Johan Stephens (Goggakil), Willie Coetzee (AGI) and Pieter Dempsey (ARK Holdings), were the three invited speakers at GOSA Cape’s workshop on 17 July 2024 at the Protea Hotel in Technopark, Stellenbosch.
Maintenance, compliance and product integrity are crucial to ensure the viability and longevity of any silo-operation. At GOSA Cape’s annual Workshop in Techno Park, Stellenbosch, three specialists of the grain handling industry outlined how simple and inexpensive monitoring, regular cleaning and occupational safety principles could prevent expensive equipment failures, safety hazards and pest outbreaks.
Willie Coetzee, regional manager for AGI Sub Saharan Africa, said that most silo accidents, malfunctions and instances of damage leave clear evidence of what went wrong and demonstrated by way of a series of real-life case studies how catastrophic and potentially fatal accidents can be prevented through regular preventative maintenance.
He said design flaws on aeration and incorrect repairs, as well as lack of temperature monitoring equipment can potentially spoil the grain stored in the silo, with resulting financial losses. It is vital to respect the equilibrium of the grain by aerating the grain when the climatic conditions are favourable. He also illustrated the risk if aeration is not done correctly. Crusting, due to condensation, excessive dust and foreign material due to lack of cleaning and the lack of coring as well as bad aeration design and practices can cause lumps in the grain, that in turn can block the central unload of a silo or even cause silo sidewall sheets to rust if exposed for a prolonged period. Proper housekeeping and maintenance are of the utmost importance to prevent losses of grain, equipment and life.
Coetzee warned that all possible steps must be taken to prevent entrapment, where a person sinks into the stored grain in a silo, if unloading equipment is started whilst a person is inside. Proper maintenance of moving parts such as bearings and belts also prevent dust explosions, which pose a grave risk, as they can be powerful enough to destroy an entire concrete silo complex, and they usually occur when the grain handling machinery is running and the full staff complement is on site, therefore also causing fatalities.
He added that most dust explosions are caused by worn bearings that spark and detonate free-moving dust particles, which leads to a succession of ever-expanding explosions. By making use of the necessary safety equipment, like belt alignment, rotation sensors and bearing temperature sensors, spot filters and centralized aspiration can all be used to reduce the risk of dust explosions. In addition to proper maintenance, keeping all parts of the silo as clean as possible will also reduce explosion risk.
Electricity compliance
Pieter Dempsey, owner of ARK Holdings, an electrical contractor specialising in the grain industry, gave an outline of the regulatory and compliance requirements that apply to grain handling facilities, and emphasised the importance of ensuring all electrical installations are compliant, as silo owners and managers are liable for damages or injury resulting from electrical failures.
He said while the cost of ensuring compliance and safety is considerable, there is also a risk of being overcharged for electrical work by unscrupulous contractors. He has seen cases where entire installations had to be re-done because incorrect components were used, but conversely it is not always necessary to replace an entire non-compliant system to achieve compliance.
A result of the training and certification regime of electricians in South Africa is that contractors who possess the required qualifications and certifications for grain handling facilities do not necessarily have experience in that field, or an understanding of the particular risks and challenges involved.
Dempsey also pointed out the inherent tension between a plant being compliant and functional; often management is only interested in getting malfunctions repaired, whereas having them repaired according to the required standards requires longer and more expensive stoppages. For this reason, he said, it is better to employ an outside contractor to handle compliance matters, as internal staff may come under pressure to bypass regulatory requirements in favour of short-term operational efficiency.
Agriculture businesses involved in grain handling join forces to develop a code of best practice for dust explosion prevention, he added.
Fumigation
Johan Stephens, owner of pest control consultancy Goggakil and grain pest control expert, discussed factors influencing the efficacy of fumigation and what alternatives are available to traditional chemical agents.
He said it is important that all silo staff can identify pest insects, as the timing and dose of fumigation depends on the species. For instance, the rust-red flour beetle (roesrooimeelkewer) requires 40% more phosphine to eradicate than the red flour beetle (malkopkewer). With conventional fumigation, gas readings should always be taken, as you are otherwise ultimately unaware whether the fumigation will be successful.
Stephens also urged anyone doing fumigation to be aware of humidity levels, as phosphine fumigation loses efficacy the further humidity levels drop below 50%. It was a significant problem during the drought of 2016 to 2018, when he saw more failed fumigations than much of the rest of his career.
Furthermore, he emphasised the importance of physical inspection of the grain and silo for insect detection, and also not to use different classes of chemicals in the same fumigation, as this may over time lead to resistance to all of them. Different classes of chemicals should be alternated. Pheromone traps are useful for insect detection, provided the traps can attract all the problem species.
Possible alternatives to conventional fumigation, some of which are not yet financially viable, include gamma radiation, ozone treatment and biological control. Heat treatment is not an option, as it requires temperatures that would damage grain.
He said substances such as diatomaceous earth hold promise, but at the quantities required to be effective, the required logistics may add considerably to costs, and could shorten the operational life of moving parts in the silo due to its abrasive nature.
Annual General Meeting
At the GOSA Cape Annual General Meeting, held after the workshop, the GOSA Cape committee was re-elected. Michal Rehr, chairman of GOSA Cape, was pleased at how well the event went in terms of time scheduling and the hospitality of the venue.
‘We were extremely fortunate with the three speakers who all have extensive experience and presented their information very cogently,’ Rehr commented. He said the topic of silo safety was chosen because of its crucial role in food security, and because most of GOSA’s membership represent farming cooperatives and agribusinesses; silos are key to their operations.
‘The demand for silo space will never go away, it will only increase, and the importance of proper maintenance is clear in the light of the risks of enormous financial losses in terms of the silo structure, stock and the implications for food security,’ Rehr concluded.
Article and photos by Jeanne van der Merwe
Arnold van Niekerk (Overberg Agri), De La Rey Knoblauch (ABInBev) and Hein Rehr (RehrCo., and president of GOSA), three founding members of GOSA Cape, who formed the branch in 1989 at a meeting in Ashton, attended the GOSA Cape workshop at the Protea Hotel in Techno Park, Stellenbosch on 17 July 2024.
