Schedule 20 and Schedule 40 are two common pressure ratings in steel pipe piping systems. The core difference lies in wall thickness, pressure bearing capacity, and applicable scenarios: Schedule 40 has thicker walls and higher strength, and is suitable for high-pressure industrial pipelines; Schedule 20 has thinner walls and is suitable for low-pressure or non-critical fluid transportation.
Looking for large-diameter S20 or standard S40 pipe? Submit your specs for a factory-direct quote within 15 minutes!
S20 VS S40 pipe
| Comparison Item | Schedule 20 (S20) | Schedule 40 (S40) |
| Definition | Light-to-Medium Wall thickness pipe | Standard / General Purpose Wall thickness pipe |
| Wall Thickness Logic | Thinner; lower pressure-bearing capacity | Thicker; higher pressure-bearing capacity |
| Common Size Range | Typically defined only for NPS 8 (DN200) and above | Full range coverage (NPS 1/8 to NPS 80+) |
| Relationship with STD | Significantly thinner than STD (Standard) | Identical to STD for sizes NPS 10 and below |
| Weight | Lighter; easier for installation and support | Heavier; higher mechanical strength |
| Cost | Lower material cost (calculated by weight) | Higher cost (due to higher steel volume) |
S20 VS S40 Dimensions & Mechanical Parameters (NPS 12 / DN300 Example)
| Parameter Category | S20 (@NPS 12) | S40 (@NPS 12) | Remarks |
| Outside Diameter (OD) | 323.9 mm | 323.9 mm | OD remains identical for both |
| Wall Thickness (WT) | 6.35 mm | 10.31 mm | S40 is ~62% thicker than S20 |
| Inside Diameter (ID) | 311.2 mm | 303.28 mm | ID decreases as wall thickness increases |
| Theoretical Weight | 49.73 kg/m | 79.73 kg/m | S40 is significantly heavier |
| Pressure Capacity | Low | Medium-High | S40 has a higher working pressure rating |
| Moment of Inertia | Lower | Higher | S40 has better resistance to bending/deformation |
S20 and S40 pipeline Application Comparison
| Scenario | Recommended Schedule | Reason |
| High-Pressure Steam / Oil & Gas | S40 | Requires thicker walls to ensure safety under high pressure. |
| Large Diameter Ventilation | S20 | Extremely low pressure; S20 reduces structural load and cost. |
| Municipal Water / Firefighting | S40 | Industry standard; allows for corrosion margin and impact resistance. |
| Low-Pressure Drainage / Temp Lines | S20 | Prioritizes economy; fluid impact on the wall is minimal. |
| Plant Utilities (Air/Water) | S40 | Most common plant spec; fittings (elbows, tees) are easiest to source. |
Schedule 20 (S20) Pipe Specification Table (Metric Units)
| Nominal Pipe Size (NPS) | Nominal Diameter (DN) | Outside Diameter (OD) mm | Wall Thickness (WT) mm | Theoretical Weight ( kg/m ) |
| 8" | 200 | 219.1 | 6.35 | 33.31 |
| 10" | 250 | 273.1 | 6.35 | 41.77 |
| 12" | 300 | 323.9 | 6.35 | 49.73 |
| 14" | 350 | 355.6 | 7.92 | 67.90 |
| 16" | 400 | 406.4 | 7.92 | 77.83 |
| 18" | 450 | 457.2 | 7.92 | 87.76 |
| 20" | 500 | 508.0 | 9.53 | 117.15 |
| 22" | 550 | 558.8 | 9.53 | 129.08 |
| 24" | 600 | 609.6 | 9.53 | 141.02 |
| 26" | 650 | 660.4 | 12.70 | 202.82 |
| 28" | 700 | 711.2 | 12.70 | 218.73 |
| 30" | 750 | 762.0 | 12.70 | 234.64 |
| 32" | 800 | 812.8 | 12.70 | 250.54 |
| 34" | 850 | 863.6 | 12.70 | 266.45 |
| 36" | 900 | 914.4 | 15.88 | 351.68 |
Schedule 40 (S40) Pipe Specification Table (Metric Units)
| Nominal Pipe Size (NPS) | Nominal Diameter (DN) | Outside Diameter (OD) mm | Wall Thickness (WT) mm | Theoretical Weight ( kg/m ) | Note |
| 1/2" | 15 | 21.3 | 2.77 | 1.27 | Same as STD |
| 3/4" | 20 | 26.7 | 2.87 | 1.69 | Same as STD |
| 1" | 25 | 33.4 | 3.38 | 2.50 | Same as STD |
| 1-1/4" | 32 | 42.2 | 3.56 | 3.39 | Same as STD |
| 1-1/2" | 40 | 48.3 | 3.68 | 4.05 | Same as STD |
| 2" | 50 | 60.3 | 3.91 | 5.44 | Same as STD |
| 2-1/2" | 65 | 73.0 | 5.16 | 8.63 | Same as STD |
| 3" | 80 | 88.9 | 5.49 | 11.29 | Same as STD |
| 4" | 100 | 114.3 | 6.02 | 16.07 | Same as STD |
| 5" | 125 | 141.3 | 6.55 | 21.77 | Same as STD |
| 6" | 150 | 168.3 | 7.11 | 28.26 | Same as STD |
| 8" | 200 | 219.1 | 8.18 | 42.55 | Same as STD |
| 10" | 250 | 273.1 | 9.27 | 60.31 | Same as STD |
| 12" | 300 | 323.9 | 10.31 | 79.73 | Thicker than STD |
| 14" | 350 | 355.6 | 11.13 | 94.55 | Thicker than STD |
| 16" | 400 | 406.4 | 12.70 | 123.30 | Thicker than STD |
| 18" | 450 | 457.2 | 14.27 | 155.87 | Thicker than STD |
| 20" | 500 | 508.0 | 15.09 | 183.42 | Thicker than STD |
| 24" | 600 | 609.6 | 17.48 | 255.00 | Thicker than STD |
GNEE Thick Wall Pipe factory
FAQ
How thick is Schedule 80 pipe?
about 0.179 inches thick
The 1 inch Sch 80 pipes are about 0.179 inches thick and 630 PSI.
How long is a S20?
Dimensions / Weight S20: 2.7" x 6.0" x 0.3" / 5.7 oz. S20+: 3.0" x 6.4" x 0.3" / 6.6 oz. S20 Ultra: 3.0" x 6.6" x 0.3" / 7.8 oz.
