BKV Holdings completed the lining of six newly-built phosphoric acid-storage tanks in record time to enable Bidvest Tank Terminals to receive already-confirmed shipments of Phosphoric acid at its state-of-the-art tank terminal in Richards Bay, KwaZulu-Natal.
The company mobilised to site in April 2018 shortly after the principal contractor, Trotech Engineering, had completed the construction of the storage tanks as part of a large capital expansion programme at the cutting-edge facility.
Notably, BKV Holdings completed the lining of more than 8300m² of surface area in only seven months – well ahead of the initial completion date – and within budget.
Jan Botha, the company’s Site Manager, attributes yet another successful BKV Holdings’ project to a firm commitment to quality that already starts in the very early planning phases to mitigate errors and the risk of having to redo work.
“We had to line at least one tank of up to 12m in height and 20m in diameter every month to ensure the timely completion of the project. Accuracy was, therefore, an imperative right from the early preparatory phases, which included the onerous task of erecting up to 30 tonnes of scaffolding inside a single structure so that our team could access the work faces,” Botha says.
An impressive 80 tonnes of Kwikstage scaffolding was erected and dismantled for this project, a task that was also greatly facilitated by accurate designs from Form-Scaff, a leading South African formwork supplier. They were further refined and optimised by BKV Holdings before mobilising to site, while the erection of the scaffolding was supervised by the highly competent Sipho Mazibuko, one of BKV Holdings’ many seasoned accredited scaffolding inspectors.
Mazibuko was joined on site by BKV Holdings Quality Control Inspector, Gladmore Maramba, as well as supervisors, Zibekile Ronoti, Bongani Mathonsi and Admire Nyamukapa.
One of the complexities was installing the tonnes of scaffolding in an extremely confined area, while the many sections had to be passed manually through a narrow 800mm-diameter manhole located just above the concrete column bases.
Extraction fans were then installed at the manhole and at the top of the storage tanks to enable the large team, sometimes comprising as many as 18 employees, to work in the restricted areas. At times, they would also have to share the limited space with and coordinate their operations around the main contracting teams that were finalising “snag items” inside the tanks.
Botha says that meetings were held almost on a daily basis between the company’s own employees, as well as with other representatives of the professional team to pre-empt any problems and proactively implement solutions to keep the project on track.
The state-of-the-art tank-lining solution deployed at Bidvest Tank Terminals was similar to the one that BKV Holdings designed and implemented for a leading fertiliser producer. Considering the excellent service it received from the contractor, the client recommended BKV Holdings’ sophisticated corrosion-protection capabilities to Bidvest Tank Terminals.
The entire area was first abrasion blasted with mineral slag grit to a NACE1/SSPC-SP5/ISO SA3 specification and, in so doing, providing a surface-anchor profile of between 50μm -75μm to aid the lining in the bonding to the surface.
“We then applied a 90:1 National Urethane Industries (NUI) salt-less neutralization wash at high pressure to the surface. This neutralised any soluble salts and oil-based contamination according to the NACE International SP1 specification. Using Wattman papers, tests were undertaken according to ISO 8502-12 standards to ensure that soluble salt levels were below 25mg/m². This was complemented by a water-break free test to confirm that there were no soluble contaminants on the surface,” Botha says.
Notably, more than 42 tonnes of grit had to be transported all the way from Rustenburg specifically for this project and the spent grit manually removed through the narrow manhole and disposed of according to a strict health, safety and environmental plan. This strategy made contingencies for the correct handling and marking of designated skips, including those used to contain hazardous and flammable substances, through to the appropriate management of the restricted dedicated bunded area. The company and the client also jointly devised and approved a comprehensive strategy to respond to any potential major spills and incidents.
Botha says that all of the welds were then stripe coated with NUI Ultraspray 400B199 Rigid Polyurethane lining system to a thickness of 1500μ.
He says, “It was applied at an optimal spraying pressure of 2000psi at 45°C using a plural component high-pressure proportioning unit with an impingement mixer at the front of the application gun to heat and mix the two parts together. A final coat of Ultraspray 400B199 Rigid Polyurethane lining system was then applied in the same manner as the first coat.”
The linings were thoroughly inspected for defects, such as pinholes, blisters, streaking or bulging, run, as well as overspray on any of the fixed equipment, and repairs instituted wherever necessary.
Notably, all of the company’s work was successfully signed off by Avax Projects’ Karyn Albrecht, an independent NACE International coating inspector, on behalf of the client.
Based on the company’s impressive performance lining the tanks, Bidvest Tank Terminals also extended BKV Holdings’ contract to include the lining of a sump and bunded area, as well as to apply base protection on all six tanks in October 2018. A portion of the existing resources available on site was swiftly mobilised to this component of the work scope.
Certainly, one of the company’s competitive edges is its extensive in-house resources, including the comprehensive range of equipment that it uses on all of its projects. BKV Holdings used two 1000cfm compressors; six 200l blasting pots; a 10000l diesel bowser and water bowser; a 15 tonne and 30 tonne crane; and three plural component-lining machines on this particular project.