MechChem Africa May 2019

Mech Chem MAY 2019 AFRICA

Member of WPIL SA Holdings Ltd

100% local manufacturing

Wastewater processing

Power generation

Petrochemicals

Leaders in pump innovation

This month: Electrocoating success for PE business

Moving targets for aviation MROs Why bother with failure analysis?

VSDs, magnetic bearings & modern refrigerants

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14

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Asset, maintenance and risk management 8 Why bother with failure analysis? MechChem Africa welcomes new columnist Tim J Carter, who will be presenting a quarterly column titled Failure and how to avoid it. Here he introduces failure analysis and why it offers value for money. 10 Assessing bearing condition using CF+ 12 Cost-effective maintenance free dust extraction solution 13 Latest in ultrasound technology from SDT Materials handling 14 FLSmidth doubles size of Supercenter in Delmas MechChem Africa reports on the opening of FLSmidth’s expanded Delmas Supercenter, along with the release of the company’s SAGwise™ process control solution for semi-autonomous grinding mills and its new cloud-connected Raptor cone crushing systems. 17 Mato makes its mark in belt cleaners 18 Chemical powders de-lumped with bulk conditioner 19 CDE unveils world’s first all-in-one wet processing system 20 Plant efficiency at risk without careful chute design 21 HPE offers McCloskey products for various applications Corrosion and coatings 22 Electrocoating success for PE-based family business MechChem Africa talks to Electrocoat MD, Angelique Adcock, about the process and the company’s business success. Heating, cooling, ventilation and air conditioning 24 VSDs, magnetic bearings and low GWP refrigerants Russell Hattingh of Johnson Controls highlights the advances driving innovation in the HVAC industry in the immediate future and how these come together in the most energy efficiency chiller in the world, the YORK YZ. 26 Optimising datacentre cooling Veolia Water Technologies, which has been behind some of southern Africa’s most important and forward-thinking water and wastewater treatment plants, celebrates 20 years of business in South Africa this year with a renewed strategic focus. Special report 30 Cummins launches state-of-the-art premises at Waterfall To ‘Challenge the Impossible’ was the theme when Cummins SouthernAfrica recently launched its state-of-the-art premises in the Waterfall Logistics Precinct in Waterfall City, Gauteng. Innovative engineering 34 Moving targets for aviation MROs Mark Martin of Swedish software solutions provider, IFS,unpacks developments to help fleet management and maintenance companies in the aviation industry to succeed. REGULARS 2 Comment: The environment crisis demands a response 4 On the cover: APE Pumps: submersible and fire suppression pumping solutions APE Pumps adds submersible dewatering and fire suppression pumps to its local offering. 6 SAIChE News: Project risk management and compliance 32 Product and industry news 36 Back page: I4.0 partnership between MESA and AAF Water and wastewater processing 28 20 years in SA and future Ambitions for Africa

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

Published monthly by Crown Publications cc 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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Front cover: APE Pumps Contact: John Montgomery +27 11 824 4810

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Publisher of the Year 2018 (Trade Publications)

May 2019 • MechChem Africa ¦ 1

The environment crisis demands a response

A s well as deadly attacks in New Zealand, Sri Lanka and now the USA, the past six weeks have seen the devastation of Cyclone Idai that hitMozambique andZimbabwe; floods andmudslides inKwaZulu-Natal killing 32people, and environmental protests across the globe. There have been more than 1 000 fatalities fol- lowing Cyclone Idai. Infrastructural damage across Mozambique, Zimbabwe, Madagascar and Malawi is being estimated to be at least US$1-billion. In the area aroundBeira, buildings havebeen submergedand severely damaged; none of Beira’s health centres re- mained functional; and cholera has become a problem due to extensive damage to thewater supply network. While cyclones are not uncommon in the region, how frightening is it that their increasing severitymay be linked to climate change? Over the Easter weekend, Extinction Rebellion protesters in France, Australia, NewZealand, Finland, Sweden, Norway, Italy, the Netherlands, the UK and other countries lay across the ground to simulate deathandgluedthemselvestotrainstodemanddrastic action to avert environmental collapse. Sympathy for the movement was enhanced by the release of David Attenborough’s very bleak climate change documen- tary. The broadcaster says conditions have changed considerably faster than he ever imagined when he first started talking about the environment 20 years ago. “Climate change is humanity’s greatest threat in thousands of years”, potentially leading to the “collapse ofcivilisationsandtheextinctionofmuchofthenatural world,” he said. The world’s attention has also been drawn to a 16-year-old Swedish climate activist, GretaThunberg, who is criticising the inane responseof theworld’s poli- ticians to climate change. “Our house is on fire.We are facing a disaster of unspoken sufferings for enormous numbers of people and now is not the time for speak- ing politely or focusing on what we can or cannot say. Now is the time to speak clearly,” she says. “Solving the climate crisis is the greatest and most complex challenge that Homo sapiens have ever faced. Themain solution, however, is so simple that even a small child can understand it. We have to stop our emissions of greenhouse gases,” she adds. Thunberg accuses the UK government of “very creative carbon accounting” in claiming that its green- house gas emissions have fallen by 37% since 1990. She told MPs in Westminster that the true reduction was more like 10%, because the 37% figure excludes

emissions from international aviation, shipping and imports. The UK’s Department for Business, Energy and Industrial Strategy (BEIS) counters by saying “the UK follows the agreed international approach for esti- mating and reporting greenhouse gas emissions under theUNFrameworkConventiononClimateChangeand the Kyoto Protocol”. Opposition politicians in the UK are trying to respond to the Extinction Rebellion and Thunberg. The Labour Party’s Jeremy Corbyn is calling on the government to become the first national legislature to declare a climate emergency, calling the wave of protests “a necessary wake-up call” that demanded “dramatic action”. Similarly in Scotland, First Minister NicolaSturgeonfromtheScottishNationalParty(SNP) has declared a ‘climate emergency’ in her speech to the SNP conference, telling delegates that she “was inspired” by the young climate change activists. But the global response remains limp. As a result of theKZNstorms, the coastline around theUmgeni River mouthwas covered in plastic debris that got washed downstream with the flood waters, triggering several organisations to mobilise people to assist in clean-ups. “The current situation is just the tip of the iceberg, said Hanno Langenhoven, strategic manager for recycling at the Wild Trust. “What we’re currently facing on the beaches is a result of a much, much bigger waste management and pollution prob- lem upriver, where smaller and poorer communities are not serviced, hence waste – especially plastic – is literally just dumped everywhere. During the course of the year it builds up into river systems andwhenwe do have a bigweather event, the river takes it down to the beach,” he said. Having banned the use of non-biodegradable polythene bags some 10 years ago, Africa’s Ruanda has established itself as one of the world’s cleanest nations. Businesses have made the transition to using paper as an alternative and, instead of providing tax incentives to companies that manufactured plastic bags, authorities encouraged them to recycle, which has createda newmarket for environmentally friendly bags that did not exist prior to the ban. The environmental problems facing the world are multi-faceted and complex. What is clear, however, is that future generations will be saddled with the enormous cost of our current neglect. AsThunbergpointsout,humanityisatacrossroads: “We must decide which path we want to take.” Her views demand a response, from all of us. q

Peter Middleton

MechChem Africa is endorsed by:

2 ¦ MechChem Africa • May 2019

A leader in fluid control solutions for the past 67 years, APE Pumps is extending its market penetration into new sectors by adding submersible dewatering and fire suppression pumps to its local offering. APE Pumps: submersible and fire suppression pumping solutions

A PE Pumps has expanded its local line-up with the introduction of a series of submersible pumps tar- geting key sectors, which include the water and wastewater markets, mine and dam dewatering and irrigation. Depend- ing on the application, capacities range up to 50 000 m 3 /h and pumps are available with either dry or wet motors. Manufactured within the APE group of companies, theseproducts havea longhistory of successful utilisation on key installations worldwide and come to market in either horizontal or vertical configurations. Three key submersible categories are: • The M, G andWQDWS dewatering pump

series, providingflowrates up to1000m 3 /h andheads up to 100 m. • TheMS sewage pump series, providing flowrates up to 6 000 m 3 /h and heads up to 70 m. • High-capacitymodelsprovidingflowvolumesup to 50 000 m 3 /h at heads up to 25 m. “A key benefit of submersible pumps is their smaller footprint, which enables engineers to de- velop more efficient installations. Examples in the

municipal field include sewage pump stations, where our pump designs achieve optimal flows andheads,” says John Montgomery, general manager, APE Pumps. The APE group of companies has extensive experience in assisting clients

with the design and equipping of rawwater systems,boosterpumps,

A key advantage of horizontal split-case-type centrifugal pumps is that they are relatively simple to operate and repair.

drainage and sew- age stations and piped water schemes. A classic example is

the revamping of the infrastructure for the Blantyre Water Board in Malawi, which was completed as a joint venture between WPIL and APE Pumps. This turnkey high-pressure pumping solution for the BlantyreWater Board is currently pumping drinking water from a water treatment plant 26 km away into distribution centre reservoirs and then a further 13 km into Blantyre. APE Pumps is currently ranked as a 7ME contractor in terms of the Construction IndustryDevelopment Boardgrading system.

Working within the group, capabilities extend from concept to commissioning. This includes hydraulic systemanalysis and pump selection;

mechanical piping and equip- ment layout; instrumenta- tion; and electrical, civil and structural engineering. “Adding submersibles to our existing offering is an exciting development, which opens up a new world of op- portunities,”Montgomery says.

Fire suppression solutions from Audoli & Bertola

Water volume and pump speed delivery are two of the most critical factorswhenitcomestode- signing fire suppression systems,

Submersible categories now on offer from APE Pumps include: the M, G and WQDWS dewatering pump series, providing flow rates up to 1 000 m 3 /h and heads up to 100 m; the MS sewage pump series, providing flow rates up to 6 000 m 3 /h and heads up to 70 m; and high-capacity models providing flow volumes up to 50 000 m 3 /h at heads of up to 25 m

4 ¦ MechChem Africa • May 2019

⎪ Cover story ⎪

an area inwhich the APE group of companies Gruppo Aturia delivers, with its Audoli & Bertola product line. These products comply withEN12845 for thedesign, installationand maintenanceof fixedfirefighting systems and automatic sprinkler systems; EN 12259-12 for the pump components required for fire- fighting sprinkler and water spray systems; and theNFPA20 standard for the Installation of stationary fire protection pumps. Audoli & Bertola also has the distinction of being the only Italian pump manufacturer to have obtained Factory Mutual (FM) sys- tem approval for its diesel-driven vertical turbine and split-case horizontal pumps. This well-known international brand is available locally via its fellowAPE group of companies, APE Pumps and Mather+Platt, both based in Germiston, Gauteng. “These pumps meet every conceivable application, fromhigh-risebuild- ings to petrochemical plants, and the set-ups canbe customdesigned to meet specific site requirements,” explains Montgomery. As well as providing standard OEM solutions, APE Pumps and Mather+Platt specialise in once-off pump designs. APE Pumps’ grading as a CIDB 7 ME contractor also enables the company to execute turnkey installations. Audoli & Bertola’s vertical pumps range in capacity from 1 900 ℓ /minute to 15 200 ℓ / minute at 50Hz and 60Hz; and the split-case series from2850 ℓ /minute to7600 ℓ /minute at 50Hz and 60Hz. These can be powered by diesel, electric or gas engines. All pumps are certified to deliver 150% of the nominal flow

The Wadeville manufacturing facilities of APE Pumps South Africa.

At its Wadeville facility in Gauteng, South Africa, APE Pumps has the capability to make engineering design and pattern changes prior to casting.

ing armof international insurance carrier, FM Global.FM-approvedproductshavebeensuc- cessfully tested tomake sure they conformto the highest standards of safety and property loss prevention. For electric drive systems, FM-approved pumps must be used with a vertical electric motor; while for gas or diesel driven fire pumps, they must be connected to an FM- approved engine through an FM-certified, right-angle gear drive. “We believe our innovative design and manufacturing capabilities place us at the heartofAfrica,withturnkeysolutionsformin- ing, water and wastewater facilities, power generation, fire suppression and for Africa’s burgeoning oil and gas and petrochemical industries,” Montgomery concludes. q

at no less than 65% of head at the working point. Designs ensure that the shut-off head does not exceed 140% of the rated head. A key advantage of Audoli & Bertola’s horizontal split-case-type centrifugal fire pumps is that they are relatively simple to operate and repair. “They are well suited for applicationswherewater supply is obtainable under a positive head,” says Montgomery. FM Approval and vertical designs Turbine-type centrifugal fire pumps have submerged impellers contained in a series bowl assembly at the bottom of a vertical shaft. They are FM approved for discharg- ing water from lakes, streams, open sumps, drilledwells and other equivalent subsurface sources.FMApprovalistheindependenttest-

Audoli & Bertola

is the only Italian pump manufacturer to have obtained Factory

Mutual (FM) system approval for its diesel-driven vertical turbine and split-case horizontal pumps.

May 2019 • MechChem Africa ¦ 5

Brad Williams of EnviroPlus Design, which focuses on compliance and risk management services, has an MSc in chemical engineering, is a registered Charted Engineer and an active member of SAIChe and SAIMM. Here he highlights the importance of and processes involved in effective risk management and compliance. Project risk management and compliance

W hat is meant by project risk andcompliance?Havingspent 20 years in a project environ- ment, either doing process engineering work or managing projects, I’ve realised that every decision taken within a project carries an element of uncertainty that needs to be guided by some sort of policy. In certain instances the level of uncertainty is small, and clear policy guidelines are in place. It’s the inverse of these instances that generate unwanted anxiety forwhich the use of risk management methodologies offers some comfort. I’moftenaskedatwhat stage in theproject timelineone shouldapplya specificmethodol- ogy, so for that reason this articlewill focus on this aspect, rather thanelaborateon themany and varied methodologies that exist. Firstly,let’sthinkaboutcompliance.Thisisa bigword,sometimesbrandishedaboutlikethe swordofDamocles, butwhat does itmean in a project situation? Let’s start byaskinga simple question. Which side of the road do you drive on? One quickly realises that by following the country policy, drivers get along with fewer risks of accidents. Compliance is the result of adhering to an accepted policy or set of guide- lines. One may ask if no policy exists, can one still comply? From experience I’ve found that the only way to deal with this circumstance is to gather the affected parties and come to an agreement on a policy to be followed, in order to achieve a particular outcome. On a daily basiswe are exposed to policies and guidelines, someofwhich governmuchof what we do. Some examples are: • The company: dress code, working hours, presentation of financial results, etc. • The environment: emission limits, noise, etc. • Safety: Occupational Health and Safety Act and others. The Occupational Health and Safety Act

(OHSA) and Mines Health and Safety Act (MHSA) provide good basic requirements for workplace safety. They also provide mecha- nisms for recording and reporting incidents in the workplace. Now having these policies in place is usu- allynot enough toensure a successful project. This is because situations or design issues may arise that require special precautions to ensure safety of operations, protection of equipment or minimal environmental expo- sure. Situations where the risk of the expo- sure to an undesirable outcome is uncertain need to be thought about in greater detail to ensure compliance. This in turn gives rise to risk management techniques where the systematic approach can be represented by the flow chart shown in Figure 1. These techniques have been found to be useful in the following circumstances: • The introduction of new or novel technology. • Sensitive political, legal, social, environ- mental, contractual or safety issues. The overall project timeline usually defines the stages at which different kinds of risk assessment become relevant. There are many risk scenarios that can beset a project, notwithstanding these, the principle areas of focus would be, in no particular order: 1. Projectcost:Identifythedriversofthisrisk and have a contingency plan. 2. Project timeline: Interrogate the sequence of events andwhat drives the critical path. 3. Quality of supply and workmanship: clearly defined specifications and QCP management. 4. Conformance: Can the work be done safely, with managed environmental im- pact and within the ambit of the law. I’ve consolidated the above along a typical project timeline, indicating the timing and emphasis that is placed on the type of risk as a project proceeds. This is by no means

exhaustive, but should act as a guideline to a more complex subject. A summary table showing how this can be achieved is shown inFigure2. Some notewor- thy points include: • A considerable degree of effort is ex- pended before the start of the detailed design phase. Much of this effort focuses on ‘external’ risks to the project. • Project closeout not only deals with de- mobilising the project team and handing over to the client any ongoing contractual obligations,butalsotheconveningofa ‘les- sons learned’ session, where key risks that arose during execution are discussed and documented. These ‘incidents’ are then comparedwith company targets: lost time injuries, no fatalities and other execution monitored statistics, for example. • A number of risk assessment methodolo- gies are available. The need (or not) for a particular assessment will be identified by conducting the Hazop 1 to 6 as a starting point. • The lifecycle of a process plant is differ- ent to a project. In the case of a plant, the risks associated with decommissioning, dismantling and restoring the site need to be considered. It is important to bear in mind that the ap- plication of aRiskManagementmethodology will not remove all risk from a project. Its principle aim is to ensure that risks are identi- fied and mitigated effectively. An acceptable mitigation is sometimes an iterative process as indicated by the reverse arrows in the il- lustrationof Figure1. It is also imperative that by applying the risk management techniques early in the conceptual and design stages of a project, the greater opportunity exists for elimination of the risk altogether. q

Mitigate • Eliminate • Manage • Protect

Evaluate mitigation against policy criteria

Implement, Document & Operational Reassessment

Identify Risk Scenario

Analyse & Assess Risk

 

 





Figure 1: A flow chart showing how risk management can be systematically applied.

6 ¦ MechChem Africa • May 2019

⎪ SAIChE IChemE news ⎪

Stage

High level focus

Achievable outcome

Key risks considered

Methodologies and reporting

Conceptual: 0-10% of design work

Conceptual work based on assumed throughput or output. Previous drawings, flow diagrams, historical data often utilised.

Order-of-magnitude estimate often adequate to reject a development but not to prove viability. Used to evaluate alternatives and to select option for further study. Estimate accuracy within +25% to - 15% relative to the base. Estimate used for pre-feasibility and for selecting technical options. Estimate in the accuracy range of +15% to - 5% used for feasibility and project acceptance, depending on the degree of risk. Design specifications drafted to include safety and environmental requirements; process flow diagrams, piping and instrumentation diagrams and electrical and control diagrams. This estimate provides detailed targets for construction costs. Labour work units define manpower requirements. Estimate accuracy is normally between 10% lower and 10% higher than the base estimate. Project control estimate used to forecast the likely project cost and as a cost management tool. A Procurement Operating Plan (POP) establishes the status of procurement activities.

Political Stability, Local Infrastructure, Social/Communities, Environmental, Permits, Power & Telecoms, Commodity Pricing, Overall Timeframes, Technology. As above plus: reserves, strategic risks, contracting skills, economic & financial issues, mergers, acquisitions and disposals, technology selection. As above plus: Health & Safety, Quality Management, Asset Management, Human Resources, Financial Management, IT Systems, Contracting and Contract administration, Detailed planning.

High level quantitative risk matrix. Risk register, determine external (country) par rating.

Preliminary: 10 to 30% of design work

Preliminary estimate of development cost. Bench scale metallurgical and material balance tests needed. General drawings prepared and major equipment sized. Feasibility estimate: a realistic assessment of a development cost. Requires pilot metallurgical test work and process flow diagrams to optimise material balance. General arrangement drawings prepared and all major equipment sized. Key equipment specification and key enquiries issued to several suppliers to supply costs. Control estimate made after approval of P&ID’s, flowsheets, block plans, specifications, equipment layouts, building configurations and site improvements. Essentially, further significant changes would constitute a change to the scope of work. engineering and design are essentially complete and construction activities have commenced. This estimate is normally between 5% lower and 5% higher than that of the base estimate. Change, Progress, Quality and Safety Management; Bringing plant into operation, and meeting Safety, Environmental, Quality and Performance requirements. A detailed re-defined estimate. Normally,

Review and update Quantitative Risk Matrix, HAZOP Level 1 Report; Updated Risk Register and rating.

Feasibility: 30 to 50% of design work

Hazop Level 2: Updated Quantitative Risk Matrix & report, Development of Cost Control plans. Simulation and Potential Fatal Flaws reports.

Detailed Design: 50 to 90% of design work

Adherence to Design Specifications and Codes, Environmental, Health and Safety Laws.

Hazop Level 3: an updated Risk Matrix. Design Plan Implementation and Cost Control Plans. FMECA (Failure, mode, effect, criticality analysis). Specialist Studies and Plans.

Procurement

Conformance of supplies with Design Specifications, Environmental, Health and Safety Laws.

Quality Control and Project Plan; Construction Hazard Assessment (HAZCON) and report; Quality, Progress and Safety Reports.

Fabrication, Installation and Commissioning

Expediting and quality control at the fabricator; Contractor Handover

Conforms to OHSA or MHSA, Environmental, Health and Safety Laws; Plant built to intended design and Hazop is incorporated; As-built installation is operable and safe. Company and legislative requirements satisfied? Health protection, emergency systems and equipment to monitor and protect the environment. Usually carried out 6 months to a year after handover to assess the effectiveness of measures taken in Hazop 5.

Safety Management Plan and Risk Assessments; Hazop Level 4 report and Commissioning Strategy.

Documentation; preparation for Performance Tests.

Handover and Close Out

Contract specified Performance Operational Period.

Baseline performance of plant and equipment. Start of warrantee period.

Hazop Level 5, Closeout and ‘Lessons Learned’ report.

Operation

Asset Return On Investment realised in a safe and in an environmentally acceptable way.

Sustainable operations.

Hazop Level 6. Ongoing safety and operational monitoring.

Figure 2: A summary table showing how risk and compliance management can be achieved.

May 2019 • MechChem Africa ¦ 7

Why bother with failure analysis?

MechChemAfrica welcomes new columnist Tim J Carter, who will be presenting a quarterly column titled Failure and how to avoid it . Here he introduces failure analysis and why it offers value for money.

O K, so the systemis brokenandhas to be repaired to restore produc- tion. Since the spares needed are imported, it’s going to be expen- sive and, if the parts needed are not in the stores as spares, it will take time. In addition, wehave thecostoftheactual repairitselfover and above the cost of the spares, and the cost ofproductionloss,whichcaneasilyexceedthe sum total of the rest. Sowhy add an additional cost of analysing the failure? Failure analysis is not a cheap undertaking. If it is suggested that such an exercise canbe carriedout cheaply, the result- ing report probablywon’t beworth the fee, no matter how small. An on-site examination is always a good place to start when it’s time to gather evi- dence, although the evidence may be ‘well distributed’ over the surrounding scenery in some of the more spectacular failures. Failure analysis frequently requires the use of complex equipment and tech- niques, such as scanning electronmicroscopy. Electron microscopes are neither cheap to install or operate. The costs of hiring one can be over R1 000 per hour, while using an up- to-date state-of-the-art instrumentmay cost a fewmillion Euros. Similarly, determination of the material of construction of the failed part – involving chemical analysis, mechanical testing and examination of the microstructure – is not cheap either. Like the SEM, these techniques use equipment that is expensive to install and operate, and theprocedures canbevery time- consuming for highly skilled and experienced

staff. Such people are hard to find and costly to keep. Examination of the fracture surface of the broken part, a technique known as ‘fractography’, requires specialist skills. I have known supposed failure analysts who simply comparetheappear- ance of the fracture

ing a mixture of ethanol vapour and ethylene gas. The leakdrewattention to itself by catch- ing fire, fortunately without significant col- lateral damageowing toanattentiveoperator with a fire extinguisher handy. The investigation was relatively simple in this case. Dismantling the joint showed that the cone ring hadbeen installedupside down, and a futile attempt made to seal the joint by over-tightening, destroying the sealing abil- ity of the system. A leak, even in a moderate pressure line carrying any gas will generate a charge of static electricity, and when the gas is flammable, the leak becomes self-igniting. More complex was a series of failures in a beverage can seamer, where themachine op- erates at a speed that makes direct observa- tion of the system in operation very difficult. The other problem was that, on failure, the speed of the machine effectively destroyed most of the components in the seamer head, leaving little evidence for the investigator to work with. It required the use of high-speed

with published images in the appropriate reference text-book, a method that will frequently lead directly up the garden path. The analyst needs to have a thorough under- standing of fracture mechanisms in order to determine which mechanism or mechanisms were responsible and what factors were involved in the initiation of failure. Sooner or later, those practicing the ‘com- parison’ method are sure to meet someone who works from first principles and under- stands fracture mechanisms, usually on the other side of the courtroom, and be made to look incompetent and foolish. Not to men- tion probably costing their client a great deal of money. Detailed knowledge of the normal opera- tion of the system and its history are neces- sary, which can then be compared with the fracture mechanism, leading towards what abnormal operation may have occurred. Let us consider a simple case, a leaking compression fitting on a small pipeline carry-

Tim J Carter After several years in private practice as a consulting engineer specialising in defect and failure analysis and materials selection, TimCarter joined ImpLabs inBenoni at the beginning of 2019. His career began in1962 as a trainee at Kirkstall Forge in Leeds, beforemoving toBradford University in 1966 as a technician. After graduating fromBrunel University in 1972, he joined the Research Division of High Duty Alloys in the UK, where he was employed as a metallurgist specialising in defect and failure analysis – testing airframe materials for the likes of Concorde and disk materials for the Rolls Royce RB-211 engine. He has since held positions as a part-time and honorary lecturer at the University of the Witwatersrand in the Department of Chemical and Metallurgical Engineering (2000-2006 and 2008-); a failure analyst and refurbishment manager for Executive Turbine in Lanseria (2003-2004); a specialist for the CSIR in the Failure Analysis Unit of the Manufacturing and Materials Technology Division (1994-2003); and head of metallurgy for Atlas Aircraft in Kempton Park (1988-1992). He has alsoworked for AECI and Iscor in South Africa andDarchem Engineering and Phoenix Tubeman in the UK. TimJ Carter has been a professional Member of the London-based Institute ofMaterials since 1984 andwas elected as a FellowMember in 2007. He is also registered as a chartered engineer with the Engineering Council in London. q

8 ¦ MechChem Africa • May 2019

⎪ Maintenance and asset management ⎪

cinematography tofindoutwhat was actually happening when the machine was in operation. We didn’tmanage to capture an actual failure, but the knowl- edge obtained led to a better understanding of the machine operation and resolution of the problem, which dropped subse- quent failure rates significantly. This is the real value of failure analysis. Failures in motor vehicles addanothersetofvariables,that of the driver and the witnesses. I have lost count of the number of times I have read the driver’s statement that the vehicle “was only travelling at 55-60kph”, but the vehicle, having hit a kerb, had had onewheel torn off. That just doesn’t happen in amodern, high performance vehicle, nor even in the ordinary family

Failure of a drum in a paper-making machine scattered debris far and wide.

hatch-back. It’s not always the case, drivers don’t necessarily lie. In one instance a bus driver, charged with twelve cases of culpable homicide when the bus he was driving rolled over, was exonerated when severe wear and corrosion was found in the steering linkage and demonstrated to the magistrate. The company responsible formaintenance, which was neither the owner nor the operator, had some awkward questions to answer, having signed the vehicle off as roadworthy only six weeks prior to the incident. In a similar case, following an incident involving several fatalities, examination of a number of supposedly ‘identical’ vehicles revealed that the layout of the instruments on the dash-board varied, leading to confu- sion for the driver. When he detected what he thought was brake failure and attempted to change to a lower gear, the vehicle’s com- puter systems, guarding against probable over-speeding of the engine, refused and left him in neutral. Disaster became inevitable. Sadly, the brakes were fully operational and catastrophe could have been averted. The authorities in this instance refused to release the data from the vehicle’s data recording system. We had to reconstruct the datafromtheon-boardcomputerscontrolling theengine, transmissionandbraking systems, all of which had non-volatile memory units. The driver’s sentence of five years was sus- pended on appeal for, as the judge said. “The man will live in his own prison for the rest of his life”. He never drove a bus again, though his employers were prepared to let him. He was given a desk job. Inanaircraft, analysing the causeof failure becomesamorepronouncedproblem.It’sone thing to sit in the safety of the laboratory and

The failed cone ring on the right with an unused exemplar on the left.

ity. “Ok,” said the manufacturer, “we’ll take it back to the factory and fix it.” The inspector quite rightly refused, saying: “You’re not flying that thing in my airspace, you’ll fix it right here!” So yes, failure analysis is costly. But it’s worth it. It stops problems coming back and it’s not as expensive as having to fix the same problem a second time. General George S Patton summed it up rather nicely. “I’m not paying for the same piece of real estate twice with my soldiers’ lives,” he said. There is no point in sitting back and waiting for the insurance company to carry out an investigation. Usually they won’t and they may even decline the claim for lack of a properly carried out investigation. Failure analysis is expensive, but the results are frequently well worth the cost, and certainly much cheaper than having to fix the same problem twice, an event which will, at the very least, get one crossed off the insurer’s Christmas card list. q

analyse failed components for days, weeks or evenmonths.Oneproblemtookmefouryears before I found evidence from a similar inci- dent, fortunately this time without fatalities, thoughwithaverylargebilltobeabletoprove the true cause of failure. Too late by then. It is quite another tobe thepilot facedwith a failure, who has only minutes or seconds to diagnose the problem, find the correct solu- tion and then apply it, all in a situation that is stressful and life-threatening. And yes, I’ve been there as the pilot in command of an aircraft. All right, it was a two-seat Cessna, not a Boeing with a hundred or more paying passengers, but I know what it feels like. In one case (not one of mine) the flight crew detected a severe vibration in one en- gine. Because of a confusing instrumentation system, they shut down thewrongengine. The aircraft crashed with loss of life. It did leave a newly delivered aircraft having a similar problem being grounded after post-delivery inspection by the local airworthiness author-

May 2019 • MechChem Africa ¦ 9

Fluke, which is represented in South Africa by Comtest, presents a white paper that explains the use of a newly developed Crest Factor Plus (CF+) Fluke 805 vibration meter. This removes the need for trending associated with using the traditional Crest Factor analysis. Assessing bearing condition using CF+

B earings ensure smoothmachine ro- tationwithminimumfriction, which saves energy, extends machine life and, on production lines, enhances final product quality. This makes them a criti- cal machine part. Even when maintained properly, bearings will sooner or laterwear out. So, the question isnotwhether abearing iswornout but rather when it will be. Knowingwhenmachine bear- ings need to be replaced enables operators to plan shutdowns, schedule personnel and order bearings more efficiently. Vibration testing Vibration testing is a proven technique for predicting bearing condition. The vibration sensors andmeasuring equipment are so sen- sitive that they detect even slight changes in bearingcondition.Broadlyspeaking,vibration testing canbedivided into twogroups: testing basedon frequencyanalysis and testingbased on ‘overall values’. Frequency analysis not only makes the bearing condition visible, but also shows exactly what is wrong with the bearing; and what type of defect is present inwhich part of the bearing. Overall values like those shown on theFluke805vibrationmeter indicate that something is wrong, without giving details about the nature of the defect or which bear- ing part is affected. This technique has the advantage of being fast and relatively simple with straightforward results, and adds the

possibility of automating bearing condition assessment.

The peak vibration value is an excellent measure of bearing condition - the more severe the defects, the higher the impact and the higher the response. However, to use this parameter, the ringing from the bearingmust be separated out from the much stronger vibrations that come fromthemachine. These stronger vibrations are caused by unbalance, misalignment or looseness. Thebearingvibra- tions are therefore filtered to frequencies between 4.0 kHz to 20 kHz by a bandpass filter. The machine vibrations are filtered to frequencies between10Hz to1.0kHz andare measured to obtain results that can be com- pared to those in the Mechanical Vibration Standard, ISO 10816. The measurement techniques used so far (filtering and peak detection) are relatively simple, which is a great advantage since it keeps measurement equipment affordable. The disadvantage however becomes clear when the measurements are conducted at different rotational speeds - as the level of impact depends on the speed. So, a much better parameter than simply the peak value is the Crest Factor, since the Crest Factor cancels out the influence of speed. The Crest Factor is defined as the peak value divided by the rootmean square, which representstheenergycontentofthevibration signal. The higher the speed, the higher the RMS and peak values, so the ratio remains the same. If the bearing condition worsens, the Crest Factor will rise (Figure 4).

Bearing wear Even when perfectly installed and regularly maintained, bearings will develop defects as a result of fatigue. The main reason for this fatigue is the loadonboth the rollingelements (balls and rollers) and raceways, whichvary as the shaft rotates. The rolling elements and raceways are compressed in the load zone (Figure 1) and expand to their original form when leaving it. This alternating stress causes microscopic cracks under the surface, which later emerge on the surface as cracks, spalls and finally permanent brinelling damage. Other causes of defects are poor lubrica- tion,contamination,overloadfromoverspeed and high load, and shaft voltages. Shaft volt- ages are causedby buildupof electric charges at themotor shaft, with the discharge current going through the bearing to the ground. This causes pits in the rolling elements and fluted raceway surfaces (Figure 2). Bearing condition assessment Each time a rolling element passes a crack or spall it impacts on the bearing structure, whichwill start to resonateor ring (Figure3B). The same kindof ringing is heardwhen a clap­ per hits a bell. The resonances in the bearing structure have a frequency of between 4.0 kHz and 20 kHz.

Figure 1: Raceway and bearings compress and expand during every revolution.

Figure 3: A diagram showing how impacts affect vibration. Top: the impacts that excite the bearing structure. Centre: the response of the structure superimposed on other machine vibrations, one response amplified. Bottom: the machine vibrations filtered out.

Figure 2: A fluted bearing raceway.

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⎪ Maintenance and asset management ⎪

Figure 6: The CF+, which uses c1, c2 and c3 factors chosen so that the decreasing Crest Factor is counteracted by the increasing RMS value, increases linearly as the motor condition progresses from good to unacceptable. (CF+ = c1×RMS+c2×Peak+c3×CF).

speed. Figure 5 shows the disadvantage of Crest Factor. ACrest Factor of, for exam- ple, 5 couldmean the bearing is in good condition but it could also mean that it must be replaced at short notice. TheCrest Factor, therefore, only makes sense as a bearing condition parameter when it is trended, in order for the maintenance staff to know the exact bearing condition over time. The parameter Crest Factor plus (CF+) has been developed to remove the need for trending, and immedi- ately gives the condition of a bearing irrespective of the rotational speed. This parameter is similar to Crest Factor but is corrected to account for the increased number of peaks so that CF+ always increases as the bearing condition worsens (Figure 6). CF+ and automatic bearing assessment

Figure 4: The peak and RMS values as a bearing deteriorates (top to bottom).

Figure 7: The Fluke 805 screen shows bearing condition, overall machine vibration and temperature measured simultaneously.

The formula for CF+ uses c1, c2 and c3 factors chosen so the de- creasing Crest Factor is counteracted by the increasing RMS value. Fluke 805 instruments use this factor to automatically assess the bearing condition (Figure 6). Fluke 805 and Fluke 805 FC Besides measuring overall machine vibration, both Fluke 805 and Fluke 805 FC (with Fluke Connect) automatically determine CF+ values (Figure 7). They therefore incorporate the advantages of Crest Factors, while eliminating the disadvantages. Like the Crest Factor itself,CF+canbeusedfortrending,butitalsogivesaunique,automated assessment of the bearing condition. The parameter is independent of rotational speed and bearing dimensions so this information is not needed to assess the bearing condition. Overall vibration, or the second parameter, is used for comparison to ISO standards and for trending. This parameter is expressed as velocity; an integration of the acceleration signal. A third parameter, temperature, is also measured simultaneously, which is useful for trending and as a ‘second opinion’ with respect to the bearing’s condition assessment. q

Figure 5: A summary of the Crest Factor behaviour as bearing wear increases, top: peak and RMS values with respect to bearing condition and, bottom: associated variation in the Crest Factor. The somewhat bumpy line on Figure 4 shows the bearing noise causedbydefault imperfections in thebearingparts. Thesearisemainly from the surface roughness of raceways and rolling elements and the waviness of the raceways. Poor lubrication will strengthen these ef- fects. Peak andRMS values are very close togetherwith aCrest Factor with typical values from 1 to 3. Figure 4 shows a defect that causes peaks. The peaks are so brief in time that the energy content tends to zero, so the RMS level remains the same as before. The Crest Factor therefore increases. In Figure 4, the number and severity of defects grows and the deterioration pro- cess gains momentum due to brinelling particles and debris that in turn cause defects. The number of peaks therefore grows and starts to contribute to the RMS level. In short, the Crest Factor starts to decrease again. The advantage of Crest Factor is that it is independent of rotational

May 2019 • MechChem Africa ¦ 11

The managing director of Tshwane-based RTS Africa Engineering, Ian Fraser, highlights the company’s spin filtration solutions for the removal of fine dust particles from motor control centres and critical mining equipment such as compressors. Cost-effective maintenance free dust extraction solution

director, IanFraser. It alsomakes them invalu- able for use in the mining industry, where at every stage of the process – blasting, loading, material handling and processing – dust is created. “The type of dust that one encounters on mines is usually from newly broken rock, compared to dust that one might encounter in domestic or urban environments. If looked at under amicroscope, minedust particles are more jagged or irregular-shaped, and thus far more abrasive,” continues Fraser. Conventional use of spin filters on mines has been as primary protection for compres- sorsincompressorrooms.Whilecompressors do have their own on-board filters, in a mine environment with high levels of dust, these filters can become clogged fairly rapidly. “Should dust permeate a compressor’s workings, it will combine with the oil to form a very effective grinding paste that will ruin

the compressor quickly. If this happens, the cost of compressor downtime – which could bring a mine to a halt – could be excessive,” Fraser adds. More recently, he observes that mines have been employing high-end electronics on the surface and underground to control equipment and systems.Metalliferous dust is particularlyharmful to sensitive IT-controlled systems and electronic controllers on large miningmachinery. Once again, whilemany of these systems might have their own second- ary filtration units, the installation of an RTS Africa spinfilterwill prevent equipment filters from being rapidly clogged up by the coarser airborne particles present. Recently, RTS Africa installed a large spin filter at a major platinum mine near Rustenburg. A key application that has emerged for spin filters is in the protection of variable speeddrives usingback channel cool-

O ften the simplest solutions are the best and leading engineering solutions provider RTS Africa’s inertial spinfilters areaverygood example of this universal truth in action. They employ a basic principle of physics very effec- tively, using a vortex to remove98%of all dust particles down to 15 μm, 93% of particulate matter above 10 μm and, for that which is above 5.0 μm, a spin filter will remove 80%of the airborne particles. “This makes RTS spin filters eminently suitable for filtering air supplied into motor control centres (MCCs) and transformer and control rooms,” explains RTSAfricamanaging

ing. This is the application at the platinum mine where the spin filter will be feeding fil- tered air at 64 000m³ an hour into a variable speed drive system. The mine’s engineers have specified that they want the intake air to the variable speed drives filtered down to onemicron, which is a particu- larly high standard of purity. “A further factor on this particular mine is that, in the immediateenvironment,there are significant amounts of SO 2 gas present, which is highly corrosive. RTS spin filters are made of high density polypro- pylene which is not affected by SO 2 . However, to prevent the ingress of this gas into the variable speed drive rooms, we will be fitting SO 2 absorb-

RTS Africa recently installed a large spin filter at a major platinummine near Rustenburg.

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⎪ Maintenance and asset management ⎪

ingmodules toour spinfilters. Thesemodules are packed with material which absorbs SO 2 very effectively,” Fraser explains. A further recent application of spin filters has been to protect large open-cast mining equipment such as drag lines and blast-hole drill rigs. A spin filter installed on this equip- ment is able to create a positive pressure inside theoperator cabs;whichkeepsdust out of the electrical control equipment, thereby extending equipment life and preventing expensive downtime. On mines, there is frequently great pressure to prioritise production, and main- tenance is sometimes a secondary consider- ation. RTS Africa’s inertial spin filters’ only moving part is an electric motor-driven fan which requires almost no maintenance. As the dust from a spin filter is removed by a cyclonic action that extracts and then ex- hausts it to the exterior, there are no filter elements which require replacement. Fraser explains that there have been spin filters on certain mines that have operated with mini- mal maintenance andwithout breakdown for more than 20 years. “The shortest life we have recorded for a spin filter was with one that was installed at a chrome mine,” he explains. Chrome dust is possibly one of the most aggressive airborne contaminantsanditerodesthepolypropylene be available to view at the African Utility Week conference and exhibition from the 14 to16 May 2019 at the Cape Town ICC. The SDT340, together with UAS4.0, is a cloud-connected condition monitoring solution that combines the power of ultra- sound, vibration, temperature and RPM in one diagnostic package. Ultrasound and vibration are the two most relevant indi- cators of asset condition, especially where the assessment of bearing and gear health are concerned. Measured with crystal clear clarity, both parameters use the SDT340’s focUS Mode, which is a new way to enhance the analysis of machines, especially gearboxes and slow speed mechanical assets. This allows rub- bing, scratching, impacting, gear meshing and reciprocating valves to be ‘seen’, all of which remain hidden at standard sample rates. The systemthereby avoids unplanned downtime as it allows for a deeper analysis of any hidden defects. The SDT340’s focUS Mode can capture long data samples with 32K, 64K, 128K or even256K resolution, so that defects canbe

A key application that has emerged for spin filters is in the protection of variable speed drives using back channel cooling.

vortex of a spin filter. “In spite of this, our spin filter module served the chrome mine in question for nine years before it needed replacement.” Fraser comments that themining industry is increasingly turning to theuseof spinfilters as a cost-effective dust extraction solution. “The mines like the fact that they are easy to install, their maintenance is minimal, they

are highly efficient and provide consistent, lengthy and trouble-free service,” he explains. “With mines facing increased cost pres- sures, the scourge of load-shedding and national power grid inconsistencies – as well as contending with ever more stringent envi- ronmental legislation – spin filters present a highly viable option to contain expenditure andincreaseprofitability,”Fraserconcludes. q

Latest in ultrasound technology from SDT M artec has announced the release of the SDT340 Ultrasound de- tector and UAS4.0, which will

found that other monitor- ing technologies simply cannot resolve. Data ac- quisition time is adjustable from a few seconds to up to 10 minutes and ultra- slow speed systems can be inspected, including machines that do not fully rotate. The internal stor- age capacity of 4.5+ GBs means never having to worry about memory or data storage cards. The larger colour dis- play works in split screen

The SDT340, together with UAS4.0, is a cloud-connected condition monitoring solution that combines the power of ultrasound, vibration, temperature and RPM.

adaptors allow data to flow seamlessly to UAS4.0 from other technologies, making it the central repository for asset condition information. WithMartec and SDT as trusted reliabil- ity solutionpartners, silos canbe removed to enableeffective teamwork.Martecprovides full ultrasound training in Southern Africa, and the next course, which includes dates for ISOCat 1UltrasoundandASNTCertified Level 1 training will take place from 2 to 5 September 2019. q www.martec.co.za

mode, so that historical measurements of the timewaveformspectrumcanbe recalled and displayed along with live recordings on a scalable x-y axis. UAS4.0 is a scalable, multi-technology, multi-platform software solution for man- aging and analysing the SDT340’s data. A stand-alone installation, a fully networkable serveroptionoracloud-hosteddatasolution can be chosen to monitor and protect the condition of assets. UAS4.0breaks down thewalls that previ- ously isolated reliability initiatives. Custom

May 2019 • MechChem Africa ¦ 13