Carbon Steel Seamless Pipe — Factory Direct Supplier | Huaxia-Steel
Carbon steel seamless pipe is the standard choice for pressure, mechanical, and structural applications where weld seams are undesirable. With no longitudinal or spiral weld, seamless pipe offers uniform strength around the circumference and reliable performance under internal pressure.
Huaxia-Steel supplies carbon steel seamless pipe in ASTM A106, ASTM A53, API 5L, DIN 1629, and GB/T 8162/8163 grades. We offer hot-rolled and cold-drawn finishes, cut lengths, and end preparations for export projects.
Product Overview
Our seamless pipe is produced by piercing a solid billet and then rolling or drawing it to final dimensions. The process eliminates the weld seam found in ERW or LSAW pipe, making seamless pipe suitable for high-pressure service, bending, and thick-wall applications.
- Product form: Round seamless pipe, plain ends or beveled.
- Standard grades: ASTM A106 Gr.B, ASTM A53 Gr.B, API 5L Gr.B / X42 / X52 / X60, DIN 1629 St37.0 / St44.0 / St52.0, GB/T 8162 20#, GB/T 8163 20#.
- Surface: Black, bare, oiled, varnished, galvanized on request.
- Ends: Plain, beveled, threaded, or with couplings.
Specifications and Size Range
| Parameter | Range |
|---|---|
| Outside diameter (OD) | 10 mm to 610 mm (1/2 inch to 24 inch) |
| Wall thickness | SCH 20 to SCH 160, XXS; 1.5 mm to 60 mm |
| Length | 5.8 m, 6 m, 11.8 m, 12 m; cut-to-length available |
| Tolerance | ASTM A530, ASTM A999, API 5L, or EN 10216 |
| End preparation | Plain end, beveled end, threaded, grooved |
| Bundle weight | 2,000-5,000 kg typical |
Common Schedules and Weights
| NPS | OD (mm) | SCH 40 wall (mm) | Weight kg/m (SCH 40) |
|---|---|---|---|
| 1/2″ | 21.3 | 2.77 | 1.27 |
| 1″ | 33.4 | 3.38 | 2.50 |
| 2″ | 60.3 | 3.91 | 5.44 |
| 4″ | 114.3 | 6.02 | 16.07 |
| 6″ | 168.3 | 7.11 | 28.26 |
| 8″ | 219.1 | 8.18 | 42.55 |
| 10″ | 273.0 | 9.27 | 60.31 |
| 12″ | 323.8 | 10.31 | 79.70 |
Available Grades
| Grade | Standard | Yield MPa | Typical use |
|---|---|---|---|
| A106 Gr.B | ASTM A106/A106M | 240 | High-temperature pressure service |
| A53 Gr.B | ASTM A53/A53M | 240 | General pressure and structural |
| API 5L Gr.B | API 5L | 245 | Oil and gas line pipe |
| API 5L X52 / X60 | API 5L | 359 / 415 | High-strength line pipe |
| St52.0 / E355 | DIN 1629 / EN 10305-1 | 355 | Mechanical and precision tubes |
| 20# | GB/T 8162 / GB/T 8163 | 245 | Structural and fluid pipe in China |
Manufacturing Standards
- ASTM A106/A106M – Seamless carbon steel pipe for high-temperature service.
- ASTM A53/A53M – Pipe, steel, black and hot-dipped, zinc-coated, welded and seamless.
- API 5L – Line pipe.
- DIN 1629 – Seamless circular tubes of non-alloy steel with special quality requirements.
- EN 10216 – Seamless steel tubes for pressure purposes.
- GB/T 8162 – Seamless steel tubes for structural purposes.
- GB/T 8163 – Seamless steel tubes for liquid service.
Applications
- Oil and gas transmission pipelines.
- Steam, water, and air pressure lines.
- Boiler and heat-exchanger tubes.
- Structural columns and casings.
- Hydraulic and pneumatic cylinders.
- Automotive and machinery parts.
- Piling and foundation casings.
Quality Assurance
Our seamless pipe is tested to the relevant standard before shipment:
- Chemical analysis per heat by spectrometer.
- Tensile test for yield, tensile strength, and elongation.
- Flattening or flaring test where required.
- Hydrostatic test for pressure pipe.
- Ultrasonic or eddy current non-destructive testing.
- Dimensional inspection of OD, wall thickness, length, and straightness.
- Visual and end inspection.
- MTC to EN 10204 3.1; third-party inspection available.
Packaging and Shipping
- Pipe ends protected with plastic caps.
- Anti-rust oil or varnish coating.
- Bare bundles or woven-wrap bundles.
- Steel strapping at multiple points.
- Marking with heat number, grade, size, standard, and order number.
- Bulk vessel, flat rack, or container loading with photos.
Pipe End Preparations
| End type | Description | Typical application |
|---|---|---|
| Plain end | Square cut, no preparation | General structural and mechanical |
| Beveled end | 30 or 37.5 degree bevel | Butt-welded pipelines |
| Threaded | Tapered NPT or BSP thread | Plumbing and low-pressure lines |
| Grooved | Roll grooved for couplings | Fire protection and HVAC systems |
| Chamfered | 45 degree edge break | Fittings and fabrication shops |
Pressure Rating Guidance
The pressure rating of seamless pipe depends on the grade, wall thickness, and temperature. For ASTM A106 Grade B at ambient temperature, a Schedule 80 2-inch pipe has a working pressure of approximately 300 psi, while Schedule 160 reaches over 600 psi. Always refer to the applicable design code such as ASME B31.3 for process piping or ASME B31.8 for gas transmission.
Testing and Certification
Every seamless pipe order can be supplied with the following tests and certificates:
- Hydrostatic test to ASTM A530 or API 5L requirements.
- Flattening test for ductility verification.
- Flaring test for selected grades.
- Ultrasonic or eddy current NDT.
- Charpy impact testing at specified temperatures.
- Hardness testing for high-strength line pipe grades.
- MTC to EN 10204 3.1 or 3.2.
Common Grades by Industry
- Oil and gas: API 5L Gr.B, X52, X60, X65.
- Power generation: ASTM A106 Gr.B, A106 Gr.C.
- Refinery and petrochemical: ASTM A53 Gr.B, A106 Gr.B.
- Mechanical and automotive: ASTM A519, EN 10305-1 E355.
- Construction: ASTM A53 Gr.B, GB/T 8162 20#.
Order Example
A typical order might read: “Carbon steel seamless pipe, ASTM A106 Grade B, SCH 80, 4 inch NPS, plain ends, 6 m fixed length, 10 tonnes, beveled ends, MTC to EN 10204 3.1.” For line pipe, the grade and wall thickness designation must exactly match the design code.
Heat Treatment for Line Pipe Grades
High-strength line pipe grades such as API 5L X52, X60, and X65 may require normalizing or quenching and tempering to achieve the specified mechanical properties and toughness. The heat treatment improves uniformity through the wall thickness and ensures adequate Charpy impact energy at low temperatures. For sour service, additional hardness restrictions apply to prevent sulfide stress cracking.
Comparison with Welded Pipe
Seamless pipe has no longitudinal weld seam, giving it uniform mechanical properties around the circumference and higher pressure ratings for a given wall thickness. Welded pipe (ERW, LSAW, SSAW) is cheaper for large diameters and lower pressures but has a weld zone with different microstructure and potential defect locations. For critical pressure, high-temperature, or cyclic-loading service, seamless pipe is the safer choice.
Corrosion Protection for Buried and Marine Service
For underground or marine applications, seamless pipe requires external corrosion protection. Common systems include fusion-bonded epoxy (FBE), three-layer polyethylene (3LPE), coal tar enamel, and cement mortar lining for water pipes. Cathodic protection may also be required. Specify the coating system and applicable standards such as AWWA, DIN 30670, or ISO 21809 when ordering.
Length Tolerance and Cutting Services
| Length type | Tolerance | Use case |
|---|---|---|
| Random length | 4-7 m or 5-7 m | General construction, lowest cost |
| Fixed length | +/- 50 mm | Fabrication shops, predictable waste |
| Exact length | +/- 3 mm | Automatic welding lines, spools |
We provide band saw and abrasive wheel cutting to exact lengths, with deburred ends and end caps supplied on request.
Storage and Handling Recommendations
Seamless pipe should be stored on level ground with adequate drainage. Use timber or rubber spacers to prevent contact with soil and standing water. Keep different grades and heats separated to avoid mixing. For long-term storage, apply a protective oil film or VCI wrapping. Lifting should use fabric slings or padded hooks to avoid denting or scratching the surface.
Value-Added Services
- Honing for hydraulic cylinder barrels.
- External and internal coating for corrosion protection.
- Threading and coupling for water well and plumbing applications.
- Fabrication of pipe spools with flanges and fittings.
- Third-party inspection and witnessing.
Connection Methods
Seamless pipe can be connected by butt welding, socket welding, threading, flanging, or mechanical couplings. Butt welding is the most common method for pressure piping and uses beveled ends and matching filler metal. Threaded connections are convenient for low-pressure plumbing but are not recommended for high-pressure or cyclic service. Flanged connections allow disassembly and are widely used in process plants.
Frequently Asked Questions
What is the maximum pressure for seamless pipe?
Pressure rating depends on grade, wall thickness, and temperature. Refer to ASME B31 codes for calculation.
Can seamless pipe be threaded?
Yes, plain-end seamless pipe can be threaded to NPT or BSP standards.
Is seamless pipe more expensive than welded pipe?
Generally yes, especially for small to medium diameters, because of the more complex manufacturing process.
What is the standard length?
Common lengths are 6 m, 12 m, and random length 4-7 m. Cut-to-length is available.
Why Buy Seamless Pipe from Huaxia-Steel
- Direct supply from Chinese seamless pipe mills.
- Wide size range from 10 mm to 610 mm OD.
- Pressure, line pipe, mechanical, and structural grades.
- Cut-to-length and end preparation services.
- Full MTC and third-party inspection support.
- Experience with export packing for long ocean voyages.
Request a Quote
Send us the standard, grade, OD, wall thickness, length, quantity, and end finish. We will confirm availability, lead time, and pricing within one working day.
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