CASE STUDIES
50 min read
April 24, 2026

Asia's Largest Cylindrical FPSO Just Signed Its HPU Contract — What It Signals for Offshore Skid Suppliers

By Qiangbin Chu
Sales Manager & Operations Lead, Suzhou Lmart Energy Equipment

The Contract That Got Our Attention
Why Cylindrical FPSOs Are Reshaping Equipment Supply Chains
FPSO Equipment Integration: What Goes on the Topsides
Modular Skid Integration — From Concept to Topsides Installation
What Makes Offshore Skid Manufacturing Different
Our FPSO Track Record: From Filters to Valve Boxes
Case Study: Deck Solenoid Valve Boxes for a Major Brazilian FPSO Programme
Case Study: ASME U Filtration Systems for Deepwater FPSO Projects
Offshore Platform Chiller and Refrigeration Systems — A Decade of Delivery
The SBM Offshore FEED Award and What It Means for the Pipeline
Design and Certification Challenges for FPSO Skid Packages
ASME U + Classification Society: Dual Certification for Offshore Skids
Material Selection for FPSO Service: Corrosion, Fatigue, and Weight
The Modular "Plug-and-Play" Trend in FPSO Topsides
Supply Chain Realities: Lead Times, Logistics, and Yard Coordination
What System Integrators Should Look for in a Skid Manufacturer
Frequently Asked Questions

The Contract That Got Our Attention

In January 2026, CSSC Wuhan Marine Machinery secured the hydraulic pump system and offshore crane contract for what will be Asia's largest cylindrical FPSO — CNOOC's Kaiping 11-4 development. The contract, reported by Ocean Energy Resources, covers the complete hydraulic power unit (HPU) package and deck handling equipment for a platform designed to operate in the South China Sea.

A few weeks later, SBM Offshore received the front-end engineering and design (FEED) award from ExxonMobil for the Longtail FPSO in Guyana — a 250,000-barrel-per-day unit destined for 1,750-metre water depth. These are not small announcements. They represent billions of dollars in equipment procurement and years of fabrication work cascading through global supply chains.

For those of us who manufacture process skids, pressure vessels, filtration systems, and auxiliary equipment for offshore platforms, these contracts are leading indicators. When a major FPSO programme signs its HPU package, the procurement cascade for topsides equipment accelerates. Valve actuator skids, filtration units, process separators, refrigeration systems, and utility skids follow within months.

This article examines what these developments mean for offshore skid suppliers, drawing on our own experience delivering equipment to FPSO and offshore platform projects across Brazil, Mozambique, Turkey, and the South China Sea over the past twelve years.

Why Cylindrical FPSOs Are Reshaping Equipment Supply Chains

The traditional FPSO is a ship-shaped vessel — typically a converted tanker hull or a purpose-built ship form. The cylindrical FPSO is a fundamentally different design concept. Originally developed by Sevan Marine (now Sevan SSP, part of SBM Offshore), cylindrical FPSOs offer 360-degree wave transparency, eliminating the need for a turret mooring system and significantly reducing the vessel's response to wave loading.

What This Means for Equipment Suppliers

The cylindrical hull changes the topsides layout in ways that directly affect skid-mounted equipment:

Deck space geometry — A cylindrical FPSO distributes processing modules radially rather than linearly. Equipment skids must fit within pie-shaped deck sectors rather than the long, narrow modules typical of ship-shaped FPSOs. This changes skid dimensions, piping run layouts, and access arrangements.

Motion characteristics — Cylindrical FPSOs have different heave, pitch, and roll characteristics compared to ship-shaped units. Equipment must be designed for the specific motion response spectrum — sloshing loads on liquid-containing vessels, fatigue loading on pipe supports, and acceleration loads on rotating equipment all differ from conventional FPSO service.

Weight distribution — The radial layout demands careful weight management. Every kilogram on the topsides affects stability. Skid manufacturers who can optimise weight without compromising structural integrity have a clear advantage.

Modularisation strategy — Cylindrical FPSOs are particularly suited to modular construction, with topsides modules fabricated at multiple yards and integrated at a final assembly site. This places premium on interface management, dimensional control, and the ability to deliver factory-tested, ready-to-connect skid packages.

The CNOOC Kaiping 11-4 Programme

The Kaiping 11-4 field development in the South China Sea represents CNOOC's largest deep-water project in the region. The cylindrical FPSO is designed for:

Oil processing capacity exceeding 50,000 barrels per day
Gas handling and compression for re-injection or export
Water injection and produced water treatment
Full utility systems including power generation, HVAC, and potable water

Each of these processing functions requires multiple skid-mounted systems — from the high-pressure separator packages in the process train to the glycol dehydration units in the gas handling system, from the chemical injection skids in the water treatment system to the chiller packages in the HVAC system.

When CSSC Wuhan secured the HPU contract, it signalled that the project is moving from FEED to detailed engineering. For skid suppliers, this means the procurement packages for topsides equipment are being prepared now.

FPSO Equipment Integration: What Goes on the Topsides

An FPSO topsides is essentially a complete oil and gas processing facility mounted on a floating hull. The equipment scope typically includes hundreds of individual skid-mounted systems, each requiring design, fabrication, testing, and certification before delivery to the integration yard.

Process Skids

The core processing train converts raw wellstream fluids into export-quality oil and gas:

Production separators — Three-phase (oil/gas/water) separation vessels, typically 3-4 stages
Heat exchangers — Crude oil heaters, gas coolers, lean/rich glycol exchangers
Compressor packages — Gas compression for export, gas lift, or fuel gas
Dehydration units — TEG glycol contactors and regeneration systems
Metering skids — Fiscal and allocation metering for production accounting

Utility Skids

Supporting systems that keep the platform operational:

Hydraulic power units (HPUs) — The system that just got contracted for Kaiping 11-4. HPUs provide motive power for subsea valve actuators, BOP systems, and deck equipment
Chemical injection skids — Corrosion inhibitor, scale inhibitor, demulsifier, and biocide injection
Filtration systems — Seawater filtration for injection, produced water treatment
Refrigeration and HVAC — Living quarters cooling, process area ventilation, equipment room temperature control
Fire and gas detection panels — Integrated safety systems

Deck Equipment Skids

Crane power units — Hydraulic and electrical systems for deck cranes
Valve actuator control panels — Solenoid valve boxes, actuator junction boxes
Pigging launcher/receiver skids — Pipeline cleaning and inspection equipment

FPSO 上部模块设备分类示意图（Process / Utility / Deck）— Gemini

Each of these categories involves specialised manufacturers. But the common thread is skid integration — taking individual components (vessels, pumps, valves, instruments, piping) and assembling them into tested, certified, ready-to-install modules.

Modular Skid Integration — From Concept to Topsides Installation

The offshore industry has been talking about modularisation for decades, but the current generation of FPSOs has pushed the concept further than ever. The driver is simple: minimise offshore hook-up time. Every day of offshore installation costs hundreds of thousands of dollars. Every system that arrives on the topsides already tested and proven saves weeks of offshore commissioning.

What "Modular" Actually Means in Practice

A modular skid is not just a frame with equipment bolted to it. A properly engineered offshore skid includes:

Structural steel frame — Designed for transportation loads (road, sea, lift), operational loads (static, dynamic, seismic), and survival loads (blast, fire, dropped object). The frame must interface precisely with the topsides module steelwork at defined connection points.

Process equipment — Pressure vessels, heat exchangers, pumps, compressors — all mounted within the frame with proper vibration isolation, thermal expansion allowances, and maintenance access.

Piping — Internal interconnecting piping between components, with defined tie-in points at the skid boundary. Offshore piping specifications are typically more stringent than onshore — higher corrosion allowances, full radiography, impact testing, and classification society witnessed hydrostatic testing.

Instrumentation and control — Local instrument panels, junction boxes, and marshalling cabinets. Wiring runs from instruments to the junction box boundary, ready for the integration yard to connect to the platform DCS.

Electrical — Local power distribution, motor starters (if applicable), lighting, and earthing. Junction boxes at the skid boundary for power and signal cable connections.

Surface treatment — Offshore paint systems (typically C5-M or CX per ISO 12944) with specific dry film thickness requirements for splash zone, atmospheric zone, and internally coated surfaces.

Factory Acceptance Testing (FAT)

Before an offshore skid leaves the manufacturer's workshop, it undergoes factory acceptance testing that can take 2-4 weeks:

Pressure testing of all vessels and piping systems
Leak testing of instrument air and hydraulic systems
Functional testing of all valves, instruments, and control logic
Vibration testing of rotating equipment
Dimensional verification against the 3D model
Documentation review with the customer's inspection team and the classification society surveyor

This is where the value of modular fabrication becomes tangible. Problems found in the workshop cost a fraction of what they would cost to fix offshore.

What Makes Offshore Skid Manufacturing Different

Manufacturing a skid for an offshore platform is fundamentally different from manufacturing the same equipment for an onshore plant. The differences go beyond the obvious (corrosion protection, motion loads) into every aspect of the manufacturing process.

Classification Society Oversight

Onshore process equipment is typically designed and fabricated to codes like ASME VIII, PED 2014/68/EU, or national standards. The manufacturer self-certifies compliance (with authorised inspector involvement for ASME).

Offshore equipment adds classification society oversight. DNV, ABS, BV, LR, CCS, or NK survey the design, witness critical manufacturing stages, and issue certificates of conformity. This means:

Design review and approval before fabrication begins — the class society reviews drawings, calculations, material specifications, and welding procedures
Hold and witness points during fabrication — critical welds, NDE, heat treatment, pressure testing, and final inspection require class surveyor attendance
Material certification — beyond standard mill certificates, class societies may require additional testing (impact testing at specific temperatures, corrosion testing for sour service, etc.)
Documentation packages — a classified offshore skid generates 500-2,000+ pages of documentation including design calculations, material certificates, welding records, NDE reports, pressure test certificates, dimensional records, and paint inspection reports

Dual Certification: ASME + Class

Many FPSO projects require dual certification — ASME U stamp for the pressure vessels and classification society certification for the complete skid assembly. This is not simply additive. The ASME AI (Authorised Inspector) and the class surveyor may have different requirements for the same weld or test, and the manufacturer must satisfy both simultaneously.

Having delivered equipment with ASME U certification across multiple classification societies — including projects requiring LR, ABS, DNV, and CCS certification — we can confirm that managing dual certification is one of the most demanding aspects of offshore skid manufacturing. It requires meticulous planning, clear communication with both certifying bodies, and a quality management system that tracks every requirement from both codes.

Environmental Design Conditions

FPSO equipment must be designed for conditions that onshore equipment rarely encounters:

Motion and acceleration — Vessel motion induces additional loads on all equipment. A pressure vessel that is perfectly stable onshore must withstand the combined effects of heave, pitch, roll, and sway when mounted on an FPSO. Design must account for sloshing in liquid-containing vessels.
Vibration — Structural vibration from hull whipping, machinery, and propeller excitation
Temperature extremes — From tropical surface waters (35C+) to North Atlantic winter (-20C)
Blast and fire — Equipment in hazardous zones must survive blast overpressure and/or fire exposure for specified durations
Marine atmosphere — C5-M corrosivity category per ISO 12944, with specific requirements for splash zone exposure

Our FPSO Track Record: From Filters to Valve Boxes

Over the past twelve years, we have delivered equipment to multiple FPSO and offshore platform projects. Our offshore and FPSO-related work includes:

FPSO Direct Supply

Deck Solenoid Valve Boxes for a Major Brazilian FPSO Programme (2023)

A leading British valve actuator manufacturer contracted us to design and fabricate 12 sets of deck solenoid valve boxes for a large-scale FPSO programme operated by Brazil's national oil company. These valve boxes are critical components in the topside actuator control system — they house the solenoid valves that control the hydraulic or pneumatic actuators operating the platform's process and safety valves.

ASME U + NR Certified Filtration Systems for a Deepwater FPSO (2021)

A major Israeli-origin filtration technology company specified our filters for a deepwater FPSO project offshore Brazil. The scope included ASME U stamped pressure vessels with NR (National Board Registration) certification — a requirement for equipment destined for Brazilian-flagged offshore units.

Filtration Equipment for Coral South Development (2014)

Seven filter units certified to both LR classification standards and ASME U stamp requirements, delivered for the Coral South floating LNG development offshore Mozambique. This project — one of the first deepwater FLNG developments in East Africa — required equipment that met both international pressure vessel codes and class society rules for offshore service.

Offshore Platform Equipment

Refrigeration and HVAC Systems for South China Sea Platforms (2012-2014)

Four offshore platform projects for CNOOC and CNPC in the South China Sea, delivering chiller units and refrigeration systems. These included the COPE9 platform (a major York Marine project), COPE7, HTB, and Platform 10 installations. Each required equipment designed for marine atmosphere corrosion, platform motion, and the specific HVAC requirements of offshore living quarters and process areas.

Refrigeration Systems for Brazilian FPSO Programme (2014-2016)

Four complete refrigeration systems delivered to a global building technologies company (headquartered in Denmark) for integration into Brazilian FPSO units. These systems were installed on four separate FPSO hulls — two operated by a major EPC consortium and two by Brazil's national oil company. The scope required equipment compatible with the Brazilian regulatory framework and class society certification.

Case Study: Deck Solenoid Valve Boxes for a Major Brazilian FPSO Programme

Project Background

In 2023, a leading British actuator and flow control company — one of the world's largest manufacturers of valve actuators — awarded us the contract to manufacture 12 sets of deck solenoid valve boxes for their FPSO programme. The end-user was Brazil's national oil company, and the equipment was destined for their P-series FPSO fleet.

What Is a Deck Solenoid Valve Box?

A deck solenoid valve box (DSVB) is the nerve centre of a topside valve actuator system. It houses:

Solenoid valves — electrically operated valves that control hydraulic or pneumatic signals to valve actuators across the platform
Manual override mechanisms — allowing operators to manually control critical valves during power failure or emergency conditions
Pressure regulators and filters — conditioning the supply medium before distribution to actuators
Junction terminals — electrical connections for solenoid coil power and position feedback signals
Enclosure — IP66 or IP67 rated weatherproof housing designed for marine atmospheric exposure, with provisions for cable glands, drain ports, and access for maintenance

Technical Challenges

Enclosure design for FPSO service — The valve boxes must withstand continuous salt spray exposure, temperature cycling between -10C and +55C, vibration from FPSO hull motion, and potential blast overpressure in hazardous zones. Material selection (316L stainless steel enclosures with silicone gaskets), surface treatment, and fastener specification all required careful engineering.

Interface management — Each valve box interfaces with the actuator manufacturer's proprietary control system, the platform's electrical distribution system, and the hydraulic/pneumatic supply network. Dimensional accuracy at every interface point was critical — the boxes had to fit into pre-defined spaces on the FPSO topsides module steelwork.

Quality and documentation — The actuator company's quality requirements reflected their own tier-one status in the offshore industry. Every component was traceable, every assembly step documented, and the final documentation package included full material traceability, assembly records, test certificates, and installation drawings.

Delivery and Outcome

All 12 sets were manufactured, tested, and delivered within the contracted schedule. The project demonstrated our capability to work as a sub-tier supplier to a major OEM, meeting their exacting quality standards while managing the complexities of FPSO-grade equipment.

Case Study: ASME U Filtration Systems for Deepwater FPSO Projects

The Bacalhau FPSO Project (2021)

The Bacalhau field, located in the Santos Basin pre-salt province offshore Brazil, is one of the world's most significant deepwater oil discoveries. The FPSO for this field — designed to process up to 220,000 barrels per day — required filtration systems that met both ASME U stamp requirements and the specific material and design standards of the international filtration technology company that specified our equipment.

Technical Scope

We manufactured two ASME U + NR certified filter vessels for this project. The National Board Registration (NR) was a specific requirement driven by the Brazilian regulatory framework — equipment installed on Brazilian-flagged offshore units must carry NR certification in addition to the ASME U stamp.

Key technical parameters:

Design code: ASME Section VIII, Division 1
Certifications: ASME U stamp + National Board Registration (NR)
Materials: SA-516 Gr.70 normalised (shell and heads), SA-105 (nozzle forgings)
NDE: 100% radiographic examination of all longitudinal and circumferential welds
Testing: Hydrostatic test at 1.5× design pressure, witnessed by ASME Authorised Inspector
Surface treatment: Internal epoxy lining compatible with the filtration media, external offshore paint system

The Coral South Connection (2014)

Three years earlier, we had delivered seven filter units for the Coral South floating LNG development offshore Mozambique. This project required dual certification — LR classification standards for the marine application and ASME U stamp for the pressure vessel code compliance.

The Coral South project was significant for several reasons:

It was among the first deepwater FLNG developments in East Africa
LR certification added a layer of design review, witness testing, and documentation beyond the ASME requirements
The project established our capability to deliver ASME-certified pressure vessels for FPSO/FLNG applications

From Coral South in 2014 to Bacalhau in 2021, these filtration projects demonstrate a continuous capability in delivering code-certified pressure equipment for the most demanding offshore applications.

Offshore Platform Chiller and Refrigeration Systems — A Decade of Delivery

South China Sea Platforms (2012-2014)

Our offshore work began with HVAC and refrigeration systems for South China Sea platforms. Between 2012 and 2014, we delivered chiller units and refrigeration systems for four offshore installations:

COPE9 Platform — A refrigeration system package for a York Marine project, serving CNOOC's operations in the South China Sea
COPE7 Platform — Air-cooled chiller unit for CNOOC Tianjin
Platform 10 — Chiller package for CNPC offshore operations
HTB Platform — Chiller system delivered through China Dalian Shipbuilding Industry

These projects taught us the specific requirements of offshore refrigeration — equipment must handle the corrosive marine atmosphere, platform motion, limited deck space, and the specific cooling loads of offshore living quarters (where precise temperature and humidity control is essential for crew comfort and equipment reliability).

Brazilian FPSO Refrigeration Systems (2014-2016)

The scale increased significantly when a global building technologies company (headquartered in Denmark, now part of one of the world's largest building technology groups) contracted us for four complete refrigeration system packages destined for Brazilian FPSOs.

The four systems were installed on:

C-023 and C-024 — Two FPSO hulls built by a major Brazilian shipyard (Estaleiro Atlantico Sul)
P-75 and P-77 — Two FPSO hulls for a major EPC and power conversion consortium

Each refrigeration system was a complete skid-mounted package including:

Compressor units (reciprocating and screw type)
Condenser and evaporator heat exchangers
Receiver vessels
Refrigerant piping with vibration-resistant connections
Control panels with local HMI
Structural frame designed for FPSO motion loads

The Brazilian FPSO programme was one of the largest ship-to-platform conversion efforts in history, and our involvement across four hulls demonstrated the ability to deliver consistent quality in a serial production environment.

The SBM Offshore FEED Award and What It Means for the Pipeline

In March 2026, SBM Offshore received the FEED contract from ExxonMobil for the Longtail FPSO — a 250,000-barrel-per-day unit for the Stabroek Block offshore Guyana. The vessel will operate in 1,750-metre water depth, making it one of the deepest FPSO deployments in the Americas.

Why This Matters for Skid Suppliers

FEED contracts typically last 12-18 months. During FEED, the engineering company finalises the process design, equipment specifications, and procurement strategy. For skid manufacturers, the FEED phase is when:

Equipment datasheets are issued — defining the technical requirements for every skid package
Vendor qualification begins — the EPC contractor and operator assess potential suppliers
Budgetary quotations are requested — manufacturers provide preliminary pricing and delivery estimates
Pre-qualification audits are scheduled — the operator's supply chain team visits potential suppliers

The Longtail FPSO FEED means that by late 2026 or early 2027, procurement packages for topsides equipment will begin hitting the market. System integrators, actuator companies, filtration specialists, and process equipment manufacturers will all be competing for scope.

The Broader FPSO Pipeline

The Kaiping 11-4 and Longtail awards are part of a broader FPSO construction pipeline that includes:

Petrobras pre-salt programme — Continuing orders for FPSO hulls in the Santos and Campos basins
Guyana Stabroek Block — ExxonMobil's multi-FPSO development (Liza Phase 1 & 2, Payara, Yellowtail, Uaru, and now Longtail)
West Africa — TotalEnergies, Eni, and BP programmes offshore Angola, Nigeria, and Mozambique
Southeast Asia — CNOOC, PTTEP, and Petronas deepwater developments

Industry analysts estimate 15-20 FPSO orders between 2026 and 2030. Each FPSO represents $3-5 billion in total investment, with topsides equipment accounting for 25-35% of the total cost.

For skid manufacturers with proven offshore track records, certified quality systems, and the capacity to deliver on tight schedules, this pipeline represents significant opportunity.

Design and Certification Challenges for FPSO Skid Packages

Dynamic Loading

The fundamental difference between onshore and offshore skid design is dynamic loading. An FPSO moves — it heaves, pitches, rolls, surges, sways, and yaws. Every component on the topsides experiences these motions as additional loads superimposed on the static operating loads.

For pressure vessels, this means:

Sloshing analysis — Liquid-containing vessels must be designed for sloshing loads. A half-full separator on an FPSO generates sloshing forces that can exceed the static pressure load. FPSO motion data (significant wave height, peak period, vessel response amplitude operators) feeds into sloshing load calculations that determine nozzle loads, support reactions, and internals design.
Fatigue assessment — FPSO equipment experiences millions of load cycles over its 20-25 year design life. Fatigue analysis per BS 7608, DNV-RP-C203, or similar standards is required for structural connections, nozzle-to-shell junctions, and pipe support attachments.
Seismic-equivalent acceleration — Even non-seismic locations require acceleration load cases derived from the FPSO motion study. Typical design accelerations range from 0.3g to 0.8g depending on the hull form, mooring system, and sea state.

Weight Optimisation

Every kilogram matters on an FPSO. Topsides weight directly affects hull design, stability, mooring loads, and construction cost. Skid manufacturers are under constant pressure to minimise weight without compromising structural integrity.

Common weight optimisation strategies include:

Material upgrade — Using higher-strength steel (S355 vs S275) to reduce structural member sizes
Duplex stainless steel — Higher allowable stress than austenitic stainless, reducing wall thickness for corrosion-resistant applications
Compact heat exchanger technology — Printed circuit, plate-fin, or welded plate designs that achieve the same duty in a fraction of the weight and volume of shell-and-tube exchangers
Piping optimisation — Reducing unnecessary fittings, using long-radius bends instead of elbows, and optimising pipe routing to minimise total pipe length
Skid frame optimisation — FEA-based structural design to eliminate over-conservatism in frame member sizing

Access and Maintainability

FPSO topsides are cramped. Equipment must be maintainable in-situ because removing a large component from an FPSO topsides is a major crane operation. Skid design must accommodate:

Tube bundle pull space for heat exchangers
Valve removal clearances
Filter element replacement access
Instrumentation calibration access
Lifting lugs and pad eyes for component replacement

ASME U + Classification Society: Dual Certification for Offshore Skids

Why Dual Certification Exists

ASME Section VIII provides the design and fabrication code for pressure vessels. Classification societies (DNV, ABS, BV, LR, CCS, NK) provide the marine certification framework. For FPSO applications, both are typically required:

ASME U stamp — Certifies that the pressure vessel was designed, fabricated, and tested in accordance with ASME Section VIII
Class certification — Certifies that the equipment meets the classification society's rules for materials, welding, testing, and documentation, and that the design is suitable for the specific marine application

Managing Two Certifying Bodies Simultaneously

In practice, managing dual certification means coordinating two independent inspection regimes:

Design phase — ASME calculations must satisfy both the ASME code requirements and the class society's additional requirements (which may include more conservative allowable stresses, additional load cases, or specific material restrictions).

Material procurement — Materials must satisfy both ASME material specifications (SA-516, SA-240, SA-312, etc.) and class society material requirements (which may include additional impact testing, through-thickness testing, or chemical composition restrictions).

Welding — Welding procedures must be qualified to both ASME Section IX and class society welding rules. In most cases, ASME Section IX qualification satisfies the class society requirement, but specific welders must be approved by both the ASME AI and the class surveyor.

NDE and testing — NDE acceptance criteria must meet both ASME Section VIII requirements and class society rules. Pressure testing must be witnessed by both the ASME AI and the class surveyor (which can be coordinated if planned in advance).

Documentation — Two separate documentation packages are required — the ASME Manufacturer's Data Report (MDR / U-1 form) and the class society certificate of conformity, plus all supporting records.

Our Cross-Certification Experience

We hold ASME U stamp certification and have delivered equipment certified by six classification societies. Our welding procedure qualification record (PQR) library covers 600+ procedures across carbon steel, stainless steel, duplex, nickel alloys, titanium, and aluminium — providing the breadth of qualified processes needed to handle diverse offshore specifications.

In 2021, we delivered ASME U + NR certified filtration systems for an FPSO project, simultaneously meeting the ASME requirements and the specific needs of the Brazilian regulatory framework. In 2014, we delivered LR-classified and ASME U stamped filter vessels for the Coral South FLNG. These projects demonstrated that dual certification, while demanding, is entirely manageable with the right quality system and inspection planning.

Material Selection for FPSO Service: Corrosion, Fatigue, and Weight

The Corrosion Challenge

FPSO equipment operates in one of the most corrosive environments on earth — the combination of salt spray, high humidity, temperature cycling, H2S and CO2 in the process fluids, and 20+ year design life creates material selection challenges that exceed most onshore applications.

Process-side materials depend on the fluid composition:

Sweet service (low H2S, low CO2): Carbon steel with corrosion allowance (3-6mm typical for FPSO)
Mildly sour service: Carbon steel with NACE MR0175/ISO 15156 compliance (hardness limits, PWHT)
Severe sour service: CRA (corrosion resistant alloy) — 316L, duplex 2205, or super duplex 2507
Seawater service: 90/10 CuNi, titanium, or GRP (depending on pressure and temperature)

External materials must withstand the marine atmosphere:

Structural steel: S355 minimum, with C5-M paint system (typically 320+ micron DFT)
Fasteners: Hot-dip galvanised or 316 stainless steel
Instrument tubing: 316 stainless steel
Cable trays: FRP or hot-dip galvanised steel

Fatigue Considerations

Material selection for fatigue-critical connections follows classification society guidance:

DNV-RP-C203 for structural steel fatigue design
ASME VIII, Division 2 for pressure vessel fatigue assessment
BS 7608 for welded joint fatigue classification

Higher-strength steels can reduce static weight but may not improve fatigue performance — fatigue life is primarily governed by joint geometry, weld quality, and stress range rather than material strength.

The Modular "Plug-and-Play" Trend in FPSO Topsides

The offshore industry is moving decisively toward what it calls "plug-and-play" modularisation. The concept is simple: maximise the scope of work completed onshore in controlled workshop conditions, and minimise the scope of work completed offshore where costs are 5-10 times higher.

What "Plug-and-Play" Means for Skid Manufacturers

For skid manufacturers, the plug-and-play trend means:

Larger scope per skid — Instead of delivering individual pressure vessels or equipment items, manufacturers are increasingly asked to deliver complete process systems. A filtration "skid" might now include the filter vessels, backwash pumps, chemical dosing system, instrument air supply, local control panel, and all interconnecting piping — all tested as an integrated system before shipment.

More stringent interface requirements — Mechanical, electrical, instrument, and piping tie-in points must match the 3D model to millimetre accuracy. Interface management becomes a core competency.

Extended FAT requirements — Factory acceptance tests now include functional testing (not just pressure testing), with the end-user's commissioning team present to verify system performance.

Documentation for commissioning — In addition to fabrication records, manufacturers must provide commissioning procedures, operating manuals, and maintenance schedules that the offshore commissioning team can use directly.

The Industry Trend: Hybrid Fuels

The FPSO industry is also embracing hybrid fuel systems as part of the broader energy transition. New-build FPSOs are being designed with:

Dual-fuel power generation (diesel + gas, or diesel + methanol)
Waste heat recovery systems
Electrification of auxiliary systems (replacing hydraulic with electric actuators)
Carbon capture readiness

Each of these trends creates demand for new types of skid-mounted systems — methanol fuel supply skids, waste heat recovery skids, electric actuator power distribution units — expanding the addressable market for modular equipment manufacturers.

Supply Chain Realities: Lead Times, Logistics, and Yard Coordination

Typical Lead Times

Offshore skid procurement follows a predictable timeline:

Phase	Duration	Activities
Enquiry to order	4-8 weeks	Technical clarification, commercial negotiation, vendor qualification
Engineering	6-12 weeks	Detail design, drawing approval, material requisitions
Material procurement	8-16 weeks	Long-lead items (forgings, special alloys, large plates)
Fabrication	12-20 weeks	Structural, piping, vessel fabrication, assembly
Testing and inspection	2-4 weeks	NDE, pressure testing, FAT, documentation
Total	32-60 weeks	Depending on complexity and certification requirements

Critical path items that drive schedule include:

Forged nozzles and flanges — Special sizes or exotic materials can take 16-20 weeks
Classification society design review — Allow 4-6 weeks for initial review plus response cycles
ASME AI scheduling — Authorised Inspector availability must be coordinated with fabrication milestones
Coating and lining — Multi-coat offshore paint systems require controlled environmental conditions and curing times between coats

Logistics for Oversized Skids

FPSO skids can be large — 15-20 metres long, 4-6 metres wide, and weighing 50-100+ tonnes. Transportation from the manufacturer's workshop to the integration yard requires:

Heavy-haul road transport (with route surveys, police escorts, and utility line clearances)
Barge transport for waterside delivery
Heavy-lift crane operations for loading and unloading
Temporary supports and sea-fastening for ocean transport

The logistics chain must be planned during the engineering phase — the skid's structural frame must include lifting lugs, transport supports, and sea-fastening pad eyes as integral design features.

What System Integrators Should Look for in a Skid Manufacturer

Based on our experience working with system integrators, EPC contractors, and OEM equipment companies on FPSO and offshore platform projects, the following capabilities distinguish qualified offshore skid manufacturers:

Certification Portfolio

ASME U stamp — Essential for pressure vessels destined for international projects
PED CE marking — Required for equipment destined for EU-flagged vessels or European operators
ISO 9001 — Baseline quality management system
Classification society approvals — Active relationships with multiple class societies, with a track record of successful certification across different societies

Technical Capability

600+ PQR library — Welding procedure qualifications across multiple material combinations, processes, and positions. A deep PQR library means the manufacturer can handle diverse specifications without lengthy qualification programmes.
NDE capability — In-house or subcontracted RT, UT, MT, PT, and TOFD capability, with certified operators
3D modelling — SolidWorks, Inventor, or equivalent for detailed skid design and interface management
FEA capability — For structural analysis, fatigue assessment, and dynamic load evaluation

Track Record

50+ countries delivered — International shipping and export documentation experience
FPSO and offshore references — Specific project references demonstrating offshore equipment delivery
OEM partnerships — Experience working as a sub-tier supplier to major OEMs (system integrators, actuator companies, filtration technology providers)
Serial production capability — Ability to maintain quality across multiple identical units (critical for FPSO programmes ordering 4-8 identical skids)

Practical Considerations

Workshop capacity — Sufficient floor space and crane capacity for the skid dimensions
Inspection facilities — Class surveyor office space, document review facilities, and witness test setup
Proximity to port — Simplified logistics for oversized equipment

Frequently Asked Questions

What is the difference between a process skid and a modular package?

A process skid typically refers to a single-function system (e.g., a filtration skid, a chemical injection skid) mounted on a structural frame. A modular package is a larger assembly that may contain multiple process functions — effectively a section of the process plant pre-assembled on a transportable frame. The terminology is often used interchangeably, but in FPSO procurement, "module" usually implies a larger scope than "skid."

How long does it take to manufacture an offshore skid?

Typical lead times range from 32 to 60 weeks from order to delivery, depending on complexity, material availability, and certification requirements. Critical path items are usually long-lead materials (special forgings, exotic alloys) and classification society review cycles.

What certifications are needed for FPSO skid equipment?

Most FPSO projects require ASME U stamp for pressure vessels, classification society certification (DNV, ABS, BV, LR, CCS, or NK depending on the vessel's flag and operator requirements), and compliance with the operator's specific technical specifications. Some projects additionally require PED CE marking, NR (National Board Registration), or specific national certifications.

Can a single manufacturer handle both pressure vessels and complete skid integration?

Yes — and this is increasingly the preferred model. Having a single manufacturer responsible for pressure vessel fabrication, piping, structural steel, and system integration eliminates the interface risks that arise when multiple suppliers contribute to a single skid. Our FPSO projects have consistently been delivered as integrated skid packages rather than individual components.

What is the typical cost premium for offshore-grade equipment vs. onshore?

The premium varies by equipment type but typically ranges from 30-80% over equivalent onshore equipment. The drivers are classification society certification costs, enhanced material specifications, additional NDE requirements, offshore paint systems, marine-grade electrical and instrumentation, and the documentation burden.

How does the manufacturer coordinate with the classification society during fabrication?

The manufacturer submits an Inspection and Test Plan (ITP) to the class society identifying all hold points (where work stops until the surveyor inspects) and witness points (where the surveyor may attend). Typical hold points include material identification, fit-up inspection before welding critical joints, NDE review, pressure testing, and final inspection. The class society assigns a local surveyor who visits the workshop at each hold point.

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Conclusion

The FPSO construction pipeline is building momentum. From CNOOC's Kaiping 11-4 cylindrical FPSO to ExxonMobil's Longtail in Guyana, the contracts being signed today will drive equipment procurement for years to come. The trend toward larger, more complex, and more modular topsides systems means that skid manufacturers with proven offshore credentials, dual certification capability, and the manufacturing depth to deliver consistent quality across serial programmes will be well-positioned.

Our twelve-year track record — from the Coral South FLNG filtration systems and Brazilian FPSO refrigeration packages to the deck solenoid valve boxes for a major actuator OEM — reflects a deliberate investment in offshore capability. With ASME U certification, ISO 9001, PED CE marking, 600+ welding PQRs, and delivery to 50+ countries, we are positioned to support the next wave of FPSO topsides equipment procurement.

For system integrators and EPC contractors evaluating skid manufacturing partners for FPSO projects, we welcome the conversation.

Contact: sales@jnlmart.net | www.jnlmart.net

Learn more about our modular skid and pressure vessel capabilities:

Last reviewed: April 24, 2026 · Technical accuracy verified by Lmart Engineering Dept.