SA Plastics

40,000-litres Biggest tank in Africa from RotoTank

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The big one – Terry Stanley and Spike Lemmer dwarfed by one of the 40,000-litre tanks moulded at RotoTank in Brits. The roto moulding of these large tanks, reputed to be the largest plastic tanks manufactured in Africa, has been a major project over the past three years for RotoTank. About 1,4 tons of polymer is used in each tank and its dimensions – 3,3m wide by 4,85m high – are formidable to say the least

ROTO TANK has put some space between itself and rivals in the tank market by producing the first 40,000-litre plastic water tank in Africa. Mind you, it has been making these large tanks for almost three years but, such was the secrecy, that it has only now unveiled its breakthrough achievement.

The problem with the production of such large capacity containers (and roto moulding is itself a challenging process) is that the sheer figures are intimidating: first of all, the mould’s 40m³ dimensions are just plain scary if not outright dangerous during the production stage, about 1,4 tons of LLDPE powder is used (reject shots are not at all welcome), and then there’s still the substantial amount of heating involved in each cycle of about six hours. It all adds up to a daunting undertaking.

Larger polymer tanks have been, but using the composites process with polyester resins and glassfibre or other reinforcement.

Large roto tanks have been done before however, in Australia (where 60,000-litre tanks are produced) and the USA for sure, so Terry Stanley and Spike Lemmer of RotoTank in Brits knew it was possible.

And there were further challenges too: because so few roto moulders are producing tanks as large as this, the processing equipment simply doesn’t exist. Manufacturers of large tanks to date have done it themselves and the nature of this undertaking is that few of the successful developers have been keen to assist others – in other words, Stanley and Lemmer literally had to develop the production plant themselves – and they’re not telling how they achieved it.

It all started out with a fairly gradual trajectory: Lemmer was supplying polymers at his previous company, Affirm Marketing, and Stanley was getting to grips with every aspect of roto moulding while at RotoTrade. Circumstances combined and RotoTank was established, mainly to produce tanks, on a plot near Brits in the Magaliesberg. The synergies appear to have worked, with Lemmer managing the polymer supply through the RotoTank subsidiary Powderplast and Stanley hands-on involved in technical developments at the plant. Noteworthy developments have been made, including Decant-a-Tank, a solution to completely drain large vessels have been achieved.

But the project to manufacture Africa’s biggest plastic tank gathered momentum and Stanley steadily cobbled the solution together, with Lemmer being the technology bouncing board. The construction of the mould for the large tank was in itself a breakthrough, with modifications to the ribbing being necessary. And the scale of the project meant that trial-and-error was not a sustainable option.

The 40,000-litre tanks are now being supplied mainly into the chemicals sector.