Steel Pipe & Tube Sizes Chart
Complete reference for Schedule 40/80 steel pipes and structural tubes with dimensions and weights
Schedule 40 Steel Pipe
| NPS | OD (in) | OD (mm) | ID (in) | ID (mm) | Wall (in) | Wall (mm) |
|---|---|---|---|---|---|---|
| 1/2 | 0.840 | 21.3 | 0.622 | 15.8 | 0.109 | 2.77 |
| 3/4 | 1.050 | 26.7 | 0.824 | 20.9 | 0.113 | 2.87 |
| 1 | 1.315 | 33.4 | 1.049 | 26.6 | 0.133 | 3.38 |
| 1-1/4 | 1.660 | 42.2 | 1.380 | 35.1 | 0.140 | 3.56 |
| 1-1/2 | 1.900 | 48.3 | 1.610 | 40.9 | 0.145 | 3.68 |
| 2 | 2.375 | 60.3 | 2.067 | 52.5 | 0.154 | 3.91 |
| 2-1/2 | 2.875 | 73.0 | 2.469 | 62.7 | 0.203 | 5.16 |
| 3 | 3.500 | 88.9 | 3.068 | 77.9 | 0.216 | 5.49 |
| 4 | 4.500 | 114.3 | 4.026 | 102.3 | 0.237 | 6.02 |
| 6 | 6.625 | 168.3 | 6.065 | 154.1 | 0.280 | 7.11 |
| 8 | 8.625 | 219.1 | 7.981 | 202.7 | 0.322 | 8.18 |
| 10 | 10.750 | 273.1 | 10.020 | 254.5 | 0.365 | 9.27 |
| 12 | 12.750 | 323.9 | 12.000 | 304.8 | 0.375 | 9.53 |
Schedule 40 is the most common pipe schedule for general applications. Standard: ASME B36.10M
Schedule 80 Steel Pipe
| NPS | OD (in) | OD (mm) | ID (in) | ID (mm) | Wall (in) | Wall (mm) |
|---|---|---|---|---|---|---|
| 1/2 | 0.840 | 21.3 | 0.546 | 13.9 | 0.147 | 3.73 |
| 3/4 | 1.050 | 26.7 | 0.742 | 18.8 | 0.154 | 3.91 |
| 1 | 1.315 | 33.4 | 0.957 | 24.3 | 0.179 | 4.55 |
| 1-1/4 | 1.660 | 42.2 | 1.278 | 32.5 | 0.191 | 4.85 |
| 1-1/2 | 1.900 | 48.3 | 1.500 | 38.1 | 0.200 | 5.08 |
| 2 | 2.375 | 60.3 | 1.939 | 49.3 | 0.218 | 5.54 |
| 2-1/2 | 2.875 | 73.0 | 2.323 | 59.0 | 0.276 | 7.01 |
| 3 | 3.500 | 88.9 | 2.900 | 73.7 | 0.300 | 7.62 |
| 4 | 4.500 | 114.3 | 3.826 | 97.2 | 0.337 | 8.56 |
| 6 | 6.625 | 168.3 | 5.761 | 146.3 | 0.432 | 10.97 |
| 8 | 8.625 | 219.1 | 7.625 | 193.7 | 0.500 | 12.70 |
| 10 | 10.750 | 273.1 | 9.562 | 242.9 | 0.594 | 15.09 |
| 12 | 12.750 | 323.9 | 11.374 | 288.9 | 0.688 | 17.48 |
Schedule 80 has thicker walls than Schedule 40, providing higher pressure ratings. Standard: ASME B36.10M
Steel Pipe vs Steel Tube: Understanding the Difference
While often confused, steel pipes and steel tubes are fundamentally different products designed for different applications:
Steel Pipes
- Purpose: Designed for transporting fluids (water, gas, oil)
- Sizing: Nominal Pipe Size (NPS) - not actual dimensions
- Wall Thickness: Defined by schedule number (40, 80, etc.)
- Standard: ASME B36.10M for steel pipes
- Focus: Inside diameter (ID) critical for flow calculations
- Applications: Plumbing, HVAC, process piping, water supply
Steel Tubes
- Purpose: Structural support and mechanical applications
- Sizing: Actual outside diameter (OD) or dimensions
- Wall Thickness: Specified directly in inches or millimeters
- Standards: ASTM A500 (structural), ASTM A513 (mechanical)
- Focus: Outside dimensions and structural properties
- Applications: Building frames, machinery, furniture, fabrication
Key Distinction
Pipes are measured by nominal size (which doesn't match actual OD) and are designed for fluid transport with pressure ratings. Tubes are measured by actual OD and are designed for structural integrity and mechanical strength.
A 2" pipe has an outside diameter of 2.375", while a 2" tube has an outside diameter of exactly 2.000".
Steel Pipe Schedule Reference
The schedule number indicates the wall thickness of a pipe. Higher schedule numbers mean thicker walls and higher pressure ratings.
Schedule 40 (Standard)
- Most common for general applications
- Lower cost than Schedule 80
- Adequate for most residential and commercial uses
- Pressure rating: Up to 150 PSI (varies by size and temperature)
- Applications: Water supply, drainage, general plumbing
Schedule 80 (Extra Strong)
- Thicker walls provide higher pressure ratings
- Greater mechanical strength
- Required for some code applications
- Pressure rating: Up to 300 PSI (varies by size and temperature)
- Applications: High-pressure systems, industrial process piping
Schedule Impact on Flow
The thicker wall in Schedule 80 reduces the inside diameter compared to Schedule 40 of the same nominal size. For example, a 2" pipe has an ID of 2.067" in Schedule 40 but only 1.939" in Schedule 80 - reducing flow capacity by about 12%.
Round Steel Tube (ASTM A513)
Round mechanical tubing is used for applications requiring precise dimensions, consistent wall thickness, and good surface finish.
Manufacturing Methods
ERW (Electric Resistance Welded)
Most common and economical. Strip steel is formed into a tube and welded along the seam. Good for general fabrication and non-critical applications.
DOM (Drawn Over Mandrel)
Higher quality with uniform wall thickness and superior surface finish. ERW tube is drawn through a die over a mandrel for improved precision. Used for critical applications.
Common Applications
- • Automotive components (drive shafts, axles)
- • Hydraulic cylinders and pneumatic systems
- • Machinery and equipment fabrication
- • Furniture frames and bicycle frames
- • Roll cages and safety structures
- • Conveyor systems and material handling
Sizing Note
Round tubes are specified by actual outside diameter and wall thickness. A 1" round tube has exactly 1.000" OD, unlike pipe where nominal size doesn't equal actual dimensions.
Square & Rectangular Steel Tube (ASTM A500 HSS)
Hollow Structural Sections (HSS) are cold-formed welded tubes designed for structural applications requiring high strength-to-weight ratios.
Grade Classifications
| Grade | Yield Strength (ksi) | Tensile Strength (ksi) | Common Use |
|---|---|---|---|
| Grade A | 39 min | 45 min | General structural applications |
| Grade B | 46 min | 58 min | Higher strength structural |
| Grade C | 50 min | 62 min | High-strength critical structures |
Structural Applications
Square Tubes
- • Building columns and posts
- • Structural bracing
- • Guard rails and fencing
- • Equipment frames
- • Sign structures
Rectangular Tubes
- • Building beams and joists
- • Architectural features
- • Truck and trailer frames
- • Industrial racks and shelving
- • Gate and door frames
Design Advantages
HSS tubes provide excellent structural efficiency with high strength-to-weight ratios. The hollow section uses material more efficiently than solid bars, and the uniform wall provides consistent properties in all directions (biaxial bending strength).
How Tube Weight is Calculated
All weight calculations use standard carbon steel density: 0.2836 lb/in³ (490 lb/ft³ or 7850 kg/m³)
Round Tube Weight Formula
Weight (lb/ft) = (π/4) × (OD² - ID²) × 0.2836 × 12
Where OD and ID are in inches. The formula calculates the cross-sectional area of the steel (annulus), multiplies by density, and converts to weight per linear foot.
Example: 2" OD × 0.120" wall → ID = 1.76" → Weight = 2.64 lb/ft
Square Tube Weight Formula
Weight (lb/ft) = (Outer² - Inner²) × 0.2836 × 12
Where Outer = nominal size and Inner = (Outer - 2×Wall). Calculates the cross-sectional area of steel in the square section.
Example: 4×4 × 0.188" wall → Inner = 3.624" → Weight = 10.89 lb/ft
Rectangular Tube Weight Formula
Weight (lb/ft) = (H×W outer - H×W inner) × 0.2836 × 12
Where H and W are height and width, and inner dimensions = (H - 2×Wall) × (W - 2×Wall).
Example: 6×4 × 0.250" wall → Weight = 16.43 lb/ft
Calculation Notes
- • Weights shown are theoretical based on nominal dimensions
- • Actual weights may vary ±2-3% due to manufacturing tolerances
- • Different steel grades have minimal density variation
- • For critical applications, verify weights with manufacturer
- • Stainless steel tubes weigh about 2% more than carbon steel
Engineering Standards Reference
ASME B36.10M - Welded and Seamless Wrought Steel Pipe
Covers dimensions and weights for carbon and alloy steel pipe in schedules from 5 through XXS. Defines nominal pipe sizes, outside diameters, wall thicknesses, and pressure ratings.
Scope: Sizes 1/8" through 80" NPS | Schedules: 5, 10, 20, 30, 40, 60, 80, 100, 120, 140, 160, STD, XS, XXS
ASTM A513 - Electric-Resistance-Welded Carbon and Alloy Steel Mechanical Tubing
Specifies requirements for electric-resistance-welded carbon and alloy steel tubing for use in mechanical applications. Covers both drawn-over-mandrel (DOM) and as-welded tubing.
Types: 1 through 6 (various carbon and alloy compositions) | Quality: MT1020, MT1026, etc.
ASTM A500 - Cold-Formed Welded and Seamless Carbon Steel Structural Tubing
Covers cold-formed welded and seamless carbon steel round, square, rectangular, and special shape tubing for welded, riveted, or bolted construction of bridges, buildings, and general structural purposes.
Shapes: Round, square, rectangular, special shapes | Grades: A (Fy 39 ksi), B (Fy 46 ksi), C (Fy 50 ksi)
Related ASTM Standards
- ASTM A53: Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless
- ASTM A106: Seamless Carbon Steel Pipe for High-Temperature Service
- ASTM A501: Hot-Formed Welded and Seamless Carbon Steel Structural Tubing
- ASTM A523: Plain End Seamless and Electric-Resistance-Welded Steel Pipe
Standard Organization Hierarchy
ASME (American Society of Mechanical Engineers)
Sets standards for mechanical engineering including piping systems, pressure vessels, and boilers. B36.10M is the primary pipe dimension standard.
ASTM (American Society for Testing and Materials)
Develops technical standards for materials, products, systems, and services. A-series standards cover ferrous metals including steel tubes.
Engineering Disclaimer
The dimensions and weights provided are based on published industry standards (ASME B36.10M, ASTM A500, ASTM A513) and represent nominal or average values. Actual products may vary within manufacturing tolerances specified by the applicable standards.
Weight calculations assume standard carbon steel density (0.2836 lb/in³). Different steel grades, coatings, or alloy compositions may result in slight weight variations. For critical structural or mechanical applications, always verify specifications with your supplier.
This reference is intended for preliminary design and material estimation. Final engineering designs should reference official standards and be reviewed by a licensed professional engineer. PipeSizing.net is not responsible for errors or omissions in the data presented.