Portable Vertical Lay System (PVLS)

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Road-transportable system for deployment and decommissioning of flexible products.

Page last modified
August 4 2023

The award-winning MDL PVLS is a portable vertical lay system for the deployment and decommissioning of flexible products such as cables and subsea umbilicals, risers and flowlines.

The innovation facilitates the transit of flexible products from on-deck carousels or reel drive systems to a vertical orientation so that they can be installed over the side, stern or through the moon pool of a vessel. The vertical orientation ensures that the product does not experience bending while under high tension during installation, minimising the risk of damage to the product.

A portable vertical lay system allows for these handling operations to be carried out from any low-cost vessel, readily available at any location around the world, converting it from a standard offshore support vessel into a dedicated flex-lay solution for the duration of the project.

The use of a locally available vessel, rather than bringing a specialist installation vessel from another geographical location, combined with the smaller tonnage of the opportunity vessel, help reduce the CO2 footprint of the project. These green efficiencies are extended when more product can be carried on board, thanks to the integrated and compact design of the MDL PVLS - reducing the number of port calls required to complete installations of longer lengths of product.

The ability to convert a bare back deck into a vertical lay solution, enables completion of projects that may otherwise be delayed due to the lack of a dedicated construction vessel available in region in the required installation window - helping the operators meet their production targets linked to the tie-back scopes.

With over 20+ track record in innovative design and manufacture of lifting and pulling equipment for the marine markets, MDL is an expert in delivering bespoke equipment that works from the get-go. The technology is developed fully in-house, including intuitive control systems that allow safe integration of systems for efficient operations.


Road-transportable for most efficient transit to mobilisation port
Fully integrated - Plug & Play - negating idle, non-productive time
Versatile - modifiable with range of MDL tensioner systems (line pull/squeeze requirements_ and top chutes (MBR)
Modular - can be assembled on quayside off critical path before vessel arrival
Single lift mobilisation on board with the vessel's crane (+ second lift for the tensioner)
Compact and adaptable to project requirements - can be mobilised on vessel stern, side or over moon pool
Minimal to no deck reinforcements required prior to mobilisation
Integrated actuated handling aids (trolley beams with hoists, tugger winches) for operational efficiencies and personnel convenience
Integrated hang-off system to enable safe mid-line connections
Safest offshore product handling thanks to MDL tensioner technology with Failsafe Grip
Proven on projects in the North Sea, Canada and Gulf of Mexico since 2015
No rental unit available


Lay Spread Type Portable Vertical Lay System
Max Pipe Tension 75Te (dynamic load)
Max Hang-off Clamp Tension 80Te (dynamic load)
Design Life 25 years
Design Temperature Operational: -10ºC +50ºC; Survival: -20ºC +65ºC
Low Tension MBR Top 4m top chute (10Te)
Min Pipe Diameter 50mm OD
Max Pipe Diameter 650mm OD
Movable Top Chute ±15º
PVLS Geometry Dimensions (approx. depending on configuration) 12m x 9.6m x 22.7m (LxBxH)
Weight (excl. tensioner) 167Te
Hang-off to Tensioner Clearance 6.6m
Moonpool Door to Tensioner Clearance 7.4m
Work platform deck area 27m²
Work Platform Deck Capacity 1Te/m²
Work Platform Opening 3m
Lifting Equipment All items supplied with dedicated rigging rated for onshore lifts
Departure Chute (option) 20º off-lead; 5º fore and aft
Power Requirements (VLS only) 1x 55kW; 1x 75kW
Design Appraisal Design appraised in accordance with DNV standards
Assumed Conditions Humidity: up to 100%; Atmosphere: marine/high salinity

Relative Business Impact


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Technology Readiness Level


Development Technology demonstration Mature / Proven
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We are the creative knowledge behind market-leading equipment and engineering. Our mission Is to be the global leader in the delivery of alternative engineering solutions, which are inspired by creativity, driven by people and add value by solving challenges faced by our clients. We will solve your engineering challenges, delivering quality and value with the creative and flexible thinking that anticipates your business needs.

We have been driven this way since 1999. An independent company, MDL offers the perfect mix of track record, technical prowess, global delivery and flexibility. This makes us your trusted partner in providing integrated energy services: from port facilities and ops; through SURF, cable and mooring installations, to equipment life extension and decommissioning. 

Our tailored approach targets the most efficient execution, minimising idle days, POB and port calls. We work closely with clients to help them find the perfect package for every challenge: from the safest, most reliable and highest quality equipment, to the most experienced people in the business - including engineering experts for efficient project planning and execution.

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