixed outside-diameter basis for the NPS	Every product family uses the same tolerance
Schedule/wall	Select the listed nominal wall for that size	One Schedule has one wall across all NPS
ID/weight	Derived lookup values for clearance and estimation	They replace tolerance and actual-weight checks

Forever Steel checks a requested size row against the applicable carbon seamless pipe or welded-pipe standard before quotation. The order should state both NPS and Schedule where used, plus the actual OD/wall requirement, tolerance source and length.