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A335 / A333 / A312 Power Plant Piping Supplier — Inox Steel India

Power plants operate under some of the highest thermal and mechanical stresses in the industrial world.
Every section — from the boiler to the turbine — requires specialized metallurgical-grade pipes that resist:

  • High pressure
  • High temperature
  • Thermal fatigue
  • Creep deformation
  • Oxidation
  • Corrosion
  • Low-temperature cracking

Inox Steel India supplies the complete piping package for all types of power plants:

  • Thermal Power Plants (Coal / Oil / Gas Fired)
  • Supercritical & Ultra-Supercritical Plants
  • HRSG / Combined Cycle Plants
  • Biomass & Waste-to-Energy Plants
  • Captive Power Plants (CPP)
  • Process Steam & Co-gen Systems

Using the core material set:

  • A335 (P11/P22/P91) → High-temperature steam lines
  • A333 Gr 6 → Low-temperature sections (cold reheat/condensate)
  • A312 (SS Grades) → Corrosion-resistant & condensate handling

Table of Contents

Why These Three Materials Dominate Power Plant Piping

Power plants operate around three temperature zones:

1. High Temperature (450°C – 700°C) — “HOT ZONE”

Material Required: A335 P11 / P22 / P91

This includes:

  • Main steam line
  • Hot reheat line
  • Superheater & reheater coils
  • Furnace coil piping
  • HP boiler external piping

Why A335?

Because Cr-Mo alloy steels provide:

  • Excellent oxidation resistance
  • Long-term creep resistance
  • High-temperature tensile strength
  • Resistance to thermal shock

P91 is essential for supercritical & ultra-supercritical plants.

2. Low Temperature (−45°C to +350°C) — “COLD ZONE”

Material Required: A333 Grade 6 (LTCS)

Used in:

  • Condensate return
  • Cold reheat lines
  • Cooling water systems
  • Auxiliary steam lines
  • Cryo-adjacent areas

Why A333?

Because it maintains impact toughness at −45°C, ensuring:

  • Crack resistance
  • High ductility
  • Strong weldability

No brittle failure under sudden temperature drops.

3. Corrosive / Wet Service — “CONDENSATE & FEEDWATER ZONE”

Material Required: A312 Stainless Steel (304 / 316L)

Used in:

  • Feedwater lines
  • LP steam lines
  • Condensate polishing units
  • Chemical dosing lines
  • Wet steam & corrosion-prone sections

Why A312?

Because stainless steel provides:

  • Excellent corrosion resistance
  • No pitting from condensate
  • Long life with low maintenance
  • Smooth flow in feed & auxiliary systems

316L is used when chlorides or chemicals are present.

Only Alloy 625 (B444) withstands this safely.

Power Plant Piping

🚂 BOILER AREA (High Temp)

  • Superheater → P22 / P91
  • Reheater → P91
  • Furnace coil → P22
  • Economizer → P11/P22

⚡ TURBINE AREA

  • Hot reheat → P91
  • HP steam inlet → P91

🧊 CONDENSER AREA

  • Condensate return → A333 / A312
  • Extraction steam → P11/P22

🌊 FEEDWATER SYSTEM

  • Feedwater → A312 316L
  • Chemical dosing → A312 316L

🔥 HRSG (Heat Recovery Steam Generator)

  • HP steam → P91
  • IP steam → P22
  • LP steam → P11
  • Condensate → A312

🛢 BALANCE OF PLANT

  • LP steam → P11
  • Cooling water → A333
  • Utility lines → A312

Industries & Power Plant Types We Serve

  • Coal-fired power plants
  • Gas-fired CCGT/HRSG units
  • Petrochemical captive power plants
  • Cement industry captive power plants
  • Textile process steam units
  • Sugar mill co-generation power
  • Biomass & biofuel plants
  • Waste-to-energy incineration plants

Why Inox Steel India Is Preferred by Power Plant EPC Contractors

  1. Wide stock of P22 & P91 steam-line pipes
  2. Guaranteed LTCS impact-tested A333 Gr 6
  3. Corrosion-resistant A312 for condensate/auxiliary lines
  4. Boiler & HRSG package specialization
  5. TPI-approved supply (SGS • TUV • DNV • BV • Lloyds)
  6. All pipes seamless — no ERW
  7. P91 → strict heat treatment & microstructure control
  8. Same-day dispatch for shutdown emergencies
  9. Export supplies to GCC, Africa, Europe, SE Asia & USA

In Power Plants, the Most Dangerous Failure Is a Pipe Failure

Creep rupture, water hammer, and thermal shock failures can cause:

  • Turbine trips
  • Boiler shutdown
  • HRSG explosions
  • Safety hazards

Inox Steel India ensures:

  • Correct metallurgy
  • Perfect heat treatment (P91)
  • True LTCS impact-tested pipes
  • No chemical mismatch
  • Full traceability (Heat No. & MTC)

Master Technical Datasheet — Power Plant Applications — A335 / A333 / A312

MATERIAL OVERVIEW — POWER PLANT PIPING

Material Standard Grades Primary Duty in Power Plants
A335 Alloy Steel ASTM A335 P11 / P22 / P91 Main steam, hot reheat, superheater, boiler lines
A333 LTCS ASTM A333 Gr 6 Low-temperature, cold reheat, condensate return, cooling sections
A312 Stainless Steel ASTM A312 TP304 / TP316L Feedwater, auxiliary steam, condensate, chemical dosing lines

TECHNICAL DATASHEET — A335 (P11 / P22 / P91)

High-Temperature Steam-Line Alloy Steel

Property P11 P22 P91
Chromium 1% 2.25% 9%
Molybdenum 0.5% 1% 1%
Temp Range 450–550°C 500–600°C 600–700°C
Steam Duty MP Steam HP Steam Supercritical / Ultra-supercritical
Creep Strength Medium High Ultra-high
Delivery N+T N+T Q+T
Used In Superheater / Reheater / Main Steam Main Steam / Boiler Lines Ultra HP Steam / Reheat

TECHNICAL DATASHEET — A333 (Gr 6)

Low-Temperature Carbon Steel (LTCS)

Property A333 Gr 6
Yield Strength 240 MPa
Tensile Strength 415 MPa
Temp Suitability −45°C to +350°C
Impact Test Mandatory @ −45°C
Best Use Cold reheat, condensate, cooling systems, LT piping
Type Seamless
Equivalents EN 10216-3 P355NL1

TECHNICAL DATASHEET — A312 (TP304 / TP316L)

Corrosion-Resistant Stainless Steel for Feed & Condensate Lines

Property TP304 TP316L
Chromium 18–20% 16–18%
Nickel 8–11% 10–14%
Molybdenum — 2–3%
Corrosion Resistance High Very High
Temperature Limit 650°C 650°C
Best Use Condensate / Feedwater Chemical dosing, wet steam
Ferrite Non-magnetic Non-magnetic

WHERE EACH MATERIAL IS USED IN A POWER PLANT

A335 (P11 / P22 / P91) — High Temperature

  • Main steam line
  • Hot reheat line
  • Superheater tubes
  • Reheater tubes
  • HP boiler external piping
  • HRSG high-temperature zones
  • Furnace/Heater piping

A333 Gr 6 — Low Temperature

  • Condensate return
  • Cold reheat lines
  • Cooling water systems
  • LT auxiliary piping
  • Cryo-adjacent lines
  • LP steam condensate

A312 (304 / 316L) — Corrosion / Clean Service

  • Condensate polishing units
  • Feedwater lines
  • Chemical dosing pipelines
  • Auxiliary steam lines
  • LP steam headers
  • Water treatment plants

AVAILABLE SIZES & SCHEDULES

Material Size Range Schedules
A335 P-Grades ½” – 26” SCH 40 / 80 / 160 / XXS
A333 Gr 6 ½” – 24” SCH 40 / 80 / 160
A312 SS ½” – 24” SCH 10S / 40S / 80S

TESTING REQUIREMENTS — POWER PLANT STANDARDS

A335 (P-Grades)

  • Tensile Test
  • Yield & Elongation
  • Hardness
  • Creep Rupture → (P91 Mandatory)
  • Microstructure Verification
  • UT / Eddy Current
  • Hydrostatic Test
  • Heat Treatment Chart (P91 mandatory)

A333 (Gr 6)

  • −45°C Impact Test
  • UT
  • Hydrotest
  • Chemical Analysis

A312 (304/316L)

  • IGC Test
  • Hydro Test
  • UT
  • PMI
  • ASME Sec II compliance

DOCUMENTS SUPPLIED

  • EN 10204 3.1 MTC
  • Hydro / NDT Reports
  • PMI Report
  • Heat Treatment Charts (A335 P91)
  • Chemical Analysis
  • Dimensional Inspection
  • Packing List + Invoice + COO
  • TPI Reports (SGS / TUV / DNV / BV / Lloyds)

Power Plant Service-Wise Material Selection

Power plants operate in 3 distinct service zones. Here is the exact material map:

HIGH-TEMPERATURE ZONE (450°C – 700°C)

✔ Required Material: A335 (P11 / P22 / P91)

Used for:

  • Main steam (HP)
  • Hot reheat
  • Superheater tubes
  • Reheater tubes
  • Boiler external piping
  • HRSG HP circuits
  • Furnace & primary steam lines

A335 Grade Selection:

Service Material
MP Steam P11
HP Steam P22
Supercritical & USC Steam P91
Reheater/Superheater P91
Primary Furnace Steam P22

B. LOW-TEMPERATURE ZONE (−45°C to +350°C)

✔ Required Material: A333 Grade 6 LTCS

Used for:

  • Condensate lines
  • Cold reheat
  • Cooling water systems
  • LP steam―condensate mix
  • Extraction steam lines
  • Auxiliary piping (cold sections)

Why A333 Gr 6?
High impact strength at −45°C, preventing brittle failures.

C. CORROSIVE / WET SERVICE (Condensate & Feedwater Zone)

✔ Required Material: A312 (304 / 316L)

Used for:

  • Feedwater lines
  • Condensate polishing unit (CPU)
  • Wet steam lines
  • Chemical dosing & water treatment
  • Low-chloride areas in the feed cycle

316L used when chlorides / chemicals are present.

Dimensional Range — Power Plant Pipe Materials

A335 P-Grades

| Size | ½” – 26″ |
| Schedules | SCH 40, SCH 80, SCH 160, XXS |
| Type | Seamless Only |

A333 Grade 6

| Size | ½” – 24″ |
| Schedules | SCH 40, SCH 80, SCH 160 |
| Type | Seamless |

A312 Stainless Steel

| Size | ½” – 24″ |
| Schedules | SCH 10S, 40S, 80S |
| Type | Seamless / Welded (we supply seamless for power plants) 

Dimensional Charts (Most Used Refinery Sizes)

A335 — Main Steam & Hot Reheat Lines

NB OD (mm) SCH 80 WT SCH 160 WT XXS WT
2″ 60.3 5.54 8.74 15.09
4″ 114.3 8.56 13.49 21.95
6″ 168.3 10.97 18.26 28.58
8″ 219.1 12.70 23.01 33.32

A333 Gr 6 — Condensate & LT Sections

Size OD (mm) SCH 40 SCH 80
1” 33.4 3.38 4.55
2” 60.3 3.91 5.54
3” 88.9 5.49 7.62
4” 114.3 6.02 8.56

A312 — Feedwater & Wet Service

Size OD SCH 10S SCH 40S
1” 33.4 2.77 3.38
2” 60.3 2.77 3.91
3” 88.9 3.05 5.49
4” 114.3 3.05 6.02

Price List — (INR + USD)

A335 Alloy Steel (P-Grades)

Grade INR/kg USD/kg
P11 ₹ 240 – 320 $3.10 – $4.20
P22 ₹ 260 – 350 $3.50 – $4.60
P91 ₹ 450 – 700 $6.00 – $9.30

A333 Gr 6 LTCS

Grade INR/kg USD/kg
A333 Gr 6 ₹ 170 – 240 $2.30 – $3.20

A312 Stainless Steel

Grade INR/kg USD/kg
304/304L ₹ 260 – 340 $3.40 – $4.30
316/316L ₹ 310 – 390 $4.10 – $5.20

Testing & QA Package for Power Plants

A335 (P-Grades)

  • Tensile Test
  • Yield / Elongation
  • Hardness Test
  • Creep Rupture (Mandatory for P91)
  • Microstructure Test (P91)
  • UT / ET
  • Hydrostatic Test
  • Heat Treatment Chart

A333 Gr 6

  • Impact Test at −45°C
  • Tensile Test
  • Chemical Analysis
  • UT
  • Hydrostatic Test

A312 (304 / 316L)

  • IGC Test
  • PMI
  • Hydrotest
  • UT / Eddy Current
  • Chemical Composition

Documentation for Power Plant EPCs

  • EN 10204 3.1 Material Certificate
  • Hydro / NDT Reports
  • PMI Reports
  • Heat Treatment Charts (P91)
  • Chemical Analysis Report
  • Dimensional Inspection Certificate
  • Packing List + Invoice + COO
  • TPI Reports (SGS / TUV / DNV / BV / Lloyds)

Value-Added Services for Power Plant Contractors

  • Pipe Cutting (±0.5mm)
  • End Beveling
  • PWHT for P11/P22/P91
  • Spool Fabrication
  • Bending Services
  • Weld Mapping Documentation
  • Ready Shutdown Stock
  • Priority Export Dispatch

Why Choose Inox Steel India for Power Plant Piping?

Power plants run under extreme thermal, pressure, corrosion, and cyclic conditions.
A failure in any line — especially steam or feedwater — leads to:

  1. Turbine trips
  2. Boiler shutdown
  3. HRSG damage
  4. Major safety hazards
  5. Huge generation losses

To prevent this, Inox Steel India supplies power-plant–grade, fully traceable, seamless pipes that are engineered for long-term reliability.

We specialize in the three critical pipe families used globally across all thermal and combined-cycle plants:

Industry Applications We Serve

A335 P11 / P22 / P91 — High-Temperature Steam Piping

Used in:

  • Main steam
  • Hot reheat
  • Superheater / Reheater
  • HRSG high-temperature circuits
  • Boiler external piping
  • Furnace steam lines

A333 Grade 6 — Low Temperature & Condensate

Used in:

  • Condensate lines
  • Cold reheat
  • Cooling systems
  • LP steam/condensate mix
  • Auxiliary LT piping

A312 (304 / 316L) — Feedwater, Condensate & Wet Service

Used in:

  • Feedwater systems
  • Condensate polishing unit (CPU)
  • Dosing & demineralized water lines
  • LP steam
  • Wet steam & corrosion-prone zones

Together, A335 + A333 + A312 cover complete power-plant piping from furnace to turbine.

Where These Materials Are Used in a Power Plant

BOILER & HRSG SECTION

  • HP steam → P91
  • IP steam → P22
  • LP steam → P11
  • Superheater / Reheater → P91/P22

Economizer section → P11

TURBINE SECTION

  • Hot reheat → P91
  • HP turbine inlet → P91

FEEDWATER & CHEMICAL SERVICE

  • Feedwater → A312 316L
  • Chemical dosing pipelines → A312
  • Boiler blowdown return lines → A312

CONDENSER AREA

  • Condensate return → A333 / A312
  • Cooling water → A333

BALANCE OF PLANT (BOP)

  • Instrument air & utilities → A312
  • LP steam → P11
  • Auxiliary piping → A333/A312

Power Plant Pipe Supplier Near Alankar Cinema, Mumbai

Inox Steel India maintains ready stock of:

  • A335 P11 / P22 / P91 (Steam lines)
  • A333 Grade 6 (Condensate/cooling service)
  • A312 304/316L (Feedwater & corrosion service)

Fast delivery to:

  • Tata Power
  • NTPC sites
  • JSW
  • UltraTech and cement CPPs
  • Industrial boiler OEMs
  • Power EPC contractors in Mumbai, Navi Mumbai, Thane & Panvel

We are located near Alankar Cinema, Mumbai, allowing same-day dispatch for shutdown jobs.

🌍 Export Capabilities — Power Sector Supply

We export complete power-plant piping packages to:

UAE • Saudi Arabia • Oman • Qatar • Kuwait • Bahrain
Egypt • Kenya • South Africa • Nigeria
Malaysia • Indonesia • Singapore • Thailand
Italy • Spain • Netherlands • Poland • UK
USA • Canada • Mexico

Each export bundle comes with:

  • Heat No. traceability
  • TPI stamping (SGS/TUV/DNV/BV/Lloyds)
  • 3.1/3.2 MTC
  • Hard stamping + color coding

Export Packaging — Power Plant Pipe Standards

✔ A335 (P11/P22/P91)

  • VCI wrap + corrosion oil
  • Bevelled cap protectors
  • Steel-strapped bundles
  • Heat No. stenciled bundle-by-bundle

✔ A333 Gr 6 (LTCS)

  • Poly coating
  • End caps
  • Weather-protected crates

✔ A312 (304/316L)

  • HDPE wrapping
  • Plastic end caps
  • Wooden box packing for small OD
  • Cleanroom-safe packing for CPU lines

Project Support Services Provided by Inox Steel India

We support EPC & power OEM customers with:

  • Material selection (steam zone vs LT vs wet service)
  • P91 heat treatment chart verification
  • Weldability & schedule selection
  • Spool fabrication
  • PWHT for P11/P22/P91
  • Dosing/water treatment compatibility checks
  • Complete pipeline package supply (Pipe + fittings + flanges)
  • Shutdown emergency dispatch
  • TPI coordination (SGS/TUV/DNV/BV)

Order Power Plant Piping Today

Inox Steel India supplies fully certified A335 / A333 / A312 pipes for:

  • Thermal power
  • Supercritical power
  • HRSG/CCGT
  • Biomass & WtE
  • Captive power
  • Process steam plants

Inox Steel India

52-A, Mulji Thackersi Bldg, Islampura Street, Shop No. 10, Near Alankar Cinema, Mumbai – 400 004

Email

alloy@inoxsteelindia.in, steel@inoxsteelindia.in

Phone

+91 9930796690

Frequently Asked Questions (FAQs)

Condensate, overhead water wash lines, reflux lines, utility lines, cooling water.

Sour gas (H₂S), chlorides, high-sulphur crude, FCC overhead, hydrocracker units.

Yes — mandatory for verifying correct metallurgy.

316L is — 304 is not recommended for high-chloride fluids.

Yes — MTC 3.1/3.2, PMI, NDT, hydro, HT chart, packing list, TPI reports.

Yes — A335/A312 always in stock; B444 on priority basis.

Inox Steel India supplies seamless A335 P11/P22/P91 alloy steel, A333 Grade 6 LTCS, and A312 stainless steel pipes for power plants. Ideal for main steam, hot reheat, condensate, feedwater & HRSG applications. TPI-approved, export-ready.

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