MechChem Africa August 2019

Mech Chem AUGUST 2019 AFRICA

35 years and more than

Celebrating

35 000 installations

This month: Turbine and generator overhauls showcase local capacity

Renewing and upscaling SA’s nanomaterials initiatives

Robotic solutions for the hospital of the future

Fast track solution to DRDGOLD tailings recovery project

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16

28

38

Asset, maintenance and risk management 8 Turbine drive train and generator overhauls showcase local capacity Marthinusen & Coutts,a division ofACTOM,has successfully completed overhauls on a 70 MVA generator set for South 32’s Metalloys – within six weeks – and a major repair at Eskom’s Ingula pumped storage hydro-electric plant. 10 Nuts of the threaded variety 12 Improving asset value maturity with reliability engineering 13 Wheel slogging and slogging hammers locally upgraded 14 RFI earns Bosch Service Centre of the Year 15 Preventative maintenance: the key to sustainability Materials handling 16 Fast track solution to DRDGOLD tailings recovery project Tyrone Willemse of WEG Automation Africa and Stuart Brown of WEG Transformers talk about the commissioning of a containerised substation and control room for DRDGOLD’s Far West Gold Recoveries Project. 17 Improved chairlift safety and ergonomic comfort 19 FLSmidth’s FerroCer panels bring longer wear life to Africa 20 Mines convert to Warman froth pumps 23 Market benefits from stronger Weba – Brelko link Corrosion and coatings 24 World class lab at CHRYSO providing solutions Upgrading its Jet Park laboratory has given CHRYSO Southern Africa the capacity to expand its solutions to customers in fields including aggregates, concrete aesthetics and cement. 25 Effective bridge preservation with MCI surface protection Heating, cooling, ventilation and air conditioning 26 York technology powers Omnia innovation Johnson Controls’ Sabroe compressors are powering the custom-build ammonia chiller plant at Omnia’s new nitro-phosphate (NP) plant in Sasolburg. 27 Data centres can be efficient and green Water and wastewater processing 28 UJ Mobile lab to combat disease outbreaks UJ’s Health Science faculty has come up with mobile solution for on-site testing of potentially contaminated water sources in remote and difficult to reach areas. 31 What the sewage sludge treatment plant of the future looks like 32 Water resilience expertise for drought-plagued SA 33 GraviFilter chooses MOVIDRIVE Innovative engineering 38 Robotic solutions for the hospital of the future ABB is to install advanced collaborative robotics systems for the new non-surgical medical facility at Texas Medical Center’s innovation campus. REGULARS 2 Comment: Reliability, skills and long-term thinking 4 Mixtec: 35 years of continuous improvement Rudi Swanepoel presents the case for the company being amongst the world’s premier manufacturers of agitation technologies. 6 SAIChE News: Renewing and upscaling SA’s nanomaterials initiatives 34 Product and industry news 40 Back page: Carbon fibre from algae

P U B L I C A T I O N S CR O WN

Published monthly by Crown Publications (Pty) Ltd Cnr Theunis and Sovereign Streets Bedford Gardens 2007 PO Box 140, Bedfordview, 2008 Tel: +27 11 622 4770 e-mail: mechchemafrica@crown.co.za www.mechchemafricamagazine.co.za Editor: Peter Middleton e-mail: peterm@crown.co.za Assistant editor: Phila Mzamo e-mail: philam@crown.co.za Advertising: Brenda Karathanasis e-mail: brendak@crown.co.za Design: Darryl James Publisher: Karen Grant Deputy publisher: Wilhelm du Plessis Circulation: Brenda Grossmann The views expressed in this journal are not necessarily those of the publisher or the editors. P U B L I C A T I O N S CR O WN P U B L I C A T I O N S CR O WN 2015/02/10 01:17:09PM

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Publisher of the Year 2018 (Trade Publications)

August 2019 • MechChem Africa ¦ 1

Reliability, skills and long-term thinking

I n his opening message for African Fusion this month, SAIW President and Eskom’s chief weld- ing engineer, MorrisMaroga urges against taking hasty and expedient decisions. Short term think- ing doesn’t help anyone and yields only short term gains, but ifwe succeed inputting theeconomybackon track, everyonewill gain for the foreseeable future, he says, before urging fabricators and manufacturers to focus on developing properly skilled young people for the future: “Without skilled people, it is impossible to realise an African continent with thriving economies, peace and prosperity – and there is no better time to upskill employees than now.” Slow economic growth seems to have become the new normal. Estimates from an Economic Research Letter put out by the Federal Reserve Bank of San Francisco suggest the ‘normal’ pace for long-term US GDP growth will remains between 1.5 and 1.75%, de- spite higher 2018 to2019 averages of 2.7%. Andwhile the reasons for South Africa’s current malaise may be more complex, it is hard to see a scenario where we will ever return to pre-2008 growth rates. ‘Keep Calm and Carry On’ was a ‘motivational’ message developed in preparation for World War II to raise the morale of the British public. At the time, the poster was rarely displayed and it was only redis- covered at the start of the 20 th century at a bookshop in Alnwick, North of Newcastle. It has since become a very well-known phrase that encapsulates British doggedness. I don’t find its 1939 ‘failure’ surprising. It is a call to endure rather than tomotivate, andmore than endur- ance was needed at that time. In hard times, however, endurance has always been a survival necessity.When it comes to ‘newnormals’, though, there is anadditional need tomakepermanent and long-termadaptations so that the hard times themselves do not remain normal. Forplantequipmentanditslong-termhealth, ‘keep- ing calm and carrying on’ is exactly what operators need. Nobody wants the drama and panic associated with plant break downs. We prefer plant equipment that continues to function, preferably forever and without any fuss. Reliability is the panacea. It is unachievable, however, without effort, long- term commitment, skills and investment. Procedures and systems have to be put into place, monitoring equipment installed and suitably trained people em- ployed to manage reliability programmes. In our Maintenance and reliability management feature for this issue, Martec asset reliability special- ist, Arveen Gobind, describes the difference between reliability engineering and maintenance engineering:

“A reliability engineer’s skill set is diverse, driving business strategies to achieve goals through a well- structured path utilising vast amounts of data, while themaintenance engineer’s skills are used for day-to- day fire-fighting activities to ensure assets that have failed are brought back into service in the shortest amount of time,” he says. Like Maroga, Gobind identifies skill-sets as key to implementing reliability strategies and maintenance programmes. The reliability journey beginswith a risk- based perspective, he says, identifying howtomanage and mitigate against failure risks and then evaluating thedirect impacts of the implementedprocedures and continuous monitoring programmes. He goes on to describe some basic techniques and data analysis that canmake overall plant effectiveness sustainable. Over time, the data quality will incre- mentally be improved, which will result in improved information quality and reliable decision making, Govind notes. In this month’s cover story, Mixtec is celebrating 35 years of doing business, having supplied more than 35 000 agitators in that time. The company has, according toRudi Swanepoel, “evolved a sophisticated after sales service offering that continuously seeks to reduce downtime and improve mixing efficiency.” Raising supplier service levels tobetter support the reliability of installed plant equipment has become a critical survival strategy for original equipmentmanu- facturers. Plant operators remain reluctant to invest in new technologies, preferring to ‘nurse’ their existing fleets to endure the hard times. In response,Mixtec has adoptedahighly cost effec- tive approach to plant up-grade projects. “With EPCs and project houses, we have successfully and cost ef- fectivelyupgradedsystemsinZambia,GhanaandDRC, retrofitting pre-existing mixers to improve mixing efficiencies while ensuring we can match production increases, improve reliability and reduce downtime,” explains Swanepoel. As a nation arguably facing near-crisis conditions, all South Africans need to doggedly endure, keep calmand carry on. In addition however, as individuals, company’s, state institutions, voters and politicians, we need to think long-term, seeking new and better ways of working and living so that ‘crisis-mode’ does not remain normal for us. The benefit of all must become the priority for all and, as Maroga suggests, what better place to start than by advancing the skills of our youth so that our plants canbemademore reliable, efficient andproduc- tive and our lives more sustainable. q

Peter Middleton

MechChem Africa is endorsed by:

2 ¦ MechChem Africa • August 2019

“In Mixtec’s 35 years of doing business we have supplied more than 35 000 agitators – and we are growing stronger every year.” Mixtec’s Rudi Swanepoel presents the case for the company being amongst the world’s premier manufacturers of mixing and agitation technologies. Mixtec: 35 years of continuous improvement

M ixtec was founded as a family- owned and operated business in 1984 by two experts in the field of agitation and mixing, Timothy Clamp and William Baguley. Mixtec director, Jonathan Clamp comments: “I con- sider myself extremely fortunate to have had the opportunity to learn from some of the most knowledgeable people in the industry.” Mixtec has sustained its continuous im- provement approach to development, while retaining its core values, most notably cus- tomer service satisfaction. “Customers have been at the heart of our success since Mixtec’s inception. As a result we have grown into a global organisation with six fabrication plants: in the United States, South Africa, Australia, the United Kingdom, Malaysia and Chile. In addition, we have specialised agents in New Zealand, Mauritius, Kazakhstan and France. We continue to network globally to defend our position as a premium provider of agitating and mixing solutions,” Rudi Swanepoel tells MechChem Africa . “We pride ourselves on providing best quality and excellent service, while building long term customer relationships. Our ef- ficient designs ensure that our mixers are economical and robust. We partner with several gearbox manufacturers to enable us to offer best- t drives with readily available

spares and expert assistance,” he adds. “In our laboratories handling facilities, experienced application engineers can test andoptimiseagitator design, including in-tank additionssuchasanti-vortexbaf es,mounting structures, nozzle orientations and economi- cal vessel shapes. Our custom design service and uidmixing laboratory can produce com- plete mixer designs, even if little or no data is available about the onsite application. “Ongoing research into the latest tech- nologies and processes allows us to provide enhanced efficiency and improved system reliability,” says Swanepoel, adding that CFD analysis enables mixer performance to be assessed under a variety of conditions to optimise and improve agitator design. Extensive nite element analysis of highly stressed components such as impeller hubs and couplings also ensuresmaximumreliabil- ity. “We then bring our design and research into the real-world through stringent inter- national fabrication standards and inspection procedures and the use of state-of-the-art machine tools that ensure accurate alignment to precise tolerances. This applies to our en- tire offering, fromsimple baseplate-mounted units to sophisticated high-pressure reactor designs that incorporate sophisticated me- chanical seals,” he says Swanepoel notes that, to plant operators, mixers are critical for achieving process

requirements. “We therefore make it our business tounderstand the large and complex number of elements that have tobe combined to efficiently achieve the best end result for our customers. Every oneof ourmixers is cus- tom-designed to perfectly match themineral being processed and the processing volumes. This requires a combination of considerable experience and knowledge of the processes and technologies. “Our first focus, therefore, is the speci cs of the process, followed by the mechanical integrity of the mixing components and the drive system. We match the right impeller to themixer by considering the pro le, pumping and power needs of an application.We factor in the velocity gradient, the super cial (in- tank) velocity, the pumping rate, tank turn- over rate, tank shape, liquid level variation, location of the impellers and the direction of pumping to ensure that each solution is successful,” he says. Mixtec aims to conduct its business in a sensible and professional manner, whilst seeking continuous improvement and ensur- ing compliance to all legal and other require- ments. From a quality perspective, Mixtec is

Above: Mixtec can supply agitators from small to very large for any greenfield or retrofit project in varieties tailored to the specific needs of a client’s processes and applications. Left: Mixtec units are manufactured under the strictest conditions and to the highest standards to suit their intended operating environments.

4 ¦ MechChem Africa • August 2019

⎪ Cover story ⎪

Mixtec director, Jonathan Clamp with one of Mixtec’s founders, Timothy Clamp. independently audited every year to ensure compliance to quality and safety. “Mixtec’s components also undergo various testing procedures such as non-destructive testing, magnetic particle, ultrasonic and x-rays, ac- cording to client requirements. In addition, Mixtec commissioning engineers are perma- nently available to oversee all installations of new equipment on site to ensure correct procedure is followed,” he adds. that better quality materials and fab- rication standards are employed for replacements. “To keep processes ef- ficient, maintenance is required and we make available all t he app r op r i a t e spares and service procedures for new and retrofit systems. “We have been

Given the wide variety of applications and processes for mixers and agitators, Mixtec offers a range of different configurations, in- cluding open top tanks; closed top tanks that requiresealing;largescaleindustrialagitators; side entry mixers; and in-line static mixers. “Experiencegleanedoverthepast35years has resulted in our agitators being employed throughout the world in mining and refining; water treatment; pulp and paper; oil and petrochemical; chemical and industrial; food andbeverageandahost of other projects.Our advanced impeller designs are used to solve problems for gold leaching, carbon in pulp adsorption, biological leaching, conditioning and attrition scrubbing, to name a few. Their use has resulted in higher quality mixing, lower power draws and better reliability in thousands of applications in these industries,” Swanepoel says. After sales and Mixtec retrofits With installations at mines, minerals pro- cessing and water treatment plants across Africa and the world, Mixtec’s business has expanded significantly over the past 35 years to include a sophisticated after sales service offering that continuously seeks to reduce downtime and improve mixing efficiency. “Through site visits and inspections, we habituallyuncover performancemaintenance issues that sites are often not aware of. We have become ideally placed to improve the efficiencyofmixing andagitatingprocesses in ways that can radically reduce the downtime causedby unplannedbreakdowns and associ- ated repairs,” Swanepoel says. “We frequently find unsuitable designs being used for specific mixing applications. We are able to evaluate thesewhile ensuring

able to make some massive improve- ments in copper/co- balt, phosphate and

gold mines across Africa through our service and retrofitting initiatives,” notes Swanepoel. “Mines in Africa tend to have increased their production over time, which impacts their processes significantly. During site visits, we analyse needs and identify ways of replacing or retrofitting our mixers to match increased plant processing requirements,” he continues, adding that Mixtec has adopted a highly cost effective approach to plant up- grade projects. “With EPCs and project houses, we have successfully and cost effec- tively upgraded systems in Zambia, Ghana and DRC, retrofitting pre-existing mixers to improve mixing efficiencies while ensuring we can match production increases, improve reliability and reduce downtime.” Citing an example of a recent plant up- grade project in the DRC at a site with about 130 mixers, Swanepoel says that the mine’s pre-existing mixers are being systemically retrofitted with modern technologies such as its high efficiency EDICT impeller design. “We can offer new and existing plants state- of-the-art designs and equipment that can be retrofitted simply and quickly into their cur- rentmixer structure, tanks anddrive systems. This is a very cost-effective way of adopting modern agitation and suspension solutions without significant amounts of downtime or capital expenditure,” he argues. To expand its African footprint, Mixtec is

renewing itsmarketingdrive through local ex- hibitions such asCaminex andElectraMining, where the Mixtec-designed EDICT system was showcased. “Knowledge and interest in our solutions are increasing as we actively showcase our world leading technologies. With our core focus on customer satisfaction andrelationshipmanagement,wearebuilding lasting long-termrelationshipswithblue-chip customers across Africa and the globe,” he informs MechChem Africa . “We are staying abreast of new possibili- ties and technologies, and actively promoting these at exhibitions, expos and trade shows across Africa. We also offer onsite training for plant operators andmaintenance person- nel and, for water plant operators, we work closely with government organisations and the public sector, visiting sites several times a year to inspect the equipment and to ad- vise on new ways of ensuring optimal mixing through maintenance and improvements to impellers, drives and tanks. “Combined, we believe that our state- of-the-art designs and equipment, our specialised capabilities in processing and mixing, and our client-servicemindset set us apart fromour competitors,” says Swanepoel in explaining why Mixtec’s footprint still continues to expand 35 years after it first began to design and manufacture mixers and agitators. q

August 2019 • MechChem Africa ¦ 5

Research into nanomaterials in South Africa was formalised in 2005 with the publication of the National Nanotechnology Strategy and its 10-year plan, but there remains a need for technologies to be developed and employed for large scale local manufacture of these materials. SAIChE IChemE President, David Lokhat compiles a technology overview. Renewing and upscaling SA’s nanomaterials initiatives

specific chemicals, nanofilms or nanoscale waxparticles. Approximately450of the1317 products available in2010werepersonal care products: cosmetics, sunscreens or textile- related materials. Some of today’s common uses for nano- materials include: • Non-scratch glasses that use ultra-fine polymer films with protective and anti- glare properties. • Building materials such as cement, tiles, grouts, sealants and windscreen glass that are coatedwith nanoparticles of tita- niumoxide to give advanced performance such as self-cleaning and anti-bacterial properties. • Clothes with advanced properties such as UV blocking, infrared reflecting, anti- bacterial, crease-proof, stain-resistance, water-repellence, moisture-control, flame-retardant, odour removing, anti- static, electric conductivity, heat retaining, temperatureregulating,wrinkleresistance and high mechanical strength. Examples include ties that repel dirt, shirts that do not need ironing, or skiing anoraks that use nanofibres to resist water and wind. • Automotive and aerospace technologies where nanoparticle additives in engine- constructionmaterials are used for lighter weight, higher strength, improved temper- ature/corrosion resistance and superior wearresistance.Metaloxidenanoparticles and carbon nanotubes and fibres (CNTs and CNFs) are used as additives in poly- mer nanocomposites for densification, improved mechanical strength and to improve the wear resistance of structural materials and tyres. • In sports equipment suchas tennis rackets, CNTs are used tomake them lighter, more flexible and more resistant. • More effective and protective cosmetics: lotions granulated to below 50 nm that let light through, giving a purer, cleaner feel; anti-wrinkle creams that use polymer nanocapsules to distribute active agents such as vitamins more efficiently; sun creams that use nanoparticles of titanium dioxide and zinc oxide, so they do not turn white when spread on the skin, while still offering the same degree of protection against UV light as traditional creams. • Silver nanoparticles used as an antibacte- rial agents in many consumables, ranging from surgical instruments and household appliances to pet food bowls. Some applications of nanomaterials that are close to industrialisation level include: • Hydrogen storage using metal or ceramic nanostructured materials. • The delivery of pharmaceuticals in nano- capsules via hollow nanoparticles such as fullerenes.

B ack in 2005, South Africa was one of the few developing economies in the world to realise the potential of nanomaterials when the South African Nanotechnology Strategy and its associated 10 year plan were put into effect. Water, energy, health care, chemical- and bio-processing, mining and minerals, along with advanced materials and manufactur- ing were explicitly identified as application specific areas to benefit fromthe programme and, while the technology’s contribution to the development of the country has been questioned, there is no doubt that valuable research has since been done. Technical projects brought to completion or in progress include: synthesis of nanopar- ticles; development of better and cheaper solar cells; nanophase and electro-catalysts; fuel cell development; synthesis of quantum dots; composites’ development; and atomic modelling, to mention but few. Projects are being carried out at eleven universities; four research organisations and several private sector companies in fields from mining and surface coatings to paper manufacturing. Moreover, almost every ma- jor university in the country has a dedicated nanotechnology or nanomaterials platform, which connects researchers and academics with funding agencies, industrial partners

and other stakeholders, in order to carry out fundamental and applied research. SouthAfrica has innovation centres at the CSIR and MINTEK, which have each devel- opedcollaborativeresearchprogrammeswith other national institutions: in the design and modelling of novel nano-structured materi- als (at the CSIR); as well as the application of nanotechnologies in all targeted fields of the nanomaterials strategy. AuTEKBiomed, a collaborativeproject be- tween the gold mining industry andMINTEK is creating gold-based chemo-therapeutics for treating diseases such as cancer, malaria and HIV & AIDS. The Rand Refinery hopes to build a nanotechnology plant if ongoing experiments prove gold nanoparticles can be used as catalysts for detoxifying air in our mines; while paper manufacturer, Sappi, is currently investigating the possibility of us- ing nanotechnology tomonitor temperature, termites and fungus in its tree plantations. Global applications Back in 2010, 1 317 consumer goods taking advantage of the unique properties of nano- materials were already estimated to be in the global market. This number has steadily riseneveryyear.Manyof theseearlyproducts used silver nanoparticles for antibacterial purposes. Carbon in the formof carbon nano- tubes and titaniumoxidewere the secondand third most adopted nanoparticles, while the remaining products contained either non-

The chemical vapour deposition (CVD) process involves precursor gases being delivered into the reaction chamber at approximately ambient temperatures. As they pass over or come into contact with a heated substrate, they react or decompose forming solid nanoparticles that and are deposited onto the substrate (boat).

6 ¦ MechChem Africa • August 2019

⎪ SAIChE IChemE news ⎪

• Catalysts, adsorbents and absorbents as nanoporousmaterials: in vehiclefilters for reducing environmental pollution and fuel consumption, for example. • Nanoscale electronic and optical instru- ments (nanocables). • Environmental protection: dendrimers exhibiting a high degree of surface func- tionality and versatility can act as ‘attrac- tors’ of metal ions. There are, of course, many other applications of specific nanomaterials under investigation. Bottom-up approaches for the production of nanoparticles include vapour phase tech- niques such as aerosol spraying onto heated surfaces to trigger a pyrolysis reaction for the creationof nanoparticles suchas carbonblack pigment particles and titania. These have uses as reinforcement in car tyres and for the production of paints and plastics. An electro- spraying process at room temperature has also been developed at OxfordUniversity for the production of semiconductors and metal nanoparticles. Atomic ormolecular (gas) condensation in a vacuum chamber is the oldest production method. Used mostly for metals, the mate- rial is heated to below its boiling point in a vacuum so that atomised/vapour particles are produced. These are then carried into an inert gas atmosphere where they condense, forming spheroidal solid nanoparticles. Electrical techniques such as arc dis- charge; laser ablation; and plasma processes are also being developed, but the most promising vapour phase technique for large scale production is probably chemical vapour deposition (CVD), which iswidelyused for the production of CNTs. CVD offers many advantages: uniform thickness of coatings; flexibility of chemical precursors –70% of elements in the periodic table have beendeposited– and an ultra-high vacuum is not required for nanoparticle pro- duction. CVDprocesses involve safety issues andhealthhazards, however. Also, despitebe- ingaflexiblemethod, CVDrequiresnumerous experiments to establish growth parameters. Liquid phase production techniques include: • The Sol-gel method, a long established industrial process for generating colloi- dal nanoparticles from the liquid phase. The process is based on hydrolysis or condensation reactions. With the correct amount of reactants, nanosized particles precipitate. • The Solvothermal method is used for crystalline solids. Solventswell above their boiling point are used in enclosed vessels. High autogenous pressures are supported Production methods for nanomaterials

High definition transmission electron micrographs of copper and iron oxide nanoparticles synthesised in the chemical engineering laboratory of UKZN using a simple precipitation method.

and the organic solvents are used to dis- perse non-oxide nanocrystallites and to stabilise metastable phases. • Hydrothermal synthesis: a subset of the Solvothermal method, this is an enabling andunderpinning technology that is ready to prove itself at industrial scale as a result of recent breakthroughs in reactor design. The process involvesmixing superheated/ supercritical water with a solution of a metal salt. • Sonochemistry: a research area in which molecules undergo chemical reaction due to the application of powerful exposure to ultrasound. There are also a number of top down ap- proaches to nanomaterial production, in- cluding: mechanical attrition such as milling and mechanochemical processing; hybrid approaches such as nanolithography using electron-beam, focused ion-beam writing, proximal probe patterning, X-ray lithography, scanningprobemicroscopy (SPM) andothers. Template fabrication is one of the most popular and maybe cheapest methods of nanolithography and used for the growth of nanowires by electrodeposition, for example. Templates of ordered nanopores have to be made before the pores are filled using one of the bottom up process options – electrode- position; the sol-gel method or chemical or physical vapour deposition. These andmany other potential processes offer enormous opportunities for South African researchers to develop industrial scaleprocessingplants as part of the initiative togrowamodern locallybasednanomanufac- turing industry. Challenges and future outlook As with any new technology, there have been concerns that the very properties of nanoparticles that render themso useful may also cause undesirable health effects. The assessment of potential risks of nanotech- nology is at an early phase of development. Technologies and practices that eliminate or prevents potential unintended effects to

Vapour and liquid phase techniques are the leaders for large scale production of inorganic nanoparticles (ref: http://nanoparticles.org/ standards/). workers, consumers and the environment will be of critical importance going forward. Research in this field needs multi- and intra-disciplinary specialists: toxicologists, environmental scientists, nanotechnologists, risk assessors, epidemiologists and others. The results of such studies will be vital if we are to support and enable industry-scale manufacturing of nanotechnology-based products in South Africa. While National Nanotechnology Strategy projects were expected to reach maturity within 10 years and result in viable commer- cial products, it was soon realised that although the base level technologies and pro- totypeswere successful, true commercialisa- tion would require further development of themanufacturingmethods. This is nowa key focus area and that which requires continued public and private sector support. Acknowledgement: Much of this article was extractedfrom ‘Manufacturingnanomaterials: fromresearchtoindustry:CostasA.Charitidis*, PantelitsaGeorgiou, Malamatenia A. Koklioti, Aikaterini-Flora Trompeta and Vasileios Markakis, from the School of Chemical Engineering at the Technical University of Athens. *charitidis@chemeng.ntua.gr The full article can be downloaded from: mfr.edp-open.org/zh/articles/mfreview/ full_html/2014/01/mfreview140013/mfre- view140013.html

August 2019 • MechChem Africa ¦ 7

Marthinusen & Coutts, a division of ACTOM, has successfully completed overhauls on a 70 MVA generator set for South 32’s Metalloys – within six weeks – and a major repair at Eskom’s Ingula pumped storage hydro-electric plant, which is the largest rewinding project ever conducted in South Africa. These achievements showcase a local capacity to take full control of large mechanical and electrical refurbishments. Turbine drive train and generator overhauls showcase local capacity

I n a recent major overhaul of a 70 MVA turbine generator set, ACTOMcompany, Marthinusen & Coutts, contracted with South 32’sMetalloys to take full respon- sibility for the entire drive train refurbish- ment for the electrical generation plant at Metalloys’ manganese plant in Meyerton, Gauteng. Working in collaboration with business unit ACTOM Turbo Machines, Marthinusen & Coutts completed the work successfully within six weeks. According to Mike Chamberlain, Marthi­ nusen & Coutts’ marketing executive, this achievementshowcasesthecapacityofthedi- visions to take full control of largemechanical and electrical refurbishments. Chamberlain highlights that the customer did not want

to split the responsibility for the complete generator and turbine drive train between separate contractors. “Marthinusen&Coutts andACTOMTurbo Machines’ capabilities enable us to control the entire process, offering peace of mind to customers, coupled with optimised cost efficiencies,” says Chamberlain. “This also reduces customers’ riskandmanagerial effort in dealing with multiple suppliers.” The scope included a complete inspection of the turbine rotor and internal components, as well as runout and dimensional inspection on the rotor. Inspections incorporated glass bead blasting and non-destructive testing of many components. High-speed balancing of the 13 t rotor was conducted, and turbine rotor journals

were repaired. White metal bearings were relinedand the thrust bearingwasmodified to improvefitment in thebearingcasing. Positive material identification tests were conducted on all the studs, nuts and shaft seals. A com- plete 3D scan was done of the centreline to allow reverse engineering drawings. At its repair facility in Cleveland, Johan­ nesburg, Marthinusen & Coutts also per- formed a number of inspections, tests and repairs on the rotor. Dimensional inspections andelectrical testswere conducted, aswell as non-destructive testing such as phases array ultrasonic testing. Slip ringswere ground, the diode wheel was inspected, and the diodes were tested. ACTOM Turbo Machines inspected and refurbished the auxiliary mechanical equip- ment. This included lubrication and control oil systems, pumps, coolers and white metal bearingsontheIDandFDfans.ACTOMTurbo Machines project manager Hannes de Jager notes that an overhaul of this magnitude and scope would usually take over two months. “Theexcellentworkingrelationshipwehad withMetalloys’ technical staff, and the coop- eration we got from them certainly contrib- uted to completing the work as quickly as we did,” says De Jager. Starting the inspections, tests and repairs in July, the team completed the overhaul by mid-August. The Ingula pump storage repair The completionof the repair at Eskom’s Ingula pumpedstoragehydro-electricplant hasbeen described as the largest winding installation ever conducted in South Africa. The contract involved the complete re- wind of a 373 MVA stator for one of Ingula’s four 14-pole motor generators. According to Richard Botton, managing director of Marthinusen & Coutts, the 342 MW unit is among the biggest in SouthAfricawith a core diametermeasuring 5.0metres, a core length of 3,2 metres and a rotor mass of 500 t. “As the stator was located deep in the turbine floor, all the winding was required to be conducted on site,” says Botton. “In this complicated repair, each replacement coil set was fitted, connected and brazed on-site from pre-manufactured and pre-packed

Marthinusen & Coutts took full responsibility for the entire drive train refurbishment on a 70 MVA generator set for the electrical generation plant at Metalloys’ manganese plant in Meyerton, Gauteng.

8 ¦ MechChem Africa • August 2019

⎪ Maintenance and asset management ⎪

A pump OEM had approached Marthi­ nusen & Coutts, the largest after-market service provider of electrical andmechani- cal rotating machines in Africa, to assess several underground pump motors. There was an urgency to the situation because of the risk of flooding should there be any undue interruptions inpumpingoperations. Investigations revealed that themotors driving the pumps were in a poor condi- tion, severely affecting the availability and the performance of the pump chambers. This required the initiation of a detailed refurbishment programme, involving the procurement of spare parts, the setting up of an on-site bearing store, and taking the lead in returning the motors to full service. Where possible, the motors were re- paired in situ – thus avoiding any possible crisis of underground flooding – while oth- ers were removed for full refurbishment. The highest levels of engineering practices where followed during repairs, re-installa- tion and commissioning. Ongoing support is also being provided, components supplied by the OEM. The most painstaking process, conducted to the high- est standards, was the resistive brazing on 1 824 joints.” Marthinusen & Coutts carried out the work with a 14-man team, completing the work in November 2018 after 100 days on site. Their extensive preparation included the establishment of training jigs at its Johannesburg facility, allowing customised training for all technicians involved in the mammoth project. “We also conducted detailed testing, and refurbishment where necessary, of all the winding equipment we would use on site,” he says.“Thiscontributedtosmoothanduninter- ruptedoperations, makingus self-sufficient in rolling out the contract.” Working closely with OEMs and Eskom, Marthinusen & Coutts took full ownership of the rewind project from start to finish, he notes. The contract was successfully com- pletedon-timewithall test criteriawellwithin specification. “Withour in-country expertise, supported by our Centres of Excellence in Benoni and Cleveland, the project showed the world class capability of Marthinusen & Coutts,”

In what has been described as the largest winding installation ever conducted in South Africa, Marthinusen & Coutts has completed a major repair at Eskom’s Ingula pumped storage hydro-electric plant. The contract involved the complete rewind of a 373 MVA stator for one of Ingula’s four 14-pole motor generators.

says Botton. “We could also contribute our specialised equipment and supply chain – elements that often present a challenge to

foreign service providers trying to conduct this kind of project work in South Africa,” he concludes. q

Motor rehabilitation keeps Zambian mine pumping Marthinusen & Coutts’ Cleveland Engi­ neering Services Division teamed up with the Marthinusen & Coutts Kitwe facility in Zambia to rehabilitate medium voltage pump motors in one of the wettest mines in Africa. including training of mine maintenance staff, development of installation and commissioning specifications, conducting of regular site inspections, management of spares, and continual engagement with mine engineering management. Marthinusen & Coutts operates six state-of-the-art repair and manufactur- ing facilities – in Johannesburg, Benoni, Sasolburg, Rustenburg, Harare and Kitwe. Supported by a network of technically equipped partners throughout Africa, it provides services not only in Africa but globally. q

Marthinusen & Coutts technical personnel monitoring the condition of a 3 300 kW pump motor in Zambia at one of the wettest mines in Africa.

August 2019 • MechChem Africa ¦ 9

Nuts of the threaded variety

T here is no mystery about nuts and bolts, or to give them their proper name, threaded fasteners. Threaded fasteners are socommon, even those who claim zero knowledge of engineering know what they are. Yet threaded fasteners are perhaps the most misunderstood engineering compo- nents. I have lost count of the times when a broken bolt has been brought to me that has clearlyfailedinfatigue,withthecommentthat ‘it must have been over-tightened’. A popular mis-conception, and sadly nothing could be further from the truth. When the tightening operation is carefully considered, it involves nothing more com- plicated than driving one inclined plane up another. That the planes arewrapped around inaspiralontheboltandinsidethenutdoesn’t change anything. It’s probablywell known, or shouldbewell In his August column, Tim Carter talks about nuts, not the sort you get in a little packet on cheap airlines with a printed ‘may contain nuts’ warning, but the ones that, together with their respective bolts, quite literally hold our engineered world together.

Three examples of fatigue failures on bolts. Only under-tightened fasteners can be exposed to the cyclic loads that produce a fatigue failure.

known, that a threaded fastener works by clamping two surfaces together. To do that, the bolt has to be in tension, exerting the needed balancing compressive force on the joint. What isn’t so well known is that only about 10% of the applied torque is used in generating that force. The other 90% is used in overcoming friction, about 40% on the threads themselves and about 50% on the under-head, or under-nut, surfaces. That iswhymost specified torque settings mandate ‘dry threads’. Any kind of lubricant will change the friction coefficients – and fiddlingwith the friction coefficients changes everything, including the clamping force generated, which has the ability to spoil somebody’s day when it comes loose and the nut falls off. As supplied, most fasteners have a coatingof some formof lubricant, even if it’s only an anti-rust treatment for storage. The other day I was treated to the sight of a wheel bounding down the road on its own. Since my car will flash warning lights and shout at me if one tyre is down on pressure, let alone going its own way, I knew it wasn’t one of mine, so I got out of the way of whoever had lost it, before pulling off the road at a safe distance to give whatever help I could. Looking at thewheel hub, I noted it

A fastener that failed when the joint came loose.

had two nutless studs and two stud stumps. The driver, a young lady, (well younger than me, she didn’t have much in the way of grey hair) told me she had recently had the tyre checked for a slow puncture. Both stumps were clearly fatigue failures. I thought this a little strange, sincewhen I have tyres changed, I take the car home, loosen the wheel nuts (often with a 20-inch long breaker bar), and then re-tighten them with a torque wrench (45-50 ft-lb) so I know I can take themoffwith the spanner in the car anddon’t needGodzilla fromthe tyre shopwho tightened them in the first place, probably with a pneumatic power wrench. I know that if I have to, it will be at

Tim J Carter is a consulting physical metallurgist previously in private practice and now with ImpLabs in Benoni: timjcarterconsulting@gmail.com.

It’s impossible for an over-tightened threaded fastener to fail in fatigue, which is the most common cause of failure.

10 ¦ MechChem Africa • August 2019

⎪ Maintenance and asset management ⎪

the side of a busy road, at night, and in the rain. And in industrial failures of threaded fasteners, it will usually be at around two o’clock, usually on a Sunday morning. And it will be cold and probably raining, if notworse. After retrievingherwheel, we re-attached it with the two remaining studs and two nuts ‘borrowed’ fromotherwheels andadvisedher to go back the tyre fitment establishment. I don’t know whether she did or not. Knowing drivers on the East Rand, she’s probably still driving around like that. A failure looking for somewhere to happen. It’s impossible for an over-tightened threaded fastener to fail in fatigue, which is the most common cause of failure. When over-tightened, the tension in the fastener is far above the fatigue limit for the bolt, as- suming it’s made of steel whichmost are, and the resulting clamping forcewill bewell above that needed – also assuming it survives being over-tightenedwithout stripping the threads or breaking, which many do. Only an under- tightened fastener can be exposed to the cyclic loads in service that produce a fatigue failure, the most common cause of in-service failure in threaded fasteners. So, threaded fasteners, nuts and bolts are well known but, sadly, how they work is poorly understood. Their rules are, however, well understood. Learn them and obey them, and theywill serve youwell andwill hold your world, and your car, together. Ignore the rules and under- or over-tighten threaded fasten- ers at your own risk. Please note that the opinions expressed in this column are mine and mine alone. q

Leading provider of gas detectors and software offers direct-to-cloud connectivity

COMTEST, the local representative of Industrial Scientific, the global leader in gas detection, has announced the expan- sion of its connected safety portfolio to include cellular and wi-fi capability in the Ventis®Pro5 Personal Gas Monitor and a satellite communication gateway to con- nect mobile workers in real time. For area gas monitoring, the Radius ® BZ1 connects to the cloud via the RGX™ Gateway, which is certified for Class 1 Division 2 and ATEX Zone 2 hazardous zones around the globe. Personal and area monitors pass real-time data to iNet ® Now softwareallowing supervisors to seewhere workers are located and what hazards they are exposed to. The combination of real-time and historical data gives organ- isations the power to increase productiv-

ity, address risky behaviour and improve safety practices in a range of applications frommobileworkers to in-plantmonitoring and confined space entries. The connected devices also improve team and site safety due to their unique ability to share alarms between monitors. Local alarm sharing al- lows for faster, more informed responses fromnearbyworkers. Additionally, the local network feature enablesmonitoringwithin confined spaceswhere traditional wireless devices have limited connectivity. “Our connected safety offerings fo- cus on aligning people, devices, sensors and data to help businesses achieve key outcomes: saving lives, saving time, and using resources more efficiently,” says Justin McElhattan, president of Industrial Scientific. sales@comtest.co.za

Threaded fasteners, nuts and bolts are well known but, sadly, how they work is poorly understood.

Connected devices improve team and site safety due to their unique ability to share alarms between monitors.

August 2019 • MechChem Africa ¦ 11

⎪ Maintenance and asset management ⎪

Improving asset value maturity with reliability engineering

goals, there has to be alignment between the following elements: • Financial factors: Return on investment and capital investments. • Customers: Serving customer needs and reducing product delays while maintain- ing quality. • Internal processes: Enhancedoperational efficiency, availability and reliability. • People: Developing the workforce with training and structured growth paths. Anasset reliabilityKPI selection should incor- porate the following: • Evaluating the effectiveness of a condi- tion-basedmaintenance tactic bymeasur- ing work orders generated by a CMMS. • Managing the risk of critical asset failures, utilising Weibull analysis techniques. • Monitoring the impact of changes to the maintenance and business strategy on reliability. • Understanding the maintainability, avail- ability and reliability of an asset through performance comparisons and trending. Asset life cyclemodellingKPI selection should incorporate the following: • Identify underperforming assets based on utilisation, availability and running costs. • Monitoring performance after modifica- tions or changes related to failures (MTTR and MTBF).

Arveen Gobind, one of Martec’sAsset Reliability Specialists, talks about the difference between reliability engineering and maintenance engineering and gives some tips about how companies can improve their business maturity through reliability.

R eliabilityengineeringisoftenassoci- atedwithmaintenanceengineering; however, a reliability engineer’s skill set is more diverse, driving business strategies to achieve goals through a well-structured path utilising vast amounts of data. Themaintenance engineer’s skills are used for day-to-day fire-fighting activities to ensure assets that have failed are brought back into service in the shortest amount of time, without compromising on quality. In attaining business maturity through reliability engineering, an organisation must define goals. The existing systems will go through an evaluation process, to determine their suitability for integration, as organisations tend have vast amounts of useful data on various platforms. The goals

will determinewhich data has the quality and integrity to be transformed into information, providing insight into asset performance and reliability. Analytics are performed on the information and interpretations result in ef- fective decisionmaking, with recommended actions. The results are then presented on dashboards and business intelligence report- ing visualisations. The reliability journey begins with a risk- basedperspective,comprisinganunderstand- ing of criticality, risk, failure-modes, effects analysis, predictive maintenance technolo- gies and analytics. Furthermore, elements such as business goals, asset reliability, KPI selection and asset life cycle modelling play a crucial role. Whenconsideringsupportforthebusiness

12 ¦ MechChem Africa • August 2019

• Identifying assets that showsigns of premature ageing or approaching end-of-life. • Evaluation of a repair versus a replacement strategy. An example for themeasurement of overall equip- ment effectiveness is adopting a condition-based maintenance tactic such as vibration analysis, oil analysis, or thermography surveys, which can be evaluated with the asset’s mean time between failure (MTBF) and mean time to repair (MTTR). These will have a direct effect on business goals and the alignment thereof.

When utilising these basic techniques and data analysis, the overall plant effectiveness will prove sustainable. Over time, the data quality will incrementally be improved, which will result in improved information quality and reliable decision making. The adoption of a continuous monitoring programme utilising data analytics reap the benefits of improved asset performance with increased return on investment. With our integrated solutions, Martec is per- fectly positioned to assist companies with the improvement of their asset value maturity. q

Wheel slogging and slogging hammers locally upgraded

BMG’s Slogging Hammer and Wheel Slogger, which form part of the company’s extensive range of tools and equipment, have recently been upgraded by local inventors, Slogging International, for greater efficiency and im- proved safety. “The versatile Slogging Hammer andWheel Sloggerseries,whichareusedinmanyindustries to loosen and tighten bolts and nuts quickly and easily, ensurehighly efficient operation and safe use for operators,” says Andrew Johns, BMG business unitmanager for tools and equipment. “Recent advancements include a combi- nation of two sizes, a new safety clip on the Slogging Hammer that prevents the shaft from sliding out when the tool is not in operation, and an all-in-one torqueing clip on the Wheel Slogger. This new clip allows the user to leave the tool attached to the wheel and gives the option of selecting different torque settings – from450 to650Nm–without having to change the clip. Previously each torque was specific to a particular clip. “There are many advantages of using the Slogging Hammer andWheel Slogger over con- ventional sloggingmethods. Productivity is sig- nificantly improved through the controlled and effective impact between the hammer and the spanner, resulting in minimal downtime when compared with other conventional methods of loosening and tightening nuts and bolts. Safety, irrespective of the industry or application, is non-negotiableand the slogging rangeensures a betterworkingenvironment. Properties include ergonomics, high power to weight ratio and single operator deployment.When the Slogging Hammer is used in combinationwith theWheel Slogger, applications are extended even further. “Conventional hammer and slogger spanner systems require two operators to tighten and loosen nuts and bolts. This method is not only dangerous when the working area is cramped and thereareother people in thevicinity, but it is alsounsafe for the operator holding and guiding the slogging spanner. Theoperator is thenat risk

of shrapnel and is effectively at themercy of the operator swinging the hammer. “The Slogging Hammer was developed to overcome the hazards associated with the tra- ditional hammer and slogging spanner method and to improve operator safetywhen loosening bolts and nuts. Other uses for this tool include pin extractions, and with an adaptor this can be used with standard impact sockets, tyre bead breakers, as well as in the removal of coal picks and other custom chisels. Safety features of the Slogging Hammer include a built-in hand-grip, which means there is no need for the operator’s hand to be near the impact zone, and an eye-bolt that prevents accidents when tightened in overhead working conditions. No heavy lifting is necessary, as only the shaft weight needs to be managed. This tool is usedeasily in confined spaces and in areas that are difficult to access. The Slogging Hammer provides greater direct impact, en- suring that the job is completed quickly and safely, with fewer blows thanwith conventional methods. q

BMG’s upgraded Slogging Hammer forms part of the company’s extensive range of tools and equipment.

August 2019 • MechChem Africa ¦ 13