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Pipe Schedule Reference - NPS 1/2" to 12" Wall Thickness, ID & Weight per ASME B36.10

Look up pipe dimensions for Schedule 5, 10, 40, 80, 160, and XXH carbon and stainless steel pipe

Quick-reference pipe schedule table showing nominal pipe size (NPS), outside diameter, wall thickness, inside diameter, cross-sectional flow area, and weight per foot for carbon steel and stainless steel pipe from 1/2 inch through 12 inch. Covers Schedule 5, 10, 40 (standard), 80 (extra heavy), 160, and XXH (double extra heavy) per ASME B36.10M (carbon/alloy) and ASME B36.19M (stainless). Includes pressure rating lookup for ASTM A106 Grade B and A312 TP304/316 at ambient and elevated temperatures.

Pro Tip: Schedule 40 and Schedule 80 are not the same as "Standard" and "Extra Heavy" for all pipe sizes, even though they are often used interchangeably. They match for NPS 1/2" through 8", but diverge for larger sizes. If a spec calls for "Standard Weight" pipe, verify whether they mean Sch 40 wall thickness or the actual STD designation from ASME B36.10. On critical pressure piping, this distinction matters for code compliance and safety.

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Pipe Schedule Quick Reference
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How It Works

  1. Select Nominal Pipe Size

    Choose the NPS from 1/2" through 12". Note that NPS is not the actual OD or ID. For sizes 14" and above, the NPS equals the OD. For sizes 12" and below, the OD is fixed per ASME B36.10 and does not match the NPS designation.

  2. Choose Pipe Schedule

    Select the schedule: 5S, 10, 10S, 40 (STD), 80 (XH), 160, or XXH. Higher schedules have thicker walls, smaller inside diameter, and higher pressure ratings. The S suffix indicates stainless steel schedules per ASME B36.19M.

  3. Review Dimensional Data

    See OD, wall thickness, ID, inside cross-sectional area (sq in), outside surface area (sq ft/ft), and weight per linear foot. All dimensions are in inches. Use the ID and area values for flow calculations and pressure drop analysis.

  4. Check Pressure Ratings

    Look up maximum allowable working pressure for the selected size and schedule based on ASME B31.1 or B31.3 using the pipe material's allowable stress at your operating temperature. Common materials include A106 Gr. B (carbon steel), A312 TP304, and A312 TP316 (stainless).

Built For

  • Pipefitters and plumbers looking up pipe dimensions for field fabrication and takeoffs
  • Mechanical engineers selecting pipe schedule for pressure and temperature requirements
  • Estimators calculating pipe weight for structural support design and material procurement
  • Maintenance techs verifying pipe wall thickness during ultrasonic thickness inspections
  • Drafters and designers dimensioning piping layouts in CAD and isometric drawings
  • Inspectors verifying pipe schedule markings against specification requirements

Features & Capabilities

Complete NPS 1/2" - 12" Data

Full dimensional data for the most commonly used pipe sizes in industrial, commercial, and residential applications. Covers every standard schedule from thin-wall Sch 5 through double extra heavy (XXH). Data per ASME B36.10M for carbon/alloy and B36.19M for stainless steel pipe.

Inside Diameter & Flow Area

Shows calculated inside diameter and cross-sectional flow area for each size and schedule combination. Essential for pressure drop calculations, velocity checks, and flow capacity analysis. Flow area values match the Darcy-Weisbach pipe friction calculator inputs.

Weight per Foot

Pipe weight in pounds per linear foot for material procurement, hanger and support design, and structural load calculations. Carbon steel density (0.2833 lb/in3) used for weight calculations. Stainless steel weight is approximately 2% higher due to slightly higher density.

Pressure Rating Reference

Maximum allowable working pressure for common pipe materials at ambient and elevated temperatures. Calculated per ASME B31.1 (power piping) and B31.3 (process piping) using material allowable stresses from ASME Section II Part D. Includes temperature derating factors for high-temperature service.

Schedule Comparison View

Side-by-side comparison of all available schedules for a single pipe size. See how wall thickness, ID, weight, and pressure rating change across schedules. Helpful for optimizing between cost (lighter schedule) and pressure capacity (heavier schedule).

Comparison

NPS OD (in) Sch 40 Wall Sch 40 ID Sch 80 Wall Sch 80 ID
1/2" 0.840 0.109" 0.622" 0.147" 0.546"
1" 1.315 0.133" 1.049" 0.179" 0.957"
2" 2.375 0.154" 2.067" 0.218" 1.939"
4" 4.500 0.237" 4.026" 0.337" 3.826"
6" 6.625 0.280" 6.065" 0.432" 5.761"
8" 8.625 0.322" 7.981" 0.500" 7.625"
12" 12.750 0.375" 12.000" 0.500" 11.750"

Frequently Asked Questions

Pipe schedule is a dimensionless number that relates to the wall thickness of a pipe at a given nominal size. It was originally defined as approximately 1000 x (P/S), where P is internal pressure and S is allowable stress. Higher schedule numbers mean thicker walls, smaller inside diameter, and higher pressure rating. Schedule 40 is the most common for general service. Schedule 80 is used for higher pressure or where threading reduces wall thickness.
Nominal Pipe Size (NPS) is a label, not a measurement. For NPS 1/2" through 12", the outside diameter is a fixed value that does not match the NPS number. For example, NPS 2" pipe has an OD of 2.375 inches. The inside diameter varies by schedule. For NPS 14" and above, the NPS equals the actual outside diameter. This naming convention dates back to the early days of pipe manufacturing when the NPS referred to the approximate bore size.
Use Schedule 80 when Schedule 40 does not provide adequate pressure rating for your design conditions, when pipe will be threaded (threading removes wall material, reducing pressure capacity by about 50%), when corrosion or erosion will reduce wall thickness over time, or when higher mechanical strength is needed for structural applications. Schedule 80 costs 30-60% more than Schedule 40 per foot due to the additional material and higher weight.
Yes, for most pipe sizes 1/2" through 12", Schedule 40 specifies the same wall thickness regardless of material. However, stainless steel pipe also comes in schedules designated with an S suffix (5S, 10S, 40S, 80S) per ASME B36.19M, where 40S and 40 have the same wall thickness for sizes up to 10". For sizes above 10", the 40S and 40 schedules may differ. Always verify the applicable standard for your material specification.
Pressure rating is calculated using the Barlow formula: P = 2 x S x t / (OD x F), where S is material allowable stress (from ASME Section II Part D), t is wall thickness, OD is outside diameter, and F is a design factor (typically 0.6 to 0.72 depending on the piping code). For example, 2" Sch 40 A106 Gr. B pipe at ambient temperature has an allowable stress of 20,000 psi, giving a pressure rating of about 2,600 psig per ASME B31.3.
For carbon steel: ASTM A106 Grade B is the standard for seamless high-temperature service, A53 Grade B for general service (welded or seamless), and A333 Grade 6 for low-temperature service (down to -50 degrees F). For stainless steel: A312 TP304 or TP316 for process and corrosion-resistant service. The material specification determines allowable stress, chemistry, and mechanical properties that affect pressure rating and code compliance.
Pipe is typically marked with: manufacturer name, material specification (e.g., A106 Gr B), size and schedule (e.g., 4" Sch 40), heat number for traceability, and sometimes pressure rating and test pressure. Markings are usually stenciled or stamped on the pipe surface. If markings are missing or illegible, use a UT thickness gauge to measure wall thickness and compare to the pipe schedule table to determine the schedule.
Disclaimer: Pipe dimensions are per ASME B36.10M and B36.19M standards. Pressure ratings shown are for reference and are calculated per applicable ASME B31 piping codes using standard allowable stresses. Actual pressure ratings depend on material grade, operating temperature, weld joint efficiency, corrosion allowance, and code-specific design factors. Always verify pipe specifications with a qualified piping engineer for pressure-containing applications. ToolGrit is not responsible for piping design or material selection decisions.

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