Boiler Tube

Boiler Tube

Product Overview

Boiler tubes are specialized steel tubes designed for heat transfer and fluid conveyance in boilers, heat exchangers, condensers, and other thermal equipment. Unlike standard line pipe or OCTG products, boiler tubes must withstand sustained high temperatures, high internal pressures, and thermal cycling while maintaining efficient heat transfer.

The fundamental distinction between boiler tubes and pipes lies in their function: tubes are designed for both heat transfer and fluid conveyance, whereas pipes serve only for conveyance. Tubes are manufactured with closer dimensional tolerances and lower carbon content to facilitate bending and welding.

Product Types

1 Conventional Boiler Tubes (Plain Tubes)

Standard seamless or welded tubes used in boiler water walls, furnace walls, and general heat exchange applications. These are the most common boiler tube products.

2 Internal Rifled / Ribbed Tubes

Tubes with spiral ribs on the internal surface that enhance heat transfer efficiency by promoting turbulence in the fluid flow. Widely used in subcritical and supercritical boiler water walls to suppress film boiling and prevent tube overheating.

3 HRSG Tubes (Heat Recovery Steam Generator)

Specialized tubes used in combined cycle power plants to recover waste heat from gas turbine exhaust. These tubes must withstand thermal cycling and often utilize finned surfaces for enhanced heat recovery efficiency.

4 Finned Tubes

Tubes with extended surfaces (fins) welded or integrally formed on the outer surface. Types include:

• Spiral Finned Tubes: Continuous helix fins for maximum surface area
• Serrated Finned Tubes: Enhanced fin geometry for improved heat transfer
• Studded Tubes: Studs welded to the surface for specialized applications

5 Header / Manifold Pipes

Large-diameter pipes used in boiler systems to collect and distribute steam and water. Headers connect multiple tubes and require high-strength materials to withstand thermal and pressure stresses.

6 Heat Exchanger Tubes

Tubes specifically designed for shell-and-tube heat exchangers, featuring precise dimensional tolerances and smooth internal surfaces to optimize heat transfer efficiency.

7 High-Pressure Drum Tubes

Thick-walled tubes used in boiler drums where steam and water separation occurs. These require superior mechanical properties and strict quality control.

8 Condenser Tubes

Tubes used in surface condensers to condense exhaust steam from turbines. Typically manufactured with corrosion-resistant materials including stainless steel, titanium, and copper-nickel alloys.

9 Gas Turbine Tubes

Specialized tubes for gas turbine exhaust systems and recuperators, requiring high-temperature oxidation resistance.

Manufacturing Processes

1 Seamless Tubes

• Produced by piercing solid billets through processes including:

Process	Size Range	Features
Mandrel Mill	Up to 340 mm OD	High-volume production with consistent quality
Plug Mill	Up to 406 mm OD	Suitable for larger diameters
Pilger Mill	Up to 700 mm OD	Best for large diameters (325 mm+), versatile but slower
Push Bench (CPE)	Up to 178 mm OD	Cost-effective for medium sizes
Extrusion	Up to 260 mm OD	Suitable for special alloys, higher cost

2 Electric Resistance Welded (ERW) Tubes

• Produced by folding and welding steel strip. ERW tubes offer:
• Smoother internal surface resulting in lower pressure drop
• Better bore concentricity (superior for tube expansion)
• Lower cost, especially for thinner walls
• Virtually identical physical and chemical properties to seamless tubes

Materials

1 Carbon Steel

Grade	Standard	Temperature Range	Applications
ASTM A179	Seamless cold-drawn low-carbon steel	Moderate temp.	Heat exchangers, condensers
ASTM A192 / ASME SA192	High-pressure seamless carbon steel	Up to ~400°C	Boiler and superheater tubes
ASTM A210 (A-1 / C)	Medium-carbon steel	Up to ~400°C	Boiler, superheater, and economizer tubes
ASTM A106 (Gr. B / C)	High-temperature carbon steel	Up to ~400°C	Refinery and power plant piping
EN 10216-2 P235GH / P265GH	Carbon steel for pressure	–20°C to 400°C	General pressure applications

2 Low-Alloy / Chrome-Moly Steel

Grade	Standard	Temperature Range	Applications
16Mo3 (1.5415)	EN 10216-2	Up to 500°C	Medium-temperature service
13CrMo4-5 (P11)	ASTM A335 / EN 10216-2	Up to 550°C	Superheaters, reheaters
10CrMo9-10 (P22)	ASTM A335 / EN 10216-2	Up to 575°C	High-temperature headers and piping
X11CrMo5-1 (P5)	ASTM A335	Up to 600°C	Elevated temperature service
X11CrMo9-1 (P9)	ASTM A335	Up to 600°C	Refinery and power generation

3 High-Strength Creep-Resistant Steels

Grade	Standard	Temperature Range	Applications
T91 / P91 (9Cr-1Mo-V)	ASTM A213 / A335	Up to 625°C	Superheaters, reheaters, sub/super-critical units
P92 (9Cr-0.5Mo-1.8W-V)	ASTM A335	Up to 650°C	Ultra-supercritical units
T23 (2.25Cr-1.6W-V)	ASTM A213	Up to 600°C	Water walls, superheaters
T24 (7Cr-0.5Mo-0.2V)	ASTM A213	Up to 600°C	Water walls, improved creep properties

Note: Grade T91/P91 demonstrates superior creep rupture strength (157 MPa at 600°C for 105 hours) and replaces 18-8 series austenitic steels in many applications.

4 Austenitic Stainless Steel

Grade	Standard	Temperature Range	Applications
TP304 / 304H	ASTM A213	Up to 800°C	Superheaters, high-temperature service
TP316 / 316H	ASTM A213	Up to 800°C	High-temperature corrosive environments
TP321 / 321H	ASTM A213	Up to 850°C	High-temperature service, thermal cycling
TP347H	ASTM A213	Up to 850°C	High-temperature superheaters, thermal stress resistance

5 Nickel-Base Alloys

Alloy	UNS	Temperature Range	Applications
Alloy 740 (N07740)	Age-hardened Ni-base	Up to 700°C+	Advanced ultra-supercritical (AUSC) units
Inconel 625	N06625	Up to 980°C	High-temperature corrosive environments
Incoloy 800H / 800HT	N08810/N08811	Up to 982°C	Superheaters, reheaters, nuclear components

Nickel-base alloys are essential for AUSC applications where conventional ferritic and austenitic tubes require unrealistically large wall thicknesses at temperatures and pressures above 700°C.

6 Low-Temperature Nickel Steels

Grade	Standard	Temperature Range	Applications
P215NL / P265NL	EN 10216-3/4	Down to –50°C	Low-temperature pressure service
P355NL1 / NL2	EN 10216-3	Down to –50°C	Low-temperature pressure vessels
X10Ni9 (9% Ni Steel)	EN 10216-4	Down to –196°C	Cryogenic applications, LNG
12Ni14	EN 10216-4	Down to –196°C	Cryogenic service

7 Material Comparison Summary

Property	Carbon Steel	Cr-Mo Alloy	Stainless Steel	Nickel Alloy
Thermal Conductivity	Good	Moderate	Lower	Low
Corrosion Resistance	Low	Moderate	High	Excellent
High-Temp Strength	Up to ~400°C	Up to ~650°C	Up to ~850°C	Up to 700°C+
Key Standards	A179, A192, A210	A213, A335	A213, A249	Special specifications

Applicable Standards

1 American Standards (ASTM / ASME)

Standard	Description
ASTM A179 / ASME SA179	Seamless cold-drawn low-carbon steel heat exchanger and condenser tubes
ASTM A192 / ASME SA192	Seamless carbon steel boiler tubes for high-pressure service
ASTM A210	Seamless medium-carbon steel boiler and superheater tubes
ASTM A213 / ASME SA213	Seamless ferritic and austenitic alloy-steel boiler, superheater, and heat exchanger tubes
ASTM A249	Welded austenitic steel boiler, superheater, heat exchanger, and condenser tubes
ASTM A106 / ASME SA106	Seamless carbon steel pipe for high-temperature service
ASTM A335 / ASME SA335	Seamless ferritic alloy-steel pipe for high-temperature service

2 European Standards (EN)

Standard	Description
EN 10216-1	Seamless steel tubes for pressure purposes – Technical delivery conditions – Part 1: Non-alloy steel tubes with specified room temperature properties
EN 10216-2	Seamless steel tubes for pressure purposes – Part 2: Non-alloy and alloy steel tubes with specified elevated temperature properties
EN 10216-3	Seamless steel tubes for pressure purposes – Part 3: Alloy fine grain steel tubes
EN 10216-4	Seamless steel tubes for pressure purposes – Part 4: Low alloy steel tubes with specified low temperature properties
EN 10216-5	Seamless stainless steel tubes for pressure purposes

3 Chinese Standards (GB)

Standard	Description
GB/T 3087	Seamless steel tubes for low and medium pressure boilers
GB/T 5310	Seamless steel tubes for high-pressure boilers
GB/T 6479	Seamless steel tubes for high-pressure chemical equipment
GB/T 13296	Seamless stainless steel tubes for boilers and heat exchangers

4 German Standards (DIN)

Standard	Description
DIN 17175	Seamless steel tubes for high-temperature service (superseded by EN standards)

5 Japanese Standards (JIS)

Standard	Description
JIS G3461	Carbon steel boiler and heat exchanger tubes
JIS G3462	Alloy steel boiler and heat exchanger tubes

Full Range of Specifications

1 Outside Diameter (OD) Range

Size Category	OD (mm)	OD (inches)	Typical Applications
Small Diameter	13.5 – 60.3	1/2 – 2 3/8	Instrumentation, heat exchangers
Medium Diameter	63.5 – 168.3	2 1/2 – 6 5/8	Superheaters, reheaters, water walls
Large Diameter	177.8 – 355.6	7 – 14	Headers, drums, high-pressure piping
Extra Large	406.4 – 711	16 – 28	Steam piping, large headers
Ultra Large	762 – 1,000+	30 – 40+	Main steam piping, power plant headers

2 Wall Thickness Range

Available wall thicknesses typically range from 1.8 mm to 60 mm, depending on diameter, material, and service conditions.

3 Lengths

Length Type	Range	Application
Fixed Length	5.8 m, 6.0 m, 11.8 m, 12.0 m	Standard production
Single Random Length (SRL)	5.0 – 7.0 m	General applications
Double Random Length (DRL)	10.0 – 14.0 m	Reducing field welds
Extended Length	Up to 30 m	Maximum available – special order

Shapes and Configurations

1 Straight Tubes

• Standard configuration for most boiler and heat exchanger applications. Available as:
• Hot-Finished (HFS): Standard tolerance, lower cost

Cold-Drawn (CDS): Closer tolerance, preferred for superheaters and reheaters where tolerance impacts performance

2 U-Bent Tubes

Tubes bent into U-shapes for heat exchangers and certain boiler configurations. U-bending requires materials with good ductility and consistent wall thickness.

3 Serpentine / Coil Tubes

Continuously bent tubes arranged in serpentine patterns for maximum heat transfer surface in confined spaces.

4 Custom Bends

Tubes can be bent to customer-specified radii and configurations for specialized boiler and heat exchanger designs. Materials with lower carbon content are preferred for tighter bending.

Service Conditions

1 Low-Temperature Service

Condition	Temperature Range	Typical Applications
Low-Temperature Service	–50°C to 0°C	Economizers, low-pressure sections
Cryogenic Service	–196°C to –50°C	LNG, specialized applications

• Materials: P215NL, P265NL, P355NL, X10Ni9 (9% Ni steel)

2 Medium-Temperature Service

Condition	Temperature Range	Typical Applications
Medium-Temperature	0°C to 400°C	Water walls, economizers, low-pressure boilers

• Materials: A179, A192, P235GH, P265GH

3 High-Temperature Service

Condition	Temperature Range	Typical Applications
High-Temperature	400°C to 600°C	Superheaters, reheaters, high-pressure sections

• Materials: P11, P22, 16Mo3, T91

4 Supercritical / Ultra-Supercritical (USC/AUSC)

Condition	Temperature Range	Typical Applications
Supercritical (SC)	Up to 600°C	Modern coal-fired units
Ultra-Supercritical (USC)	Up to 650°C	Advanced power plants
Advanced Ultra-Supercritical (AUSC)	>700°C	Next-generation plants

Materials: T91/P91, T92/P92, austenitic stainless steels (304H, 321H), nickel-base alloys (Alloy 740)

5 Nuclear Service

Application	Requirements
Nuclear Power Components	Long-term radiation environment reliability, stringent quality control, specific nuclear-grade material certifications

• Materials: Nuclear-grade austenitic stainless steels and nickel alloys

Surface Treatments and Finishes

Finish Type	Description
Bare / Plain	Standard as-rolled finish
Lightly Oiled	Temporary corrosion protection during storage and transport
Black / Red / Yellow Painting	Color-coded protective coatings for identification and corrosion protection
Zinc / Anti-corrosive Coating	Enhanced corrosion protection for longer storage or aggressive environments
Polished Surface	Smooth internal surface for reduced pressure drop in heat exchangers

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