Every Cargo Switch Costs 48 Hours — How CIP Skids Cut LPG Carrier Turnaround Time
Table of Contents
- The 48-Hour Problem Nobody Talks About
- What Is a CIP Skid and Why Do Gas Carriers Need One?
- The Economics of Cargo Switching on VLGCs
- How CIP Systems Work on LPG Carriers
- CIP Skid Components: What Goes Inside the Package
- Our CIP Skid Track Record: 23+ Units Delivered Since 2016
- Case Study: CIP Units for 93K VLAC Programme — NK Certified
- Case Study: 18 CIP Units Across Five Major Gas Carrier Programmes in 2025
- Design Challenges for Marine CIP Skids
- Classification Society Requirements for CIP Systems
- CIP vs. Manual Tank Cleaning: A Cost Comparison
- The Multi-Cargo Trend: LPG, Propylene, Butadiene, and Ammonia
- Material Selection for CIP Skid Pressure Components
- Integration with Cargo Handling Systems
- What System Integrators Should Look for in a CIP Skid Manufacturer
- Frequently Asked Questions
The 48-Hour Problem Nobody Talks About
The global VLGC fleet now exceeds 350 vessels in active service, with order books pointing to 400+ within two years. These ships are not just carrying LPG anymore. Multi-cargo operations — LPG, propylene, butadiene, ammonia, ethylene — have become the norm for owners seeking flexibility in volatile freight markets. Every cargo grade switch requires thorough tank cleaning to prevent cross-contamination, and every cleaning cycle costs time.
How much time? Between 24 and 48 hours per switch, depending on cargo compatibility, tank condition, and cleaning method. For a VLGC earning $40,000-80,000 per day in a strong market, a single cargo switch represents $40,000 to $160,000 in lost revenue — not counting bunker costs, port charges, and crew overtime.
Multiply that across a fleet of 10 carriers doing 3-4 cargo switches per year each, and you are looking at millions of dollars in annual turnaround losses. Shipping companies have tried everything from optimising voyage planning to reducing the number of cargo grade changes. But when the arbitrage between LPG and propylene is wide enough, the switch has to happen. The question becomes: how fast can you clean?
This is where CIP (Cleaning In Place) skids enter the picture. Purpose-built, skid-mounted cleaning systems designed specifically for gas carrier cargo tanks — capable of reducing cleaning time by 30-50% compared to manual methods while delivering consistent, verifiable cleanliness standards.
We have been manufacturing CIP skids for gas carrier programmes since 2016. Over the past decade, we have delivered 23+ CIP units across 10+ vessels, working exclusively as the OEM manufacturer for two of the world's leading gas carrier system integrators. This article examines the CIP skid from the manufacturing floor — what goes into these systems, why they matter for carrier economics, and what makes them technically challenging to build.
What Is a CIP Skid and Why Do Gas Carriers Need One?
CIP — Cleaning In Place — is a process technology borrowed from the food, beverage, and pharmaceutical industries, where it has been used for decades to clean processing equipment without disassembly. In those industries, CIP systems circulate cleaning solutions (water, caustic, acid, sanitiser) through tanks, pipes, and vessels at controlled temperature, flow rate, and concentration to remove residues.
On gas carriers, the principle is identical but the application is fundamentally different. Cargo tanks on VLGCs and large LPG carriers are Type C independent pressure tanks — typically cylindrical or bi-lobe design, constructed from high-tensile steel or 9% nickel steel for low-temperature service. These tanks hold 80,000-100,000 cubic metres of liquefied gas at temperatures as low as -104 degrees C (for ethylene service) or -48 degrees C (for LPG).
When a carrier switches from one cargo grade to another — say, from commercial propane to polymer-grade propylene — the cargo tanks must be cleaned to specification. Propylene purity requirements are stringent: total sulphur below 1 ppm, moisture below 5 ppm, and zero detectable hydrocarbon cross-contamination. Any residue from the previous cargo renders the next cargo off-spec, potentially resulting in cargo claims worth millions.
Traditional Cleaning Methods
Before CIP skids became standard, gas carrier tank cleaning relied on several methods:
Gas freeing and ventilation — Purging cargo tanks with inert gas (nitrogen) followed by air ventilation. Effective for removing vapours but not surface residues or waxes.
Hot water washing — Manual or semi-automated hot water spray through portable nozzles. Labour-intensive, time-consuming, and inconsistent. Cleaning verification requires multiple rounds of vapour testing.
Solvent washing — Using compatible solvents to dissolve residues. Expensive, creates waste disposal issues, and requires hazardous material handling procedures.
Steaming — Injecting steam into cargo tanks to vaporise residues. Effective but slow, and condensate management is complex on large tanks.
Each of these methods requires the vessel to be out of commercial service for extended periods. More importantly, they produce inconsistent results — cleaning effectiveness depends on crew skill, weather conditions, tank geometry, and the specific contaminants involved.
How CIP Skids Change the Equation
A CIP skid is a self-contained, skid-mounted system that automates the cleaning cycle. It includes pumps, heaters, filters, chemical dosing systems, spray nozzles (or rotating spray heads), piping, instrumentation, and a control system — all pre-assembled and tested in the factory, delivered as a plug-and-play module.
The key advantages:
Repeatability — Every cleaning cycle follows the same parameters: flow rate, temperature, chemical concentration, contact time, spray pattern. The result is consistent, auditable cleanliness.
Speed — Automated systems run faster than manual methods because they operate continuously at optimal parameters. A CIP cycle that takes 12-16 hours replaces a manual process that might take 36-48 hours.
Reduced chemical usage — Precise dosing means less chemical waste, lower disposal costs, and reduced environmental impact.
Documentation — Modern CIP systems log every parameter — temperatures, flow rates, chemical concentrations, cycle times — providing the evidence trail that charterers and cargo surveyors require.
Safety — Minimises the need for crew to enter confined spaces or handle hazardous chemicals manually.
The Economics of Cargo Switching on VLGCs
To understand why CIP skids matter commercially, consider the economics of a typical VLGC operation.
Fleet Growth and Multi-Cargo Demand
The global VLGC fleet (vessels of 80,000 cbm and above) has grown from approximately 280 ships in 2020 to over 350 in 2026. Another 80+ vessels are on order for delivery through 2028. This fleet growth has been driven by expanding LPG export capacity from the US Gulf Coast, the Middle East, and increasingly from West Africa and Australia.
But fleet expansion alone does not explain the surge in CIP demand. The real driver is cargo diversification. Modern VLGCs are increasingly designed for multi-cargo service:
- LPG (propane and butane) — the traditional staple
- Propylene — polymer-grade propylene commands premium freight rates
- Butadiene — key feedstock for synthetic rubber production
- Ammonia — emerging as both a fertiliser feedstock and a potential marine fuel
- Ethylene — requires ultra-low temperature capability (-104 degrees C)
Each cargo transition requires cleaning. The more cargo grades a vessel is certified to carry, the more frequently it switches, and the more valuable turnaround time becomes.
The Cost of Downtime
A VLGC on a Middle East Gulf to East Asia LPG run earns approximately $50,000-70,000 per day at current market rates. A cargo switch that takes 48 hours costs:
| Cost Component | 48 Hours | 24 Hours (with CIP) | Savings |
|---|---|---|---|
| Lost revenue (at $60K/day) | $120,000 | $60,000 | $60,000 |
| Bunker (idle/slow steam) | $15,000 | $7,500 | $7,500 |
| Chemical costs | $8,000 | $5,000 | $3,000 |
| Crew overtime | $3,000 | $1,000 | $2,000 |
| Total per switch | $146,000 | $73,500 | $72,500 |
At 3-4 cargo switches per year, a single vessel saves $217,500 to $290,000 annually. For a fleet of 10 VLGCs, the annual saving exceeds $2 million — easily justifying the capital cost of CIP skid systems.
Beyond Direct Savings
The financial case for CIP extends beyond direct time savings:
Cargo quality assurance — Consistent cleaning reduces the risk of off-spec cargo claims. A single contamination incident on a polymer-grade propylene cargo can result in claims of $500,000 to $2 million.
Charterer preference — Major charterers (petrochemical companies, trading houses) increasingly specify CIP-equipped vessels in their chartering requirements. Vessels without CIP systems face a narrowing pool of available cargoes.
Regulatory compliance — IMO and flag state regulations for cargo tank cleaning are becoming more prescriptive. Automated systems with documentation trails simplify compliance.
Insurance — Some P&I clubs offer preferential terms for vessels with documented automated cleaning systems.
How CIP Systems Work on LPG Carriers
A CIP system on a gas carrier operates through a carefully sequenced cleaning cycle. While specific protocols vary by system integrator and cargo type, the general process follows these stages:
Stage 1: Gas Freeing
Before liquid cleaning begins, the cargo tanks must be gas-freed. Nitrogen purging displaces residual cargo vapours until the oxygen content reaches safe levels (typically below 1% for subsequent hot work, or below the lower explosive limit for ventilation-only operations).
The CIP skid does not perform gas freeing directly — this is handled by the vessel's cargo system (N2 generator or shore-supplied nitrogen). However, the CIP control system monitors gas-free status before initiating the liquid cleaning cycle.
Stage 2: Pre-Rinse
The first liquid cycle uses fresh water or heated water to dissolve and flush out water-soluble residues. The CIP skid circulates water through the spray system at a controlled flow rate and temperature (typically 60-80 degrees C for hydrocarbon residue removal).
Stage 3: Chemical Cleaning
A chemical cleaning solution — typically an alkaline or solvent-based detergent formulated for hydrocarbon removal — is circulated through the system. The CIP skid's chemical dosing system maintains precise concentration levels throughout the cycle. Temperature, flow rate, and contact time are controlled to match the cleaning protocol for the specific cargo transition.
Stage 4: Intermediate Rinse
Fresh water flushes the chemical solution from the tank surfaces and piping. The CIP system monitors rinse water quality (conductivity, pH, hydrocarbon content) to verify complete removal of cleaning chemicals.
Stage 5: Final Rinse and Drying
A final fresh water rinse followed by nitrogen drying (or vacuum drying in some systems) prepares the tank for the next cargo. The CIP system verifies final cleanliness through conductivity measurement and, in some cases, automated sample analysis.
Stage 6: Verification
The system generates a cleaning report documenting all parameters — flow rates, temperatures, chemical concentrations, cycle times, and final cleanliness readings. This report serves as the cleaning certificate for the next cargo loading.
CIP Skid Components: What Goes Inside the Package
A marine CIP skid is a complex assembly of pressure-rated equipment, instrumentation, and control systems. Here is what a typical unit contains:
Pressure Components
Circulation pump — Centrifugal or positive displacement pump rated for the required flow rate and system pressure. Marine-grade construction with mechanical seals rated for chemical service. Typically 316L stainless steel wetted parts.
Heat exchanger — Heats the cleaning solution to the required temperature. Shell-and-tube or plate type, depending on the system integrator's specification. Steam-heated or electric, depending on the vessel's available utilities.
Filter/strainer — Removes particulates from the circulating cleaning solution. Basket strainers with mesh inserts, rated to the system design pressure.
Chemical dosing tank — Holds concentrated cleaning chemical. Constructed from corrosion-resistant material (316L or higher). Includes level indication, temperature monitoring, and a dosing pump.
Collection/buffer tank — Receives return flow from the cargo tank spray system. Provides settling time for particulate removal before recirculation.
Piping and Valves
All piping within the skid is typically 316L stainless steel, with connections to the vessel's cargo piping system through flanged or welded interfaces. Valves include isolation, throttling, check, relief, and sample valves — all rated for the design pressure and temperature range.
Instrumentation and Control
Flow meters — Electromagnetic or ultrasonic, monitoring circulation rate in real time.
Temperature sensors — RTDs or thermocouples at multiple points: heater outlet, tank inlet, tank return, chemical tank.
Pressure transmitters — Monitoring system pressure at pump discharge, filter differential, and tank spray header.
Conductivity meters — Measuring rinse water quality to verify cleaning effectiveness.
pH sensors — Monitoring chemical concentration during the cleaning cycle.
PLC/HMI — Programmable logic controller with a human-machine interface panel. Stores cleaning recipes, controls the sequence, and generates cleaning reports.
Skid Frame
The entire assembly sits on a welded steel frame — typically carbon steel with marine-grade coating (epoxy primer + polyurethane topcoat). The frame is designed for lifting (pad eyes certified to the total skid weight), transportation securing (lashing points), and deck mounting (bolt-down pattern matching the vessel's foundation design).
Our CIP Skid Track Record: 23+ Units Delivered Since 2016
Since 2016, we have manufactured and delivered 23+ CIP cleaning skids for gas carrier programmes. Every unit has been built as an OEM manufacturer for one of two internationally recognised gas carrier system integrators — our role is to fabricate the equipment to their engineering specifications, under their quality management and classification society oversight.
Here is the delivery timeline:
2016 — First CIP Units
2 sets of CIP Units — Manufactured for a leading international gas carrier system integrator, NK (Nippon Kaiji Kyokai) certified. These units were installed on a VLGC built at a major Japanese shipyard. This was our first marine CIP skid programme, and it established the manufacturing processes, quality procedures, and classification society coordination protocols that we have used on every subsequent delivery.
2018 — Expanding the Relationship
1 set of CIP Unit — Manufactured for a German engineering company specialising in gas carrier cargo handling systems, also NK certified. Installed on a vessel at another prominent Japanese shipyard. This programme extended our CIP manufacturing capability to a second system integrator, demonstrating that our processes could adapt to different engineering standards and specification formats.
2019 — Return Customer
2 sets of CIP Units — The same international system integrator from our 2016 programme returned with a new order. NK certified, these units were destined for a large gas carrier built at a major Chinese shipyard. By this point, our CIP production had become routine — standardised processes, trained welders with qualified procedures, established inspection protocols with the classification society.
2025 — The Step Change
18 sets of CIP Units — This is where the scale shifted. A single order covering 18 CIP units for five separate gas carrier programmes, all for the same international system integrator:
| Programme | Vessel Type | Quantity |
|---|---|---|
| COSCO programme | 88K VLGC | Multiple sets |
| HENGLI programme | 93K VLAC | Multiple sets |
| Jiangnan programme | 99K VLEC | Multiple sets |
| Yangzijiang programme | 100K VLEC | Multiple sets |
| Iino programme | 93K VLGC | Multiple sets |
These 18 units are manufactured to GB (Chinese national standard) for the pressure components, with the overall system meeting the integrator's proprietary performance specification. The sheer volume — 18 units in a single production campaign — required us to implement serial production techniques: standardised jigs and fixtures, batch material procurement, parallel fabrication streams, and coordinated classification society inspections across multiple units simultaneously.
Case Study: CIP Units for 93K VLAC Programme — NK Certified
The VLAC (Very Large Ammonia Carrier) is a relatively new vessel type — essentially a VLGC designed with the additional capability to carry anhydrous ammonia as cargo. The 93K VLAC programme represents one of the most technically demanding CIP applications because ammonia introduces unique cleaning challenges.
Why Ammonia Complicates Tank Cleaning
Ammonia is not just another hydrocarbon. It is a polar molecule that interacts differently with tank surfaces compared to LPG or propylene:
Surface adhesion — Ammonia can form persistent films on steel surfaces, particularly in the presence of moisture. These films may contain ammonium salts that are difficult to remove with standard hydrocarbon cleaning protocols.
Material compatibility — Ammonia is corrosive to copper alloys and can cause stress corrosion cracking in certain steel grades. CIP system components must be selected for ammonia compatibility — no brass, bronze, or copper-bearing alloys anywhere in the wetted path.
Odour retention — Ammonia's pungent odour can persist in tank coatings and weld root gaps long after the bulk residue is removed. Subsequent cargoes (particularly food-grade LPG for aerosol propellant) may be rejected if ammonia odour is detectable.
Cleaning verification — Standard conductivity and hydrocarbon testing is insufficient for ammonia. Specific ammonia detection methods (Nessler reagent, ion-selective electrodes) must be incorporated into the CIP system's verification protocol.
What We Built
The CIP units for the 93K VLAC programme were designed to handle the full range of cargo transitions — LPG to propylene, LPG to ammonia, ammonia to LPG, ammonia to propylene — with specific cleaning recipes for each transition pair.
Key manufacturing requirements:
- All wetted parts 316L stainless steel minimum — no copper alloys
- Heat exchanger rated for elevated temperature cleaning cycles (up to 90 degrees C)
- Chemical dosing system capable of handling multiple cleaning formulations
- Enhanced filtration for ammonia salt removal
- Ammonia-specific sensors in the verification loop
- NK classification society certification for all pressure components
- Full material traceability from raw material to final assembly
The NK certification process required:
- Drawing review and approval by NK surveyor
- Material certification witnessed by NK
- Welding procedure qualification (WPQ) witnessed by NK
- Hydrostatic testing witnessed by NK
- Final inspection and documentation review
Case Study: 18 CIP Units Across Five Major Gas Carrier Programmes in 2025
The 2025 order for 18 CIP units represented the largest single CIP manufacturing programme we have undertaken. Five separate vessel programmes, four different shipyards, vessels ranging from 88K to 100K cubic metres — all requiring CIP skids built to the same system integrator's specification but with programme-specific adaptations.
The Serial Production Challenge
Manufacturing 18 units of the same basic design sounds straightforward — but each programme had specific requirements:
Dimensional variations — Each vessel type has different cargo piping routing, deck space allocation, and foundation arrangements. Skid footprints, connection orientations, and lifting arrangements varied between programmes.
Utility interfaces — Steam supply pressure and temperature, electrical supply voltage and frequency, control system communication protocols, and alarm integration interfaces differed between shipyards.
Documentation packages — Each shipyard and each vessel's flag state had specific documentation requirements. Material certificates, welding records, NDT reports, and test certificates all needed to be formatted and compiled programme by programme.
How We Managed It
Standardised core, customised interfaces — We established a standard manufacturing approach for the core pressure components (heat exchangers, vessels, piping assemblies) and customised only the interface elements (connection flanges, electrical terminations, control system configurations) for each programme.
Batch material procurement — Ordering steel plate, pipe, fittings, and valves in bulk across all 18 units reduced lead times and cost. A single material heat of 316L plate served multiple units, simplifying traceability.
Parallel fabrication streams — At peak production, we had three CIP units in simultaneous fabrication — one in welding, one in assembly, one in testing. This required careful scheduling of classification society inspections to avoid bottlenecks.
Standardised quality procedures — One set of welding procedures, one set of NDT protocols, one set of inspection and test plans — applied consistently across all 18 units. This consistency reduced the risk of quality deviations and simplified the classification society's oversight.
Delivery Performance
All 18 units were manufactured and delivered within the programme schedule, meeting the shipyard integration timelines for five separate vessel construction programmes. The ability to deliver serial production quantities while maintaining quality consistency was the key differentiator.
Design Challenges for Marine CIP Skids
Building CIP skids for gas carriers presents engineering challenges that go beyond standard industrial skid fabrication.
Weight and Space Constraints
Gas carriers allocate limited deck space and structural capacity for auxiliary equipment. A CIP skid must deliver full cleaning capability within a compact footprint and strict weight budget. Every component selection decision — pump type, heat exchanger configuration, valve body material — involves a weight trade-off.
Our approach: use 316L stainless steel for wetted parts (lighter than carbon steel with cladding), compact plate-type heat exchangers where the specification allows, and lightweight but structurally sound skid frames with optimised member sizing.
Vibration and Dynamic Loading
Ships move. A CIP skid bolted to a gas carrier deck experiences continuous vibration from the main engine, wave-induced motions (heave, pitch, roll), and occasional slamming loads. Every pipe connection, instrument mounting, and electrical termination must withstand years of cyclic loading without fatigue failure.
We design pipe supports with vibration damping, use socket-weld connections (not threaded) for small-bore piping, and specify flexible connections at the interface between the skid and the vessel's piping system.
Corrosion Environment
A CIP skid on a gas carrier operates in a marine environment — salt spray, humidity, temperature cycling. The skid frame gets a multi-layer marine coating system (zinc primer, epoxy intermediate, polyurethane topcoat). But the real corrosion challenge is internal: cleaning chemicals, cargo residues, and process water create a demanding environment for wetted surfaces. Material selection for internal components is critical — 316L minimum, with duplex or super-duplex stainless steel for particularly aggressive service.
Temperature Range
LPG carriers operate in a wide temperature range — cargo at -48 degrees C, cleaning solution at up to 90 degrees C, ambient temperatures from -20 degrees C (Arctic routes) to +45 degrees C (Middle East). The CIP skid must function across this entire range without thermal stress failures, seal degradation, or instrument drift.
Hazardous Area Classification
CIP skids on gas carriers are located within hazardous areas (Zone 1 or Zone 2 per IEC 60079). All electrical equipment — motors, instruments, junction boxes, control panels — must be certified for hazardous area use (Ex d, Ex e, Ex i, or Ex n as appropriate). This limits component choices and increases cost, but it is non-negotiable for safety.
Classification Society Requirements for CIP Systems
Marine CIP skids must comply with the rules of the vessel's classification society. Our CIP units have been certified by NK (Nippon Kaiji Kyokai / ClassNK), and our broader product range covers six major classification societies: DNV, ABS, BV, LR, CCS, and NK.
What Classification Involves
For CIP skid pressure components:
Design review — The classification society reviews drawings, calculations, and material specifications before fabrication begins. For pressure vessels and heat exchangers, this includes stress analysis, fatigue assessment (where applicable), and verification of material grades against the society's rules.
Material certification — Raw materials (plates, pipes, forgings, fittings) must carry mill certificates traceable to the material heat. The classification society may require witnessing of material testing at the mill.
Welding qualification — Welding procedures must be qualified per the applicable code (ASME Section IX, EN ISO 15614, or the classification society's own requirements). Welders must hold valid qualifications for the specific material, thickness, and position combinations involved.
In-process inspection — The classification surveyor witnesses critical fabrication steps: fit-up inspection, weld root pass inspection (for critical welds), NDT (radiography, ultrasonic, magnetic particle, dye penetrant), and dimensional verification.
Pressure testing — Hydrostatic testing of all pressure components at 1.5x design pressure (or as specified by the applicable code), witnessed by the classification surveyor.
Final inspection — Physical inspection of the completed skid, review of all documentation, and issuance of the classification certificate.
Our Classification Capability
With 600+ PQR (Procedure Qualification Records) in our welding procedure library, we can match most material and thickness combinations without needing new qualifications. Our NDT team holds Level II and Level III certifications across all four major NDT methods. We maintain active relationships with all six major classification societies, with surveyors regularly visiting our facility for ongoing projects.
CIP vs. Manual Tank Cleaning: A Cost Comparison
The decision to install a CIP skid is ultimately financial. Here is how the numbers stack up over a vessel's 25-year service life.
Capital Cost
A marine CIP skid system for a VLGC typically costs between $200,000 and $500,000, depending on capacity, complexity, and certification requirements. Installation costs (foundations, piping connections, electrical integration) add another $50,000-150,000.
Operating Cost Comparison
| Parameter | Manual Cleaning | CIP System |
|---|---|---|
| Cleaning time per switch | 36-48 hours | 12-24 hours |
| Chemical cost per switch | $6,000-10,000 | $3,000-6,000 |
| Crew overtime per switch | $2,000-4,000 | $500-1,000 |
| Water consumption per switch | 50-100 m3 | 20-40 m3 |
| Cargo claims (per incident) | $500K-2M | Near zero |
| Annual maintenance | $2,000-5,000 | $5,000-10,000 |
25-Year Total Cost of Ownership
Assuming 3.5 cargo switches per year at a daily charter rate of $55,000:
| Item | Manual (25 yr) | CIP (25 yr) |
|---|---|---|
| Capital cost | $0 | $400,000 |
| Lost revenue | $11,550,000 | $4,812,500 |
| Chemicals | $1,400,000 | $787,500 |
| Labour/overtime | $262,500 | $65,625 |
| Maintenance | $87,500 | $187,500 |
| Cargo claims (est. 2 incidents) | $1,500,000 | $0 |
| Total | $14,800,000 | $6,253,125 |
The CIP system pays for itself within the first two years of operation. Over the vessel's life, it saves approximately $8.5 million — a 21x return on the initial investment.
The Multi-Cargo Trend: LPG, Propylene, Butadiene, and Ammonia
The CIP skid market is being driven by a fundamental shift in gas carrier operations: the move from single-cargo to multi-cargo service.
Why Owners Want Multi-Cargo Capability
Freight rate arbitrage — Different cargo grades command different freight rates at different times. A vessel that can switch between LPG, propylene, and ammonia can always chase the highest-paying cargo.
Contract flexibility — Multi-cargo capability allows owners to serve a wider range of charterers and trade routes. Petrochemical companies need propylene carriers; fertiliser producers need ammonia carriers; energy traders need LPG carriers. A multi-cargo vessel can serve all three.
Ammonia as fuel — As ammonia emerges as a potential zero-carbon marine fuel, vessels designed to carry ammonia cargo can also potentially use ammonia as fuel — creating a dual revenue stream.
What This Means for CIP Systems
Multi-cargo operations dramatically increase the number of cargo switches — and therefore the number of cleaning cycles — a vessel performs over its lifetime. A single-cargo VLGC might never need tank cleaning between voyages. A multi-cargo carrier might switch 4-6 times per year.
This increased cycling places higher demands on CIP systems:
- Multiple cleaning recipes — Each cargo transition pair requires a specific cleaning protocol. The CIP system must store and execute different recipes for LPG→propylene, propylene→ammonia, ammonia→LPG, and so on.
- Faster cycle times — More frequent cleaning means each cycle must be faster to minimise cumulative downtime.
- Broader chemical compatibility — Different cargo residues require different cleaning agents. The CIP system's chemical handling components must be compatible with all agents used.
- Enhanced verification — Each cargo grade has different purity requirements. The CIP system's analytical instruments must cover the relevant contaminants for all cargo grades handled.
Material Selection for CIP Skid Pressure Components
The material selection for marine CIP skids is driven by three competing requirements: corrosion resistance, mechanical strength, and weight.
Wetted Components
316L stainless steel — The standard choice for most CIP skid wetted parts. Excellent corrosion resistance against cleaning chemicals and cargo residues. Good weldability. We procure 316L plate, pipe, and fittings in bulk across CIP programmes, maintaining material traceability from mill certificate to finished assembly.
Duplex stainless steel (2205) — Used where higher strength is needed at lower wall thickness (weight saving) or where chloride stress corrosion cracking is a concern. More expensive than 316L and requires more controlled welding procedures (heat input, interpass temperature, ferrite content verification).
Super duplex (2507) — For the most aggressive service conditions. Rarely used in standard CIP skids but may be specified for specific components in high-chloride or high-temperature applications.
Non-Wetted Components
Carbon steel (SA516 Gr.70 or equivalent) — For the skid frame, lifting lugs, and structural elements. Marine coating system for corrosion protection.
Aluminium — Occasionally used for lightweight components (covers, brackets, instrument housings) where weight savings are critical.
Seals and Gaskets
PTFE and modified PTFE — Standard gasket material for flanged connections. Compatible with all common CIP chemicals.
Viton (FKM) — For O-rings and shaft seals. Good resistance to hydrocarbons and cleaning chemicals at elevated temperatures.
Kalrez (FFKM) — For the most demanding seal applications. Higher cost but broader chemical resistance and temperature range.
Our Material Capability
Our welding procedure library includes 600+ PQR covering carbon steel, austenitic stainless steel (304/304L/316/316L/321/347), duplex and super duplex, nickel alloys (Inconel 625, Monel 400, Hastelloy C-276), titanium (Grade 2, Grade 5), and aluminium (5083, 6061). For CIP skid manufacture, we typically work with 316L and duplex — both well within our standard capability.
Integration with Cargo Handling Systems
A CIP skid does not operate in isolation. It interfaces with the vessel's cargo handling system, and the quality of that interface determines the system's effectiveness.
Physical Interfaces
Cargo piping connections — The CIP skid connects to the vessel's cargo piping system through flanged connections (typically ASME B16.5 or EN 1092). The interface flanges must match the vessel's piping specification — rating, facing, material, and bolt hole pattern.
Utility connections — Steam supply (for heating), cooling water return, compressed air, nitrogen, and electrical power. Each interface has specific pressure, temperature, flow rate, and quality requirements.
Drain connections — Spent cleaning solution must be directed to the vessel's slop tank or overboard discharge system (in compliance with MARPOL regulations). Drain piping routing and valve arrangements are vessel-specific.
Control System Integration
The CIP skid's PLC communicates with the vessel's integrated automation system (IAS) through standard industrial protocols (Modbus TCP, Profinet, or hardwired signals). The integration typically includes:
- Start/stop permissives from the vessel's safety system
- Alarm signals to the vessel's central alarm panel
- Status indication on the vessel's cargo control room displays
- Emergency shutdown (ESD) integration
Our Role in Integration
As the OEM manufacturer, we build the CIP skid to the system integrator's specification — including all physical and electrical interface requirements. The system integrator handles the overall system design, the interface engineering with the shipyard, and the commissioning at the vessel. Our responsibility is to deliver a skid that meets the specification, passes all factory acceptance tests, and arrives at the shipyard ready for installation.
What System Integrators Should Look for in a CIP Skid Manufacturer
For system integrators evaluating manufacturing partners for marine CIP skids, here are the capabilities that matter:
Classification Society Track Record
The manufacturer should have established relationships with the relevant classification societies and a history of producing classification-certified equipment. Our facility has been audited and approved by six classification societies (DNV, ABS, BV, LR, CCS, NK), and we maintain these approvals through regular audits and ongoing project work.
Serial Production Capability
CIP skids for a fleet programme may require 10-20+ units on a compressed timeline. The manufacturer needs the shop floor capacity, material procurement systems, and quality management infrastructure to handle serial production without quality degradation. Our 2025 programme — 18 units across five programmes — demonstrated this capability.
Welding Procedure Coverage
CIP skids involve multiple material combinations and thicknesses. A manufacturer with a comprehensive PQR library can start production immediately without waiting for new welding procedure qualifications. Our 600+ PQR library covers the full range of materials used in CIP skid manufacture.
Quality Management System
ISO 9001 certification is the minimum. For marine CIP skids, the manufacturer should also demonstrate experience with classification society quality requirements — including material traceability, welder qualification management, NDT protocols, and documentation systems.
Logistics and Schedule Management
CIP skids must arrive at the shipyard within a tight installation window. Late delivery can delay the vessel's overall construction schedule. The manufacturer needs proven project management and logistics capabilities for international shipments — including export documentation, marine packaging, and coordination with freight forwarders.
Frequently Asked Questions
What is a CIP skid for gas carriers?
A CIP (Cleaning In Place) skid is a self-contained, skid-mounted system that automates the cleaning of gas carrier cargo tanks between different cargo grades. It includes pumps, heaters, chemical dosing, filtration, spray systems, and controls — all pre-assembled and tested in the factory for plug-and-play installation on the vessel.
How much time does a CIP system save compared to manual cleaning?
A CIP system typically reduces cargo tank cleaning time by 30-50%, from 36-48 hours (manual) to 12-24 hours (CIP). The exact saving depends on tank size, cargo type, contamination level, and the specific cleaning protocol.
What classification societies have you built CIP skids for?
Our CIP skids have been certified by NK (ClassNK). Our broader product range covers six classification societies: DNV, ABS, BV, LR, CCS, and NK.
How many CIP units have you delivered?
Since 2016, we have delivered 23+ CIP cleaning skids for gas carrier programmes, covering 10+ vessels ranging from 88K VLGC to 100K VLEC.
Do you build CIP skids for ammonia carriers?
Yes. Our CIP units for the 93K VLAC (Very Large Ammonia Carrier) programme are designed for the full range of cargo transitions including ammonia. All wetted components are ammonia-compatible (no copper alloys), with ammonia-specific cleaning protocols and verification instruments.
What materials do you use for CIP skid pressure components?
Standard wetted parts are 316L stainless steel. Duplex stainless steel (2205) is used where higher strength or chloride resistance is required. Skid frames are carbon steel with marine-grade coating. Seals are PTFE or Viton depending on chemical compatibility requirements.
Can you handle large batch orders?
Yes. Our 2025 programme delivered 18 CIP units across five vessel programmes in a single production campaign. We have the shop floor capacity, material procurement systems, and quality management infrastructure for serial production of marine equipment.
What is the typical lead time for a CIP skid?
Lead time depends on design complexity, material availability, and classification society coordination. A standard CIP skid typically requires 12-16 weeks from order to delivery. Serial production orders may offer shorter per-unit lead times due to batch efficiencies.
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Last reviewed: April 28, 2026 · Technical accuracy verified by Lmart Engineering Dept.