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Alloy Steel Welded Tubes Manufacturer, Supplier & Exporter – INOX STEEL INDIA

INOX STEEL INDIA is a recognised manufacturer and global supplier of Chrome-Moly Alloy Steel Welded Tubes, engineered for high-temperature, high-pressure, creep-resistant, and critical service environments.

These tubes are manufactured as welded equivalents of seamless ASTM A335 tubes, using high-alloy chrome-moly plates/strips and advanced welding technologies like:

TIG Welding (thin to medium wall)
SAW – Submerged Arc Welding (medium to thick wall)
HFIW / ERW (small OD welded tubes)

Alloy Steel Welded Tubes are the backbone of power plants, boilers, refinery heaters, petrochemical furnaces, and steam distribution networks, delivering superior durability and stability under extreme conditions.

What Are Alloy Steel Welded Tubes?

Alloy Steel Welded Tubes are formed by welding chrome-moly alloy steel plates/strips to produce a tube that can withstand:

High temperatures (400°C to 650°C)
High-pressure steam
Oxidation, scaling & creep
Thermal fatigue

Because they contain Cr + Mo + V + Nb depending on grade, these tubes offer:

Exceptional strength
High thermal stability
Resistance to corrosion & oxidation
Long service life in aggressive industrial conditions

Also known as:

Chrome-Moly Welded Tubes
ASTM A691 Welded Tubes
High-Temperature Alloy Tubes
Alloy Pressure Tubes
P-Grades Welded Tubes (P1, P5, P9, P11, P22, P91)

How Alloy Steel Welded Tubes Are Manufactured (Technical Explanation)

1️⃣ Material Selection

High-quality chrome-moly steel plates or coils are selected based on the grade:

P1 → 0.5 Mo
P5 / P9 → 5–9% Chromium
P11 / P22 → Creep strength for boiler & steam lines
P91 → Advanced modified alloy for ultra-supercritical power plants

2️⃣ Forming & Welding

Depending on wall thickness & OD:

Weld Method	Usage
ERW / HFIW	Small OD alloy welded tubes
TIG Welding	Clean, precise welds for thin-wall tubes
SAW Welding	High-strength welds for thick-wall tubes
Manual GTAW	Special joints & custom fabrication

INOX ensures full weld penetration and uniform seam quality.

3️⃣ Post Weld Heat Treatment (Critical Step)

All alloy steel welded tubes undergo PWHT at 720–780°C depending on grade.

Purpose of PWHT:

Restores grain structure
Removes residual stresses
Improves toughness & creep resistance
Ensures weld metal and HAZ stability

4️⃣ Heat Treatment Cycles (Grade Specific)

P1 / P11 → Normalising + tempering
P5 / P9 → Normalising + stabilising
P22 → Stress relieving + tempering
P91 → Normalising + tempering + controlled cooling

5️⃣ Testing & NDT

Every tube undergoes:

PMI (Positive Material Identification)
Hardness testing
Hydro testing
Ultrasonic / radiographic weld testing
Microstructure examination for P22 / P91

MASTER TECHNICAL DATA SHEET — ALLOY STEEL WELDED TUBES

Grades: ASTM A691 (P1, P5, P9, P11, P22, P91 small-OD equivalents) • Chrome-Moly Alloy Tubes
Brand: INOX STEEL INDIA
Application: High-temperature • High-pressure • Power plant • Boiler • Refinery

Section	Parameter	Technical Specification
General	Product	Alloy Steel Welded Tubes (Chrome-Moly)
	Alternate Names	AS Welded Tubes • Chrome Moly Welded Tubes • ASTM A691 Welded Tubes
	Manufacturing Method	Welded from chrome-moly plates/strips using TIG / SAW / ERW / HFIW depending on OD
	Functional Category	High-temperature service • Pressure piping • Boiler tubing • Steam lines
Material Grades	Chrome-Moly Grades	ASTM A691 P1, P5, P9, P11, P22, P91
	Equivalent Standards	ASTM A335 (seamless equivalent) • ASME SA691
	Alloy Composition	Grades contain Cr (1–12%) + Mo (0.5–1.25%) for heat & creep resistance
Dimensional Range	OD	19 mm – 508 mm (small to medium OD welded equivalents)
	Thickness	2.0 – 20 mm
	Length	Up to 12m / custom cut
Mechanical Properties	P1 (0.5 Mo)	YS ≥ 205 MPa • TS ≥ 380 MPa
	P11 / P22	YS ≥ 275–310 MPa • TS ≥ 485–620 MPa
	P91	Ultra high temperature, creep resistant
Chemical Composition (Typical)	P1	0.1% C • 0.5% Mo
	P5	5% Cr • 0.5% Mo
	P9	9% Cr • 1% Mo
	P11	1.25% Cr • 0.5% Mo
	P22	2.25% Cr • 1.0% Mo
	P91	9% Cr • 1% Mo + V + Nb
Welding Characteristics	Weld Types	TIG • SAW • HFW • ERW
	Filler Wire	ER80S-B2 / ER90S-B3 / ENiCrMo rods depending on grade
	Post Weld Heat Treatment	Mandatory PWHT (760–780°C) depending on grade
Testing & QA	Mandatory Tests	Hydro test • PMI • Hardness • Tensile • Impact Test
	NDT	UT • RT • MPI • DPT
	Special Tests	Creep test (for P22/P91) • Microstructure
Standards	Welded Alloy Tubes	ASTM A691, ASME SA691
	Equivalent	ASTM A335 (seamless)
Applications	High-Temp Service	Steam lines • Power plant headers • Refinery heaters
	High-Pressure Service	Feedwater piping • Superheaters • Reheaters
	Petrochemical	High-temperature reactor coils
End Conditions	Ends	Plain • Bevelled • Weld-prep ends
HSN Code	Carbon/Alloy Welded Tubes	7306.50.90

Alloy Steel Welded Tubes vs Seamless Alloy Tubes

Feature	Welded Alloy (A691)	Seamless Alloy (A335)
Cost	Lower	Higher
Availability	Faster	Longer lead time
Sizes	Excellent for large OD	Limited to small OD
Weld Strength	Very high (SAW/TIG)	No weld
Temperature & Pressure	High	Very high
Fabrication	More flexible	Less flexible

Conclusion:
Welded alloy tubes (A691) provide cost-effective performance for 80% of high-temperature service applications.

Key Advantages of INOX Alloy Steel Welded Tubes

01.

Manufactured to ASTM A691 Standards:

Fully compliant with ASME Boiler & Pressure Vessel Codes.

02.

Suitable for Temperatures Upto 620°C:

Ideal for: Boilers, Superheaters, Reheaters, Furnace coils, and Power plant steam lines.

03.

Available in All Chrome-Moly Grades:

P1 • P5 • P9 • P11 • P22 • P91.

04.

PWHT Performed on Every Weld:

Ensures maximum safety & stability under thermal stress.

05.

Wide OD Range (19 mm – 508 mm):

Suitable for both small OD piping and large-diameter steam lines.

06.

Industry-Leading NDT & Documentation:

Including weld map, heat treatment charts, 3.1 certification.

Applications of Alloy Steel Welded Tubes

A. Power Plants

Steam headers
Boiler tubes
Reheater & superheater coils
Ash handling systems

B. Refinery & Petrochemical Plants

Heater tubes
Furnace coils
Reactor feed piping
Hydrogen reformer tubes

C. Chemical Plants

High-temperature reactors
Catalytic cracking units

D. Industrial Steam Systems

High-pressure steam distribution
Feedwater lines

E. Oil & Gas Processing

High-temperature separators
Riser systems

Market Demand – India & Global

🇮🇳 India Demand Drivers:

NTPC power plants
Petrochemical expansion
Boiler manufacturing clusters (Tiruchirappalli, Pune, Gujarat)

Export Markets:UAE • Saudi Arabia • Oman • Kuwait • Qatar • South Africa • Indonesia • Malaysia

APPLICATION MAPPING — GRADE-WISE

ASTM A691 P1 — Low Alloy (0.5 Mo)

Application	Temperature	Notes
Feedwater lines	Up to 400°C	Good weldability
General boiler piping	Moderate temp	Economical alloy

ASTM A691 P5 / P9 — Medium Chrome-Moly

Grades	Cr-Mo %	Application
P5 (5Cr-0.5Mo)	Medium-temp steam	Refinery heaters
P9 (9Cr-1Mo)	High-temp & oxidation	Furnace coils

ASTM A691 P11 / P22 — High Temperature Steam Applications

Grade	Properties	Used For
P11 (1.25Cr-0.5Mo)	Good creep resistance	Steam piping
P22 (2.25Cr-1Mo)	Higher creep & heat resistance	Boiler headers, reheaters

ASTM A691 P91 — Ultra High-Temperature Alloy

9Cr-1Mo-V-Nb modified steel used in ultra-supercritical power plants.
Best resistance to:
creep
thermal fatigue
oxidation at 600°C+
Typical applications: main steam lines, hot reheat lines, high-pressure boiler circuits.

SIZE RANGE, OD/WT CHART & DIMENSIONAL CAPACITY

ROUND ALLOY STEEL WELDED TUBES

Outside Diameter (OD)	Wall Thickness (WT)	Length
19 – 60 mm	2.0 – 6.0 mm	Up to 12m
60 – 168 mm	2.5 – 12 mm	Up to 12m
168 – 323.9 mm	3 – 18 mm	Up to 12m
323.9 – 508 mm	4 – 20 mm	Up to 12m

(Weld types depend on WT & OD: TIG for thin-wall, SAW for thicker tubes.)

ALLOY SELECTION CHART (GRADE FINDER)

Temperature	Pressure	Recommended Grade	Reason
300–400°C	Medium	P1	Cost-effective, stable
400–500°C	High	P11	Good creep strength
500–580°C	Very high	P22	Excellent thermal fatigue resistance
580–620°C	Extreme	P5 / P9	Strong oxidation resistance
600°C+	Ultra-critical	P91	Highest creep strength

TESTING & QUALITY ASSURANCE (PQRS Compliant)

Mandatory Tests

PMI (100% material verification)
Hydrostatic Test
Tensile Test
Yield & Elongation
Hardness (HBW)
Flattening / Flaring

NDT Tests

RT – Radiographic Test on Weld
UT – Ultrasonic Testing
Magnetic Particle Test (for weld HAZ)
Dye Penetrant (DPT)

Special Tests for P22/P91

Microstructure examination
Charpy Impact Test
Creep rupture test
PWHT validation curve

Documentation

EN 10204 – 3.1 / 3.2
Weld Map
Heat Treatment Chart
NDT Report
Chemical & Mechanical test report
Traceability Chart (Heat-wise, Lot-wise)

WELDING PROCEDURES & FILLER WIRES

Welding Methods: TIG (GTAW), SAW (Submerged Arc Welding), HFIW / ERW, SMAW (site welding).

Recommended Filler Wires (Per Grade)

Alloy Grade	Welding Rod / Filler Wire	Standard
P1	ER70S-2	Mild alloy filler
P5	ER80S-B2	1.25Cr-0.5Mo
P9	ER90S-B3	2.25Cr-1Mo
P11	ER80S-B2	Similar chemistry
P22	ER90S-B3	High creep resistance
P91	ERNiCrMo-3 (Inconel filler)	For metallurgical stability

Post Weld Heat Treatment

Grade	PWHT Range
P1	620–650°C
P11	700–750°C
P22	740–780°C
P5 / P9	720–760°C
P91	750–780°C (Controlled cooling required)

PRICE LIST (2025 — INR & USD)

Alloy Steel Grade	Type	Price (INR/kg)	Price (USD/kg)
P1 Alloy Steel Welded Tubes	Black	₹ 145 – ₹ 185	$1.80 – $2.30
P5 / P9 Welded Tubes	Black	₹ 210 – ₹ 280	$2.50 – $3.40
P11 Welded Tubes	PWHT	₹ 180 – ₹ 240	$2.20 – $3.00
P22 Welded Tubes	PWHT	₹ 210 – ₹ 300	$2.60 – $3.60
P91 Welded Tubes	Normalised + tempered	₹ 380 – ₹ 550	$4.50 – $7.00

Price varies based on OD, WT, welding method, test level & heat treatment.

TYPICAL APPLICATIONS — ENGINEERING CHART

Application	Grade	Reason
Boiler tubes	P11 / P22	Heat + creep resistance
Steam headers	P22 / P91	High pressure & temperature
Refinery heater tubes	P5 / P9	Oxidation resistance
Superheater / reheater	P22 / P91	Creep-rupture strength
Petrochemical piping	P5 / P9	High stability in hot gases
Power plant main steam lines	P91	Ultra high temperature

Why Choose INOX STEEL INDIA for Alloy Steel Welded Tubes?

Alloy steel welded tubes require precision metallurgy, controlled welding processes, mandatory PWHT, and strict NDT compliance. INOX STEEL INDIA is trusted by power plants, refineries, boiler manufacturers, and EPC contractors because:

All Grades Available: P1, P5, P9, P11, P22, P91: We are among the few manufacturers/suppliers offering chrome-moly welded tubes across the entire P-grade spectrum, matching A691 & A335 specifications.
Strict PWHT (Post Weld Heat Treatment) Control: Each weld is heat-treated based on Grade chemistry, Wall thickness, and Intended service temperature. We maintain full PWHT Cycle Charts for documentation.
Welded with TIG / SAW / HFIW for Complete Penetration & Integrity: Ensures Uniform microstructure, No porosity, and High creep & fatigue resistance.
Complete NDT + Metallurgical Testing: Every batch includes RT / UT of weld, PMI, Hardness, Tensile, Impact (for P22/P91), and Microstructure analysis.
Guaranteed Material Traceability: We provide heat numbers, weld maps, PWHT charts, and 3.1 certificates for every tube.
Ready Stock + Custom Production: Small OD tubes, Thick-wall SAW welded tubes, and Large OD tubes up to 508 mm.
Export Quality Packaging & Documentation: Used across refineries, petrochemical units & power plants in GCC, EU, Africa, and Southeast Asia.

Alloy Steel Welded Tube Supplier in Mumbai, Gujarat, Chennai, Hyderabad, Pune & Pan-India

Customers searching for:
“alloy steel pipe specifications”, “alloy steel pipe grades”, “alloy pipe price per kg”, “alloy steel welded tubes supplier near me”, “A691 P22 welded tubes”, “P11/P22/P91 alloy tubes price”.

Find INOX STEEL INDIA because:

Stock locations include: Mumbai • Ahmedabad • Vadodara • Surat • Pune • Chennai • Hyderabad • Delhi NCR • Bengaluru
Export capability: UAE • Saudi Arabia • Kuwait • Oman • South Africa • Indonesia • Malaysia • Bangladesh • Europe

Industries We Serve

Industry	Applications	Grade Range
Thermal Power Plants	Steam lines, headers, reheaters	P11, P22, P91
Refineries	Heater tubes, reformers	P5, P9
Petrochemicals	Furnace coils, reactors	P5, P9
Boiler Manufacturers	Superheater, economizer	P11, P22
Chemical Plants	High-temperature process lines	P1, P11
Oil & Gas	High-pressure piping	P22, P91

Packaging & Export Readiness

STANDARD PACKAGING

Heavy-duty steel-strapped bundles
Anti-rust oiling
Plastic/LDPE wrapping

EXPORT PACKAGING

Wooden crates or pallets
VCI moisture protection
End caps for cleanliness
Export marking with grade, heat number, batch

DOCUMENTATION

EN 10204 Type 3.1 / 3.2 Certificates
Heat Treatment (PWHT) Charts
NDT Reports (RT/UT)
Mechanical & Chemical test reports
PMI Mapping & Weld Map Documentation

Get Best Price for Alloy Steel Welded Tubes (P1, P11, P22, P91)

For Chrome-Moly Alloy Steel Welded Tubes manufactured to ASTM A691 & ASME SA691:

Inox Steel India

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

Email

alloy@inoxsteelindia.in

Phone

+91 9930796690

FAQs

What are alloy steel welded tubes used for?

They are used for high-temperature, high-pressure service such as boilers, power plants, refineries & steam lines.

What is the price of alloy steel tubes per kg in India?

Alloy steel welded tubes range from ₹145/kg to ₹550/kg, depending on grade (P1 to P91), OD & WT.

Which grades are available?

ASTM A691 P1, P5, P9, P11, P22, P91.

What welding process is used?

TIG, SAW, and HFIW/ERW depending on thickness & OD.

What filler wire is used for alloy steel welding?

Grades like P11/P22 use ER80S-B2 / ER90S-B3, while P91 requires Inconel-based ENiCrMo fillers.

What is the difference between A691 welded and A335 seamless?

A691 is welded and economical; A335 is seamless and preferred for extreme pressure.

Are PWHT and NDT mandatory?

Yes — PWHT is critical for chrome-moly tubes and NDT ensures weld integrity.

Manufacturer & supplier of Alloy Steel Welded Tubes in ASTM A691 grades P1, P5, P9, P11, P22, P91. Chrome-moly high-temperature welded tubes for boilers, power plants, refineries & steam lines. PWHT + NDT tested. Exporter to GCC, Europe, Africa & Asia.