-- | ------------------- | -------------------------------------- | | SCH 5 | Extra thin | Low pressure, non-critical | | SCH 10 | Thin | Low pressure water, drainage | | SCH 40 | Standard | Most common — water, steam, structural | | SCH 80 | Extra strong | High pressure, structural columns | | SCH 120 | Heavy | High pressure, heavy structural | | SCH 160 | Extra heavy | Very high pressure | | XXS | Double extra strong | Extreme pressure, special applications |

Steel Pipe Size Chart

Small Diameter (NPS 1/8 to NPS 2)

NPS OD (in) SCH 40 Wall (in) SCH 40 ID (in) SCH 40 Wt (lb/ft) SCH 80 Wall (in) SCH 80 ID (in) SCH 80 Wt (lb/ft)
1/8 0.405 0.068 0.269 0.24 0.095 0.215 0.31
1/4 0.540 0.088 0.364 0.42 0.119 0.302 0.54
3/8 0.675 0.091 0.493 0.57 0.126 0.423 0.74
1/2 0.840 0.109 0.622 0.85 0.147 0.546 1.09
3/4 1.050 0.113 0.824 1.13 0.154 0.742 1.48
1 1.315 0.133 1.049 1.68 0.179 0.957 2.17
1-1/4 1.660 0.140 1.380 2.27 0.191 1.278 3.00
1-1/2 1.900 0.145 1.610 2.72 0.200 1.500 3.63
2 2.375 0.154 2.067 3.65 0.218 1.939 5.02

Medium Diameter (NPS 2-1/2 to NPS 8)

NPS OD (in) SCH 40 Wall (in) SCH 40 ID (in) SCH 40 Wt (lb/ft) SCH 80 Wall (in) SCH 80 ID (in) SCH 80 Wt (lb/ft)
2-1/2 2.875 0.203 2.469 5.79 0.276 2.323 7.66
3 3.500 0.216 3.068 7.58 0.300 2.900 10.25
3-1/2 4.000 0.226 3.548 9.11 0.318 3.364 12.50
4 4.500 0.237 4.026 10.79 0.337 3.826 14.98
5 5.563 0.258 5.047 14.62 0.375 4.813 20.78
6 6.625 0.280 6.065 18.97 0.432 5.761 28.57
8 8.625 0.322 7.981 28.55 0.500 7.625 43.39

Large Diameter (NPS 10 to NPS 24)

NPS OD (in) SCH 40 Wall (in) SCH 40 ID (in) SCH 40 Wt (lb/ft) SCH 80 Wall (in) SCH 80 ID (in) SCH 80 Wt (lb/ft)
10 10.750 0.365 10.020 40.48 0.594 9.562 64.43
12 12.750 0.406 11.938 53.52 0.688 11.374 88.63
14 14.000 0.438 13.124 63.44 0.750 12.500 106.15
16 16.000 0.500 15.000 82.77 0.844 14.312 136.67
18 18.000 0.562 16.876 104.67 0.938 16.124 170.92
20 20.000 0.594 18.812 123.11 1.031 17.938 208.97
24 24.000 0.688 22.624 171.29 1.219 21.562 296.58

Weight Calculation Formula

Weight per foot: W = 10.68 × (OD - t) × t

where:

Example: Calculate weight for 6 inch SCH 40 pipe (OD = 6.625, t = 0.280): W = 10.68 × (6.625 - 0.280) × 0.280 = 10.68 × 6.345 × 0.280 = 18.97 lb/ft

Common Structural Applications

Application Typical Size Schedule Notes
Handrails 1-1/2" or 2" SCH 40 ADA requires 1-1/4" to 2" grip
Guardrail posts 2-1/2" SCH 40 Embed in concrete or base plate
Bollards 4" to 8" SCH 40 or 80 Concrete-filled for impact resistance
Pipe columns (1-2 story) 4" to 6" SCH 40 or STD Architectural columns
Pipe columns (3-5 story) 8" to 12" STD or SCH 40 Calculate capacity per AISC
Pipe piles 10" to 24" STD or XS Driven or drilled, concrete filled
Pipe truss chords 4" to 12" Varies Space frame and truss applications
Sign poles 6" to 16" SCH 40 Wind load governs design
Flagpoles 6" to 10" SCH 80 Tapered sections common

ASTM Specifications

Spec Description Common Grades Application
A53 Black and galvanized pipe Gr B (Fy=35 ksi) Water, steam, structural
A106 Seamless carbon steel Gr B (Fy=35 ksi) High temperature service
A500 Cold-formed welded/seamless Gr B (Fy=42-46 ksi) Structural (round HSS)
A501 Hot-formed welded/seamless Gr B (Fy=35 ksi) Structural
A1085 Cold-formed HSS Gr A (Fy=50 ksi) New high-performance HSS spec

For structural applications: Use ASTM A500 or A1085, not A53. A500 and A1085 have higher yield strengths and are designed for structural loading.

Pipe Column Capacity (Quick Reference)

Approximate axial capacity for A500 Gr B pipe columns (Fy = 46 ksi, K = 1.0):

Size SCH Weight (lb/ft) Area (in²) r (in) 10 ft φPn (kips) 14 ft φPn (kips) 20 ft φPn (kips)
4" STD 10.79 3.17 1.41 116 105 88
6" STD 18.97 5.58 2.25 213 200 180
8" STD 28.55 8.40 3.00 327 314 293
10" STD 40.48 11.90 3.75 468 453 430
12" STD 53.52 15.73 4.50 620 603 578

Values are approximate. Use AISC Chapter E for actual design.

Pressure Rating Overview

Approximate internal pressure rating for ASTM A53 Gr B seamless pipe:

NPS SCH 40 Rating (psi) SCH 80 Rating (psi)
1/2 2,140 3,040
1 1,900 2,760
2 1,650 2,500
4 1,430 2,180
6 1,270 2,060
8 1,120 1,860
10 1,030 1,800
12 960 1,730

Values are approximate working pressures at ambient temperature using Barlow's formula with a safety factor of 4.

Frequently Asked Questions

What is the difference between SCH 40 and SCH 80 pipe? Schedule 80 has a thicker wall than Schedule 40 for the same outside diameter. This means higher pressure rating and more weight, but a smaller inside diameter. SCH 40 is standard for most structural applications. SCH 80 is used where higher strength or pressure capacity is needed.

Is steel pipe the same as round HSS? No. Steel pipe (ASTM A53) is manufactured to pipe standards with a round shape. Round HSS (ASTM A500) is manufactured to structural standards with higher yield strength (42-46 ksi vs 35 ksi). For structural columns, always use A500 round HSS. For plumbing and fluid transport, use A53 pipe.

How much does 6 inch steel pipe weigh? 6 inch SCH 40 steel pipe weighs 18.97 lb/ft. A 20 foot section weighs approximately 379 lb.

What pipe size should I use for a handrail? Per ADA requirements, handrail gripping surfaces must be between 1-1/4 inch and 2 inch diameter. Use 1-1/2 inch or 2 inch SCH 40 pipe for standard handrails.

Can I use steel pipe for structural columns? Yes. Round HSS (ASTM A500 Gr B) pipe is commonly used as structural columns. Design per AISC 360 Chapter E. Common sizes range from 4 inch to 12 inch depending on load and height. Larger sizes (up to 24 inch) are used as pipe piles.

What is STD pipe? STD (Standard) pipe refers to Schedule 40 for NPS 1/8 through NPS 10, and to a specific wall thickness for NPS 12 and larger. In practice, STD is the most common wall thickness for structural applications.

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Disclaimer

This is a calculation tool, not a substitute for professional engineering certification. All results must be independently verified by a licensed Professional Engineer (PE) or Structural Engineer (SE) before use in construction, fabrication, or permit documents. The user is responsible for the accuracy of all inputs and the verification of all outputs.