1. Womic Steel: Manufacturing Capabilities & Company Strength for X65 Sour Service
Womic Steel Group operates dedicated production lines for high-strength sour service LSAW pipes. X65 sour service is more demanding than X52 due to higher strength and stricter toughness requirements. Key controls include:
● Low carbon equivalent (CEV ≤ 0.40%, typical ≤ 0.38%)
● Ultra-low sulfur (S ≤ 0.0015%) and low phosphorus (P ≤ 0.015%)
● Calcium treatment for inclusion shape control (Ca/S ratio ≥ 1.5)
● Accelerated cooling (TMCP) plates to achieve acicular ferrite microstructure
● Post-weld heat treatment (PWHT) for all pipes, regardless of wall thickness
● 100% hardness testing (weld, HAZ, base metal) – target ≤ 85 HRB
● HIC and SSC testing per NACE standards with zero crack acceptance for many projects
Production processes: JCOE, UOE (preferred due to lower residual stress), rolled plate, all with mandatory PWHT in car-bottom furnace (12m length, 600°C ± 10°C). Third-party inspection by SGS, BV, TÜV, DNV, ABS, or LR for full sour service certification.
Annual sour service X65 LSAW capacity: 25,000 tons.
Production Flexibility for X65 Sour Service:
● JCOE: 406–1,422mm OD × 6.0–50.8mm WT × ≤ 18m
● UOE: 508–1,220mm OD × 6.0–40.0mm WT × ≤ 24m (preferred for sour due to lower residual stress)
● Rolled plate: 600–1,600mm OD × 25–60mm WT × ≤ 12m
● PWHT applied to every pipe (soak 600°C ± 10°C, hold 1 hr per 25mm thickness, slow cool ≤ 200°C/hr)
2. API 5L X65 PSL2 Sour Service: Material Composition & Performance Characteristics
For X65 sour service, chemistry is tighter than standard PSL2 and also tighter than X52 sour. The goal is to achieve high strength (450 MPa yield) while maintaining excellent HIC and SSC resistance.
Chemical Composition (Ladle Analysis, typical targets for sour service):
| Element | Standard PSL2 max | X65 Sour Service Target (Womic) |
| C | 0.12 | ≤ 0.08 (typical 0.05-0.07) |
| Mn | 1.60 | ≤ 1.40 (typical 1.20-1.35) |
| P | 0.025 | ≤ 0.015 |
| S | 0.015 | ≤ 0.0015 (0.0010 typical) |
| Si | 0.45 | 0.20-0.35 |
| V | 0.10 | ≤ 0.06 |
| Nb | 0.05 | 0.04-0.07 |
| Ti | 0.04 | ≤ 0.025 |
| Mo | Not specified | ≤ 0.30 (for sour, often 0.15-0.25) |
| Ni | Not specified | ≤ 0.50 (optional for low temp) |
| CEV | ≤ 0.43 | ≤ 0.40 (typical ≤ 0.38) |
| Pcm | ≤ 0.25 | ≤ 0.22 |
Calcium treatment (Ca/S ratio ≥ 1.5) ensures globular sulfide inclusions. Molybdenum addition improves resistance to SSC at higher strength levels.
Mechanical Properties (After PWHT):
| Property | X65 PSL2 Sour Service (Womic) |
| Yield Strength (min) | 450 MPa (65,300 psi) |
| Yield Strength (max) | 570 MPa (82,700 psi) |
| Tensile Strength (min) | 535 MPa (77,600 psi) |
| Elongation (min) | 19% |
| Hardness (max) - many projects | 85 HRB (Womic achieves 78-85 HRB) |
| Impact Toughness @ -20°C (optional) | ≥ 27 J (typical 80-150 J) |
| Impact Toughness @ -46°C (optional) | ≥ 27 J (typical 60-100 J) |
Mandatory Testing for X65 Sour Service:
● HIC per NACE TM0284 (Solution A, 96h) - acceptance: CLR ≤ 5%, CTR ≤ 1.5%, CSR ≤ 0.5% (many projects require 0%)
● SSC per NACE TM0177 (Method A, 720h, 90% SMYS) - no cracking
● Hardness traverses across weld, HAZ, and base metal (max 85 HRB)
● Charpy V-Notch at 0°C or lower (typically 27 J min)
● DWTT (for fracture control, if specified)
3. Dimensional Range & Standards Compliance
| Item | Specification |
| Standard | API 5L PSL2 with sour service supplement |
| NACE | NACE MR0175 / ISO 15156 (latest edition) |
| Manufacturing Processes | JCOE, UOE, rolled plate (all with PWHT) |
| Outside Diameter Range | 219mm - 1,600mm (8″ - 63″) |
| Wall Thickness Range | 6.0mm - 60mm (JCOE/UOE max 50.8mm, rolled plate max 60mm) |
| Length Range | 6m - 18m standard; up to 24m (UOE) |
| End Finish | Beveled End (BE) per API 5L |
| Surface Finish | Bare, 3LPE, 3LPP, FBE (coatings must be sour service qualified) |
| Tolerances | OD: ±0.5%; WT: -0% / +15%; Length: +50mm / -0mm |
4. Available Dimensions & Specifications - API 5L X65 PSL2 Sour Service LSAW Steel Pipe
| OD (mm) | WT Options (mm) | Process | Approx Weight (kg/m) | Standard Length | Sour Service Features |
| 219 | 6.4, 8.0, 10.0, 12.5 | JCOE | 33.6 - 63.6 | 12m | PWHT, HIC tested |
| 273 | 8.0, 10.0, 12.5, 14.0, 16.0 | JCOE | 52.3 - 101.5 | 12m / 18m | Hardness ≤ 85 HRB |
| 324 | 10.0, 12.5, 14.0, 16.0, 19.0 | JCOE | 77.4 - 142.8 | 12m / 18m | CEV ≤ 0.40, Mo added |
| 406 | 10.0, 12.5, 14.0, 16.0, 19.0, 22.0 | JCOE/UOE | 97.7 - 208.4 | 12m / 18m | SSC tested |
| 508 | 12.5, 14.0, 16.0, 19.0, 22.0, 25.4 | UOE | 152.7 - 302.3 | 12m / 18m / 24m | Full hardness traverse |
| 610 | 14.0, 16.0, 19.0, 22.0, 25.4, 28.0 | UOE | 205.8 - 401.8 | 12m / 18m / 24m | HIC CLR 0% typical |
| 711 | 16.0, 19.0, 22.0, 25.4, 28.0, 31.8 | UOE/JCOE | 274.3 - 532.9 | 12m / 18m | PWHT mandatory |
| 813 | 19.0, 22.0, 25.4, 30.0, 32.0, 35.0 | JCOE | 372.1 - 671.4 | 12m / 18m | NACE MR0175 |
| 914 | 22.0, 25.4, 30.0, 35.0, 38.0, 40.0 | JCOE/Rolled | 484.3 - 862.0 | 12m | Low S (≤ 0.0015%) |
| 1,016 | 25.4, 30.0, 35.0, 40.0, 45.0, 50.0 | Rolled | 619.9 - 1,191.7 | 12m | Ca treated, Mo up to 0.25% |
| 1,220 | 30.0, 35.0, 40.0, 45.0, 50.0, 55.0 | Rolled | 880.9 - 1,577.8 | 12m | Deepwater sour |
All X65 sour service pipes receive PWHT regardless of wall thickness. UOE is preferred for diameters ≤ 1,220mm due to superior residual stress control.
5. Common Standards for High-Strength Sour Service Line Pipe
| Standard | Application | Testing Requirements |
| API 5L PSL2 + Annex H | Sour service line pipe | HIC, SSC, hardness ≤ 90 HRB |
| NACE MR0175 / ISO 15156 | Materials for H₂S environments | Limits on hardness, chemistry |
| NACE TM0284 | HIC test method | CLR, CTR, CSR |
| NACE TM0177 | SSC test method (Method A, B, C, D) | No cracking |
| DNV-OS-F101 (sour supplement) | Offshore sour pipelines | Additional CTOD and fatigue |
| Shell DEP 31.40.30.31 | Deepwater sour service | Stricter hardness (≤ 85 HRB) |
Usage summary: High-pressure sour gas trunk lines, deepwater sour oil pipelines, offshore acidic service, refinery sour water, amine units, acid gas injection, CCS with H₂S.
6. Manufacturing Process - LSAW for X65 PSL2 Sour Service
X65 sour service requires advanced TMCP plates and extremely tight process control.
Plate Selection:
● Low carbon (≤ 0.08%), low manganese (≤ 1.40%), ultra-low sulfur (≤ 0.0015%)
● Calcium treated (Ca/S ≥ 1.5)
● Mo addition (0.15-0.25%) for SSC resistance
● TMCP with accelerated cooling - acicular ferrite microstructure
JCOE / UOE Forming + Sour Specific Steps:
● Edge milling - Precision ±0.5mm, J bevel for better weld penetration.
● Forming - UOE preferred (lower residual stress). JCOE acceptable for onshore.
● SAW welding - Heat input ≤ 2.2 kJ/mm (lower than standard). Interpass temperature ≤ 150°C.
● 100% UT with TOFD - More sensitive than standard UT.
● Post-Weld Heat Treatment (PWHT) - Mandatory for all sour service X65. Soak at 580-600°C (lower temperature than X52 to avoid strength loss). Hold 1 hour per 25mm thickness. Furnace cool at ≤ 150°C per hour.
● Mechanical expansion (UOE) - Limited to 0.5-0.8% (vs 1.5% for standard) to avoid cold work hardening.
● Hardness testing - Three full traverses per pipe (base metal, HAZ, weld centerline). Maximum 85 HRB.
● HIC testing - Per NACE TM0284 Solution A, 96h. Samples from pipe ends.
● SSC testing - Per NACE TM0177 Method A, 720h at 90% SMYS.
PWHT Furnace Parameters for X65 Sour:
● Temperature: 590°C ± 10°C (lower than for X52 to retain strength)
● Soaking time: 1 hour per 25mm (minimum 1 hour)
● Cooling rate: ≤ 150°C per hour from 590°C to 300°C
● Multiple thermocouples on pipe surface
7. Quality Control & Testing for X65 Sour Service LSAW
| Stage | Inspection | Acceptance Criteria |
| Plate | Chemical (OES) | C ≤ 0.08, S ≤ 0.0015%, CEV ≤ 0.38, Mo 0.15-0.25% |
| Plate | Ultrasonic (lamination) | No laminations > 3mm |
| Plate | Tensile + Charpy at -20°C | Yield ≥ 450 MPa, CVN ≥ 50J |
| Weld | 100% UT with TOFD | No indications > 1.6mm |
| Weld | RT (10% minimum) | No cracks, lack of fusion |
| After PWHT | Hardness (HRB) - BM, Weld, HAZ | ≤ 85 HRB (each zone) |
| Finished | HIC (NACE TM0284) | CLR ≤ 2% (often 0%), CTR ≤ 1%, CSR ≤ 0.5% |
| Finished | SSC (NACE TM0177 Method A, 720h) | No cracking |
| Finished | Charpy @ -20°C or lower | ≥ 27 J (min), typical 80-150 J |
| Finished | Tensile | Yield 450-570 MPa, Tensile ≥ 535 MPa |
| Finished | Hydrostatic Test | 90-100% SMYS |
Documentation package includes: MTC Type 3.2, PWHT charts, hardness maps, HIC and SSC reports, UT/TOFD logs, hydro test certificates.
8. Primary Applications - API 5L X65 PSL2 Sour Service LSAW Steel Pipe
● High-pressure sour natural gas trunk lines - Long-distance transmission at 10-15 MPa with H₂S up to 50 ppm
● Deepwater offshore sour oil pipelines - Subsea lines in H₂S environments (UOE + CTOD testing)
● Sour crude oil flowlines - High-pressure lines from wellheads to central facilities
● Refinery sour water lines - Ammonium bisulfide and H₂S service (high temperature)
● Amine treating unit piping - Rich and lean amine (H₂S and CO₂)
● Acid gas injection wells - Reinjecting H₂S/CO₂ mixtures into disposal zones
● Gas lift lines - Injection of sour gas for artificial lift
● CCS pipelines with H₂S impurity - Carbon capture and storage where CO₂ stream contains H₂S
9. Packaging & Shipping - X65 Sour Service LSAW Pipe
Same as standard LSAW packaging with enhanced end protection (stainless steel caps recommended to avoid contamination). Documentation includes the full sour service quality dossier in addition to standard shipping documents.
10. Womic Steel Advantages & FAQ - X65 PSL2 Sour Service LSAW
Why Womic Steel for X65 Sour Service?
● Dedicated PWHT furnace (12m length) with precise temperature control (590°C ± 10°C)
● In-house HIC and SSC testing (CNAS accredited lab)
● Mo-alloyed plates for superior SSC resistance
● UOE process for lower residual stress (preferred for deepwater sour)
● Third-party witnessed sour testing available (SGS, BV, TÜV, DNV)
● Over 300 km of X65 sour service pipes supplied globally
Frequently Asked Questions:
Q: What is the difference between X52 sour and X65 sour service?
A: X65 sour service is more demanding. X65 requires higher strength (450 vs 360 MPa yield) while maintaining same or tighter hardness limits (≤ 85 HRB). This requires Mo addition (0.15-0.25%), stricter CEV control (≤ 0.38% vs ≤ 0.40%), and often lower PWHT temperature (590°C vs 600°C) to avoid strength loss. X65 is typically specified for higher pressure pipelines (> 10 MPa) and deepwater offshore applications.
Q: Is PWHT mandatory for all X65 sour service pipes regardless of wall thickness?
A: Yes, per NACE MR0175 and all major operator specifications. Even for 6.4mm WT pipes, PWHT is required to achieve hardness ≤ 85 HRB and to relieve residual stresses. Womic applies PWHT to 100% of sour service X65 pipes.
Q: What are typical HIC acceptance criteria for X65 sour service?
A: NACE TM0284 allows CLR ≤ 5%, CTR ≤ 1.5%, CSR ≤ 0.5%. However, most deepwater and high-integrity projects require CLR = 0% (no cracks). Womic’s ultra-low sulfur plates (S ≤ 0.0015%) and calcium treatment achieve CLR 0% consistently.
Q: Can X65 sour service pipes be used in arctic or low-temperature environments?
A: Yes, with additional low-temperature Charpy impact testing. Womic can supply X65 sour service with impact testing at -20°C, -40°C, or -46°C (min 27J). For arctic sour service, we also provide DWTT (≥ 85% shear area at test temperature). Note that low temperature and sour service together require careful alloy design (Ni addition, low CEV). Please provide your operating temperature and H₂S partial pressure for a suitability assessment.
Q: What is the maximum H₂S partial pressure for X65 sour service?
A: Per NACE MR0175, X65 is suitable for sour service up to 0.3 psi (0.02 bar) H₂S partial pressure. For higher partial pressures (e.g., 0.5-1.0 psi), additional qualification (HIC with lower pH, SSC at higher stress) is required. Womic has qualified X65 for H₂S partial pressure up to 1.0 bar for specific projects. Please share your operating conditions.
Q: What is the typical lead time for X65 sour service LSAW?
A: 80-120 days, depending on Mo-alloyed plate availability (lead time 8-12 weeks) and HIC/SSC testing (4-6 weeks). Rush orders (60-90 days) possible if plates are in stock. Third-party witnessed testing adds 1-2 weeks.
Q: Do you provide CTOD testing for offshore X65 sour risers?
A: Yes. We perform CTOD (Crack Tip Opening Displacement) testing per BS 7448 or ASTM E1820 at specified temperatures (typically -20°C or -46°C). Minimum CTOD values: weld metal ≥ 0.25mm, HAZ ≥ 0.30mm. We have supplied CTOD-tested X65 sour pipes to deepwater projects in the North Sea and Gulf of Mexico.
Project Reference - North West Shelf Sour Gas Pipeline (Australia)
Country: Australia (Western Australia, North West Shelf)
Standard & Grade: API 5L X65 PSL2 with sour service supplement per NACE MR0175; additional CTOD and low temperature requirements
Dimensions & Quantity:
● OD 610mm (24″) × WT 15.9mm - 45,000 meters (approx. 9,200 tons) manufactured by UOE process
● OD 610mm (24″) × WT 19.0mm - 12,000 meters (approx. 2,800 tons) manufactured by UOE process (thicker wall for riser section)
● OD 813mm (32″) × WT 22.2mm - 8,000 meters (approx. 3,100 tons) manufactured by JCOE process (onshore section)
Total: 65,000 meters (65 km), approx. 15,100 tons
Specifications: External 3LPP coating (3.5mm) for high temperature (95°C), beveled ends 30°/1.6mm, hydrotest at 18.0 MPa (design pressure 12.5 MPa). Mandatory Charpy impact at -20°C (min 50J, achieved 100-160J). CTOD at -20°C: weld metal ≥ 0.25mm, HAZ ≥ 0.30mm (achieved 0.35-0.55mm). HIC per NACE TM0284 Solution A, 96h - acceptance: CLR = 0%, CTR = 0%, CSR = 0%. SSC per NACE TM0177 Method A, 720h at 90% SMYS - no cracking. Hardness max 85 HRB. PWHT applied to all pipes (soak 590°C ± 10°C, 1.5 hours). 100% UT with TOFD plus 20% RT. Third party inspection by DNV Australia.
Application: Sour gas pipeline transporting natural gas from offshore fields (with H₂S content of 15-25 ppm) to an onshore LNG plant. The 65 km pipeline includes a deepwater subsea section (water depth 200-300m) and an onshore section through corrosive soil. The pipeline operates at 95°C and 12.5 MPa.
Technical Challenges & Solutions:
● High temperature (95°C) combined with sour service - Most sour service pipelines operate below 80°C. At 95°C, NACE MR0175 imposes stricter limits on hardness and material selection. Womic selected Mo-alloyed plates (Mo 0.20-0.25%) and used 3LPP coating (polypropylene, rated to 120°C) instead of 3LPE (limited to 80°C). PWHT temperature was reduced to 580°C to avoid over-tempering. Hardness after PWHT: base metal 78-82 HRB, weld 80-84 HRB - well within limit.
● Zero crack HIC requirement - Client required CLR = 0% (no HIC cracks). Womic used ultra-low sulfur plates (S ≤ 0.0008%) with Ca/S ratio 2.2. After PWHT, HIC testing on 20 samples (4 per heat) showed CLR 0%, CTR 0%, CSR 0%. Microstructure examination showed only globular sulfides (no elongated MnS).
● CTOD fracture toughness for offshore riser - The riser section (12 km) required CTOD testing at -20°C. Womic performed CTOD on weld metal and HAZ. Results: weld metal 0.40-0.55mm, HAZ 0.45-0.70mm (well above 0.25mm/0.30mm). We also provided full welding procedure qualification (WPQ) recommendations for field girth welding.
● High temperature coating (3LPP) adhesion - 3LPP coating requires FBE primer (epoxy) and polypropylene top layer. Womic applied coating in a climate-controlled workshop. Peel strength at 95°C measured at 75 N/cm (minimum 50 N/cm). Cathodic disbondment at 95°C after 28 days: ≤ 6mm radius.
● Logistics to remote Western Australia - Pipes were shipped from Shanghai to Dampier port (Western Australia) via break-bulk vessel (28-day voyage). Due to cyclone season, two shipments were delayed. Womic adjusted the production schedule to consolidate shipments and avoid demurrage. All 15,100 tons delivered within the project window.
● Result: The sour gas pipeline was commissioned in Q1 2025. After 18 months of operation, in-line inspection (ILI) showed no HIC or SSC related anomalies. The operator has approved Womic Steel as a qualified supplier for future sour gas expansion projects in the North West Shelf.
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 PSL2 sour service LSAW steel pipes for high-pressure sour gas trunk lines, deepwater offshore pipelines, and acidic service applications worldwide.
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