Case Study – Petredec Mauritius. Marine Warranty Survey.

Petredec Mauritius. Marine Warranty Survey.

The construction of a new 15,000 tonne Liquified Petroleum Gas (LPG) Storage Terminal has recently been completed at Mer-Rouge, Port Louis, on the island of Mauritius.  The terminal will import & supply 65,000 tonne of LPG per annum to Mauritius and will be a strategic trading hub for the re-export of 100,000 tonne of LPG per annum to regional markets in and around the Indian Ocean.

 

Braemar (Incorporating The Salvage Association), (“Braemar SA”), was appointed for the project by Petredec SAM.  Based in Monte Carlo, Petredec SAM is one of the world’s largest LPG trading companies, delivering over 10 million tonnes of gas per year across Asia, the Americas, the Caribbean and Europe. 

The contract for the engineering, procurement, installation & commissioning (EPIC) was awarded to Lloyd Jones Construction, a Mauritius-based company set up specifically for the project.  Mott MacDonald ICase Study - MWS - Petredec Mauritius LPG Terminal 4nternational was appointed to act as Petredec’s consultant engineers for the Project.  The UK-based design company BC&T Consultants was appointed by Lloyd Jones Construction to undertake the engineering aspects of the Project.

The LPG Terminal was to be built on reclaimed land adjacent to a coal yard and an oil storage terminal.  Space was limited and the design of the LPG Terminal required the design of storage facilities which would provide the maximum storage capacity within a confines of a relatively small site whilst providing an adequate level of fire protection. The final design was a mounded storage arrangement with a number of LPG pressure vessels buried within a sand mound under a concrete-block cladding, this providing a stable internal temperature and an appropriate level of fire protection.

The plans included the fabrication of three super-sized bullet-type LPG pressure vessels or bullets which were to be the largest diameter ever built, pushing the boundaries of LPG pressure vessel  design from 8m diameter up to 15m diameter.  The use of a high strength steel specially cast in Germany allowed the wall thickness of the bullets to be reduced, giving a significant reduction in  weight.  Internally, these super-sized bullets were to be stiffened with radial, spider-like frames.  The fabrication of the bullets was to be undertaken by Walter Tosto, a specialist pressure vessel manufacturer based in Ortona, Italy.

The three Bullets were identified as the critical items for the project.  The transport plan for the shipment of the three Bullets included a load-out operation, a transhipment operation, an ocean passage, a load-in operation and road movement to the construction site.  Self propelled modular transporters (SPMTs) were to be used to lift and move the three Bullets.  The Fagioli barge ‘MAK’ was chartered for the load-out operations and the heavy lift ship ‘ZHEN HAU 21’ was chartered for the ocean shipment of the three Bullets.

Walter Tosto, the fabricator for the Bullets, was conveniently located on the Riva Quay in the Port of Ortona. However, the water depth adjacent to the load-out quay was insufficient to allow the berthing of a heavy lift ship.  The proposed solution was to load each Bullet in turn onto a barge, tow the loaded barge to a position off Ortona where the heavy lift ship could anchor in deep water and then tranship each Bullet from the bare to the heavy lift ship.  Permission to undertake the transhipment in coastal waters was withdrawn by the Italian Administration at short notice and it was necessary to find a suitable port which could accommodate the heavy lift ship and allow the transhipment to proceed.  Working with Lloyd Jones Construction and Walter Tosto, we identified the Port of Bari as the most suitable port for the transhipment operation.  This late change of plan introduced a 24 hour tow into the transport plan and Braemar SA worked with the contractor to update the Transport Manual and review seafastening arrangements for the tow.

The load-outCase Study - MWS - Petredec Mauritius LPG Terminal 1s, towage and transhipment of the three Bullets proceeded without incident and following each transhipment operation, the installation and welding of the seafastenings was completed.  The seafasteneings were designed to meet the conditions likely to be encountered on the passage from Bari, Italy, to Port Louis, Mauritius via the Cape of Good Hope which included the possibility of cyclones in the Southern Indian Ocean.  Based on a significant wave height of 6.5m the seafastenings

comprised of 20” tubular main struts capable of restraining 600mt, secondary 10″ tubuar struts capable of restraining 230mt and load mats attached to the transport saddles for distributing the vertical loads into the deck of the heavy lift ship.

Following departure from the Port of Bari the ‘ZHEN HAU 21’ and the three Bullets arrived safely off Mauritius.  Due to the adverse swell conditions the heavy lift ship was diverted to a temporary berth to await an improvement in the weather conditions.

The load-in at Port Louis was undertaken at the Container Terminal.  The construction of the quay was such that no significant loads could be placed on the outer 5.25m of the quay and to allow for this issue, Lloyd Jones Construction had designed and fabricated a bespoke bridge which was attached to the side of the ‘ZHEN HAU 21’ to span the outer extent of the quay.  A graduated temporary off-load ramp was also constructed between the bridge and container park, the length and gradient of the ramp carefully measured to allow the three Bullets to safely clear a flood defence wall between the quay and the container park.

The route between the Container Terminal and the installation site was surveyed and a number of issues were identified and addressed.  Fences were removed, street lighting was removed and drainage ditches were back-filled and covered with steel plates.

Heavy lift contractors ALE mobilised from South Africa and used two clusters of SMPTs to off-load  and transport the three Bullets to the installation site.

The transport route from the Container Terminal to the installation site required the three Bullets to be moved through the coal yard and the surface had been levelled and compacted; however, the surface condition had deteriorated following recent heavy rain and it was nesessary to lay a temporary plywood track along parts of the route in order to provide additional support for the SPMTs.  With all preparations complete, the three Bullets were safely delivered to the installation site where ALE undertook the lifting and skidding operations to install the three Bullets in the sand mound.

The Liquefied Petroleum Gas facility was inaugurated in March 2014.


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