Multi-Rifled Seamless Steel Tubes are precision-engineered seamless steel tubes with internal rifling designed to enhance heat transfer efficiency in high-pressure boilers and heat exchangers. Compliant with standards like ASME SA213 and DIN 17175, these rifled boiler tubes optimize thermal performance, offering superior strength and corrosion resistance for demanding industrial applications.

Manufactured from low-carbon or alloy steels, such as SA213 T2, T12, or 15Mo3, seamless heat transfer tubes are produced through cold-drawing or hot-rolling processes, with internal helical ribs formed to increase surface area and promote turbulent flow. Available in outer diameters from 19 mm to 76.2 mm and wall thicknesses from 2 mm to 8 mm, these tubes are ideal for water-tube boilers, superheaters, and heat exchangers. The rifled design enhances heat transfer by up to 30% compared to smooth tubes, improving energy efficiency.

High-strength rifled tubes undergo rigorous testing, including hydrostatic, ultrasonic, and eddy current tests, to ensure defect-free material and compliance with standards. With tensile strengths ranging from 415 MPa (T2) to 510 MPa (T12), these tubes resist thermal stress and high-pressure conditions. Surface treatments like pickling or anti-corrosion coatings enhance corrosion-resistant rifled tubes durability in environments with acidic or high-temperature fluids, such as those in power plants or petrochemical facilities.

Compared to smooth seamless tubes, multi-rifled seamless steel tubes offer superior heat transfer due to their internal ribs, which induce turbulence and improve fluid mixing. This design reduces fouling and scaling, extending tube lifespan. Customizable rifling patterns (e.g., 4, 6, or 8 ribs) and dimensions meet specific boiler or exchanger requirements, addressing challenges like thermal inefficiency and material degradation.

From power generation to chemical processing, rifled boiler tubes deliver reliable, efficient, and safe solutions for heat transfer applications. Their advanced design and compliance with international standards make them a preferred choice for optimizing thermal performance in industrial systems.

Comparison with Other Grade Pipes

Multi-Rifled Seamless Steel Tubes (SA213 T2, T12, 15Mo3) are optimized for enhanced heat transfer in boilers, offering superior thermal efficiency compared to smooth seamless tubes or standard pressure pipes like ASTM A106. Below is a comparison highlighting differences in application, heat transfer, and strength.

Comparison of Multi-Rifled Seamless Tubes with ASTM A179 and ASTM A106 Pipes
Feature	Multi-Rifled Tubes (SA213 T2, T12, 15Mo3)	ASTM A179 Smooth Tubes	ASTM A106 Pipe (Grade B)
Application	High-pressure boilers, superheaters, heat exchangers	Heat exchangers, condensers	High-temperature pressure piping
Tensile Strength (MPa)	415–600	325	415
Yield Strength (MPa)	205–270	180	240
Heat Transfer Efficiency	High (rifling increases by up to 30%)	Moderate (smooth surface)	Low (not designed for heat transfer)
Corrosion Resistance	High (coatings for acidic fluids)	Moderate (basic coatings)	Moderate (depends on environment)
Seamless Design	Seamless with internal rifling	Seamless, smooth	Seamless
Operating Conditions	High thermal stress, high pressure	Moderate thermal stress	High temperature, pressure

Why Choose Multi-Rifled Tubes?
Unlike smooth ASTM A179 tubes or ASTM A106 pipes, multi-rifled tubes provide enhanced heat transfer efficiency due to internal ribs, making them ideal for high-pressure boilers and superheaters requiring optimal thermal performance.

Key Benefits

Enhanced Heat Transfer

Rifling increases efficiency by up to 30%.

Corrosion Resistance

Coatings protect against acidic and high-temperature fluids.

High Strength

Withstands high pressure and thermal stress.

Reduced Fouling

Rifled design minimizes scaling and deposits.

Customizable Rifling

Tailored rib patterns for specific applications.

Standards Compliance

Meets ASME SA213 and DIN 17175 standards.

CDS

What Is Internally Rifled Boiler Tube?

Their unique design, with internal spiral ribs, delays the boiling crisis, allowing for better heat transfer and preventing potential overheating. This makes them particularly valuable in subcritical and supercritical pressure boilers, though they come at a higher cost compared to plain tubes.

Internally rifled boiler tubes are characterized by their internally rifled shape, which features spiral ribs on the inner surface. This design is accomplished through a cold - drawing process, with a lead angle (spiral angle) of 30 degrees relative to the tube axis plane. The primary function is to boost heat transfer efficiency by deferring the boiling crisis. The boiling crisis is a situation where heat transfer becomes inefficient due to film boiling. By preventing film boiling and overheating, these tubes ensure safer and more efficient operation within high - pressure boiler systems.

The internal rifles generate turbulence and increase the internal surface area, which aids in maintaining nucleate boiling and eradicating the steam film that may form on the tube's inner surface. This is especially vital in subcritical and supercritical pressure boilers, where the operating conditions are extreme.

Customized

Rifle Geometries

As described above the heat transfer rate can be optimized by varying the rifling geometry based on operation conditions.

In addition to the standard rifle tubes (covered in this brochure), SunnySteel manufactures rifled tubes to suit any customized geometry and in all boiler steel grades. We regularly manufacture and deliver such customized solutions at short notice.

Customized

Internally Ribbed Boiler Tubes

Specialized steel pipes with internal ribs, designed to prevent film boiling and enhance heat transfer efficiency in high-temperature, high-pressure boilers.

Internally ribbed boiler tubes are used in furnace power plants and facilities with extreme conditions to optimize heat transfer. In subcritical steam power plants, water in water wall tubes boils into steam. Under high-temperature and high-pressure conditions, film boiling can occur, forming a steam layer at the liquid-tube interface that reduces heat transfer efficiency. This can lead to overheating, risking boiling explosions and equipment damage.

These tubes feature butterfly-shaped fins on their inner surface, creating turbulence that suppresses film boiling. The ribs increase the internal surface area compared to unribbed tubes, enhancing boiler energy output efficiency. They also reduce mass flow and ensure adequate cooling of the tube’s internal surfaces, supporting safer and more efficient operations.

Modern power plants demand improved fuel efficiency and reduced CO2 emissions, requiring highly pressurized and heated steam. Internally ribbed tubes meet these needs by optimizing heat transfer and maintaining stable performance under extreme conditions.

Multi-Rifled Seamless Steel Tube Standard Specifications

Rifle Tubes can be supplied against ASTM, ASME, A/SA 192, 209, 210 and 213 specifications and all associated grades. Tubes can be supplied against equivalent specifications like EN 10216, DN 17175, BS 3059, JIS 3461, 3462. Tubes can be supplied to bath A and B type profiles. Detailed dimensions for each profile are given in the table.

Multi-rifled seamless steel tube are produced to meet specific end use requirements, specifications, tolerances and chemistries.
Grade	O.D.(mm)	W.T.(mm)	Number of rib
20G 15CrMoG SA-210A1 SA-210C SA-213 T2 SA-213 T12	22-83	4.5-13	4-14

Chemical Composition of Multi-Rifled Seamless Steel Tube (wt%)
Material (Grade)	C	Mn	Si	Cr	Mo	S	P
20G	0.17~0.23	0.35~0.65	0.17~0.37	---	---	≤0.020	≤0.025
20MnG	0.17~0.23	0.70~1.00	0.17~0.37	---	---	≤0.020	≤0.025
25MnG	0.22~0.29	0.70~1.00	0.17~0.37	---	---	≤0.020	≤0.025
12CrMoG	0.08~0.15	0.40~0.70	0.17~0.37	0.40~0.70	0.40~0.55	≤0.020	≤0.025
15CrMoG	0.12~0.18	0.40~0.70	0.17~0.37	0.80~1.10	0.40~0.55	≤0.020	≤0.025
SA-210A1	≤0.27	≤0.93	≥0.10	---	---	≤0.035	≤0.035
SA-210C	≤0.35	0.29~1.06	≥0.10	---	---	≤0.035	≤0.035
SA-213T2	0.10~0.20	0.30~0.61	0.10~0.30	0.50~0.81	0.44~0.65	≤0.025	≤0.025
SA-213T12	0.05~0.15	0.30~0.61	≤0.50	0.80~1.25	0.44~0.65	≤0.025	≤0.025

Mechanical Properties of Multi-Rifled Seamless Steel Tube
Material (Grade)	Tensile strength (MPa)	Yield strength (MPa)	Elongation(%)	Hardness
20G	410~550	245	≥24	---
20MnG	≥415	≥240	≥22	---
25MnG	≥485	≥275	≥20	---
12CrMoG	410~560	≥205	≥21	---
15CrMoG	440~640	≥235	≥21	---
SA-210C	≥415	≥255	≥30	≤143HBW
SA-210A1	≥485	≥275	≥30	≤179HBW
SA-213T2	≥415	≥205	≥30	≤163HBW
SA-213T12	≥415	≥220	≥30	≤163HBW

Dimensions of Drilling Tubes by Series (mm)
Material (Grade)	Heat treatment
20G	Normalizing at 900℃~930℃, the holding time is 1min/mm according to the wall thickness, but should not be less than 12min.
20MnG	Normalizing at 900℃~930℃, the holding time is 1min/mm according to the wall thickness, but should not be less than 12min.
25MnG	Normalizing at 900℃~930℃, the holding time is 1min/mm according to the wall thickness, but should not be less than 12min.
12CrMoG	900°C~930°C normalizing; 670°C~720°C tempering, holding time: Periodic furnace is more than 2h, continuous furnace is more than 1h.
15CrMoG	Normalizing at 930°C~960°C; tempering at 680°C~720°C, holding time: periodic furnace greater than 2h, continuous furnace greater than 1h.

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Standards and Specifications

• ASME SA213 rifled boiler tubes
• DIN 17175 seamless heat transfer tubes
• Multi-rifled seamless steel tube standards
• High-strength rifled tubes specifications

Applications

• Rifled tubes for water-tube boilers
• Seamless heat transfer tubes for superheaters
• Multi-rifled tubes for petrochemical processing
• High-strength rifled tubes for power generation

Material and Grades

• SA213 T2 rifled boiler tubes
• SA213 T12 seamless heat transfer tubes
• 15Mo3 high-strength rifled tubes
• Corrosion-resistant rifled tubes materials

Manufacturing and Testing

• Multi-rifled seamless steel tube manufacturing
• Rifled boiler tube production process
• Seamless heat transfer tube testing standards
• High-strength rifled tube quality assurance

Note: Multi-rifled seamless steel tubes meet international standards, ensuring enhanced heat transfer and durability. Contact suppliers for detailed specifications.

Seamless steel tubes with internal helical ribs designed to enhance heat transfer in boilers and heat exchangers, improving efficiency by up to 30% compared to smooth tubes.

Low-carbon or alloy steels like SA213 T2, T12, or 15Mo3, ensuring strength, thermal conductivity, and corrosion resistance for boiler applications.

- SA213 T2: C 0.10–0.20%, Si 0.10–0.30%, Mn 0.30–0.61%, P ≤0.025%, S ≤0.025%, Cr 0.50–0.81%, Mo 0.44–0.65%
- SA213 T12: C 0.05–0.15%, Si ≤0.50%, Mn 0.30–0.61%, P ≤0.025%, S ≤0.025%, Cr 0.80–1.25%, Mo 0.44–0.65%
- 15Mo3: C 0.12–0.20%, Si 0.10–0.35%, Mn 0.40–0.80%, P ≤0.035%, S ≤0.035%, Mo 0.25–0.35%

- SA213 T2: Tensile ≥415 MPa, Yield ≥205 MPa, Elongation ≥30%
- SA213 T12: Tensile ≥415 MPa, Yield ≥220 MPa, Elongation ≥30%
- 15Mo3: Tensile 450–600 MPa, Yield ≥270 MPa, Elongation ≥22%

Outer diameters from 19 mm to 76.2 mm, wall thicknesses from 2 mm to 8 mm, customizable per requirements.

Hydrostatic, ultrasonic, and eddy current tests ensure defect-free material and compliance with ASME SA213 and DIN 17175 standards.

Multi-rifled seamless steel tubes enhance heat transfer by up to 30% compared to smooth tubes, perform effectively at lower mass flux, and reduce mean metal temperature through their rifled geometry. They suppress film boiling, maintain nucleate boiling, and improve fuel efficiency, reducing CO2 emissions in modern power plants.

Pickling or anti-corrosion coatings, combined with alloy steels like SA213 T2 and T12, protect against acidic and high-temperature fluids, ensuring durability in harsh environments.

Historically known as Serve tubes, named after their French inventor, early designs were for fire-tube boilers with lobes or fins. Modern multi-rifled tubes, designed for water-tube boilers, feature helical ribs with helix angles of 30° (Type A, B) or up to 40°+ for optimized versions, enhancing performance in power stations.

Compared to smooth tubes, multi-rifled tubes offer up to 30% better heat transfer, with optimized versions providing an additional 20% improvement. They provide a larger safety margin for circulation, suppress film boiling, reduce material and operational costs, and are ideal for high-pressure boilers.

While costlier than smooth tubes due to complex manufacturing and materials, multi-rifled tubes reduce operational costs in high-pressure applications through improved thermal efficiency and reduced fuel consumption, offering economic benefits over time.

Current research, such as Siemens' SLMF (Siemens Low Mass Flux) project, focuses on optimizing rifled tube designs for lower mass flux applications, aiming to enhance power plant efficiency and performance in modern boiler systems.

Variants include Type A and Type B multi-lead rifled tubes with a 30° helix angle, and optimized multi-lead rifled tubes with helix angles up to 40°+, offering enhanced heat transfer performance for specific boiler requirements.

ASME SA213, DIN 17175, and other standards upon consultation, ensuring compliance for high-pressure boiler and heat exchanger applications.

Industrial Applications

These tubes are predominantly utilized in the power generation and energy industry, specifically in boiler systems for subcritical and supercritical pressure operations. They are employed in furnace walls and other heat - exchange components, enhancing safety for both natural and assisted circulation. Their use decreases the weight of downcomers, headers, drums, connecting pipes, and pump power, while also reducing the framework weight, contributing to the overall system efficiency.

Water-Tube Boilers

Optimizes steam generation efficiency.

Superheaters

Enhances heat transfer in high-pressure systems.

Heat Exchangers

Improves thermal efficiency in industrial processes.

Power Generation

Supports high-efficiency boiler systems.

Petrochemical Processing

Handles high-temperature fluid transfer.

Chemical Plants

Resists corrosion in chemical heat exchangers.

Why Choose These Tubes? Their rifled design and high strength ensure superior heat transfer and durability in demanding applications.

Multi-Rifled Seamless Steel Tube