Stainless Steel

Stainless Steel 304H Pipe

High-Carbon Austenitic Stainless Steel Seamless, Welded, ERW & Boiler Pipes for Elevated Temperature Service

Grade SS 304H / TP304H (UNS S30409, Werkstoff 1.4948, X5CrNi18-10, SUS 304H, 304S11)
Standard ASTM A312, ASME SA312, ASTM A376, ASME SA376, ASTM A358, ASTM A249, ASTM A213, ASTM A409, ASTM A813, ASTM A814, ASME B36.19M, ASME B36.10M, EN 10216-5, DIN 17456 / 17458
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Product Overview

Om Export India Pvt Ltd is a premier manufacturer, stockist, and global supplier of high-temperature Stainless Steel 304H Pipes and Tubes (ASTM A312 TP304H / UNS S30409 / Werkstoff 1.4948). Grade 304H is a controlled high-carbon modification of standard 18-8 austenitic stainless steel (0.04% to 0.10% Carbon), formulated specifically to enhance creep rupture strength, mechanical load resistance, and structural stability at continuous operating temperatures ranging from 500°C up to 800°C (932°F to 1472°F) and short-term scaling resistance up to 920°C (1688°F).

Our complete production range includes cold-drawn seamless pipes, high-frequency ERW pipes, heavy-wall boiler tubes, and longitudinal EFW piping manufactured strictly in compliance with ASTM A312, ASTM A376, ASTM A358, and Indian Boiler Regulations (IBR). With an austenitic density of 8.00 g/cm³ and a minimum yield strength of 205 MPa, our SS 304H piping systems deliver high thermal efficiency, internal cleanliness, and fatigue resistance across petroleum refineries, petrochemical cracker furnace lines, thermal power plant steam loops, and industrial superheater manifolds.

  • Elevated Temperature & Creep Strength: Controlled 0.04%–0.10% carbon content delivers superior creep and stress-rupture properties above 500°C compared to 304 or 304L.
  • High Oxidation Resistance: Resists scaling and oxidation in continuous high-temperature atmospheres up to 920°C.
  • IBR & Pressure Vessel Certified: Available with statutory Indian Boiler Regulation (IBR Form III-A / III-D) documentation for high-pressure steam utility circuits.

Key Features

  • High Creep Rupture Strength: Formulated with 0.04%–0.10% Carbon for structural load retention up to 800°C (1472°F).
  • Oxidation & Scaling Resistance: Resists surface oxidation in continuous service up to 920°C (1688°F).
  • Dual ASTM / ASME Conformance: Fully compliant with ASTM A312, ASTM A376, ASTM A358, and ASME Boiler & Pressure Vessel Code.
  • Indian Boiler Regulation (IBR) Approved: Supplied with official IBR inspection certification for legal installation in utility steam boilers.
  • Formability & Toughness: High elongation (≥40%) allows cold bending, expansion into tubesheets, and swaging without micro-fracturing.
  • Versatile Structural Finishes: Available in pickled and passivated (No. 1), bright annealed (BA), electropolished, and mirror finishes.

Product Specifications

Specification Parameter Standard Specification / Technical Value
Nominal Size Range (Seamless) 1/8" NB to 24" NB (Outer Diameter: 6.00 mm to 609.6 mm OD)
Nominal Size Range (Welded / ERW / EFW) 1/8" NB to 48" NB (Outer Diameter: 6.00 mm to 1219.2 mm OD)
Wall Thickness & Schedules 0.30 mm to 50.0 mm (SCH 5S, SCH 10S, SCH 40S/STD, SCH 80S/XS, SCH 160, SCH XXS)
Governing Standards ASTM A312 / ASME SA312, ASTM A376, ASTM A358, ASTM A213, ASTM A249, ASTM A409, ASTM A813, ASTM A814
Manufacturing Methods Cold Drawn Seamless (CDS), Hot Finished Seamless, High-Frequency Induction ERW, Automated TIG/Plasma Welded, EFW
Heat Treatment & Delivery State Solution Annealed at 1040°C – 1150°C (1900°F – 2100°F) followed by rapid water quenching; Bright Annealed (BA)
Standard Lengths Single Random Length (SRL), Double Random Length (DRL), Custom Cut Lengths up to 26,000 mm (26 Meters)
End Configurations & Protection Plain Square Cut (PE), Beveled End (BE 30°/37.5° per ASME B16.25), Threaded Ends with Protective Plastic End Caps

Dimensions & Sizes

Nominal Pipe Size (NPS) Outside Diameter (OD mm / in.) Wall Thickness (WT mm / in.) Nominal Schedule Nominal Weight (kg/m) Nominal Weight (lb/ft)
1/2" NB 21.34 mm (0.840") 1.65 mm (0.065") SCH 10S 0.81 kg/m 0.54 lb/ft
1/2" NB 21.34 mm (0.840") 2.77 mm (0.109") SCH 40S / STD 1.29 kg/m 0.85 lb/ft
1/2" NB 21.34 mm (0.840") 3.73 mm (0.147") SCH 80S / XS 1.65 kg/m 1.09 lb/ft
3/4" NB 26.67 mm (1.050") 1.65 mm (0.065") SCH 10S 1.03 kg/m 0.69 lb/ft
3/4" NB 26.67 mm (1.050") 2.87 mm (0.113") SCH 40S / STD 1.71 kg/m 1.13 lb/ft
3/4" NB 26.67 mm (1.050") 3.91 mm (0.154") SCH 80S / XS 2.23 kg/m 1.48 lb/ft
1" NB 33.40 mm (1.315") 1.65 mm (0.065") SCH 5S 1.31 kg/m 0.88 lb/ft
1" NB 33.40 mm (1.315") 2.77 mm (0.109") SCH 10S 2.13 kg/m 1.43 lb/ft
1" NB 33.40 mm (1.315") 3.38 mm (0.133") SCH 40S / STD 2.54 kg/m 1.68 lb/ft
1" NB 33.40 mm (1.315") 4.55 mm (0.179") SCH 80S / XS 3.29 kg/m 2.17 lb/ft
1-1/4" NB 42.16 mm (1.660") 2.77 mm (0.109") SCH 10S 2.73 kg/m 1.83 lb/ft
1-1/4" NB 42.16 mm (1.660") 3.56 mm (0.140") SCH 40S / STD 3.44 kg/m 2.31 lb/ft
1-1/2" NB 48.26 mm (1.900") 2.77 mm (0.109") SCH 10S 3.16 kg/m 2.12 lb/ft
1-1/2" NB 48.26 mm (1.900") 3.68 mm (0.145") SCH 40S / STD 4.11 kg/m 2.72 lb/ft
1-1/2" NB 48.26 mm (1.900") 5.08 mm (0.200") SCH 80S / XS 5.49 kg/m 3.63 lb/ft
2" NB 60.33 mm (2.375") 2.77 mm (0.109") SCH 10S 3.99 kg/m 2.64 lb/ft
2" NB 60.33 mm (2.375") 3.91 mm (0.154") SCH 40S / STD 5.52 kg/m 3.66 lb/ft
2" NB 60.33 mm (2.375") 5.54 mm (0.218") SCH 80S / XS 7.60 kg/m 5.03 lb/ft
2-1/2" NB 73.03 mm (2.875") 3.05 mm (0.120") SCH 10S 5.35 kg/m 3.59 lb/ft
2-1/2" NB 73.03 mm (2.875") 5.16 mm (0.203") SCH 40S / STD 8.77 kg/m 5.89 lb/ft
3" NB 88.90 mm (3.500") 3.05 mm (0.120") SCH 10S 6.56 kg/m 4.34 lb/ft
3" NB 88.90 mm (3.500") 5.49 mm (0.216") SCH 40S / STD 11.47 kg/m 7.58 lb/ft
3" NB 88.90 mm (3.500") 7.62 mm (0.300") SCH 80S / XS 15.51 kg/m 10.26 lb/ft
4" NB 114.30 mm (4.500") 3.05 mm (0.120") SCH 10S 8.50 kg/m 5.62 lb/ft
4" NB 114.30 mm (4.500") 6.02 mm (0.237") SCH 40S / STD 16.32 kg/m 10.80 lb/ft
4" NB 114.30 mm (4.500") 8.56 mm (0.337") SCH 80S / XS 22.67 kg/m 15.00 lb/ft
6" NB 168.28 mm (6.625") 3.40 mm (0.134") SCH 10S 14.04 kg/m 9.30 lb/ft
6" NB 168.28 mm (6.625") 7.11 mm (0.280") SCH 40S / STD 28.69 kg/m 18.99 lb/ft
6" NB 168.28 mm (6.625") 10.97 mm (0.432") SCH 80S / XS 43.21 kg/m 28.60 lb/ft
8" NB 219.08 mm (8.625") 3.76 mm (0.148") SCH 10S 20.27 kg/m 13.62 lb/ft
8" NB 219.08 mm (8.625") 8.18 mm (0.322") SCH 40S / STD 43.20 kg/m 28.55 lb/ft
8" NB 219.08 mm (8.625") 12.70 mm (0.500") SCH 80S / XS 65.63 kg/m 43.39 lb/ft

Chemical Composition

Element ASTM A312 TP304H (%) UNS S30409 (%) DIN 1.4948 / X5CrNi18-10 (%)
Carbon (C) 0.04 – 0.10 0.04 – 0.10 0.04 – 0.08
Chromium (Cr) 18.00 – 20.00 18.00 – 20.00 17.00 – 19.00
Nickel (Ni) 8.00 – 10.50 (11.00 Max) 8.00 – 11.00 8.00 – 11.00
Manganese (Mn, Max) 2.00 2.00 2.00
Silicon (Si, Max) 0.75 (1.00 Max) 0.75 0.75
Phosphorus (P, Max) 0.045 0.045 0.035
Sulfur (S, Max) 0.030 0.030 0.015
Nitrogen (N, Max) 0.10 0.10 0.10
Iron (Fe) Balance Balance Balance

Mechanical Properties

Mechanical Property ASTM A312 TP304H Specified Limits Typical Production Values
Tensile Strength, Ultimate (Min) 515 MPa (75 ksi / 75,000 psi) 560 – 620 MPa
Yield Strength (0.2% Proof, Min) 205 MPa (30 ksi / 30,000 psi) 230 – 290 MPa
Elongation in 2 in. / 50 mm (Min) 35% – 40% Min 45% – 55%
Hardness (Rockwell B / Brinell, Max) 92 HRB Max / 201 HBW Max 80 – 88 HRB (150 – 180 HBW)
Density & Modulus of Elasticity Density: 8.00 g/cm³ (8000 kg/m³) Modulus of Elasticity: 193 GPa (28 x 10⁶ psi)
Thermal Expansion (0–100°C / 0–538°C) 17.2 µm/m·°C (0–100°C) 18.4 µm/m·°C (0–538°C)
Thermal Conductivity & Specific Heat 16.2 W/m·K at 100°C | 21.5 W/m·K at 500°C Specific Heat (0–100°C): 500 J/kg·K

Standards & Specifications

Standard Designation Governing Organization Scope & Product Description
ASTM A312 / ASME SA312 ASTM / ASME Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes (TP304H / UNS S30409)
ASTM A376 / ASME SA376 ASTM / ASME Seamless Austenitic Steel Pipe for High-Temperature Central-Station Service
ASTM A358 / ASME SA358 ASTM / ASME Electric-Fusion-Welded Austenitic Chromium-Nickel Stainless Steel Pipe for High-Temperature Service
ASTM A213 / ASME SA213 ASTM / ASME Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes (Grade TP304H)
ASTM A249 / ASME SA249 ASTM / ASME Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes
ASTM A409 / ASME SA409 ASTM / ASME Welded Large Diameter Austenitic Steel Pipe for Corrosive or High-Temperature Service
EN 10216-5 / DIN 17456 / 17458 European / German Standards Seamless Steel Tubes for Pressure Purposes (Grade 1.4948 / X5CrNi18-10)
Indian Boiler Regulations (IBR) Central Boilers Board IBR Certified Steam and High-Pressure Stainless Steel Boiler Piping

Applications

Stainless Steel 304H high-temperature pipes and tubes are utilized across major thermal, chemical, and heavy process installations:

  • Petroleum Refining & Petrochemicals: Catalytic cracker regenerators, furnace tubes, thermal hydrocracking loops, and refinery flare stacks.
  • Thermal Power Generation & Utility Boilers: Superheater tube banks, reheater loops, steam headers, boiler economizers, and IBR high-pressure steam distribution lines.
  • Chemical Processing Infrastructure: High-temperature chemical reactor vessels, waste heat recovery steam generators (HRSG), and hot gas exhaust ducts.
  • Nuclear Power Utilities: Core cooling loops, steam condenser circuits, and elevated-temperature auxiliary reactor pipework.
  • Heat Exchangers & Condensers: High-temperature shell and tube exchangers, radiant coils, and reboilers operating continuously above 500°C.
  • Heavy Fabrication & Architecture: Industrial exhaust manifolds, furnace structural members, and high-strength hot fluid transport lines.

Frequently Asked Questions

Q1: What is the difference between Stainless Steel 304, 304L, and 304H?
The primary difference lies in the carbon content: SS 304 has a standard carbon maximum of 0.08%, SS 304L is low carbon (≤0.030%) to prevent sensitization during welding, and SS 304H has a controlled higher carbon range (0.04% to 0.10%). The elevated carbon in 304H gives it significantly higher tensile, yield, and creep-rupture strength at operating temperatures above 500°C.

Q2: Why is ASTM A312 TP304H specified for boiler superheaters instead of standard 304?
Standard austenitic grades experience severe creep deformation, microstructural softening, and loss of allowable stress above 500°C. Grade 304H maintains stable allowable design stresses and high creep-rupture life up to 800°C under continuous pressure in accordance with ASME Section II Table 1A.

Q3: Can SS 304H pipes be welded easily, and is post-weld heat treatment required?
Yes, SS 304H is weldable using GTAW, GMAW, and SMAW with matching AWS ER308H or E308H consumables. In severe high-temperature or aggressive corrosive environments, solution annealing at 1040°C–1150°C followed by water quenching is recommended to redissolve chromium carbides and restore full corrosion resistance.

Q4: What quality certifications accompany Om Export India Pvt Ltd SS 304H pipes?
All deliveries are accompanied by EN 10204 Type 3.1 / 3.2 Material Test Certificates, IBR Form III-A or Form III-D statutory documents, 100% Positive Material Identification (PMI) spectro reports, and 100% Hydrostatic / Eddy Current test certificates.

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