Views: 52 Author: Monica Publish Time: 2026-02-09 Origin: Site
Schedule 80 steel pipe is one of the most widely specified heavy-wall piping products in industrial fluid-handling, oil & gas, chemical processing, and marine engineering. Unlike Schedule 40, which serves low-pressure applications, Schedule 80 delivers the wall thickness and pressure rating required for high-pressure, high-temperature, and corrosive service — all within the same nominal pipe size (NPS) envelope.
This article provides the complete Schedule 80 dimensions chart (NPS 1/8 to NPS 12).
The schedule number is a dimensionless designator that defines the wall thickness of a pipe. A higher schedule means a thicker wall, which directly increases the pipe's allowable working pressure rating. Schedule 80 has walls approximately twice as thick as Schedule 40 at the same nominal pipe size (NPS), making it the standard choice for industrial applications that demand robust mechanical performance in corrosive or high-pressure service.
The schedule system originated with the ANSI/ASME B36.10 standard (first published in 1935) and was later extended to stainless steels via ASME B36.19M. The schedule number itself is not directly proportional to wall thickness — it is a nominal designator. The actual wall thickness is tabulated in the ASME standard for each combination of NPS and schedule. For example:
· NPS 2 Schedule 40: wall = 0.154 in (3.91 mm)
· NPS 2 Schedule 80: wall = 0.218 in (5.54 mm) — 42% thicker than Sch 40
· NPS 2 Schedule 160: wall = 0.344 in (8.74 mm) — more than double Sch 40
[Source] ASME B36.10M-2022, Table 1, “Wall Thicknesses of Welded and Seamless Wrought Steel Pipe.”
For most NPS sizes, Schedule 80 and Schedule 80S have identical wall thicknesses. The “S” designation (per ASME B36.19M) specifically denotes stainless steel pipe — the dimensional requirements are the same as the carbon/alloy Schedule 80 per ASME B36.10M, with the exception of NPS 10 and NPS 12, where Schedule 80S uses a 0.500 in wall. Always verify against your project specification before specifying.
In practice, the term “Schedule 80” is used interchangeably for both carbon and stainless steel pipe in industrial contexts. The mechanical performance (pressure rating, temperature limit) of the pipe is determined by the wall thickness and the material grade, not by the "S" designation.
How Do the Three Most Common Schedules Compare?
Use Schedule 40 for low-pressure, non-critical service (drainage, HVAC, water). Choose Schedule 80 for standard industrial pressure applications — it is the most commonly specified heavy-wall schedule across chemical, oil & gas, and marine applications. Reserve Schedule 160 for small NPS sizes (up to NPS 8) that require extremely high pressure ratings.
The choice between schedules is driven by three design variables: operating pressure, fluid temperature, and pipe size (NPS). The Barlow formula gives the exact allowable working pressure for each combination — but in practice, most engineers select from these rules of thumb:
Schedule | Wall vs. Sch 40 | Typical Pressure Rating | Typical Applications |
Schedule 10 | Thinner | Low pressure only | Drainage, structural, low-pressure air |
Schedule 40 | Baseline | ~1,100 psi at RT | Water, air, low-pressure steam, drainage |
Schedule 80 | ~2x Sch 40 | ~2,300 psi at RT | Chemical, oil & gas, marine, steam, high-pressure water |
Schedule 120 | ~2.5–3x Sch 40 | ~2,800–3,200 psi at RT | Very high pressure; specialized applications |
Schedule 160 | ~3x Sch 40 (max) | ~3,500+ psi at RT | Instrument lines, blowdown, nuclear; NPS ≤8 |
Note: Actual allowable pressures depend on the specific NPS, material grade, and operating temperature. Always calculate per ASME B31.3 (Process Piping) or the applicable code for your system.
The allowable working pressure of Schedule 80 pipe is calculated using the Barlow formula: P = (2 × S × t) / D. For 316L stainless Schedule 80 pipe at room temperature, the allowable stress S = 16,650 psi per ASME B31.3. A 2-inch NPS 316L stainless Schedule 80 pipe has an allowable pressure of approximately 2,300 psi — double the ~1,100 psi of the same pipe in Schedule 40.
The Barlow formula calculates the internal pressure that will cause circumferential (hoop) stress in the pipe wall equal to the allowable stress of the material. It is the foundation of ASME B31.3 pressure design:
P = (2 × S × t) / D
Variable | Meaning | Typical Value for 316L SS |
P | Allowable working pressure (psi) | Calculated result |
S | Allowable stress of material (psi) | 16,650 psi at room temperature (ASME B31.3 Table K-1) |
t | Nominal wall thickness (inches) | See Schedule 80 dimension chart |
D | Outside diameter (inches) | See dimension chart |
Temperature derating: as temperature increases, the allowable stress S decreases. At 400°F (204°C), the allowable stress for 316L drops to approximately 14,400 psi. At 600°F (316°C), it is approximately 12,300 psi. Always use the applicable ASME B31.3 temperature derating table for the material specified.
Material | Allowable Stress S at RT (psi) | Sch 80 NPS 2 Pressure (psi, approx.) | Temperature Limit |
Carbon Steel (A53 Gr B) | 12,650 | ~1,750 | Up to ~450°F (232°C) |
304L Stainless | 16,650 | ~2,300 | Up to ~850°F (454°C) |
316L Stainless | 16,650 | ~2,300 | Up to ~850°F (454°C) |
904L Stainless | 20,000 | ~2,760 | Up to ~850°F (454°C) |
2205 Duplex | 25,000 | ~3,450 | Up to ~600°F (316°C) |
Inconel 625 (N06625) | 30,000 | ~4,140 | Up to ~1,000°F (538°C) |
Hastelloy C-276 (N10276) | 28,700 | ~3,960 | Up to ~1,000°F (538°C) |
How Do You Select the Right Material Grade for Schedule 80 Pipe?
Schedule 80 dimensions (outside diameter and wall thickness) are standardized by ASME B36.10M/B36.19M and are identical across all material grades. The dimensional fit — flange compatibility, fitting match, mating pipe — is always the same. However, the mechanical properties, corrosion resistance, temperature limit, and pressure rating vary dramatically. Always select the alloy grade based on your corrosion, temperature, and pressure environment — not just the dimensional fit.
The three broad material families for Schedule 80 pipe, in order of corrosion resistance and cost:
· Carbon steel (ASTM A53 Grade B / API 5L Grade B): Lowest cost; suitable for water, air, natural gas, and non-corrosive industrial fluids. Not suitable for chloride, acid, or seawater service without internal coating.
· Stainless steel (304L/316L/321/347/904L, 254 SMO, 2205/2507): The chromium-rich passive film provides excellent corrosion resistance in most industrial environments. 316L is the standard for chemical and marine service; 904L handles stronger chlorides and dilute sulfuric acid; 254 SMO and super-duplex 2507 offer the highest chloride resistance among stainless options.
· Nickel alloys (Inconel 625, Hastelloy C-276, Incoloy 800/825, Monel 400): Specified when stainless steel cannot survive the environment. Inconel 625 and Hastelloy C-276 are the top choices for seawater under pressure, sour gas, strong acids, and high-temperature corrosive service.
Application Environment | Recommended Grade | UNS / Specification | Key Advantage |
Water, air, low-pressure steam | Carbon Steel A53 Gr B | API 5L / ASTM A53 | Lowest cost |
General chemical, food, pharma | 316L Stainless | UNS S31603 / ASTM A312 | Best all-round stainless |
Marine, seawater, coastal | 316L or 904L | UNS S31603 / S90445 | Chloride resistance |
High-chloride brine, acid-chloride | 904L or 254 SMO | UNS N08904 / S31254 | PREN > 40 |
Sour gas, H2S, high-temp acid | Inconel 625 | UNS N06625 / ASTM A312 | Immune to Cl⁻ SCC; NACE approved |
Strong reducing acids, seawater | Hastelloy C-276 | UNS N10276 / ASTM B622 | Highest reducing-acid resistance |
High-temp oxidation, thermal cycling | Incoloy 800 / Inconel 625 | UNS N08800 / N06625 | High-temp strength + oxidation |
Caustic, alkaline environments | Monel 400 | UNS N04400 / ASTM B165 | Excellent caustic resistance |
The chart below gives standardized Schedule 80 dimensions per ASME B36.10M-2022 (carbon and alloy steel) and ASME B36.19M-2022 (stainless steel). Weight values are calculated for a density of 8.00 g/cm³ (the standard density for 300-series stainless steel). For nickel alloys, apply the density correction factor provided below the table.
Density correction for nickel alloys: Weight(kg/m)_alloy = Weight(kg/m)_table × (Density_alloy / 8.00)
NPS (DN) | OD (inch) | OD (mm) | Wall (inch) | Wall (mm) | Weight (lb/ft) | Weight (kg/m) |
1/8 (DN 6) | 0.405 | 10.29 | 0.095 | 2.41 | 0.31 | 0.47 |
1/4 (DN 8) | 0.540 | 13.72 | 0.119 | 3.02 | 0.54 | 0.80 |
3/8 (DN 10) | 0.675 | 17.14 | 0.126 | 3.20 | 0.74 | 1.10 |
1/2 (DN 15) | 0.840 | 21.34 | 0.147 | 3.73 | 1.09 | 1.62 |
3/4 (DN 20) | 1.050 | 26.67 | 0.154 | 3.91 | 1.47 | 2.20 |
1 (DN 25) | 1.315 | 33.40 | 0.179 | 4.55 | 2.17 | 3.24 |
1-1/4 (DN 32) | 1.660 | 42.16 | 0.191 | 4.85 | 3.00 | 4.47 |
1-1/2 (DN 40) | 1.900 | 48.26 | 0.200 | 5.08 | 3.63 | 5.41 |
2 (DN 50) | 2.375 | 60.33 | 0.218 | 5.54 | 5.03 | 7.49 |
2-1/2 (DN 65) | 2.875 | 73.03 | 0.276 | 7.01 | 7.67 | 11.41 |
3 (DN 80) | 3.500 | 88.90 | 0.300 | 7.62 | 10.25 | 15.27 |
3-1/2 (DN 90) | 4.000 | 101.60 | 0.318 | 8.08 | 12.51 | 18.63 |
4 (DN 100) | 4.500 | 114.30 | 0.337 | 8.56 | 14.98 | 22.32 |
5 (DN 125) | 5.563 | 141.30 | 0.375 | 9.53 | 20.78 | 30.95 |
6 (DN 150) | 6.625 | 168.28 | 0.432 | 10.97 | 28.57 | 42.56 |
8 (DN 200) | 8.625 | 219.08 | 0.500 | 12.70 | 43.39 | 64.64 |
10 (DN 250) | 10.750 | 273.05 | 0.500 | 12.70 | 54.74 | 81.53 |
12 (DN 300) | 12.750 | 323.85 | 0.500 | 12.70 | 65.42 | 97.46 |
[Source] All dimensions per ASME B36.10M-2022 Table 1 and ASME B36.19M-2022 Table 1. Weights calculated at stainless steel density 8.00 g/cm³.
Alloy | Density (g/cm³) | Correction Factor vs. 8.00 g/cm³ |
304L / 316L Stainless | 8.00 | 1.000 |
310S Stainless | 7.90 | 0.988 |
321 / 347 Stainless | 8.03 | 1.004 |
904L Stainless | 7.95 | 0.994 |
254 SMO (6Mo) | 8.02 | 1.003 |
2205 Duplex | 7.80 | 0.975 |
2507 Super Duplex | 7.80 | 0.975 |
Inconel 625 | 8.44 | 1.055 |
Inconel 718 | 8.19 | 1.024 |
Hastelloy C-276 | 8.89 | 1.111 |
Hastelloy C-22 | 8.73 | 1.091 |
Incoloy 800 / 800H / 800HT | 7.95 | 0.994 |
Incoloy 825 | 8.14 | 1.018 |
Monel 400 | 8.80 | 1.100 |
Carbon Steel (A53) | 7.85 | 0.981 |
Schedule 80 pipe is specified across oil & gas, chemical processing, marine and offshore, power generation, and industrial water treatment. Its heavier wall provides the mechanical strength, pressure rating, and corrosion allowance needed for these demanding environments, while using the same flange and fitting dimensions as Schedule 40.
Industry | Typical Service | Common Materials | Why Sch 80 Is Chosen |
Oil & Gas | Downhole flow lines, process piping | 316L, 904L, Inconel 625 | High pressure; H2S/CO2 resistance |
Chemical Processing | Acid, chloride, caustic lines | 316L, 904L, Hastelloy C-276 | Corrosion resistance; pressure rating |
Marine & Offshore | Seawater cooling, ballasted systems | 316L, 904L | Seawater immunity; strength |
Power Generation | Boiler feedwater, condensate, steam | 316L, Carbon Steel | High temperature; pressure |
Water Treatment | High-pressure piping, injection | 316L, Carbon Steel | Pressure; cost-effective for clean water |
Food & Beverage | Clean-in-place (CIP) systems | 316L (polished) | Corrosion resistance; sanitary surface |
Pharmaceutical | Pure water (WFI), process lines | 316L (EP/polished) | High purity; corrosion resistance |
Desalination | Brine transfer, high-pressure pumps | 316L, Duplex 2205/2507 | High-pressure brine; chloride |
A complete purchase specification for Schedule 80 pipe should include the following six elements:
· NPS and DN designation: e.g., “NPS 4 DN 100 Schedule 80”
· Material grade and UNS number: e.g., “316L stainless, UNS S31603”
· Product specification: e.g., “ASTM A312 / ASME SA-312, Seamless”
· Heat number and lot traceability: request Mill Test Report (MTR) / EN 10204 3.1
· End preparation: Plain end (PE), beveled (BE), or threaded (T\&C) as required
· Pressure test or hydrostatic test requirement: e.g., “Hydrostatic test at 1.5 × design pressure”
Material Family | ASTM / ASME Specification | Product Form | Pressure Test |
Carbon Steel | ASTM A53 Type E or S, Grade B / ASME SA-53 | Seamless or ERW | Per A53 Section 6 |
304L / 316L Stainless | ASTM A312 / ASME SA-312 | Seamless or Welded | Per A312 Section 6 |
321 / 347 Stainless | ASTM A213 / ASME SA-213 | Seamless only | Per A213 |
904L / 254 SMO | ASTM A312 / ASTM A269 | Seamless or Welded | Per specification |
2205 / 2507 Duplex | ASTM A790 / ASME SA-790 | Seamless or Welded | Per A790 |
Inconel 625 | ASTM B444 / ASME SB-444 (NPS > 1) | Seamless or Welded | Per ASTM B444 Section 8 |
Hastelloy C-276 | ASTM B622 / ASME SB-622 | Seamless | Per ASTM B622 |
Incoloy 800 / 825 | ASTM B163 / ASME SB-163 (NPS ≤1) | Seamless | Per ASTM B407 |
Q1: What is the wall thickness of Schedule 80 pipe?
The wall thickness of Schedule 80 pipe varies by nominal pipe size (NPS). Representative examples: NPS 1/2 has a wall thickness of 0.147 in (3.73 mm); NPS 2 has 0.218 in (5.54 mm); NPS 4 has 0.337 in (8.56 mm); NPS 8 has 0.500 in (12.70 mm); and NPS 12 has 0.500 in (12.70 mm). All values are standardized per ASME B36.10M-2022. See the full Schedule 80 dimensions chart above for all sizes from NPS 1/8 to NPS 12.
Q2: How much pressure can Schedule 80 pipe handle?
Schedule 80 stainless steel pipe (316L) can handle approximately 1,000 to over 3,000 psi depending on size and material, compared to roughly 150–700 psi for Schedule 40 at equivalent NPS sizes. A 2-inch NPS 316L stainless Schedule 80 pipe has an allowable pressure of approximately 2,300 psi at room temperature, calculated per the Barlow formula (P = 2St/D) with S = 16,650 psi. Higher-strength alloys (Inconel 625, Hastelloy C-276) achieve proportionally higher pressure ratings.
Q3: What is the difference between Schedule 80 and Schedule 80S?
For most NPS sizes, Schedule 80 and Schedule 80S have identical wall thicknesses. The “S” designation per ASME B36.19M specifically denotes stainless steel, while the carbon/alloy standard Schedule 80 is per ASME B36.10M. For NPS 10 and NPS 12, Schedule 80S uses a 0.500 in wall per B36.19M. In practice, the two are used interchangeably for both carbon and stainless steel. Always verify the applicable schedule and specification for your project.
Q4: What is the weight of Schedule 80 pipe per meter?
Plain-end weight depends on pipe size. Representative values: NPS 1/2 Schedule 80 weighs 1.62 kg/m; NPS 2 weighs 7.49 kg/m; NPS 6 weighs 42.56 kg/m; NPS 12 weighs 97.46 kg/m. These weights are based on stainless steel density of 8.00 g/cm³. For nickel alloys, apply the density correction factor: Weight_alloy = Weight_table × (Density_alloy / 8.00). For example, Inconel 625 (density 8.44 g/cm³) gives a correction factor of 1.055.
Q5: Can Schedule 80 pipe be used for natural gas?
Yes. Schedule 80 steel or stainless steel pipe is commonly approved for natural gas distribution and transmission lines, subject to compliance with ASME B31.3 (Process Piping) or ASME B31.8 (Gas Transmission and Distribution), local code requirements, and hydrostatic pressure testing. Stainless 316L or 904L Schedule 80 is preferred for sour gas or high-CO₂ environments where carbon steel would corrode. Nickel alloy Schedule 80 (Inconel 625, Hastelloy C-276) is specified for the most aggressive high-pressure gas containing H₂S.
Q6: What is the difference between Schedule 80 and Schedule 160 pipe?
Schedule 160 pipe has a significantly thicker wall than Schedule 80. For NPS 1/2, Schedule 80 has a 0.147 in wall while Schedule 160 has a 0.281 in — nearly double. Schedule 160 is only produced in NPS sizes up to NPS 8 and is used for the highest-pressure instrument and control lines, and nuclear service. Schedule 80 is the standard “heavy wall” choice for most industrial piping systems requiring pressure ratings beyond Schedule 40 capability.
Q7: Does JN Alloy supply Schedule 80 pipe in nickel alloys?
Yes. JN Alloy supplies Schedule 80 pipe in stainless steel (304/304L, 316/316L, 321, 347, 904L), super-austenitic stainless (254 SMO, AL-6XN), duplex and super-duplex (2205, 2507), and nickel alloys including Inconel 625 (UNS N06625), Hastelloy C-276 (UNS N10276), Incoloy 800/800H/800HT, Incoloy 825, and Monel 400. All material is certified per applicable ASTM/ASME specifications with Mill Test Reports (EN 10204 3.1) accompanying every order. Contact JN Alloy at jnalloy123@gmail.com for a specific project inquiry.
Q8: How do I calculate the weight of a pipe spool made of Schedule 80 pipe?
Calculate total pipe weight in three steps: (1) Find the plain-end weight per meter from the Schedule 80 dimensions chart for each NPS and length in the spool; (2) If using a nickel alloy, apply the density correction factor (e.g., 1.055 for Inconel 625); (3) Add fitting and flange weights from the respective weight charts. As a quick example, a 10-meter spool of NPS 4 Schedule 80 316L stainless pipe: 22.32 kg/m × 10 m = 223.2 kg of pipe. For the same pipe in Inconel 625: 22.32 × 1.055 × 10 = 235.5 kg.
Jinie Technology (Jiangsu) Co., Ltd. (JN Alloy) is a specialized manufacturer and global supplier of specialty steel and nickel alloy piping products, including the complete range of Schedule 80 pipe in stainless, duplex, and nickel alloy grades. We supply Schedule 80 pipe in NPS 1/8 to NPS 12, in seamless and welded form, with full traceability and Mill Test Reports (EN 10204 3.1) accompanying every order.
Carbon Steel Schedule 80 — ASTM A53 Grade B / API 5L, Seamless and ERW
Stainless Steel Schedule 80 — ASTM A312 316L/304L/321/347, Seamless and Welded
Super-Austenitic Schedule 80 — ASTM A312 904L / 254 SMO / AL-6XN
Duplex & Super-Duplex Schedule 80 — ASTM A790 2205 / 2507 / S32760
Nickel Alloy Schedule 80 — Inconel 625 (B444), Hastelloy C-276 (B622), Incoloy 800 (B407), Monel 400 (B165)
Pipe Fittings — Butt-weld elbows, tees, reducers, caps per ASME B16.9
Flanges — Weld neck, slip-on, blind, threaded per ASME B16.5 / B16.47
