Pipe Schedule Chart: Steel Pipe Dimensions and Wall Thickness

Use NPS or OD first when reading a pipe schedule chart. SCH 40 and SCH 80 are wall-thickness series, not universal millimetre values or pressure ratings; confirm the standard, size, wall, ID and theoretical-weight basis for the selected pipe.

For a supply enquiry, compare the relevant seamless pipe options or ERW size and specification requirements; a schedule table alone does not confirm manufacturing-route availability.

Quick lookup: SCH 40 dimensions | SCH 80 dimensions | 6-inch and 12-inch weight examples | Full schedule table

When a schedule is used to purchase a weld-neck flange, the flange bore and pipe-wall fit-up guide explains which mating dimensions still require verification.

These are nominal carbon steel pipe reference dimensions, not guaranteed inventory. For schedule notation, unit conversion and gauge, see the steel pipe wall thickness guide. On a phone, scroll each table sideways to view all columns.

Schedule 40 Pipe Dimensions, Wall Thickness and Weight

Read SCH 40 by pipe size. For example, 1-inch Schedule 40 pipe has a nominal OD of 1.315 in and wall of 0.133 in; the calculated bore is 1.049 in. NPS is a nominal designation, not the measured OD or ID.

Schedule 80 Pipe Dimensions, Wall Thickness and Weight

For the same NPS, SCH 80 uses the same outside diameter with a thicker wall and smaller bore. SCH 80 is not universally the same as XS or SCH 80S; check those designations separately, particularly at NPS 10 and 12.

*Calculation basis: ID = OD - 2 × nominal wall. Metric dimensions shown here are rounded conversions of the listed inch values. Theoretical plain-end carbon steel mass uses density 7,850 kg/m³ and unrounded dimensions: kg/m = π × 7,850 × t × (D - t) / 1,000,000, with D and t in mm; lb/ft = kg/m × 0.3048 / 0.45359237. Coating, threads, couplings, tolerances and packaging are excluded. Minor differences from published weight charts can result from density and rounding conventions. Use the contract's dimensional units and controlled standard for acceptance.

Dimension cross-check: American Piping Products printable pipe chart. The applicable dimensional standard remains ASME B36.10; confirm the ordered edition. SCH 40S/80S stainless-series values require separate verification.

6-Inch and 12-Inch SCH 40 Pipe Weight: Worked Examples

6-inch SCH 40: OD 6.625 in, nominal wall 0.280 in, calculated ID 6.065 in. Theoretical plain-end weight is approximately 18.99 lb/ft (28.27 kg/m); a 20-ft length is approximately 379.9 lb before coatings, fittings and packing.

12-inch SCH 40: OD 12.750 in, nominal wall 0.406 in, calculated ID 11.938 in. Theoretical plain-end weight is approximately 53.58 lb/ft (79.74 kg/m); a 20-ft length is approximately 1071.6 lb before coatings, fittings and packing.

Pressure rating: no single pressure rating applies to every SCH 40 or SCH 80 pipe. The design code, grade, temperature, joint factors, permitted wall tolerance and corrosion allowance must be evaluated for the actual size and service.

For supply, compare ASTM A106 seamless pipe and ERW steel pipe against the approved product standard and manufacturing route. State the grade, NPS, schedule, length, ends and inspection requirements in the enquiry.

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.

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.

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.

Frequently Asked Questions

If SCH 40 is replaced by SCH 80 at the same nominal size, is flow capacity unchanged?

No. At the same OD, greater wall thickness reduces the internal flow area. At a fixed volumetric flow, velocity increases. Recalculate the system pressure loss using the actual bore, fluid and fittings; the schedule change alone does not tell you the new operating flow.

Will replacing the line with a larger steel pipe always fix low pressure at the outlet?

No. A larger bore can reduce pipe friction at a given flow, but it does not establish the cause of low outlet pressure. Check the pump duty, flow, elevation, pipe length and losses through valves and fittings before replacing pipe. Compare the complete system at the required operating point.

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.