In early 2019, Scorpio Tankers chose Choice Ballast Solution to assist with the first of 55 planned ballast water management system retrofits, scheduled to take place over the next five years
As part of a substantial retrofit project involving 55 vessels, product tankers STI Duchessa and STI Opera have been fitted with the Ecochlor Ballast Water Management System (BWMS). Choice Ballast Solutions (Choice) was selected to undertake the engineering for all 55 retrofits.
Choice president John P. Dooley explained how the process came together. “In preparation for the Scorpio fleet of BWMS installations, Choice looked at the entire installation process for each vessel type and assigned technicians and design engineers. Considerations included class of vessel, scheduled surveys, 3D scanning, and conceptual design. Choice also met with Ecochlor, the vessel manager and the shipyard to begin the basic design, prior to preparation of the detailed design, class documentation and installation specifications.”
The first two installations were completed successfully and illustrate clearly that using a firm that can offer a full range of BWM integration services results in an efficient, less costly option for the owner.
The STI Duchessa and STI Opera were both retrofitted in China within five days of each other. This allowed for a smooth transition of the experienced installation team from one ship to the next. Mr Dooley added: “We deployed one engineering project manager for both vessels, ensuring consistency and continuity during the installation of the STI Duchessa and the STI Opera. In addition, the BWMS manufacturer sent an installation supervisor for each vessel to ensure that the details of the installation were carried out according to specifications.”
“When the flush pump was delayed in delivery at customs for eight days, the shipyard continued laying the piping to where the pump would be installed using a model of the missing equipment”
“The approach requested by Scorpio for the STI Duchessa and STI Opera was to survey and scan them as being the first of a class vessel and then to apply the design to the sister vessels in the class,” Mr Dooley explained. “This meant that we had to verify that the sisters were indeed true sisters. STI Duchessa and STI Opera have an additional 10 sister vessels. Verification on board for the two sisters revealed that they were in fact not true sisters and needed to be treated as individual projects. If we had not taken the time to inspect the vessels properly and just assumed that they were sisters, then we would have given ourselves some major problems during the installation.”
Ecochlor installation manager Tyler Harvey recommends that, even when sister status is confirmed, the shipowner document and should maintain accurate records of required changes from the initial ship design after construction. He explained that “sister vessels aren’t exactly the same, but typically, unless radical modifications have been made, many of the issues seen on the first vessel can be avoided on future installations.”
Installation Engineering Design
Organisation and management are essential to the success of any retrofit. Both Ecochlor and Choice have significant retrofit installation experience. The companies were able to bring together engineers and project managers that could draw on a large bank of knowledge to execute the Scorpio BWMS projects.
The owner’s superintendent also has a major role to play during the installation. “Working with the superintendent is a critical part of the integration specialist’s responsibilities while at drydock,” said Mr Dooley. “The superintendent has a million and one other things to do, and each shipyard has their own approach to things. So as the onsite BWMS engineering firm, we act as an interface to interpret requirements, provide clarification and ensure a smooth installation.”
Prior to the drydock period, the Ecochlor BWMS equipment was delivered to the shipyard pre-mounted on skid frames. It was pre-wired, painted and FAT shop tested. For both the STI Duchessa and STI Opera the installation programme included a new deckhouse to house the chlorine dioxide (ClO2) generator and chemical storage tanks, which are at the heart of the Ecochlor BWMS.
The Ecochlor system is approved for installation on both US flag and foreign flag vessels in hazardous zones rated Zone 1 or Zone 0. The treatment system deckhouses were installed aft of the accommodation stack, in a non-hazardous area. Both vessels use submerged ballast pumps, located in the ballast tanks, meaning that there was no pump room to accommodate the filters. To overcome this situation, the Ecochlor BWMS filter units were installed in a Zone 1 space within a deckhouse on the main deck. Piping then connected the filtration system deckhouses to the treatment system deckhouse, where the ClO2 injection points are located. A hazardous boundary loop seal was used where the ClO2 solution piping passes from the non-hazardous to the hazardous areas.
“If we had not taken the time to inspect the vessels properly and assumed that they were sisters, we would have given ourselves some major problems during the installation”
Tyler Harvey commented: “Typically, the chemical fill station is located above the treatment system so as to allow easy access for the Ecochlor representative to carry out the resupply of the chemicals once or twice per year. The entire process is closed, using specially selected equipment and Ecochlor-trained personnel. The ship’s crew have no role to play in the resupply, other than to operate the ship’s crane to lift the chemicals on board the ship. Ecochlor technicians take care of the actual chemical transfer, but even here there is absolutely no human contact with the chemicals.”
Expect the Unexpected
Good planning and preparation meant that there was some spare capacity when unexpected issues occurred. Ecochlor’s Mr Harvey shared some of the day-to-day experiences during the STI Duchessa installation: “When the flush pump was delayed in delivery at customs for eight days, the shipyard continued laying the piping to where the pump would be installed using a model of the missing equipment. Once the missing pump arrived, they carried out the necessary final modifications without any change to the schedule.”
Additionally, during one of Ecochlor’s regular project inspections, Mr Harvey noticed the chemical resupply cradle was installed incorrectly. “The cradle is angled to allow for the chemical IBCs to drain properly. The cradle was installed backwards, which made the hose connections inaccessible. To fix this issue the crew had to cut the treatment cradle and rotate it 180 degrees so that it would work correctly.”
Mr Dooley said: “Working together with Scorpio, Ecochlor and the shipyard, we identified many opportunities to improve the next group of installations. Since completing the first Scorpio retrofit, the STI Duchessa, we have implemented design revisions for all upcoming installations based on these lessons. Two of the key findings had to do with the filter deckhouse construction and piping arrangement. Choice realised that the filter deckhouse could be redesigned to save both weight and cost. In the case of the piping, we designed it to allow field-fit for the final connections. However, the shipyard preferred isometric drawings for 100% of the piping to allow for prefabrication. This requirement is a shipyard preference, and we have found that each shipyard has a different approach. The lesson learned is to have extensive conversation with the shipyard prior to final drawing release.”