1. Womic Steel: Manufacturing Capabilities & Company Strength
Womic Steel Group operates multiple LSAW production lines covering three primary forming methods plus specialized heavy wall capabilities. X65 production requires advanced thermomechanical controlled processing (TMCP) of plates and precise heat input control during welding.
● JCOE Line: For diameters 406mm – 1,422mm (16″–56″), wall thickness up to 50.8mm. Step-by-step J-C-O forming with mechanical expansion. Suitable for most onshore X65 trunk line applications.
● UOE Line: For diameters 508mm – 1,220mm (20″–48″), wall thickness up to 40mm. U-forming then O-forming with hydraulic expansion. Best-in-class dimensional accuracy (±0.2% OD), preferred for deepwater offshore pipelines, risers, and sour service.
● Rolled Plate (Single Seam): For diameters 600mm – 1,600mm (24″–63″), wall thickness from 25mm up to 70mm. Single plate rolled into a cylinder. Ideal for heavy wall X65 pipelines requiring high collapse resistance.
● Rolled Plate (Double Seam): For wall thickness > 50.8mm up to 80mm, using two plates welded longitudinally. Used for ultra-high pressure CO₂ pipelines and water injection.
Total LSAW capacity exceeds 300,000 tons annually, with dedicated X65 production exceeding 70,000 tons per year. Womic Steel holds API 5L Monogram, ISO 9001, CE PED, and is regularly audited by ABS, DNV, TÜV, and BV. Global track record in 80+ countries with over 1,200 km of X65 pipelines supplied.
Production Flexibility:
● JCOE: 406–1,422mm OD × 6.0–50.8mm WT × ≤ 18m
● UOE: 508–1,220mm OD × 6.0–40.0mm WT × ≤ 24m (mechanical expansion, roundness ±0.2%)
● Rolled plate (single seam): 600–1,600mm OD × 25–70mm WT × ≤ 12m
● Rolled plate (double seam): 1,000–2,000mm OD × 25–80mm WT × ≤ 12m
All X65 pipes can be supplied with PWHT (post-weld heat treatment) for thick wall or sour service. Low-temperature impact testing available down to -46°C and -60°C.
2. API 5L X65: Material Composition & Performance Characteristics
API 5L X65 (L450) is a high-strength line pipe grade extensively used for long-distance high-pressure gas transmission and deepwater offshore pipelines. Minimum yield strength of 450 MPa (65,300 psi) and tensile strength of 535 MPa (77,600 psi). X65 is produced using controlled rolling (TMCP) with microalloying (Nb, V, Ti, often with Mo for sour service) to achieve fine acicular ferrite or bainitic microstructure.
Chemical Composition (Ladle Analysis, max % by mass):
| Element | API 5L X65 PSL1 (max %) | API 5L X65 PSL2 (max %) | Sour Service (typical target) |
| C | 0.22 (typical 0.08-0.10) | 0.12 | ≤ 0.08 |
| Mn | 1.60 | 1.60 | ≤ 1.50 |
| P | 0.025 | 0.025 | ≤ 0.015 |
| S | 0.015 | 0.015 | ≤ 0.003 |
| Si | 0.45 | 0.45 | 0.15-0.40 |
| V | 0.10 | 0.10 | ≤ 0.08 |
| Nb | 0.05 | 0.05 | 0.03-0.05 |
| Ti | 0.04 | 0.04 | ≤ 0.025 |
| Mo | Not specified | Not specified | ≤ 0.30 (for sour) |
| CEV | Not specified | ≤ 0.43 | ≤ 0.40 (typical ≤ 0.38) |
For sour service, Womic maintains CEV ≤ 0.40% and uses low-carbon, low-manganese, low-sulfur plates with calcium treatment for inclusion shape control.
Mechanical Properties (Room Temperature):
| Property | API 5L X65 PSL1 | API 5L X65 PSL2 |
| Yield Strength (min) | 450 MPa (65,300 psi) | 450–600 MPa |
| Tensile Strength (min) | 535 MPa (77,600 psi) | 535–760 MPa |
| Elongation (min) | 19% (for 50mm gauge) | 19% |
| Yield Ratio (max) | Not specified | 0.93 |
| Hardness (max) | Not specified | 90 HRB (sour: 85 HRB typical) |
| Impact Toughness (min) | Not required | 27 J @ 0°C (optional -20°C, -40°C, -46°C) |
Comparison with X60 and X70:
| Grade | Yield MPa | Tensile MPa | Yield Ratio | Typical Application |
| X60 | 415 | 520 | ≤ 0.93 | High-pressure gas, onshore |
| X65 | 450 | 535 | ≤ 0.93 | Very high pressure, deepwater |
| X70 | 485 | 570 | ≤ 0.93 | Ultra-high pressure, long-distance |
3. Dimensional Range & Standards Compliance
| Item | Specification |
| Standard | API 5L PSL1 / PSL2 (also ISO 3183 L450, DNV-OS-F101 L450) |
| Manufacturing Processes | JCOE, UOE, rolled plate (single/double seam) |
| Outside Diameter Range | 219mm – 1,600mm (8″ – 63″) |
| Wall Thickness Range | JCOE/UOE: 6.0mm – 50.8mm; Rolled plate: 25mm – 70mm (up to 80mm custom) |
| Length Range | Standard: 6m, 12m, 18m; Extended: up to 24m (JCOE/UOE) or 12m (rolled plate) |
| End Finish | Plain End (PE), Beveled End (BE) per API 5L (30° bevel, 1.6mm root face) |
| Surface Finish | Bare, Oiled, 3LPE, 3LPP, FBE, Coal Tar Epoxy, Liquid Epoxy |
| Tolerances | OD: ±0.5% or ±3.2mm (whichever less); WT: -0% / +15%; Length: +50mm / -0mm |
4. Available Dimensions & Specifications – API 5L X65 LSAW Steel Pipe (Selected Typical Sizes)
| OD (mm) | WT Options (mm) | Process | Approx Weight (kg/m) | Standard Length | Typical Application |
| 273 | 6.4, 8.0, 10.0, 12.5 | JCOE | 42.1 – 80.1 | 12m | Gas lateral lines |
| 324 | 8.0, 10.0, 12.5, 14.0 | JCOE | 62.4 – 107.1 | 12m / 18m | Gas gathering |
| 406 | 8.0, 10.0, 12.5, 14.0, 16.0, 19.0 | JCOE/UOE | 78.5 – 181.4 | 12m / 18m | Trunk lines |
| 508 | 10.0, 12.5, 14.0, 16.0, 19.0, 22.0 | UOE | 122.8 – 263.8 | 12m / 18m / 24m | High-pressure gas |
| 610 | 12.5, 14.0, 16.0, 19.0, 22.0, 25.4, 28.0 | UOE | 184.2 – 401.8 | 12m / 18m / 24m | Main gas trunk lines |
| 711 | 14.0, 16.0, 19.0, 22.0, 25.4, 28.0, 30.0 | JCOE/UOE | 240.7 – 503.8 | 12m / 18m | Cross-country gas |
| 813 | 16.0, 19.0, 22.0, 25.4, 30.0, 32.0, 35.0 | JCOE | 314.4 – 671.4 | 12m / 18m | Offshore export |
| 914 | 19.0, 22.0, 25.4, 30.0, 35.0, 38.0, 40.0 | JCOE | 419.5 – 862.0 | 12m / 18m | Deepwater gas |
| 1,016 | 22.0, 25.4, 30.0, 35.0, 40.0, 45.0, 50.0 | JCOE/Rolled | 539.2 – 1,191.7 | 12m | Ultra-deepwater |
| 1,220 | 25.4, 30.0, 35.0, 40.0, 45.0, 50.0, 55.0 | Rolled (single) | 748.4 – 1,577.8 | 12m | Arctic pipelines |
| 1,422 | 30.0, 35.0, 40.0, 45.0, 50.0, 55.0, 60.0 | Rolled (single) | 1,030 – 2,016 | 12m | High-pressure CO₂ |
| 1,600 | 35.0, 40.0, 50.0, 60.0, 70.0 | Rolled (double) | 1,350 – 2,640 | 10m / 12m | Special project |
*Heavy wall X65 pipes (≥ 25mm for sour service, ≥ 32mm for non-sour) require PWHT. X65 for deepwater requires Charpy impact at -20°C or lower and CTOD testing.*
5. Common Standards & Grades – LSAW Line Pipe & Structural Pipe
| Standard | Steel Grades | Typical Application | Forming Process |
| API 5L PSL1/PSL2 | X65, X70 | Oil/gas transmission | JCOE/UOE/Rolled |
| API 5L PSL2 (sour) | X65, X70 | Sour service (H₂S) | UOE + PWHT |
| ISO 3183 | L450, L485 | International projects | JCOE/UOE |
| DNV-OS-F101 | L450, L485 | Subsea pipelines | UOE |
| EN 10217-1 | S355JR | Pressure tubes | JCOE |
| NORSOK M-120 | X65 | Offshore platform | UOE |
| ASTM A671 | CC65, CC70 | Low temperature | Rolled |
Usage summary: Deepwater gas export pipelines, high-pressure gas trunk lines, sour service pipelines, CO₂ pipelines for CCS, subsea risers, arctic gas transmission.
6. Manufacturing Processes – LSAW (JCOE / UOE / Rolled Plate) for X65 Steel Pipe
X65 requires TMCP (thermomechanical controlled processing) plates and strict heat input control during SAW welding to maintain HAZ toughness.
JCOE Process (406–1,422mm OD, 6.0–50.8mm WT):
● Plate edge milling (X or J bevel) with precision ±0.5mm
● Pre-bending of edges
● J-C-O sequential forming
● Tack welding (spaced tacks)
● Inner SAW (heat input ≤ 2.5 kJ/mm for X65)
● Back-gouging
● Outer SAW (multi-pass, interpass temperature ≤ 200°C)
● Mechanical expansion (1-1.5% OD)
● Suitable for most onshore X65 trunk lines
UOE Process (508–1,220mm OD, 6.0–40mm WT):
● U-press (2000-4000t)
● O-press (3000-6000t)
● Mechanical expansion (48-72 segments)
● Welding with heat input control
● Preferred for deepwater offshore pipelines (±0.2% roundness, low residual stress)
Rolled Plate (Single Seam) for Heavy Wall (600–1,600mm OD, 25–70mm WT):
● 4-roll bending into cylinder
● Multi-pass SAW (root, fill, cap)
● PWHT mandatory for wall thickness ≥ 25mm for sour service
● Used for high-pressure CO₂ and water injection
Post-Weld Heat Treatment (PWHT): For X65 sour service, PWHT is applied for all wall thicknesses ≥ 25mm (or as specified). Soaking temperature 580-620°C, hold 1 hour per 25mm. Cooling rate ≤ 200°C per hour. Hardness after PWHT: base metal 78-85 HRB, weld 82-88 HRB.
Low-Temperature & CTOD Capability: For offshore and arctic applications, Womic supplies X65 with Charpy impact at -46°C (min 27J, typical 100-150J) and CTOD (Crack Tip Opening Displacement) testing per BS 7448 or ASTM E1820. Typical CTOD value: ≥ 0.25mm at -20°C for weld metal and HAZ.
7. Quality Control & Testing Procedures for API 5L X65 LSAW Steel Pipe
| Stage | Inspection Method | Purpose | Applicable Process |
| Plate | Chemical Analysis (OES) | Verify X65 composition | All |
| Plate | Ultrasonic (lamination) | Detect internal flaws | All |
| Plate | Tensile (L+T) | Mechanical properties | All |
| Plate | Grain size (ASTM E112) | Fine grain (ASTM 10+) | X65 PSL2 |
| During forming | Dimensional (OD, ovality) | Ensure uniformity | All |
| Weld seam | 100% Automated UT (TOFD) | Detect weld defects | All |
| Weld seam | RT (spot/full) | Weld quality | All |
| Weld seam | MPI (toes/HAZ) | Surface cracks | All |
| Weld seam | Hardness traverse (weld, HAZ, BM) | Sour service | PSL2 sour |
| Finished pipe | Hydrostatic Test | Pressure integrity | All |
| Finished pipe | Charpy V-Notch (PSL2) | Low-temperature toughness | PSL2 only |
| Finished pipe | Hardness (HRB/HV10) | Sour compliance | PSL2 sour |
| Finished pipe | Guided Bend / Flattening | Ductility | All |
| Finished pipe | DWTT (optional) | Fracture propagation | Arctic |
| Finished pipe | CTOD (optional) | Fracture toughness | Offshore/deepwater |
Optional for critical service:
● HIC per NACE TM0284 (Solution A or B, 96h)
● SSC per NACE TM0177 (Method A, 720h)
● Low-temperature impact at -46°C, -60°C
● DWTT at -20°C or lower (≥ 85% shear area)
● CTOD at -20°C or -46°C (≥ 0.25mm)
● Full-body UT (not just seam)
Corrosion testing (CO₂, brine)
8. Primary Applications – API 5L X65 LSAW Steel Pipe
Deepwater offshore gas export pipelines – Water depths up to 3,000m, high external pressure resistance (UOE process with tight roundness)
High-pressure natural gas trunk lines – Operating pressures up to 15 MPa (2,200 psi), wall thickness reduction vs lower grades
Sour service oil and gas pipelines – H₂S-containing environments (PSL2 with HIC/SSC, PWHT, hardness ≤ 85 HRB)
CO₂ pipelines for carbon capture and storage (CCS) – High-pressure CO₂ transport, requires low-temperature toughness
Subsea risers and flowlines – Dynamic applications requiring CTOD and fatigue testing
Arctic and permafrost gas pipelines – Low-temperature impact down to -46°C, DWTT for fracture control
High-pressure water injection lines – Enhanced oil recovery, pressure up to 35 MPa
Pipeline expansion loops – High-strain applications requiring strain-based design (X65 with specified yield ratio)
9. Packaging & Shipping – API 5L X65 LSAW Steel Pipe
Same as previous products with additional care for coating protection on high-value X65 pipes. Pipes are individually packed with padded wooden dunnage, end caps, and corrosion inhibitor vapor bags for long sea voyages. For deepwater projects, special attention to bevel protection is provided.
10. Womic Steel Advantages & FAQ – API 5L X65 LSAW Steel Pipe
Why Womic Steel for X65 LSAW?
● UOE process delivers ±0.2% OD roundness – critical for deepwater collapse resistance
● Sour service certified with HIC/SSC and PWHT capability
● Low-temperature impact down to -60°C and CTOD testing for fracture mechanics
● API 5L Monogram + DNV approval for offshore
● Over 1,200 km of X65 pipelines supplied globally
● Third-party inspection by DNV, ABS, BV, SGS, TÜV
Frequently Asked Questions:
Q: What is the difference between X65 and X60 for offshore pipelines?
A: X65 offers 8% higher yield strength (450 vs 415 MPa), allowing slightly thinner walls. For deepwater (≥ 1,000m), X65 is often preferred for its better collapse resistance and fatigue performance. However, X65 requires more stringent welding procedures and is more sensitive to hydrogen cracking. For water depths < 500m, X60 may be more economical.
Q: Can you supply X65 with CTOD testing for offshore risers?
A: Yes. We perform CTOD testing per BS 7448 or ASTM E1820 at specified temperatures (typically -20°C or -46°C). Minimum CTOD values: 0.25mm for weld metal, 0.30mm for HAZ. We have supplied CTOD-tested X65 to北海 and Southeast Asia offshore projects.
Q: What is the maximum wall thickness for X65 LSAW pipe?
A: JCOE/UOE max 50.8mm, rolled plate single seam up to 70mm, rolled plate double seam up to 80mm. For wall thickness > 50.8mm, PWHT is mandatory. We recently supplied X65 1,016mm OD × 60mm WT for a high-pressure CO₂ pipeline.
Q: How do you ensure HAZ toughness for X65 field welding?
A: We control plate chemistry (low CEV, ≤ 0.40%), heat input during SAW (≤ 2.5 kJ/mm), and interpass temperature (≤ 200°C). We provide welding procedure qualification (WPQ) recommendations to clients and can supply welding consumable samples. Typical HAZ Charpy impact at -20°C: 120-200J.
Q: Is X65 suitable for sour service (H₂S)?
A: Yes, but requires PSL2 with low CEV (≤ 0.40%), PWHT for all wall thicknesses ≥ 20mm, hardness ≤ 85 HRB, and HIC/SSC testing. Womic has supplied sour service X65 to Middle East (30 ppm H₂S) and Canada (sour gas).
Q: What is the typical lead time for X65 LSAW pipe?
A: Standard X65 PSL1: 40-55 days. X65 PSL2 with sour service and PWHT: 60-80 days. Rush orders (30-45 days) for quantities < 2,000 tons possible if plates are in stock.
Project Reference – North Sea Deepwater Gas Export Pipeline
Country: Norway (North Sea, Balder field area)
Standard & Grade: API 5L X65 PSL2 with sour service and CTOD requirements
Dimensions & Quantity:
● OD 610mm (24″) × WT 22.2mm – 28,000 meters (approx. 9,200 tons) manufactured by UOE process
● OD 610mm (24″) × WT 25.4mm – 6,000 meters (approx. 2,300 tons) manufactured by UOE process (thicker wall for riser section)
● OD 813mm (32″) × WT 30.0mm – 4,000 meters (approx. 2,500 tons) manufactured by rolled plate single seam (for shore approach)
Total: 38,000 meters (38 km), approx. 14,000 tons
Specifications: External 3LPP coating (3.5mm total thickness) for high-temperature service (110°C), beveled ends 30° / 1.6mm root face with stainless steel bevel protectors, hydrotest at 22.5 MPa (design pressure 17.0 MPa). Mandatory Charpy impact at -20°C (min 50J, achieved 120-200J) and at -46°C (min 27J, achieved 80-150J). CTOD testing per BS 7448 at -20°C – acceptance: weld metal ≥ 0.25mm, HAZ ≥ 0.30mm. HIC per NACE TM0284 (Solution A, 96h) – acceptance: CLR 0%, CTR 0%, CSR 0%. SSC per NACE TM0177 – no cracking. PWHT applied for all pipes due to sour service. 100% UT with TOFD and full-body UT (not just seam). DNV third-party inspection throughout production.
Application: Deepwater gas export pipeline from the Balder field (water depth 800-1,200m) to an onshore receiving terminal in Norway. The 38 km pipeline includes a dynamic riser section (2 km, 25.4mm WT) and a shore approach through rocky terrain (4 km, 30mm WT rolled plate).
Technical Challenges & Solutions:
● Deepwater collapse resistance – Water depth up to 1,200m imposes external pressure of 12.5 MPa. The 24″ × 22.2mm UOE pipe needed to meet collapse pressure ≥ 25 MPa (safety factor 2). Womic produced UOE pipes with ovality ≤ 0.2% (measured at 0.15-0.18%) and residual stress ≤ 35% SMYS. We performed finite element analysis (FEA) on the manufacturing parameters and validated with collapse pressure testing on two full-scale samples (achieved 28.5 MPa and 29.2 MPa).
● Sour service with high H₂S – The gas contains 50 ppm H₂S at 90°C operating temperature. Womic selected low-carbon (C ≤ 0.07%), low-manganese (Mn ≤ 1.40%), low-sulfur (S ≤ 0.002%) plates with calcium treatment. CEV was maintained at 0.35-0.38%. PWHT was applied for all pipes (soaking 600°C ± 10°C, hold 1.5 hours). Hardness after PWHT: base metal 78-84 HRB, weld 82-86 HRB, HAZ 80-84 HRB. HIC and SSC tests passed with zero cracks.
● CTOD fracture toughness for riser – The dynamic riser section requires high fracture toughness to withstand wave loading. Womic performed CTOD testing on weld metal and HAZ at -20°C. Results: weld metal 0.35-0.55mm (≥ 0.25mm required), HAZ 0.40-0.70mm (≥ 0.30mm required). We also performed low-temperature Charpy at -46°C (average 110J). DNV witnessed all CTOD testing.
● High-temperature coating (3LPP) – Operating temperature 90°C, with peak 110°C during shut-in. Standard 3LPE (polyethylene) is limited to 80°C. Womic applied 3LPP (polypropylene) coating with thickness 3.5mm (top layer 2.5mm + adhesive 0.5mm + FBE 0.5mm). Coating passed cathodic disbondment test at 110°C (disbondment radius ≤ 8mm after 28 days). Peel strength at 110°C measured at 60 N/cm (minimum 50 N/cm).
● Extreme dimensional tolerances for reel-lay installation – The pipeline was installed using reel-lay method (pipe spooled onto a reel vessel). This requires extreme ovality control (≤ 0.2%) and weld reinforcement height ≤ 0.5mm. Womic's UOE process achieved ovality 0.15-0.18%. We ground weld caps to ≤ 0.3mm height. All pipes passed a special "reelability" test: 10 full-scale spooling cycles without cracking.
● Logistics to Norway – Pipes were shipped from Shanghai to Stavanger, Norway via break-bulk vessel (specialized pipe carrier). Winter North Sea crossing required anti-condensation packaging. Womic used VCI (vapor corrosion inhibitor) bags and silica gel desiccants inside end caps. All 14,000 tons arrived without corrosion or coating damage
Result: The Balder field gas export pipeline was installed in Q3 2024. The reel-lay installation (performed by a leading offshore contractor) reported zero pipe body or weld seam failures during spooling and deployment. All 38 km passed pressure testing on the seabed. The client (a major Norwegian operator) issued a "Supplier Performance Award" to Womic Steel, noting "exceptional dimensional consistency and CTOD results." Womic is now an approved supplier for two additional North Sea tie-back projects.
Contact:
Website: www.womicsteel.com
E-mail: sales@womicsteel.com
Tel / WhatsApp / WeChat:
Victor: +86 15575100681
Jack: +86 18390957568
Womic Steel – Your reliable partner for API 5L X65 LSAW pipes for deepwater offshore pipelines, high-pressure gas trunk lines, sour service, and arctic applications worldwide.
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