Offshore terminal anchor leg replacements completed
10 June 2020 | Web Article Number: ME202019278
DURING May 2020, AMSOL completed an anchor leg replacement project at the Single Buoy Mooring (SBM) for which preparations had been underway over the previous year.
AMSOL provides specialised marine and terminal management services at the offshore terminal off Durban for client SAPREF, a joint venture between Shell Refining South Africa and BP Southern Africa, the largest crude oil refinery in the country.
Routine diver inspections of the chains indicated that a replacement of components of the mooring system was necessary. A replacement plan, which included the use of local SBM expertise to minimise costs and maximise existing resources, was drafted in 2018. Part of this plan included initially replacing the four northerly and southerly legs as these lie in the direction of the most environmentally induced stress in the mooring system.
According to AMSOL’s Terminals, Harbour Towage & Subsea Executive Norman Jensen, the planning and preparation work the project team conducted was vital in ensuring the successful completion of the project
“The project methodology was developed in early 2019 and finalised at a joint operations workshop in July last year. May 2020 was identified as the best time to do the replacement project as it is statistically the best weather month for marine operations offshore Durban,” Jensen said.
The project included several local subcontractors and suppliers to ensure maximum local content, with engineering consultants ZAA EPNA engaged to design working platforms for the SBM, which were cast in Durban. Glass reinforced plastic members were extruded in Tshwane, and the steel elements were fabricated in Durban.
In October of 2019, a Hazard And Operability (HAZOP) study workshop was held at the SAPREF Training Centre, bringing together key project stakeholders to ensure alignment and understanding of the complex nature of the project in the offshore environment; ensuring that safety standards were met to prevent harm to people, assets and the environment.
A few months later in March of 2020, a Methods Workshop was held and attended by the full Project ensemble of Client SAPREF, Contractors and Subcontractors, including representatives from Swire Pacific Offshore, EBH Shipyard and AMSOL.
SAPREF then took on the responsibility for the procurement of the anchor and chain, assisted in system design by Shell technical authorities in The Hague. Shell requirements for Marine Assurance, Project Methodology Assurance, Diving Assurance and Dynamic Positioning Operational Assurance were successfully met thereafter. Activity Specific Operational Guidelines and Activity Marine Operational Guidelines were also developed and implemented on board the Project Vessel ‘Pacific Dolphin’.
After COVID-19 Lockdown began in South Africa on 27 March 2020, the Project was declared an Essential Service, supporting the Transport, Energy and Oil Refining industry.
Despite constraints, the project was able to commence after all personnel involved were tested for the virus and were thereafter subject to strict hygiene and safety protocols
The fleet, which included the chartered DP2 anchor handling vessel Pacific Dolphin and AMSOL’s tug Siyanda, were mobilised and sailed for the SBM field on 26 April to begin the execution phase of the project. For the duration of the replacement works, the Siyanda managed the hoses and supported the day shift SBM team whilst the Pacific Dolphin accommodated the night shift dive team.
A priority for AMSOL’s Norman Jensen was completing the project safely and within the scheduled time frame to meet client expectations.
“We were extremely fortunate that from 1 May and for the next eight days we had very favourable weather and sea conditions. The old chains and anchors were recovered to the Pacific Dolphin and the new ones installed. The fourth anchor leg was safely secured in the SBM stopper on 8 May, and the project was safely completed to the client’s satisfaction ahead of schedule.”