Specifically engineered for harsh offshore environments-including offshore oil & gas platforms, deepwater jackets, offshore wind monopiles & transition pieces, and FPSO support structures-our offshore structures pipe are manufactured from premium carbon and low-alloy steels via hot-rolled or cold-drawn processes. They offer exceptional strength, excellent low-temperature toughness (-40°C to -60°C), good weldability, through-thickness (Z-direction) properties, and uniform wall thickness/microstructure. These features ensure long-term structural integrity and reliability under high loads, corrosion, and cyclic stresses. Compared to welded tubes, seamless tubes eliminate weld defect risks, making them ideal for critical load-bearing and high-fatigue areas.
Key Features
Standards:
International:
API SPEC 5L (PSL2 for offshore piles)
EN 10225-1/-2 (Seamless tubes for offshore structures)
ISO 3183 (Petroleum and natural gas industries – Steel pipes for pipeline transportation systems)
DNV-RP-C208 (Design of piles)
Domestic:
GB/T 30067 (Steels for offshore structures)
SY/T 6954 (Technical specification for seamless tubes in offshore jacket structures)
GB/T 8162 (Structural seamless steel tubes)
Others: NORSOK M-120
Materials:
Seamless steel tubesl: S355J0H, S355J2H, S355K2H (EN 10225)
High-Strength Low-Alloy Steel:
S420MH, S460NH, S460ML (for deepwater & heavy-duty structures)
API 5L Grades: X52, X56, X60, X65, X70 (PSL2 with strict chemistry & mechanical control)
Z-Toughness Steel: Z15, Z25, Z35 (per GB/T 5313), for critical welded joints.
All steels are ladle-refined (LF+VD), with strict control of P, S, O, N to enhance purity and impact toughness.
Dimensions:
Outer Diameter (OD): 89 mm – 630 mm (hot-finished seamless)
Wall Thickness (WT): 6 mm – 80 mm
Length: Fixed (e.g., 12m, 18m) or custom (up to 24m)
Note: Large diameters (>630mm) are typically welded; seamless tubes are ideal for medium/small high-stress components.
Applications:
Chords, braces, and node connectors in offshore jacket structures;
Internal stiffeners and support frames in offshore wind monopiles & transition pieces;
Key load-bearing columns and beams in FPSO modules;
Subsea support piles (medium/small), port wharf piles;
Hydraulic lines and instrument supports in high-fatigue zones.
Certifications:
Classification Society Approvals:
Factory approval for seamless tubes from major class societies:
DNV, ABS, BV, LR, CCS, NK, RINA
Full compliance with material, manufacturing, and inspection.
Mill Test Certificates (MTC, Type 3.1/3.2) with class society stamp available per ISO 10474.
End-User & Engineering Company Qualifications:
Approved supplier for:
International: Shell, BP, TotalEnergies, Equinor, Chevron, ExxonMobil
Domestic: CNOOC, CNPC, CNOOC ETS
EPCs: TechnipFMC, Subsea 7, Saipem, McDermott, Fluor, Bechtel, COOEC, Shanghai Offshore Electric Power Design Institute
Quality & System Certifications:
ISO 9001:2015, ISO 14001:2015, ISO 45001:2018
API 5L Monogram (including seamless marking)
PED 2010/35/EU (CE Marking)
EN 10225 & ISO 3183 Compliance
NORSOK M-120 Conformance Statement
Common Customer Questions (Q&A Format)
Q: Are your offshore structural tubes seamless? What are the advantages over welded tubes?
A: Yes, they are hot/cold-finished seamless tubes. Seamless tubes have no weld defects (e.g., lack of fusion, slag), uniform microstructure, and superior fatigue resistance-ideal for high-stress, cyclic-loading critical zones.
Q: Can you supply S460ML or API 5L X70 seamless offshore tubes? Do they meet -40°C impact requirements?
A: Yes. We produce S355 to S550 and API 5L X52-X70 (PSL2) seamless tubes, all tested at -40°C per standard. Some grades support -60°C testing.
Q: What is your maximum seamless tube size? Can it be used in offshore wind transition pieces?
A: Max OD: 630mm, WT: 80mm. Ideal for internal stiffeners, node connectors in transition pieces. Successfully supplied to multiple wind farm projects.
Q: Do you have DNV, ABS, or other class approvals? Can you provide stamped MTCs?
A: Yes, we hold factory approvals from DNV, ABS, BV, CCS, etc. Each batch comes with class-stamped MTC (Type 3.2), meeting international project requirements.
Q: Are you approved by Shell, CNOOC, or other operators? Can you provide vendor codes?
A: Yes, we have passed technical audits by Shell, CNOOC, TotalEnergies, and hold official vendor codes for bidding and supply.
Q: Do you provide Z-direction (Z15/Z25/Z35) test reports? Where are they used?
A: Yes, Z15, Z25, Z35 through-thickness tensile reports available. Used in welded joints and thick-section connections to prevent lamellar tearing.
Q: What is the typical lead time? Can you support phased delivery for large wind projects?
A: Standard lead time: 45–65 days. We support phased delivery plans aligned with construction schedules for offshore wind projects.
Q: Do you offer end finishing, beveling, or sandblasting?
A: Yes, we provide end chamfering, V/X-groove beveling, sandblasting to Sa2.5, and rust preventive coating to reduce on-site prep time.
Q: Can you manufacture per customer drawings or MDS?
A: Yes, we fully support custom production per drawings, MDS, or technical specifications, including special dimensions, tolerances, and heat treatment (e.g., normalized, normalized + tempered).
Q: What is your export packaging? Is it suitable for sea transport and harsh climates?
A: Packaged with rust-proof paper, plastic end caps, steel strapping in hexagonal bundles, and supports for long tubes. Meets international shipping standards for moisture and impact protection.
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