Retrofitting (ship conversion or modification) an existing vessel to run on methanol may seem easy on a desktop P&ID. However, when that design reaches the shipyard floor, things can change rapidly.
The Methanol Fuel Treatment Room (FTR), one of the most sensitive spaces on a vessel using methanol as fuel, houses several equipment items and plays a vital role.
Without the right engineering approach, designing this space can lead to multiple pipe interferences with the existing structure, integration issues with ducting, and missing sensors and cables.
As a result, rework is required to bridge the gaps or resolve interferences, putting additional pressure on the drydock schedule and overall project delivery.
Quick Facts
– Without the right engineering approach, FTR retrofits may lead to pipe rework.
– The FTR must carry A-60 fire insulation whenever it shares a bulkhead with a Category A machinery space.
– 3D laser scanning captures the vessel’s real geometry at 1–3 mm accuracy, replacing guesswork from tape-measure surveys.
– Double-walled methanol piping can’t be bent on site, so spools need explicit field-fit allowances of 30–80 mm at critical bulkhead and equipment interfaces.
The Layout Challenge of Low-Flashpoint Fuel Infrastructure
Retrofitting an FTR introduces significant structural and spatial demands that standard machinery spaces do not require. The fuel treatment room in a retrofitted vessel must incorporate:
- A-60 Passive Fire Protection: Under the Interim Guidelines for methanol as fuel (MSC.1/Circ.1621) and the methanol rules that class societies have built on top of them, the FTR must be enclosed by A-60 fire-resistant insulation whenever it shares a bulkhead with a Category A machinery space. When the vessel being retrofitted has limited space, it’s essential to account for the thickness the A-60 rockwool actually needs. A missed or incorrect assessment at this stage can easily turn into extensive piping rework or a spatial conflict due to insufficient clearance, and on a retrofit, that clearance was never generous to begin with.
- 30 ACH Ventilation: Running an independent duct capable of handling 30 air changes per hour (ACH) requires a generous cross-section. In a retrofit layout, finding the correct route for a duct that size can be very difficult, and it tends to have knock-on effects on existing ship structures and components. A thorough investigation and an on-site inspection are fundamental to avoiding design errors that could result in costly rework on ducts already fabricated and delivered onboard.
De-Risking the Installation: The 3D Scanning
To prevent costly steel, pipe or duct modifications, the transition from design to production must be strictly controlled through precise spatial engineering.
Relying on the original vessel drawings may seem the most logical starting point, but in reality this approach is not the correct one. Structural sagging, past modifications and hull deflections mean that the actual physical space always differs from the drawings, sometimes by more than you’d expect on a vessel that’s been in service for fifteen or twenty years.
Therefore, when using ship plans for small and constrained spaces to locate all equipment and piping of the fuel treatment room, there is a high probability of issues arising during the assembly phase, resulting in costly rework.
Deploying 3D laser scanning during the initial engineering phase is therefore mandatory, not optional. The resulting point cloud captures the coordinates of every structural frame, beam and existing pipe run, typically with an accuracy in the range of 1–3 mm depending on the scanner and the scanning distance involved. That’s more than enough to design the new FTR equipment, piping and fittings around the vessel’s actual geometry rather than a theoretical plan, and it removes most of the guesswork that used to come from tape-measure surveys.
Maximizing Out-of-Dock Prefabrication
Every day a vessel spends in drydock costs tens of thousands of dollars in off-hire losses and yard fees. Piping engineering should therefore focus on maximising prefabrication while the ship is still at sea:
- Modular Skids: The fuel treatment equipment should be engineered to be as compact as possible. Ideally, a skid-based solution is the best approach for methanol retrofit projects. Skids delivered by established manufacturers come with all FAT documentation and certifications already in order at the time of delivery, which means the pipelines only need pressure testing before the commissioning phase of the whole system starts.
- Strategic Field-Fit Allowances: Double-walled (coaxial) methanol piping is not so “flexible” as other pipes; it can’t be bent or adjusted on site the way a single-wall pipe sometimes can, which means more demanding assembly and much more thorough pre-assembly preparation on the EPC’s side. In our experience, spools should be engineered with explicit field-fit allowances of 30 to 80 mm at critical bulkhead and equipment interfaces. This isn’t a class requirement, it’s a practical margin that gives the shipyard room to absorb the small discrepancies that always show up between as-built conditions and detailed engineering drawings.
Streamlining Yard Workflow and NDT Sequencing
The engineering design must directly support the shipyard’s physical construction sequence.
This is especially true for the rigorous Non-Destructive Testing (NDT) required for low-flashpoint fuel systems.
Listed below are key engineering deliverables to keep in mind in order to accelerate shipyard works:
- Labeled structural penetration drawings linked directly to the 3D point cloud: allows the shipyard to cut penetrations and reinforce bulkheads before equipment arrives.
- Heavy-lift routing paths and temporary access opening dimensions: prevents rigging delays and ensures the skid can physically pass through the hull opening.
- Detailed isometric spool drawings with Welding Procedure Specifications (WPS) for both the inner and the outer pipe
Practical Engineering Saves the Schedule
In complex retrofit projects such as dual-fuel conversions, the goal is not only to install a new fuel treatment room or a new low-flashpoint fuel system onboard, but also to minimise costly mistakes.
Given the high complexity involved, pipe interferences, missing cables and sensors, or additional authority requirements can arise.
This is where experienced marine systems engineers can anticipate issues and class requirements, integrating the right solutions directly into the design.
At Flowazur Consulting, we have experienced marine systems engineers with years of practical onboard experience, ready to support your engineering team during the piping engineering and system integration phases.
Book a call with our engineers to discuss your project in detail.
Frequently Asked Questions
Q: When must the fuel treatment room have A-60 fire insulation?
A: Whenever it shares a bulkhead with a Category A machinery space, per the Interim Guidelines (MSC.1/Circ.1621).
Q: How accurate is 3D laser scanning for retrofit engineering?
A: Typically within 1–3 mm, depending on the scanner and the scanning distance.
Q: Why does double-walled methanol piping need field-fit allowances?
A: It can’t be bent or adjusted on site like single-wall pipe, so spools need explicit margins of 30–80 mm at critical interfaces to absorb as-built discrepancies.
Q: What makes modular skids useful for methanol retrofits?
A: They arrive with FAT documentation and certifications already in order, so pipelines only need pressure testing before commissioning.
Q: What does poor FTR engineering cost during drydock?
A: Every day in drydock costs tens of thousands of dollars in off-hire losses and yard fees, on top of the rework itself.