Extendable tension deck engineering was at the centre of a fast-track scope Noble Drilling awarded ICON Engineering: conceptual development, detailed design, fabrication, installation and commissioning of a 300-tonne capacity tension deck for the newly built Noble Tom Prosser jack-up rig.
Noble Drilling — now part of Noble Corporation, one of the world’s largest offshore drilling contractors — built the Tom Prosser as a new-generation jack-up rig, and needed the tension deck ready before its very first extended campaign. The North West Shelf, off the coast of Western Australia, is one of the country’s most active offshore exploration and production regions, and cyclone readiness is a standing requirement for any rig operating there during the wet season.
The rig was contracted for an extended exploration drilling campaign on the North West Shelf, where the riser and surface blowout preventer (BOP) had to remain deployed even in the event of a cyclone.
Retaining the riser and BOP on a jack-up rig through a cyclone rather than retrieving them is a deliberate operational choice: it avoids the time and risk of a full riser pull ahead of a storm, but it demands equipment capable of holding tension reliably under extreme, unattended conditions. That requirement shaped everything about the tension deck’s design, from its load rating to how quickly and simply it could be deployed by the rig crew alone.
Designing an extendable tension deck to tight physical limits
Noble needed a tension deck that could be rapidly deployed while fitting within strict stowage limits: a maximum overall length of 30ft when stowed, but a 35ft cantilever reach once deployed. Drawing on its previous tension deck design experience, ICON developed a new concept using a sliding section that let the deck extend to the required reach only once deployed.
A 12-week timeline for the extendable tension deck
The schedule pressure was significant. Noble first contacted ICON in June 2015, with the rig due to depart Singapore on 1 September that year. The entire scope — from concept development through to installation and commissioning — was completed in 12 weeks, including fabrication and testing of the 300-tonne tension unit and a range of ICON’s gripper clamps. A team of ICON engineers was deployed to Singapore to oversee fabrication and installation within that timescale.
Built for simple offshore deployment
Simplicity of deployment was a core design requirement. ICON’s engineers developed a deployment method that used the rig’s existing capabilities, with no additional equipment or modification needed, then worked closely with the rig’s crew to familiarise them with the offshore deployment procedure. During offshore operations, the deck was fully deployed in under 40 minutes.
The completed extendable tension deck achieved a 35ft deployed reach from a 30ft stowed footprint, a 300-tonne deck capacity, and passed a 450-tonne load test — all deployable using existing rig equipment in under an hour, with the full concept-to-installation programme delivered in under 12 weeks. The gripper clamps used on this project are part of ICON’s wider Conductor Lift Clamps range, engineered for exactly this kind of high-load, rapid-deployment application.
ICON’s tension deck and lift frame capability today
This project sits alongside ICON’s ongoing work in Tension Lift Frames and MODU & Vessel Modifications, where the same rapid-turnaround, rig-compatible design approach is applied to jack-up and semi-submersible campaigns worldwide. A decade on, the underlying engineering challenge — building compact, high-capacity deck systems that a rig crew can deploy unaided — remains central to ICON’s tension deck and lift frame work today.
Need an extendable tension deck or similar rig modification delivered to a tight schedule? Get in touch with ICON’s team.
