SAME: Mar 2010

THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010 1

2 THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010

THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010 �

Will the first set at Medupi Power Station be com-missioned on due date in 2012? Eskom says it will. Credibility may throw some doubt on this. Eskom has told us to be ready for load shedding in the run-up to 2012. Industry that saw the supply problem arising and made representations to government to interconnect private cogen have been waiting for 3 years, and still no answer.

It will be interesting to see how Eskom will man-age the demand during the World Cup. If forecasts are on track, some extra 400 000 to 500 000 first-world type energy users will be adding to the winter load. Who is going to sacrifice consumption over this period?

Shortly, a NIASA initiative to produce a video for public consumption on an energy model for SA will be available to the public. This has been the sterling work of John Walmsley and a NIASA subcommit-tee and it will hopefully take an experienced look at the energy position and an approach will make sense in the future.

Slight stirringsEnergy policy of course includes hydrocarbons, and this area insofar as SA is concerned appears to also be a mystery to the observer. In 2005, after years of inactivity due to the licensing and royalty changes by government, the exploration off the west coast commenced. Business has been hoping for 5 years now that the African west coast oil exploration gear north of us would find expanded maintenance and servicing in Cape Town and Saldanha Bay. If you look closely and keep still, you may see some very slight stirrings taking place.

Without a plan the musical chairs of the shuffling elites will continue to wreak havoc with our infra-structure, ably assisted by a poor level of governance across the board.

Chris ReayChairman of the Working

Committee: Communications(SA Institution of Mechanical

Engineering)

AN ENGINEER’S VIEW

C itizens have a right to be in-formed on some fundamental policies and plans that affect them both as citizens and as

business persons. Let’s take a look at the Planning Commission that was introduced after the last elections.

Seen or heard anything yet? Manuel and Co have been heard to be considering choosing the members of the commission. Amazing progress after nearly a year.

Well, as an Engineer in SA I am very concerned about the state of the energy industry and what appears to be a complete lack of an energy policy, and if it does exist, then the communication of that is ap-palling. What is going on with the topic of nuclear power? One minute we see the effective demise of the PBMR project with a shrinkage policy of 75% of specialised 800 employees, the option of a PWR station, which was on and then off and maybe on again, a maybe to resurrect uranium enrichment, no stated policy on cogen and renewables intercon-nection and a NERSA sop to the Eskom created funding mess. Then there is the Act that governs the Regional Electricity Distributors or REDS.

If a track existsCan anyone actually determine what they have achieved so far, and are they on track if a track exists, and if so when will that happen, and whose engineering resources will they employ to take over distribution, connections and maintenance, and will they be friends or enemies of the municipalities and Eskom whose roles they are going to replace?

So what does Mr. Citizen/ Businessman make of all this? It’s a mess whatever way you look at it and no-one in government can convince me otherwise. Talk is cheap: where is the action?

Energy Policy? What Energy Policy?The Dinokeng Scenarios paint a number of likely outcomes that depend on the in-

put criteria we follow at present. The worst case is characterised by the practice of “shuffling of the elites”, Ministers who simply cannot get their acts together. Time it seems does not matter in the life of ministerial decision making. Leadership is

seriously lacking, skills and experience to run a ministry appear not be required, all that is needed are political connections and a score card of past freedom fighting.

It’s a mess whatever way you look at it and no-one in government can convince me otherwise

� THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010


Monthly Column8 Don’t Drink and Die

Cover Story11 Giants in Pressure Parts

Power Transmission13 Chain Reaction15 Endurance Calculations for Bearings

POWER GENERATION TODAY23 To Our Shores25 About the AP100026 Power Generation News

Produced by:PROMECH PUBLISHING,P O Box 373, Pinegowrie, 2123Republic of South AfricaTel: (011) 781-1401, Fax: (011) 781-1403Email: [email protected]: www.promech.co.zaManaging Editor Susan CustersEditor Kowie HammanAdvertising Pauline BouwerCirculation Catherine MacdivaDTP Zinobia Docrat/Sanette LehanieDisclaimerPROMECH Publishing and The South African Institution of Mechanical Engineering as well as any other body do not take responsibility for the opinions expressed by individuals.Printed by: Typo Colour Printing, Tel: (011) 402-3468/9

Official Publication ofTHE SA INSTITUTION OF MECHANICAL ENGINEERINGand endorsed by:

CORROSION INSTITUTE OF SA SA PUMP MANUFACTURERS ASSOCIATION SA VALVE AND ACTUATORS MANUFACTURERS ASSOCIATION THE SA INSTITUTE OF TRIBOLOGY NUCLEAR INSTITUTE SA INSTITUTE FOR NON-DESTRUCTIVE TESTING NATIONAL SOCIETY OF BLACK ENGINEERS INSTITUTE FOR CERTIFICATED MECHANICAL AND ELECTRICAL ENGINEERS SOUTH AFRICAN ASSOCIATION OF CONSULTING ENGINEERS ASSOCIATION OF SOCIETIES FOR OCCUPATIONAL SAFETY AND HEALTH

Hydraulics & Pneumatics29 Know What You Sell32 Bigger is Better

Mills35 Cost-effective Milling

Regulars3 An Engineer’s View6 Institution News19 SAIT28 Nuclear Institute (SA Branch)39 Market Forum46 On the Move

Contents

The monthly circulation is 4 242

CopyrightAll rights reserved. No editorial matter published in “SA Mechani-cal Engineer” may be reproduced in any form or language without written permission of the publish-ers. While every effort is made to ensure accurate reproduction, the editor, authors, publishers and their employees or agents shall not be responsible or in any way liable for any errors, omissions or inaccuracies in the publication, whether arising from negligence or otherwise or for any consequences arising therefrom. The inclusion or exclusion of any product does not mean that the publisher or editorial board advocates or rejects its use either generally or in any particular field or fields.

March 2010 VOLUME 60 NUMBER �

Featured on the Cover

Steinmüller

Tel: (011) 806-3000

Fax: (011) 806-3330

Email: [email protected]


THE SA INSTITUTION OF MECHANICAL ENGINEERING

Council 2009/2010

Office BearersPresident .......................... . . . . . . . . . . . . . . . . . . . . . . . . G Barbic (George)President Elect ........................... . . . . . . . . . . . . . . . ... D Findeis (Dirk)National Treasurer ................................. K Nyangoni (Kudzai)

Branch ChairpersonsCentral ..................................... . . . . . . . . . . . . . . . . . M Cramer (Mike)Eastern Cape ............................. Prof Dr DG Hattingh (Danie)KwaZulu/Natal ........................................... AG Fileczki (Alex)Western Cape ........ . . . . . . . . . . . . . . . . . Prof B Collier-Reed (Brandon)

Portfolios:Communications .............................................. CD Reay (Chris)Education - Universities................... Prof JL van Niekerk (Wikus)Education: Universities of Technology............... E Zawilska (Ewa)Membership .................................................... E Zawilska (Ewa)Seminars and Workshops.................................. D Findeis (Dirk)Technology Programme ................................. SZ Hrabar (Steve)

Chief Executive Officer: Vaughan Rimbault

National Office Manager: Anisa Nanabhay PO Box �11, Bruma, 2026Tel: (011) 61�-�660, Fax: (011) �88-��6Email: [email protected] Website: www.saimeche.org.zaMembership: Central, Eastern Cape & KZN: [email protected] Membership: Western Cape: [email protected]

Company AffiliatesAinsworth Engineering (Pty) LtdAlstom Power Service SABabcock Africa LimitedBateman Engineered Technologies Fluor SAGEA Air-cooled SystemsHansen Transmissions SAHatch AfricaHowden PowerIndustrial Water CoolingMegchem Eng & Drafting ServicesOsborn Engineered Products SARotek Engineering RSD a division of DCD-DorbylS.A.M.E WaterSasol TechnologiesSEW Eurodrive Siemens LtdSNC-Lavalin SASpicer Axle SASpirax Sarco SAThyssenkrupp Engineering Transvaal Pressed Nuts & BoltsVital EngineeringWeir Warman AfricaWinder Controls

SAIMechE CEO Visits SecundaOn Wednesday, 17 February 2010, Vaughan Rimbault was hosted by Sa-sol Technology and Megchem at the Sasol Recreation Club in Secunda. Reaching far into their respective companies, the hosts were able to gather over 90 participants to the event. Following on an introductory safety talk on the new Pressure Equipment Regulations by Sasol Technology, Vaughan presented the gathering with information on ECSA, SAIMechE, the relationship between the bodies and implications for engineer-ing professionals.

Both Sastech and Megchem are Company Affiliates of SAIMechE, and their support of the Institution within their own ranks is to be commended. Both companies have indicated that the successful de-velopment of the profession should be driven by the Voluntary Associations, and have pledged their support to see this come to fruition.

---------------------------------------------------

SAIMechE Endorses Pneudrive Challenge“SAIMechE considers the PneuDrive Challenge to offer a valuable bridge between the theory and practice of mechanical engineering, and we are happy to extend our endorsement and sup-port of the challenge” says Vaughan Rimbault, CEO of SAIMechE. “Industry’s en-gineering human resources are provided via tertiary education institutions, and it makes good business sense for industry to be involved in the education process. Challenges of this kind can establish a useful platform for industry to influence the education of their future engineering resources.

Visit the Pneudrive Challenge website: www.pneudrive.co.za

News! News! News!

Vaughan Rimbault, CEO SAIMechE


Training Events Calendar - 2010Whilst every effort is made to ensure that events take place as scheduled, SAIMechE reserves the right to change the

sechedule as circumstances dictate. A registration form and full terms and conditions may be obtained from Carey Evans on email: [email protected] or Tel. (031) 764-7136. Detailed individual event programmes are available from Carey.

Corporations wishing to book In-House Workshops may contact Linda Robinson on email: [email protected] or Tel: (031) 764-7136.

Event Code

Full Title Date Region

D0310 Steam Distribution; Pipeline Ancillaries; Steam Flow Metering; Desuperheating 7-Apr-10 Vereeniging

A2110 The Management of Health & Safety Risks/Hazards 8-Apr-10 Durban

F0310 Steam Distribution; Pipeline Ancillaries; Steam Flow Metering; Desuperheating 14 to 15-Apr-10 Secunda

A3310 Stainless Steel - Complete Overview for Engineers Including Design with Stainless Steel 20-Apr-10 Durban

A3410 Aluminium - A Complete Overview for Engineers Including Design with Aluminium 21-Apr-10 Durban

C0310 Steam Distribution; Pipeline Ancillaries; Steam Flow Metering; Desuperheating 21 to 22-Apr-10 Cape Town

A3510 Plastics - A Complete Overview for Engineers Including Design with Plastics 22-Apr-10 Durban

F1310 Structured Problem Solving Techniques 28-Apr-10 Secunda

J0610 The Engineer As Manager 28-Apr-10 Pretoria

Geoff is a Pr Tech (Eng). He changed his employ-ment to that of Airconditioning draughtsman in Durban during 1957 and has remained directly involved with the Airconditioning Industry ever since. He uprooted for a stint with “Carrier” in Melbourne and Brisbane, before returning perma-nently to Durban.

Geoff became a roving nationwide ‘technical troubleshooter’ for his company, gaining consid-erable practical experience along the way. He headed a commissioning department for a number of years.

In the early 1970s, he was given a brief to con-duct regular technical training sessions within his company. He took it upon himself to always self-generate the material for use in the sessions, a principal from which he has never deviated. His employer sent Geoff on a 3-month overseas study period with companies in the US and France.

Since 1979, Geoff has been contributing regular technical articles to the various trade magazines covering the airconditioning industry in South Af-

Geoff Alder - Consultant, author, publisher and SAIMechE’s Refrigeration course developer

D3610 Project Management - A Review of Essentials 05-May-10 Vereeniging

A0410 Steam Trapping; Condensate Removal; Condensate Recovery 05-May-10 Durban

D4710 Capital Budgeting for Projects 06-May-10 Vereeniging

E2710 Philosopy of Mechanical Maintenance 12-May-10 East Rand

A2910 Practical Lubrication and Lubricants 13-May-10 Durban

D1310 Structured Problem Solving Techniques 19-May-10 Vereeniging

C3410 Aluminium - A Complete Overview for Engineers Including Design with Aluminium 26-May-10 Cape Town

F2910 Practical Lubrication and Lubricants 26-May-10 Rivonia

rica. His material is widely filed by readers as ‘technical resource material’.

In his earlier retirement years, he spent much time presenting In-house com-pany teaching for various companies in Durban and Cape Town, and latterly for SAIMechE.

Through his career, Geoff has presented numerous technical papers to meet-ings of the South African Institute of Refrigeration and Air Conditioning, including two at international confer-ences. He has published a book and much other technical material, and holds the Gold Medal of the South African Institute of Refrigeration and Air Conditioning (SAIRAC).

www.alder.co.za

THE SA INSTITUTION OF MECHANICAL ENGINEERING

Geoffrey Alder Developer & Presenter of “Refrigeration Explained”

Workshop & “Psychrometrics & Psychrometric Processes” Workshop


A policeman who can attest to this is super-intendent George Archer, commander of the SAPS dive school in Pretoria, who has sacrificed many of his public holidays in

his thirty years as a diver to go out and search for people who have drowned unnecessarily.

“SA Mechanical Engineer” speaks to him at the dive school in Pretoria where he has been training police divers for the past eighteen years. “Many drownings, especially over the festive season, long weekends and warm sunny days, could have been avoided if people had been wearing life jackets,” he says. “They load plenty of drink and food on the boat, but the last thing they think about is a life jacket.”

TasksRecovering bodies from watery graves is just one of the police diver’s grim tasks. Other times they do normal investigative detective work under water, searching for evidence, recovering vehicles from the water, assisting at boating events and searching for explosives under water for security purposes.

This is in addition to their normal duties as police-men because the divers in the SAPS are all volun-teers who have gone through a strenuous training course to become class IV commercial divers, the level that sport and professional commercial divers generally aspire to.

Training“Police diving and training is very different from sports and even navy diving, there’s a complete paradigm shift in our work,” says George. “A police diver, for instance, more often than not works in murky ‘black water’ where visibility is zero, so we have to learn to use our fingers as well as our eyes.

“Through touch, we are able to distinguish between a potato and a hand grenade under the water. In theory, a flashlight enables you to see in black water, but our divers often work in water where even a flashlight doesn’t help, so they have to use their bare hands to search for objects be it a gun, explosives or a body.”

Although there is sophisticated equipment such as side-scan sonar and multi-beam sonar detectors on the market, this is a luxury police divers can’t afford. George says “There are some technologies we can use to a limited extent, but ultimately it is up to the diver to do the job.”

Best momentThat this is a psychologically challenging job which

Don’t Drink and Die

Contrary to popular belief, brandy and water don’t always go well together, especially when you’re skippering a boat, yacht or canoe. Intoxication on the water may end up with

your body being recovered from the deep murky waters after drowning because drunken courage made you do silly things.

MONTHLY COLUMN

Superintendent George Archer, commander of the SAPS dive school in Pretoria

A police diver in clear water

Able to distinguish between a potato and a hand grenade under the water


requires special dedication leaves no doubt. In his thirty years of diving, George has only once in his life picked up something live from flooding waters. “It was during the Laingsburg floods. After three days of searching, I ended up on a small section of the roof of a house sticking out the water,” he recalls while suddenly picking at a speck of dust in his eye.

“As I pulled back a sheet of roofing, the light fell on a small swallow perched between the rafters and huddled next to it a kitten lifted its head. That moment will be with me forever.”

DangersPolice diving is dangerous and can also be scary. “The risk is compounded by the fact that it is dark and in the case of flooding, the water is moving in all directions all the time,” says George. “Once you’re down there, you are on your own and totally dependent on the training you’ve had regarding unex-pected eventualities. Because police divers are volunteers, they know the score, but you can never be prepared for everything that comes your way, and then we do get people who opt out after a while.

“Diving can be compared with parachuting,” adds George. “Under controlled conditions you can train the person for every even-tuality, but the moment the parachutists jumps out the plane, he’s on his own out there and may react differently from the way he was taught.

Safety record“The same applies to us. Will the driver remember the drill when he first loses a mask, or his line gets snagged? We simply don’t know as there’s always the human factor which means we can’t predict the behaviour of each person under certain conditions, it’s just too complex. However, the norm among our divers is that they’re mature enough to know when to pull out of a situation that will endanger their life.”

The SAPS divers have an impeccable safety record that has been recognised by the many international diving schools who’ve worked with them. “I am very proud of this track record and ascribe it to the dedication of our volunteers who often put their life on the line around the clock,” says George. “We work with the laws of physics and, unlike our constitution, they aren’t forgiving. If you step over the line, they’ll kill you.”

Respect natureThe three elements divers work with are personal limitations, equipment limitations and mother nature’s limitations.” Explains George, “If you

exceed your personal or equipment limitations, you’re pushing up the risk of injury. If you fail to comply with mother nature’s limitations such as barometric pressure laws, or any one of the other two, then you’re guaranteed to go to hospital. But,

MONTHLY COLUMN

Recovering an expensive boat

Recovering evidence in a suicide case

You can never be prepared for everything that comes your way


if you exceed all three, then you’re likely to end up paying with your life. This is what we hammer home in our training and probably the reason we have such a good track record in terms of safety.” “Our values service orientated team work, integrity, committment and quality also resonate from the dedication of our trainers to raise the bar of efficient

Too often fun on the water ends like this

MONTHLY COLUMN

service delivery at all levels witin the SAPS.”

In conclusion, George warns boaters who go out on the water while under the influence, not to do it. “The percentage of unnecessary drownings due to alcohol misuse is too high,” he says. “One way or another we’re going to meet and it’s sad that too often it is to haul your body from the water.”

George Archer, SAPS Dive School, Tel: (012) 353-9338, Email: [email protected]

When to pull out of a situation that will endanger their life


For almost 50 years Steinmüller Engineering Services has been raising the bar in boiler pressure parts for power generation – but

there is so much more to the firm

S teinmüller in South Africa is a well-known company specialising in, among others, the design, manufacture, construction and maintenance and spare part offerings in

pressure parts for boilers. Since its establish-ment in 1962, the Group has been providing a comprehensive range of technical, engineering, maintenance and project management services, as well as plant and equipment hire and various innovative technologies

Permanent presence“We have a permanent presence at around 11 power stations, where we maintain and optimise plant operations, extend plant life cycle or bring mothballed stations back into service. We have played a leading role in the highly successful de-mothballing Camden, Komati and Grootvlei power stations” says Business Development Consultant, Bob Stevens.

He attributes the growth in the company’s stature

to the long-term relationships such as the main-tenance contract with Eskom now in its eighth year and a ten year Mill and Feeder contract with petrochemical giant, Sasol.

Recent venturesThe most recent ventures by Steinmüller include a new factory that opened in July 2009 and has already expanded from the original 27 000 square metres to the present 55 000 square metres. The new facility is manufacturing boilers for the national power utility’s two new power stations, Medupi and Kusile.

“Manpower is up to over 800 already and we are bringing in an exciting new piece of kit, an induction bender system which will be used for bending HP piping,” adds Bob. Additionally, the group acquired KOG fabricators, a company specialising in low to medium pressure piping systems and the manufac-ture of the “Lisega” range of pipe supports as well as various stainless steel expansion bellows.

Conquer the marketThe current focus on pressure parts is a precursor to the next stage - the capability of working in the realm of high pressure feedwater heaters, which in turn will be followed by looking at pressure vessels. Steinmüller’s vision is to eventually conquer the 120 tonne pressure vessel market.

The company is clearly not short on ambition and

Giants in Pressure Parts

COVER STORY

Steinmüller’s vision is to eventually conquer the 120 tonne pressure vessel market


vision. Bob explains how this is expected to play out. “The key to the future is good management and skilled artisans. We run our own internal training programs at the EBS Academy as well as Eduardo Construction where we hone our artisan and technician skills. These facilities located in Bethal, Witbank and Pretoria are going full-bore to equip our artisans and graduates with the necessary skills and knowledge.”

Short supplySkilled staff is in short supply the world over, and according to Bob, Steinmüller spares no effort in looking after and keeping the best personnel. “We make a conscious effort to discuss the future of the company, where we intend going and where people would fit in. This is an ongoing process aimed at showing our people that the company is making progress and instilling in them the desire to move with it.”

But what are the individual departments of the firm and what do they do? Well, firstly, the Techni-cal Services Department, with a team of over 80

Spares no effort in looking after and keeping the best personnel

COVER STORY

Engineers equipped with core competencies such as the commissioning of new plants, re-commis-sioning of plants after outages or maintenance interventions and boiler and boiler auxiliary plant optimisation.

Many activitiesThe section’s other activities include providing process specialists to industry for due diligence, fault finding and root cause analysis of incidents or occurrences; the generating of technical documentation with focus on technical-, operating- and maintenance manuals; client interface for the development of new projects during technical assessments and feasibility studies; assistance with technical and financial analysis of projects or modifications on plant; maintenance engineering for plant shut down; management for maintenance and repair activities.

Tel: (011) 806-3000, Fax: (011) 806-3330, Email: [email protected]

THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010 1�

POWER TRANSMISSION

Sugar mills use such a chain in diffusers and it is an area where no chances should be taken with inferior components manufactured by fabricators who do not have experience

in the highly-specialised field of chain and compo-nent manufacturing. A sugar mill in Mozambique recently had this experience when the links supplied

to them from an ‘unknown’ source arrived on site with cracks which promptly started breaking after installation.

Saving the dayRoller Chain-Opti, a Durban-based Bearings Inter-national (BI) company, which specialises in sugar chain products throughout Africa, was called to the rescue. To learn how they saved the day, “SA Mechanical Engineer” speaks to Adrian Vorster,

power transmission director of Bearings International. “The speed with which branch manager Robin Blake and his team responded ensured that the wheels at the mill kept on turning,” he says. “They found that the cast inner and outer links on the 500 mm pitch chain were break-ing and needed to be replaced, and quickly, in time for crushing the sea-sonal crop.”

Chain of this type, however, is not an off-the-shelf item purchased in haste from the shop around the corner. “Usually chain of

this type is manufactured with forged links, but we couldn’t find a local company who could do the forgings within the time constraints,” explains Adrian.

“It was then decided to manufacture the inners and outers out of VRN 400 material locally. This involved profile cutting and then machining and boring the parts to specified tolerances. The two engineering companies who did this job for us deserve praise

Chain ReactionA chain is only as strong as its weakest link. Each link con-sists of several parts that have to be cast or forged and then

machined to precise quality-controlled tolerances.

The old chain that had to be replaced

Adrian Vorster of Bearings International

Not an off-the-shelf item purchased in haste from the shop around the corner

1� THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010

POWER TRANSMISSION

as they really pulled out all the stops to deliver a world-class product we could endorse.”

InstallationThe mill contracted Roller Chain Opti to do the installation of the replacement links as well. “This was a challenge in itself because the work had to be carried out on site with minimal disruption to their production schedule,” adds Adrian. “Robin and his team of subcontractors carried out the installation over a three-week period, installing thirty metres of chain at a time while the diffuser was still in operation.”

A test to destruction on a chain link

The hardening (dark area on the sides) of link material

The total length of chain that was changed came to 1 320 metres. Within the first week, produc-tion throughput returned to normal and the mill was back up to speed to produce 380 tonnes of crushed cane an hour.

Replacement linksAlthough Bearings International has been supplying imported chain for many years, Roller Chain Opti’s handling of this project has now paved the way for more projects of this nature to take place. And BI has been approached by several other mills around Africa for replacement links. “As we could not find a large enough press locally to forge 500mm pitch links, we’ve had to import. But even if we have to have the links made elsewhere, we make sure that the manufacturer has the right equipment and can produce a product within our specified tolerances,” says Adrian.

“We then undertake a local destruction test of the link plates to 2300 kilo-Newtons to make sure they’re strong enough before proceeding with a project and with the prior approval of our customers.

Hardening“The machining and induction hardening on the sliding surfaces of the link plates is also carried out under our supervision and has to be certified,” adds Adrian. “Similarly the bushes and pins are made of special materials that are manufactured to very specific tolerances.

“We’re working on a project now where we have to make use of an engineering company across the border because it will take too long to import and export the components. As it is our responsibility to deliver a quality product, we will strictly supervise the manufacturing process and have appointed a third party company close to the manufacturer to monitor the quality control on the project.”

AwardAlthough most mills are aware of the importance of only buying chain from reputable manufacturers, the temptation to go for the lower cost products on the market is always present. “We pride ourselves on providing a world-class product to the steadily growing sugar industry in Africa,” says Adrian.

“Whether the product is made locally or imported, we go to great lengths to ensure that our quality is on a par with the best there is. Roller Chain Opti has become specialists in chain solutions, not only for the sugar cane industry, but for all industrial chain such as bucket elevators, transmission chains, conveyor chains and many other chain applications. This was recognised recently when we received an award from the biggest sugar company in South Africa,” Adrian concludes proudly.

Robin Blake, Roller Chain Opti, Tel: (031) 468-5420, Email: [email protected]. Adrian Vorster, Bearings International, Tel: (011) 345-8000, Email: [email protected]. Frans Pienaar, Bearings International (011) 345-8000, Email: [email protected]

The temptation to go for the lower cost products on the market is always present


The industry turns to standardised life cal-culations for good reason: It is realistically impractical from a time and cost perspective to test the number of bearings for a specific

application and its operating conditions for required acceptable confidence.

A growing list of factors relevant for bearing life calculations have been integrated over the years in keeping with an increasing understanding about operating conditions and the related “system” influ-

ences of solid contamination, lubrication, operation regimes, internal stresses from mounting, residual stresses from hardening and other manufacturing processes, the material cleanness, matrix and fatigue stress limit, and others.

Predict more accuratelyThe evolution of standards has been to refine the life calculation methods to predict more accurately the actual life in a specific application, given cer-tain operating parameters: In other words, a closer match of the calculated life with the experienced service life. Recent scientific advances in bearing manufacturing, tribology, materials, end-user con-dition monitoring, and computation abilities have led to more sophisticated and accurate bearing life calculation possibilities.

In 2007, ISO (the International Organisation for Standardization) published a revised ISO-281

Standard further advancing the capabilities for life calculations by including a bearing

material’s fatigue stress limit and a fac-tor for the effect of solid contamination for different lubrication systems (such as grease, circulating oil, oil bath, and others) on bearing life.

In defining the term “life”, several types often will be referenced.

Attain or exceedA bearing’s basic life or its L10 (as defined

in ISO and ABMA standards) is based on the life that 90% of a sufficiently large

group of apparently identical bearings can be expected to attain or exceed. The median

or average life (sometimes called MTBF, or Mean Time Between Failure) is approximately

five times the calculated basic rating life.

Service life represents the actual life of a bearing in real operating conditions before it fails or is deemed necessary to be replaced for whatever reason. The specification life is generally a requisite L10 basic rating life and is grounded in a manufacturer’s experience with similar applications.

Getting startedBearing selection is usually based on bearing life and rolling contact fatigue models to predict the

Practical experience has shown that seemingly identical rolling bearings operating under identical conditions will not necessarily exhibit the same endurance life. Standardised life calculation methods help make educat-

ed choices about a bearing size’s suitability for a particular application.

Endurance Calculations for Bearings

POWER TRANSMISSION

Grounded in a manufacturer’s experience with similar applications


life. Therefore, selection of initial bearing size for an application normally starts by comparing its load ratings to the applied loads that generate fatigue, causing stresses with regard to the requirements for service life and reliability. Both dynamic and static bearing load conditions must be indepen-dently verified.

The basic dynamic load rating will be used for life calculations involving dynamically stressed bearings, such as those bearings that will rotate under load. This rating defined in ISO 281 expresses the bearing load that will provide a basic rating life (L10) of 1 million revolutions. Dynamic loads should be checked using a representative duty cycle or spectrum of load conditions on the bearing, including any peak (heavy) loads that may possibly occur.

Static loadThe basic static load rating applies to calculations when the bearings will rotate at speeds less than 10 rpm, become subjected to very slow oscillating movements, or will remain stationary under load during certain periods. Static loads are not only those applied with the bearing at rest or at very low rotational speeds, but should factor in the static safety of heavy shock loads (very short duration loads). Excessive static loads can compromise the integrity of a bearing by causing plastic deforma-tions on the contact surfaces.

The loads acting on a bearing can be calculated ac-cording to classical mechanics if the external forces are known or can be calculated. As examples, these external forces may include resultant forces from power transmission, shaft or housing supports, or inertia effects.

Sake of simplificationWhen calculating the load components for a single bearing, the shaft is assumed to be a beam resting on rigid, moment-free supports.

In basic catalog or simplified calculations, elastic deformations in the bearing, the housing, or the machine frame usually are not considered, nor are the moments produced in the bearing as a result of shaft deflection. Historically, standardised methods for calculating basic load ratings and equivalent bearing loads are grounded in similar assumptions for the sake of simplification.

Same influenceIf the calculated bearing load fulfills the require-ments for the basic dynamic load rating (meaning the load is constant in magnitude and direction and acts radially on a radial bearing or axially and centrically on a thrust bearing), then the load may be inserted directly into the life equations.

In all other cases, an equivalent dynamic bearing load should be ascertained. This is defined as the

hypothetical load (constant in magnitude and direc-tion and acting radially on radial bearings or axially on thrust bearings), which, if applied, would exert the same influence on bearing life as the actual loads to which the bearing is subjected.

Radial bearings often are subjected to simul-taneously acting radial and axial loads. If the resulting load is constant both in magnitude and direction, the equivalent dynamic bearing load can be obtained from the equation:

P = XFr + YFa

where

P = equivalent dynamic bearing load

Fr = actual radial bearing load

Fa = actual axial bearing load

X = radial load factor for the bearing

Y = axial load factor for the bearing

An additional axial load only influences the equivalent dynamic load P for a single row ra-dial bearing if the ratio Fa/Fr exceeds a certain limiting value. With double row radial bearings even light axial loads are significant.

The same general equation is also applied for spherical thrust bearings and other thrust types that can take both axial and radial loads. For thrust ball bearings and other types that can carry only purely axial loads, the equation can be simplified (P = Fa), provided the load acts centrically. For thrust bearings that sup-port both axial and radial loads, designs vary such that manufacturers’ catalogues need to be consulted.

Basic rating life equationThe calculation of bearing life has its roots back almost 60 years ago, when Gustaf Lundberg from Chalmers Institute of Technology and Arvid Palmgren from bearing company AB SKF applied the Weibull probability theory of fatigue to the calculation of rolling bearing life. Their fundamental assumptions and derivations in 1947 and 1952 regarding inter-nal load distribution, equivalent loads, and Weibull statistical distribution of bearing life form the basis for ANSI/ABMA and ISO life rating standards and most bearing manufacturers’ catalogues.

First adopted by ISO in 1962, the simplest method for bearing life calculation is represented by the ISO 281 or ABMA Standards 9 and 11 equation for basic non-adjusted rating life:

L10 = (C/P)p or C/P = L10 1/p

where

L10 = basic rating life, millions of revolutions

C = basic dynamic load rating

POWER TRANSMISSION

In practice, of course, the basic rating life may deviate significantly from the actual service life


POWER TRANSMISSION

corrosion, mounting damage, lubrication, or seal-ing systems.

Followed suitOver the years, science and bearing technology advances have resulted in improved designs and manufacturing processes to extend bearing life and reduce their sensitivity to severe operating condi-tions. Calculation methods have followed suit to predict service life more accurately. The ISO bearing rating and life calculation standard (ISO 281) has developed along with these advances as bearing manufacturers and users universally accepted and used newer technologies.

Examples of related progress are inclusion of a reliability factor to adjust life for those applications requiring higher reliability; a factor on life consider-ing the effects of lubricant and lubrication operat-ing conditions; increased load ratings accounting for better material properties and manufacturing processes; and, in 2000, recognition of a fatigue stress limit for bearing steels and the effects of solid contamination on bearing life.

Modified equationThe new revision to the ISO rating and life standard (ISO 281) offers a modified life equation along with agreed-upon calculation methods for high-quality bearings to supplement the basic rating life. This will account for the lubrication and contamination condition of the bearing and the fatigue limit of the material.

P = equivalent dynamic bearing load

p = exponent of the life equation

(p = 3 for ball bearings and p = 10/3 for roller bearings)

For bearings operating at constant speed it may be more convenient to deal with a basic rating life expressed in operating hours using the equation:

L10h = 1,000,000/60 n (C/P)p

or

L10h = 1,000,000/60 n L10

where

L10h = basic rating, operating hours

n = rotational speed (r/min)

As an application example, a deep groove ball bearing operating in an electric motor at 3,600 rpm is subjected to a radial load of 100 lbs. To calculate the L10h:

n = 3,600 rpm

P = 100 lbs.

C = 3,330 lbs. (from manufacturer’s catalogues or other supplied information)

p = 3 (for ball bearing)

Using these values and the “operating hours” equation, the basic life expressed in hours for the bearing in this case would be 166,375 hours.

Since individual bearing life can only be predicted statistically, it is especially important to consider that life calculations refer only to a bearing population and a given degree of reliability. The basic rating life L10 is associated with 90% reliability using bearings made from high-quality material, exhibit-ing good manufacturing quality, and performing in conventional operating conditions.

Deviate significantlyIn practice, of course, the basic rating life may deviate significantly from the actual service life in a given application. As an example, published results have shown that actual tested life can devi-ate from the basic rating life by a factor of nearly five times.

“Service life”, then, represents the actual life of a bearing in real operating conditions before it fails.

“Service life” further underscores that field failures can result from “root causes” instead of bearing fatigue. While the bearing is the victim and has failed, most times today it is the abnormal stresses in the bearing as a result of poor operating envi-ronments leading to the failure. Examples of root causes include contamination, wear, misalignment,

Can deviate from the basic rating life by a factor of nearly five times

While the individual bearing manufacturer should be consulted on the applicable specifics, the following new equation expresses modified life in operating hours (when speed is constant):

Lnm = a1aISOL10

where

Lnm = manufacturer’s rating life (at n% reliability), millions of revolutions (C/P)p

Lnmh = manufacturer’s rating life (at n% reliability) operating hours

L10 = basic rating life (at 90% reliability), millions of revolutions

a1 = life adjustment factor for reliability (1.0 for 90% reliability)

aISO = manufacturer’s life modification factor according to ISO 281

The determination of aISO involves the use of a contamination factor based on the lubrication system and cleanliness class of the lubricant system as defined in ISO 4406. Graphs for differ-ent cleanliness classes considering bearing size and lubrication operating conditions are provided. This contamination factor is then used along with the ratio of the bearing fatigue load limit to the bearing equivalent load limit and the lubrication condition to determine a life adjustment factor, aISO.


Generally, the better the lubrication condition and lower the equivalent load, the less sensitive a bearing will be to contamination levels. Conversely, the higher the load and the poorer the lubrication condition, the more sensitive bearing life is to contamination cleanliness level.

Advantages and cautionThe bearing life calculated according to the new methods (whether the new ISO 281 or similar meth-odology offered by individual bearing manufacturers) today greatly enhances a user’s ability to predict and ascertain the actual service life with known operating conditions to a much greater extent.

This leads to a variety of advantages:

• The possibility to downsize a bearing under good operating conditions to reduce friction, energy and weight.

• Select lubrication and filtration to maximise bear-ing and system life.

• Extend warranties or service intervals under con-trolled operating conditions.

• Ability to better evaluate the influence of operating parameters on specific bearing types and designs.

Some pitfallsBut life calculations do not come without pitfalls. Cautions include:

• The calculations are sensitive to operating condi-tions of load, temperature, lubrication condition and contamination. If improper operating conditions are used in conjunction with bearing selection it could lead to premature bearing problems.

• The methodology and calculations assume bearings are made according to modern designs, manufacturing processes, and bearing material specifications.

• The bearings are installed and maintained cor-rectly.

Input and support from experienced resources with demonstrated engineering expertise and bearing knowl-edge can serve users well for a bearing’s lifetime.

Daniel R Snyder PE, is Director, Applications Engineering for SKF Industrial Division, SKF USA Inc. E-mail: [email protected], Website: www.skfusa.comSKF South Africa (Pty) Ltd, Tel: (011) 821-3500, Fax: (011) 821-3501, Email: [email protected], www.skf.co.za

POWER TRANSMISSION

The possibility to downsize a bearing under good operating conditions to reduce friction, energy and weight

Log onto www.promech.co.za to read back issues of

“SA Mechanical Engineer”


THE SA INSTITUTE OF TRIBOLOGY

Are you Getting what You’re Paying For?

Obviously if the manufacturer is an ISO 9001 ac-credited company there can be some assurance that the blending is conducted consistently and correctly to the tested formulation and that the product is appropriately certified. Complete engine testing for these products is rather cumbersome and expensive, which opens the door for unscrupulous blenders of lubricants to make fancy packaging and labels claiming international performance standards on their products.

Due to the fact that the majority of the end us-ers in the automotive field are Joe Public and not familiar with these standards, comebacks on product performance against these suppliers would be limited.

It is time for action in this regard as the implemen-tation of the Consumer Protection Bill, later this year, will bring about interesting challenges with regard to compliance for the lubricant marketer and recourse from a consumer’s point of view.

Andrew Kirk, SAIT Committee MemberGill Fuller, Tel: (011) 802-5145, Fax: (011) 804-4972, Email: [email protected], www.sait.org.za

In South Africa we rely on the South African Bureau of Standards (SABS), who regulate and control the SANS (South African National Standards). These are developed in conjunc-

tion with the input from industry, interested and affected parties and their accredited bodies through the various technical committees. Standards are typically based on international standards and or best practices and are then adapted for the South African conditions and requirements.

These standards are regularly quoted on the prod-ucts in the South African lubricant market. There is however very little chance of testing these products completely against the quoted standards, due to the cost and complexity in doing so. So, this begs the question, how does the end user, ie, the consumer know that what they are getting?

Sure, the label and packaging might state that this product meets certain performance specifications such as API CH4/SJ, but how can the consumer be sure that this is indeed the case?



CopyrightAll rights reserved. No edi-torial matter published in “Power Generation Today” may be reproduced in any form or language without written permission of the publishers. While every effort is made to ensure accurate reproduction, the editor, au-thors, publishers and their employees or agents shall not be responsible or in any way liable for any errors, omissions or inaccuracies in the publication, whether arising from negligence or otherwise or for any conse-quences arising therefrom. The inclusion or exclusion of any product does not mean that the publisher or editorial board advocates or rejects its use either generally or in any particular field or fields.

Produced by:

PROMECH PUBLISHING,P O Box 373, Pinegowrie, 2123Republic of South AfricaTel: (011) 781-1401Fax: (011) 781-1403Email: [email protected]: www.promech.co.za

Managing Editor Susan CustersEditor Kowie HammanAdvertising Pauline BouwerCirculation Catherine MacdivaDTP Zinobia Docrat/Sanette Lehanie

DisclaimerPROMECH Publishing does not take responsibility for the opinions expressed by individuals.

Printed by: Typo Colour PrintingTel: (011) 402-3468/9

Introducing Our New Monthly SectionDo you remember when beneficiation was on everybody’s lips? Then it was all about globalisation followed shortly by skills training. I have seen ‘fashion’ come and go in the engineering field as well. Not that these issues aren’t always important, it’s just that one or the other takes turns at being centre stage. The new ‘fashion’ is energy efficiency.

When my colleagues and I debated the idea of starting this monthly Power Generation section, we wanted to be sure that energy efficiency and power generation would not be superseded by a more important focus. We came to the conclusion that energy is a commodity that is unlikely to reduce in cost. The opposite, in fact.

Whereas we were all guilty of wasting energy in the past, no reader has to be told about the huge increases in energy costs which are bearing down on us. So energy efficiency is very much a business imperative but it has the added bonus of conserving resources too.

Our new monthly section entitled “Power Generation Today” has great things in store for readers. In this issue, we kick off with the great news that South Africans will be part of Westinghouses’ international programme. Through the year, we will be discussing traditional sources such as coal and oil, we’ll also be talking about wind, tidal, natural gas, landfill gas, solar and molten salt energy among others.

Barry MacColl, Manager of Technology Strategy and Planning at Eskom has helped us to compile our list of topics and is championing this section together with the staff and readers of “SA Mechanical Engineer”. We are very fortunate to have such an experienced advisor on board.

As we tell all our reader and advertisers, there isn’t a single thing that moves in industry that hasn’t involved a mechanical engineer along the line. All of these technologies have needed or will need input from the mechanical engineering fraternity. We will be talking all things Power Generation, up until Power Distribution which we leave to the electricals.

I hope you will enjoy and benefit from our new venture. Please get in touch with us with criticisms,

comment and suggestions.

Yours sincerelySusan Custers, Managing Editor

Barry MacColl



They soon came across DCD-Dorbyl in Vereeniging and after carefully assessing each other, the two companies have just signed a (MOU) whereby DCD-Dorbyl has

the opportunity to become part of Westinghouse’s international supply chain for large fabricated components for the power stations being built.

“This MOU will allow the collaboration on work associated with bringing the AP1000 nuclear power plant to the global marketplace, potentially including the Republic of South Africa,” says Bob

Pearce, director of international customer projects at Westinghouse at the signing ceremony in Ver-eeniging.

The MOU between Westinghouse and DCD-Dorbyl covers areas such as design, production, fabrication and integration of AP1000 nuclear power plant modules, nuclear component manufacturing and supply chain development support.

PartnersThe agreement is a key milestone in a process that is expected to result in significant construction and

To Our Shores

POWER GENERATION

W e s t i n g h o u s e Electric Company has signed a memorandum of understanding (MOU) with DCD-Dorbyl in Vereeniging to help build six AP1000 modular nuclear power stations for the US and four for China. In order to fulfil its obligations on such a huge project, Westinghouse went in search of capable fabricators around the world for the highly specialised components.

One every five daysAcross the world, nuclear power generation is growing steadily. Last year, 15% of the world’s electricity came from nuclear power. According to the World Nuclear Association, during the 1980s, one new nuclear reactor started up every 17 days on average. By the year 2015, this rate could increase to one every five days.

America produces the most nuclear energy, at 19% of its total electricity supplied, while in France, this figure stands at 80%. In the European Union as a whole, nuclear energy provides 30% of the electricity with only a handful of countries such as Austria, Estonia, and Ireland having no active nuclear power stations at all.

Fourteen altogetherWestinghouse has a unique approach and a demonstrated track record in localising the supply chain for a new nuclear build. This approach is currently being implemented in China, where work is already underway on the first two of a series of four AP1000 plants being constructed there.

In addition to the four AP1000 plants that are under construction in China, Westinghouse and the AP1000 have been identified as the supplier and the technology of choice for no fewer than 14 plants that have been announced for construction in the United States, including six for which engineering, procurement and construction contracts have been signed.

Additionally, Westinghouse and China are currently discussing plans for additional AP1000 plants to be sited inland of China’s coastal areas.

Louise Taljaard and Bob Pearce after signing MOU

2� THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010

export opportunities for potential South African supply chain partners. A significant percentage of the work and services required to build any new AP1000 unit could come from the South African supply chain.

“We are absolutely delighted to be working with DCD-Dorbyl,” says Rita Bowser, Westinghouse regional vice president for South Africa. “This partnership is a vital component in our ambition to bring the AP1000 to South Africa as part of the government’s drive to have new nuclear capacity coupled with manufacturing localisation. It represents a significant step towards realising the major opportunity nuclear energy presents to South African businesses and its economy as a whole.”

Localisation idealsLouise Taljaard, managing director of DCD-Dorbyl, lauds the agreement signed between the two com-panies. “This is a wonderful opportunity for us to be associated with a world leader, such as Westinghouse, in the nuclear technology arena. We see the signing of this agreement as the first step in establishing this manufacturing technology and expertise in South Africa.

The DCD Dorbyl Group is a multi-faceted black economic empowered company, committed to serv-ing its diverse clients throughout the mining, rail, marine and metallurgical industries. With a uniquely holistic approach to business based on the measur-able criteria incorporating a scientific, engineered, quality-based, cost effective and flexible approach, the company has positioned itself as both a national and international engineering industry leader. Already, 85% of the company’s heavy engineering work is being exported.

PWRWestinghouse believes the AP1000 modular nuclear power station is ideally suited for the worldwide nuclear power marketplace. The AP1000 technol-ogy is based on standard Westinghouse pressurised water reactor (PWR) technology that has achieved more than 2 500 reactor years of highly successful operation. It is an 1100 MW design that is both ideal for providing base load generating capacity and is also modular in design, promoting ready standardisation and high construction quality.

The plant is economical to construct and maintain as it uses less concrete and steel and fewer components and systems which means there is less to install, inspect and maintain.

The plant is designed to promote ease of operation while still featuring the most advanced instrumenta-tion and control systems available in the industry. Westinghouse supplied the world’s first PWR in 1957 and today, the company’s technology is the basis for approximately one-half of the world’s operating nuclear plants, including 60 percent of those in the United States.

Sias Booysen, DCD-Dorbyl, Tel: (016) 428-0019, Email: [email protected]

POWER GENERATION


The technologyThe AP1000 is composed of components that incorporate many design improvements distilled from 50 years of successful operating nuclear power plant experience. The reactor vessel and internals, steam generator, fuel, and pressurizer designs are improved versions of those found in currently operating Westinghouse-designed PWRs. The reactor coolant pumps are canned-motor pumps, the type used in many other industrial applications where reliability and long life are paramount requirements.

Licensed passive safety systemsThe unique feature of the AP1000 is its use of natural forces - natural circulation, gravity, convec-tion and compressed gas - to operate in the highly unlikely event of an accident, rather than relying on operator actions and AC power. Even with no operator action and a complete loss of all on-site and off-site AC power, the AP1000 will safely shut down and remain cool.

Because natural forces are well understood and have worked as intended in large-scale testing, no demonstration plant is required. The Westinghouse advanced passive reactor design underwent the most thorough pre-construction licensing review ever conducted by the US NRC.

Large safety marginsThe AP1000 meets the US NRC deterministic-safety and probabilistic-risk criteria with large margins. The safety analysis is documented in the AP1000

Design Control Document (DCD) and Probabilistic Risk Assessment (PRA). Results of the PRA show a very low core damage frequency (CDF) that is 1/100 of the CDF of currently operating plants and 1/20 of the CDF deemed acceptable in the Utility Requirements Document for new, advanced reactor designs. It follows that the AP1000 also improves upon the probability of large release goals for advanced reactor designs in the event of a severe accident scenario to retain the molten core within the reactor vessel.

Unequalled safetyThe AP1000 pressurized water reactor is based on a simple concept: in the event of a design-basis accident, such as a main coolant-pipe break, the plant is designed to achieve and maintain safe shutdown condition without operator action, and without the need for ac power or pumps. Rather than relying on active components, such as diesel generators and pumps, the AP1000 relies on natural forces - gravity, natural circulation, and compressed gases - to keep the core and the containment from overheating.

The AP1000 provides multiple levels of defence for accident mitigation (defence-in-depth), resulting in extremely low core-damage probabilities while minimizing the occurrences of containment flood-ing, pressurization, and heat-up.

Defence-in-depth is integral to the AP1000 design, with a multitude of individual plant features includ-ing the selection of appropriate materials; quality assurance during design and construction; well-trained operators; and an advanced control system and plant design that provide substantial margins for plant operation before approaching safety limits. In addition to these protections.

About the AP1000

POWER GENERATION


Improving power plant efficiencyIn November 2009, power and automation technology group ABB won an $54 million order from Eskom, to provide electrical and automation solutions that will improve reliability and energy efficiency at three of its largest power plants.

As the turnkey contractor, ABB is responsible for the design, installation and commissioning of the electrical and au-

tomation equipment. ABB will also conduct a performance analysis and refurbishment of motors in the plants to boost efficiency and extend the service life of the thermal power stations, located in the north-east of the country. Each plant has six generating units and a combined capacity of about 4,000 megawatts.

“Energy-efficient generation can make a significant contribu-tion to our collective effort to reduce fuel consumption and lower carbon emissions,” said Peter Leupp, head of ABB’s

Compressed air systems “While pressure to use energy frugally is mounting, there are tremendous opportunities when it comes to energy saving,” says Philip Herselman, Atlas Copco Business Line Manager, Industrial Air Division. “To assist customers achieve maxi-mum production, we focus on reducing cost and eliminating production downtime.”

Says Philip, “Having a good understanding of the ur-gency of conserving energy, Atlas Copco has teamed up with a number of other manufacturers and suppliers of major energy consuming plant to offer ‘Seminars for Mining and Industrial Energy Efficiency and Energy Saving’.

The aim is to assist mining and industry to identify energy savings opportunities to be found in systems fitted with compressors, conveyors, drives, fans, mo-tors, and pumps, among others.

“Having the wrong, or poorly maintained, compressed air system adversely affects energy efficiency. By ad-dressing areas such as maintenance, leakages, pressure drops, control and design efficiency, for example, it is possible to reduce power consumption by at least 10%, which is in line with Eskom’s directive. This translates to 40% saving on the initial capital outlay.

“A 10mm diameter leak can result in as much as R100 000.00 in energy loss a year, a waste which can be easily prevented by regular monitoring and daily maintenance.” Inappropriate use of compressed air is also a source of unnecessary energy consump-tion. A centralised control and monitoring system and the elimination of operational inefficiencies will also reduce energy consumption.

Mechanical and electrical designs and the construc-tion methods of compressor and ancillaries have an effect on overall efficiency. Electrical design also has an influence as a high efficiency electric motor is a major part of the compressor unit.

Philip points out that through a holistic approach,

Peter Leupp, head of ABB’s Power Systems divisions

Power Systems divisions.

ABB will supply key equipment like dry-type transformers and energy-efficient variable-speed drives, as well as several other products for the plants. The drives will optimize the performance of boiler-feed water pumps that typically con-sume around 2.5% of the energy generated by a coal-fired power plant.

“Technology transfer has provided ABB in South Africa with the opportunity to gain further expertise in energy efficient technologies,” says Carlos Poñe, Chief Executive Officer, ABB in South Africa.

Shivani Chetram, Tel: (010) 202-5090, Email: [email protected], www.abb.com

POWER GENERATION NEWS


energy efficiency in any production plant can be boosted by up to 60%. “Changing technology, installing the correct and most efficient equipment and operating efficiently will make a vast difference to the energy bill.”

Atlas Copco South Africa Pty Ltd, Tel: (011) 821-9000, Fax: (011) 821-9106, www.atlascopco.co.za

Industrial. “Electrical back-up systems a necessity, not a luxury,” he says.

Engine Applications has an extensive product range that covers mobile and fixed diesel generators, static or rotary uninter-ruptible power supplies, switchboard and metering systems for generator sets, standby battery banks, die-sel driven pump sets, and remote monitoring systems and building management systems.

The company, which is fully BEE compliant, has already supplied power generation products to major organisations such

as Volvo Penta, Southern Africa’s mines, Natalspruit Hospital, Mamelodi Hospital, Maxidor, and Plascon, and has exported its products to many African states such as Ghana, Nigeria, Sierra Leone and the DRC.

Gerald Spaans, Engine Applications, Email: [email protected]

Engine Applications’ new Western Cape manager, Gerald Spaans, says electrical power back-up systems are now vital

Western Cape power generationEngine Applications Western Cape, a new branch of a 30-year-old Gauteng-based supplier of standby power to industrial, commercial, residential has begun operating in the Western Cape. The company, based in Gordons Bay, is headed by Gerald Spaans, formerly MD of the power generation company Spa

POWER GENERATION NEWS


NUCLEAR INSTITUTE (SA BRANCH)

John Walmsley

S tatistically there should have been one – if that. Successive investigations have shown that the maximum radiation exposure that the Seascale villagers could conceivably

have received is at least two orders of magnitude too small to have done the damage.

Similar clusters have since been found around other nuclear and non-nuclear rural industrial sites. Conventional wisdom is that the effect is viral due to the invasion of peaceful rural communities by thousands of urban roughies.

Others disagree. In particular, Dr Chris Busby, scientific secretary of the UK Green Party’s self-proclamed European Committee on Radiation Risks, consid-ers that there are biological mechanisms that render the cells in the human body hundreds of times more vulnerable to io-nising radiation, particularly if the source of the radiation is itself within the body, than most of us believe.

Indeed, Chris Busby and friends believe that not only is radiation linearly dangerous right down to the minutest doses, but that very small doses are actually disproportionally

dangerous. Damage done by such doses somehow creeps in under the body’s defensive radar.

A little radiation does you goodThese are the introvert pessimists. At the far end of the scale stand the optimists who believe in ra-diation hormesis, a little radiation does you good. Their champion is, or was then, Dr Bernard Cohen who was responsible for a massive study in the USA which appears to show beyond doubt that the incidence of lung cancer decreases in homes in areas with relatively high concentrations of naturally occurring radioactive radon gas.

Nowadays, the optimists can also point to epide-miological studies of literally hundreds of thousands of past and present radiation workers which show unequivocally that up to age 85 radworkers have a twelve to fifteen percent lower incidence of cancer than peers in other industries. Fence-sitters like myself tend to say that that’s probably due to the

medical care they receive, particularly pre-employ-ment medical examinations intended to weed out cancer suspects and other undesirables. But even I am not entirely happy with the logic. Medical examinations surely do not prevent cancer.

Now, suddenly, we have two reports, or rather one report and one book, that will gladden the hearts of even the most cockeyed of optimists. EPRI Technical Report 1019227, as summarised in this January’s ‘Nuclear News’, reviews over two hundred recent reports on aspects of low-level radiation. It appears to conclude that low doses have disproportionally small effects and that there is no evidence at all of adverse health effects due to acute radiation exposures below 100 millisieverts.

For comparison, radiation workers are allowed to receive up to 100 mSv averaged over five years and, at both Pelindaba and Koeberg, actually average less than 1 mSv per year. The surrounding public is limited by law to the same one millisievert per year and actually receive a few microsieverts at most over and above natural background radiation at around 2,4 mSv per year.

Lesser exposureProf. Wade Allison is described as a nuclear and medical physicist at the University of Oxford. In ‘Radiation and Reason’ he makes the same point, namely that adverse radiation effects such as can-cer cannot be detected against the natural cancer background for population exposures less than 100 mSv. He discusses the body’s natural defence mechanisms which evidently cope with damage due to lesser exposure. He concludes that current allowed exposure levels are vastly too restrictive and proposes limits for single exposures of 100 mSv, a monthly allowance of 100 mSv and a lifetime limit of 5000 mSv – without distinguishing between radiation workers and the general public.

One wonders, after decades of what Professor Allison considers gross over-regulation, how the public would react to being told that radioactive effluent discharges could actually be increased a thousand fold.

The book deals with Japanese data (around ninety additional leukaemia deaths and some four hundred other cancer deaths among 87 000 monitored bomb survivors between 1950 and 2000) and, in particular, with Chernobyl. If Allison is right, and I see little reason to doubt him, that the threshold for biological radiation damage is indeed around 100 mSv, then the ‘official’ estimates of several thousand eventual ‘statistical’ (ie, unobservable) deaths in Belarus and the Ukraine reduce to the sixty or so deaths already documented.John Walmsley

No-threshold DebateIn 1983, Yorkshire Television caused a sensation by revealing

the existence of a leukaemia cluster associated with the village of Seascale, a few miles south of the then Windscale Works on the then Cumberland coast. There had been seven cases of leukaemia in people under 25 over a period of thirty years

since the plant started up.

Radworkers have a twelve to fifteen percent lower incidence of cancer


This message was driven home to Festo who conducted a customer survey which indicated that while the company provided a high level of service, there was room for

improved efficiency and increased response times to customer enquiries. To address the issue, the company has established a Sales Inter@ction Department (SID).

“SA Mechanical Engineer” speaks to Nico Landman, SID Manager: Festo South Africa about the concept. “The SID includes an automatic fax handling (E-Fax) system, E-Procurement Solutions (E-Business) and an Online Shop,” he explains. “This concept, which

Festo has implemented globally, is revolutionising the manner in which orders are processed and service is delivered to industry.

Client comes first“Our primary focus with the SID is efficient Customer Relationship Management (CRM) to ensure that the needs of our clients come first while good service is paramount,” Nico says. “For the SID, we’ve recruited twelve employees who are not only qualified in engineering, but also come from diverse engineer-ing backgrounds. In this way, clients will be able to speak to specialists relevant to their industries in order to expedite the service process.”

The new recruits have undergone extensive hands-on training in all departments. “In addition, SID specialists and agents have attended a plethora of training courses through our Didactic and other well-established training facilities,” says Nico. “At the heart of the SID is the SAP system, coupled to an advanced PABX, as well as a data/telephony operating system called Genesys.”

DataThis system delivers customer specific data to the agents with every call. It records the phone number of origin for every call that reaches the SID and, once the number has been put into the database, agents then add on the appropriate company de-tails and all other relevant data, including account information, the nature of the query and transac-tion histories.

The system is capable of drilling down to extension numbers from internal company switchboards, enabling agents to store data on specific personnel from various companies.

HYDRAULICS & PNEUMATICS

Know What You Sell

There is nothing more frustrating than talking to a salesperson who does not fully understand a product, its application, its associated problems, nor the industry it’s

intended for.

All Festo SID em-ployees come from diverse engineering backgrounds. This ensures that clients will always receive sound advice relevant to their specific industries

Clients will never have the typical call centre experience where they have to ‘talk to’ an automated answering machine

�0 THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010

“We can now deliver support and services which are not only relevant to the company, but also to the individual calling,” adds Nico. “The technology and interfaces offered by Genesys have been in operation for a number of years, but this is the first time that they have been applied to the automation industry in South Africa.”

Prompt serviceUsing optimal resource planning and configuration, Festo has adopted the 80/20 performance metric. “In essence, 80 percent of all calls that reach the SID must be answered in less than 20 seconds,” says Nico. “This means that clients will never have the typical call centre experience where they have to ‘talk to’ an automated answering machine.”

The SID will also act as a telecommunications hub. “Each call made to any of our eight branch offices will be routed through the SID first,” adds Nico. “The SID is tasked with handling and resolv-ing most incoming calls to guarantee faster, more accurate service. If a call is routed to a branch or department, we carry all routing costs which means clients are only charged for a local call.”

Mobile agentsEach SID agent and specialist is equipped with a wireless headset which is capable of operating one hundred metres from its work station. This allows operators to freely consult relevant resources, includ-


Wallboards have been strategically p laced around the SID to allow sales agents and specialists to ac-tively monitor their progress and the overall operational status of the SID. This allows them to prioritise their work load in accordance with client require-ments

ing a reference library, or, if need be, the technical department on the floor above. “Similarly, each SID work station is equipped with the latest PC hard-ware, including two monitors to enable agents to view all relevant client information in conjunction with digital technical references,” says Nico.

“In addition, a comprehensive metrics system monitors the performance of each agent. Without a quantifiable means of measuring performance, you cannot identify areas which can be improved.”

Digital Information Wallboards have been placed in full view around the SID to allow staff to gauge their own performance, as well as the performance of the SID as a whole. “Genesys supervisor tools allow us to accurately monitor the performance of each SID member, identify areas of improvement, and implement the appropriate training measures to ensure premium service delivery across the board,” Nico explains.

Track trends“We can also track SID traffic trends, so we can ensure we have enough agents to handle calls during peak periods. Follow-up calls, targeted campaigns and value-added service offerings further enhance customer relations.”

Joanne Dexter, Festo, Tel: (011) 971-5560, Fax: (011) 974-4203, Email: [email protected]

We have enough agents to handle calls during peak periods

www.engineerplacements.com

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THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010 �1

Jointing

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This is the challenge that faced hydraulic rock breaker designer and manufacturer, Gunter Wodak of HME Sales. “SA Mechani-cal Engineer” speaks to him at his office

in Randburg. “The problem with hydraulics is that you can’t just fit bigger cylinders and power packs to get more power out of machine, as the costs simply go sky-high,” he explains. “To increase the capacity, you have to design a more sophisticated system with high precision in order to get the optimum performance out of a rock breaker with a longer reach and a heavier hammer fitted at the end of the boom.”

Biggest in the worldThis led to Gunter designing, building and com-missioning the largest rock breaker in the world for an iron ore mine in South Africa. “Considering my track record of designing and building rock breakers and hydraulic grabs for over thirty years, the mine engineer showed confidence in my work and asked me to build the 13-metre reach rock breaker,” he says, showing us the 3D CAD model of the breaker he created in SolidWorks.

“Mechanically, I diverted from the traditional design to fit an extra hydraulic manipulation on the back of the boom so that the boom can extend much more, both vertically and horizontally, on a fixed base. The boom reaches vertically down right at

the base, something no other rock breaker on the market can do.”

Getting the feelHydraulically, the reach of 13 metres presents it own challenges. “Once the distance between boom and operator controls exceeds a certain distance, operation becomes difficult, as a standard pilot control system has a time lag reaction on the move-ments,” explains Gunter.

“Therefore we have to make use of proportional electro-hydraulics to get the signal from the joy-stick to valve block instantly. These are ‘sensitised electronics’ so that the operator still has the ‘feel’ of a hydraulic system in order to manipulate the boom accurately.”

No more over-designingOn site, a special concrete foundation had to be built to withstand the forces generated from this unusually large rock breaker. The specifications were supplied by Gunter according to the software simulation he performed in the design package. “In the old days, when we designed our first grabs and rock breakers on old-fashioned drawing board, you simply could not take chances, especially for equipment working in Africa, so we simply over-designed everything,” he says.

“Today, sophisticated software allows stress tests and analysis to support a much more economical design before you even start building.

Bigger is Better

Bigger yields require bigger crushers to handle bigger chunks of rock. But as an oversized rock can jam a crusher to the point that it takes days to break the rock down before the

crusher can continue its work, bigger hydraulic rock breakers and grabs are the order of the day.


A big rock breaker built for an iron ore mine

The boom reaches vertically down right at the base

THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010 ��

Hydraulics“Previously, I used to design the mechanical sys-tem as well as all the hydraulics, but today, there are reputable companies that do the hydraulic side for you,” says Gunter. “I just give them my specifications and they design and manufacture all the hydraulic components I need for an advanced system such as this rock breaker.

“The client also wanted computer control of the system, but I still believe a machine for African conditions should be kept as simple as possible. It just means there is less that can go wrong over time.”

Bring bigger onesBeing the first of its kind, the commissioning of the rocker breaker had everyone out on site keen to witness the breaker’s performance. “The client had trucks ready with the biggest lumps of rock they could find which were dumped into the pit while many engineers watched anxiously,” recalls Gunter.

“It took five minutes to break a huge rock, some-thing that would usually take a couple of hours or even days. The onlookers still had doubts and called for more large rock, but the breaker handled everything they threw at it with ease. Since then I have built three similar large ones for other mining companies.”

Three jawsHME’s bread and butter comes from the familiar octopus hydraulic grab with six arms that is used in the steel industry, but Gunter has also designed one that only has three jaws for a mining operation.

“With an octopus grab, the operator can’t position the grab properly to take an oversized rock out of


Gunter Wodak of HME Sales

One of Gunter’s special grabs, similar to theone that works under water

the crusher, so I set out to make one with three jaws so that the operator can clearly see and eas-ily manipulate the jaws around the rock before grabbing it and lifting it out,” explains Gunter. “We have built many of these, from small to large grabs that can lift three cubic-metre rocks out of the crusher pit.”

Under waterAnother first from a copper mine in Zambia was for a hydraulic grab that could work under water. “There is a huge 20-metre deep pit filled with water into which the slag flows to cool down. This has to be cleaned out regularly,” explains Gunter.

“I used one of my standard “Electro Hydraulic” eight cubic metre grabs that goes all the way down under water to pick up the slag. So the whole power pack, built into the grab, was modified to

The onlookers still had doubts and called for more large rock

�� THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010

work under water with just a cable going up to the surface for electricity and control. This meant special seals for the hydraulics, and electrics. After sorting out minor glitches in the beginning, it has been working for years now.”

The standrad rock breaker HME has been manufacturing for years

That Gunter is a practical hands-on engineer is clear. “I evolved as design evolved over the years, from a draw-ing board to fancy 3D software that makes life much easier today,” he says in conclu-sion. “However, there is nothing that beats practi-cal experience in the field. The 3D design concept has helped me to think in 3D, as you would when you’re actu-ally building some-

thing, but you still need to get your hands dirty to learn how things work. Young engineers should get out there and learn how things work in the field, otherwise they’ll believe the first person who tells them it can’t be done.”

Gunter Wodak, HME Sales, Tel: (011) 478-1715, Email: [email protected]


You still need to get your hands dirty to learn how things work


Many OEMs have revised the way they build machines so that they fulfil an order quickly without having to keep stock to meet demand.

This is particularly applicable to capital equipment like large mills that are not fabricated on a continuous production line and stocked until a buyer walks in to purchase the item off

the showroom floor.

Reducing the lead time by simplifying the manufacturing process was just one of the considerations when mill manufacturer Polysius, a division of ThyssenKrupp, came

up with a mill design that has several unique features.

“SA Mechanical Engineer” speaks to Gerhard Sauermann, marketing manager of minerals at

Polysius. “Just the fact that the mill end-walls and girth gears on our mills are fabricated as op-posed to the conventional practice of casting, has reduced production time significantly because we don’t have to wait for the foundries. We also have much better control on the overall manufacturing quality,” he says.

Mill end walls“The fabricated end walls of the shell-supported mill also allow for more flexibility in terms of selecting the correct size of the in- and outlet for different applications. It is also possible to modify the outlet size in the end wall at a later stage.

“Over the past decade, mines have gone for larger equipment to move higher tonnages which has naturally led to a demand for larger processing equipment. By following the market demand for larger-sized mills with more powerful drive trains, our latest generation shell-supported mills have many technical advantages,” says Gerhard. “The

MILLS

Cost-effective Milling

Reduced production time significantly because we don’t have to wait for the foundries


design has been applied successfully and proven in installations around the world.”

FeaturesThe development of a hydrodynamic multi-shoe bearing as support for mill shells allowed Polysius to get rid of the need for a cast trunnion. “We also no longer need large roller bearings for trunnion support,” adds Gerhard. “The entire mill shell is fabricated and can even be designed to be split in several sections to make transport to site easier before it is bolted or welded together on site. This provides us with very attractive delivery times.

“These latest developments are a result of the evolution of our original design through practical experience gained in the field,” says Gerhard. “Through innovation, our design engineers have eliminated unnecessary and costly components allowing us to construct a mill from carefully-con-sidered components of the highest quality while remaining price competitive.

“For example, the entire mill shell is constructed from high quality low-sulphur steel. Mills often operate in remote areas where the skill levels of operators and maintenance staff are the bare minimum. To this end, the robust ergonomic design is specifically developed to make maintenance easy.

MILLS

Gerhard Sauermann of Polysius

A Scrubber at Voorspoed mine

Shell supporting bearings“The hydrodynamic four-shoe bearing principle we developed provides exceptional reliability compared with the large percentage of conventional mills that use single-shoe trunnion bearings,” explains Gerhard. “As loads and bearing sizes are increased in conventional grinding mills, bearing problems usually occur due to the lack of a proper oil gap

Multi-shoe bearings provide predictability and high bear-ing performance


resulting from distortion of the trunnions, machining allowances or deflections of the sleeve bearing.

“These factors have forced manufacturers to reduce the circumferential shoe angle thereby reducing the inactive bearing area which, in turn, increases the friction losses caused by oil turbulence. In contrast, multi-shoe bearings provide predictability and high bearing performance as each shoe is mounted on a pivot support so that deflections caused by ovality and bending of the mill shell under load can be accommodated.”

Drive trainAnother unique feature in Polysius mills is the drive train. “The Combiflex reducer is a twin pinion gear reducer, made up of standard stock components,” says Gerhard. “The Combiflex can be installed for drive trains transmitting from 1.5 MW to 14 MW as either single or dual drives. The design has sev-eral advantages over conventional girth gear/pinion drives in that the number of components used in the complete drive train have been minimised. The twin pinion arrangement spreads the load across girth gear teeth allowing us to incorporate a nar-rower girth gear.

“This was achieved by incorporating the girth gear and the reducer into one common housing together with the slide shoe bearings, eliminating parts like high torque couplings, transmission shafts and separate pinion bearings.

“Spur-geared pinions mesh with the girth gear in a self-aligning arrangement,” says Gerhard. “They are mounted on spherical bearings and assembled

A SAG mill installation

onto shafts so that torque is transmitted from the shafts to the pinions through toothed couplings. The toothed couplings and spherical bearings make the tilting of the pinion possible which provides an optimal load pattern on the torque transmitting tooth flanks.”

The motorThe high-speed motor is directly connected to the reducer through a flexible coupling to absorb shock loads and vibration. One common lubrication system is used to provide oil to the bearings, the reducer and to the girth gear. “As fewer components need to be aligned, the mill drive installation is consider-ably simplified and the installation time shortened,” adds Gerhard. “The reduced number of components also means there are fewer parts to be monitored, again simplifying maintenance.

References“The more than 1 500 installations we have worldwide, is an indication that this technology has proven itself ,” says Gerhard in conclusion. “We’re currently manufacturing an eleven-metre mill - one of the biggest we’ve ever made - in Vereeniging for an American company. This large mill follows on the two 10.4-metre, 12MW mills recently commissioned in Australasia.”

Gerhard Sauermann, Polysius, Tel: (011) 236-1176, Email: [email protected]

We’re currently manufacturing an eleven-metre mill - one of the biggest we’ve ever made

MILLS


Munters (Pty) Ltd22 Angus Crescent, Longmeadow East, ModderfonteinEmail: [email protected] , Web: www.munters.co.za

Call us on 0860 MUNTERS


Market ForumBBBEEE accreditation in top gearIn South Africa’s new de-mocracy, BBBEE affiliation is of the utmost importance to companies looking to grow and extend their standing from one industry to the next. It is no surprise that David Brown Gear Industries is a leader in this field, having achieved value-adding supplier level 6 BBBEE compliance on 22 May 2009.

Human Resources Business Partner at David Brown Gear Industries, Tumi Mametse

is part of the team that spearheaded this accreditation. In three to four months, David Brown progressed from a level 8 to a level 6 accreditation by fulfilling four of the seven pillars necessary in the BBBEE scorecard. “What we’re most excited about is our new status as a value-adding supplier” as it means we are making a difference in the society Tumi says.

According to BBBEE certification codes, labour based com-panies with salaries and wages that form a large part of their expenses are awarded value-adding supplier status. “This means that even though recognition for level 6 suppliers is at 60%; clients and suppliers who do business with David Brown are rewarded by being able to multiply their procurement recognition level at 75% which is only 5% less from a level 5 recognition level,” adds Tumi.

David Brown Gear Industries, Tel: (011) 748-0000, Fax: (011) 421-2553, Email: [email protected]

a compact installation when compared size for size with conventional swing and lift type check valves.

DCV wafer check valves are available in a wide range of body materials from bronze to austenitic stainless steel and with seating options of stainless steel, viton or EPDM to match most applications.

When boilers are shut-down and steam pressure lost, the head of water above the pump can cause flow through the pump which may flood the boiler. The DCV2B fitted with a heavy-duty spring and installed after the feedpump will prevent any gravity flow.

Spirax Sarco, Emily Heath, Tel: (011) 230-1300, Fax: (011) 393-1922, E-mail: [email protected], www.spiraxsarco.com/za

Tumi Mametse

Wafer check valves stop reverse flowSpirax Sarco’s DCV wafer check valves can be used in a wide variety of applications such as hot and cold water systems, process line sprin-kler installations and in steam and condensate lines. Installed in ‘reverse’ mode, the DCV will act as a vacuum breaker preventing any back syphoning of liquids damaging upstream equip-ment when the steam supply is turned off and the equipment cools.

The DCV wafer check valves provide an effective maintenance-free solution for the prevention of reverse flow in pipelines carrying most types of liquids, steam and gases. Designed to fit between two pipeline flanges, they provide

Munters (Pty) Ltd22 Angus Crescent, Longmeadow East, ModderfonteinEmail: [email protected] , Web: www.munters.co.za

Call us on 0860 MUNTERS

Pipe replacement projectEThekwini Water Services is in the process of replacing mu-nicipal asbestos cement pipes of up to 150mm diameter. The R1.653-billion Asbestos Cement (AC) Pipe Replacement Project is one of the biggest projects of its kind ever undertaken by a municipality in South Africa. The project which commenced


Market Forum

Opportunities to address new export marketsCredit insurer Coface South Africa has launched a service giving exporters financial and credit information on more than 50-million companies globally.

“South African exporters currently face massive challenges in the global market. The international economic slowdown has resulted in many financially-stable companies becoming unstable almost overnight,” says Coface Operations Director, Jacqui Jooste.

“Countries that a year ago would were classified as ‘safe’ to trade with have been turned upside down. Whilst the current global economy is a minefield, exporters should be exploiting the opportunities available to them using the right information as a guideline,” she says.

“The information Coface provides is based on data essential for doing export business. Researching business opportuni-

Nonkuthula Sithole, Health and Safety Officer and Nokubonga Ngcobo, site clerk, work for Royal Africa Trading, a sub-contractor on the AC Pipe Replacement Project

in July 2007 is sched-uled for completion in June 2010.

“Initially the municipal-ity identified 1750 km of old AC pipe which needed replacement. However, in certain ar-eas, especially smaller local authorities that were taken over by eThekwini, the length of pipe needing re-placement was un-known” says eThekwini Project Executive, Alan Kee.

“It was this unknown factor which led pro-curement specialists in the municipality to identify the New Engineering Contract 3 (NEC3) as the most appropriate method of managing this pro-cess,” says Kee.

The NEC3 family of contracts is especially designed to allow for a variety of unknown factors in a large project. For this project, an op-tion was selected that has schedules that can be adapted to suit the needs of a given area, in a flexible and effective manner.

This project encourages the development of teams consist-ing of a design consultant, a large contractor and smaller developing sub contractors. Within designated areas, the contract provides the flexibility to match the skills of the team to the needs of the project.

One of the mainstays of the project is the mentorship pro-gramme that has encouraged the development of 16 small emerging sub contractors, working under four large, main contractors.

Jochen Dedekind (Lead Programme Manager): 033 342 8721 or 082 907 3205. Evan Smith (Lead Project Manager): 031 266 5255 or 083 635 8236, www.durban.gov.za/Durban/services/waterandsanitation/services/replacement-of-ac-secondary-watermains

THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 2010 �1

Market Forum

New compressors for Impala PlatinumGE Oil & Gas will supply two new compressors for miner Impala Platinum’s sulphuric acid plant in Rustenburg, South Africa. The new compressor packages will be commissioned in mid-2010.

The $2-million contract for the supply, and commissioning of the two compressor trains was awarded through GE’s local agent, Flotech. The compressor packages include auxiliary equipment such as lubrication oil systems, electric motors, gearboxes, and instrumentation.

GE Oil & Gas account manager South Africa Shawn Prince said, “We focused on reducing the delivery time to assist in having the plant operating at full capacity in the shortest time possible.”

GE Oil & Gas has developed a strong presence in South Africa’s mining and petrochemical sector, as well as throughout the region. Beyond South Africa, GE Oil and Gas is pursuing opportunities in Namibia, Mozambique and Zambia, where platinum, coal and copper are being mined.

Nigel O’Connor, GE Oil & Gas, Tel: +44 (0) 207 302 6941, Fax: +44 (0) 776 611 5135, nigel.o’[email protected]

ties can be difficult because the quality information often comes into ques-tion,” says Jacqui. Without good qual-ity information on specific companies and markets, many SA exporters are nervous to invest time and money.

Coface provides exporters with up-to-date reports on overseas companies through its international network of information providers in over 94 countries. “The information is always up to date because, daily, it is used for our credit insurance business worldwide,” concludes Jacqui.

Coface South Africa, Natasha Hardy, Tel: (011) 208-2517, Fax: (011) 208 2601, Email: [email protected]

Steam/thermal oil rotary joint Yale Engineering Products, sole distributors of Kadant John-son products throughout Southern Africa, has introduced a new self-supported rotary joint for steam and thermal oil applications.

SAP now available on monthly subscriptionSCT Services, has announced a new licensing and delivery option for SAP Business All-in-One (SAP BAiO) solutions. The new hosted and subscription-based delivery model is designed to help midsize companies obtain a world-class business application with a lower up-front cost.

SCT Services CEO, Victor van der Watt says this model means customers will avoid up-front software licensing fees and hardware purchase charges, freeing them from the need to maintain or support an on-premise solution within their own IT infrastructure.

The hosted delivery model is available from SAP partners such as SCT Services that participate in the SAP BAiO fast-start programme and who are certified by SAP to provide application management and hosting services for SAP BAiO solutions. The subscription-based hosted delivery model for SAP BAiO solutions is available immediately on a two, three or four-year basis.

The new SNX rotary joint is designed specifically for appli-cations with a rotating pipe and two flow passages. It also features a convex seal ring and two carbon graphite support bearings. The two support bearings are widely spaced to support the joint and rotating horizontal pipe. The external bearing is free to rotate, distributing overall wear and extend-ing the rotary joint life.

The rotating pipe is sealed and supported by the end of the nipple, thereby eliminating drive key wear resulting from rotating pipe misalignment. In addition, the o-ring sealed spring shoulder and internal differential seal for the rotating siphon pipe provide a positive seal between the steam inlet and condensate outlet. The SNX rotary joint is available with a 1” threaded or quick-release flange nipple connection and is rated up to 260°C, 20 bar pressure and 450 RPM for steam service. In addition to steam applications, the SNX rotary joint can be applied to thermal oil applications up to 343°C and 10 bar pressure.

Yale Engineering Products, Sales: Tel: (011) 794-2910, Email: [email protected]


Market ForumVictor recognises that one size and one delivery model does not fit all. “In the current economic situation, many midsize customers struggle to get much needed investment capital. To this end, we have expanded our SAP product range of-fering by adding subscription-based hosting of SAP to our portfolio. It gives our prospects and customers another sound option when deciding to acquire SAP.”

As the cash outflow on this investment is driven from opera-tional and not the capital expenditure, subscription-based hosting is perfect for growing businesses who prefer to rent rather than buy.

SCT Services, Alan Yates, Tel: (012) 345-5669, Email: [email protected]

Goba/K’enyuka joint venture enters wastewater sectorK’Enyuka, a South African hydro-pyrometallurgical and mineral processing engineering and project management company, has announced that it has formed a joint venture with the independent South African consulting engineering firm, Goba.

Mike Symonds, managing director of K’Enyuka

The Goba/K’Enyuka joint venture will focus on projects in the water and wastewater treatment sectors in the mining, municipal, parastatal and industrial markets. According to Mike Sy-monds, managing direc-tor of K’Enyuka, it is the JV’s intention to operate as an EPCM contractor and cover the whole gambit from upgrading small to larger plants as well as participating in greenfields wastewater treatment projects.

“Both companies have strong project manage-ment capabilities and this, together with our access to multi-disciplinary service offerings, will allow us to become a serious player in the market,” he says.

“It is our belief that by adopting a flexible approach we will be able to accommodate the diversity of client and project requirements and applications, and provide the most suit-able total solution for a particular problem or application,” Symonds says. “Moving into the water and wastewater sector for K’Enyuka is a natural evolution for the company and will include mine wastewater treatment and acid mine drainage applications. Embarking on this joint venture will allow us to diversify into a new market where we see substantial potential,” he adds.

Resources within the Goba/K’Enyuka JV include highly qualified people across a spectrum of disciplines, including process, mechanical, civil and structural engineers.

Mike Symonds, K’enyuka, Tel: (011) 498-6000, Fax: (011) 498-6060, Website: www.kenyuka.com

Increased availability from Greenside plantA contributing factor to the 30% increase in availability of plant at Greenside Colliery is the use of service exchange units supplied and installed by Weir Warman Africa’s Wit-bank branch.

“Usually these components or pumps are simply supplied to the mine for installation by the mine’s personnel,” Nico Smit, branch manager for Weir Warman Africa Mpumalanga, says. “In the case of Greenside Colliery, Weir Warman Africa technicians installs the components or pumps.”

Nico explains the rationale behind this unconventional approach in what is often a very conventional industry. “It is all very well using service exchange units in pump


Market Foruminstallations, but another factor is the time it takes to remove and reinstall the replacement. This becomes critical when limited time is available, and artisans have to un-dertake maintenance to other areas of the plant as well.

“Using our technicians to remove and replace pumps, translates into a far more productive use of labour and skills,” Nico says. “On most plants, generally only one day is allocated for maintenance each week, which limits the mine artisans’ avail-able time. Our pump spe-cialists are better equipped and skilled to do pump and pump component changeouts.”

Weir Warman Africa’s Witbank branch operates In the case of Greenside Colliery, the components or pumps are being installed by Weir Warman Africa

technicians

�� THE SOUTH AFRICAN MECHANICAL ENGINEER VOL 60 March 201030 Supply Chain Today Jan 2010

This prestigious award recognises people, projects and products

that have gone above and beyond the call of duty to

enhance the environment in which they operate.

The inaugural awards in 2009 enjoyed a wonderful response

from the supply chain community and everything is on track to make this year’s event one of the indus-try’s most prestigious accolades.

Come and see who walks away with the coveted trophies and

enter your product or project for this year’s event.

Entries for this year’s event close in June and the awards ceremony is being planned for 26 August 2010.

GreenSupplyChainAwards

Contact: Catherine Larkin on

Tel: (011) 789-7327/787-9127,

Cell: 083 300 0331, Fax: (011) 787-7865

Email: [email protected]

Are You Doing Your Bit?


Market Forumoperating and maintenance costs, while delivering better, more sustained yield consistency.

The high density alumina ceramic used for these impellers is second only to a diamond’s hardness. It is the most versatile and effective wear-resistant material for use in process plants. Few materials can compete on a cost to life basis.

The ceramic impeller comprises a steel frame that takes up the mechanical forces and a ceramic outer lining, for optimum wear resistance. The ceramics are bonded to the steel by means of Multotec’s proprietary adhesive. This re-silient bonding absorbs impacts from foreign objects passing through the pump, when used in arduous pumping applica-tions. Alumina-ceramic impellers are particularly resistant to the tearing damage caused by sharp objects often found in slurries. Ceramic impellers are chemically inert and suit-able for use in hazardous and hostile environments. The impeller, however, has to be adapted when pumping acidic materials.

Multotec impellers combine the same performance char-acteristics as the original equipment manufacturer (OEM) specifications. The extreme hardness and high density of ceramic impellers lead to superior erosion and corrosion

resistance at both high and low im-pingement angles.

The increased life of ceramic impellers, in some cases between four and six times more than conventional rubber or steel impellers, results in substantially reduced downtime.

In addition, the performance of the ceramic impeller results in increased pump volute life and greatly reduced maintenance costs. The mass of the ceramic impeller is about half that of a steel impeller, again resulting in substantially reduced bearing main-tenance.

Bernadette Wilson, Multotec Group, Tel: (011) 923-6193, Email: [email protected], www.multotec.com

Multotec Wear Linings offers a range of ceramic impellers for slurry pumps

a fully equipped service centre with a comprehensive parts stockholding. “Service exchange units are generally the complete pump unit and we can supply and install Warman 1/1.5 AH pumps right up to the Warman 16/14 AH pumps from this branch,” Smit says.

“With this coordinated approach,” Smit explains, “the mine makes its maintenance schedule available to our branch and we are able to forecast the parts necessary to build up the service exchange units. These are prepared in advance to ensure that on the day of maintenance the pumps will be immediately available. This system is effected in such a manner that specific sections of the plant are addressed at each maintenance interval.

Rene Calitz, Weir Warman Africa (Pty) Ltd, Tel: (011) 929-2622, www.weirminerals.com

Ceramic pump impellersMultotec Wear Linings offers a range of ceramic impellers for slurry pumps. These ceramic impellers significantly reduce


Index to Advertisers

Afzelia 46AST Inside Front CoverAxiom Hydraulics 20Bearings International 4BMG 10Chorus Call 42DCD-Dorbyl 22Donaldson 19Engineer Placements 30EPNS 34Festo 40GEA Grasso 18Hansen Transmissions 12KSB Pumps Inside Back CoverMaizey 31Multi Alloys 26Munters 38SAID 43SEW Outside Back CoverSteinmüller Outside Front CoverWCNDT 24Yellow Tec 27, 45

Please fax us if you wish to subscribe to “SA Mechanical En-gineer” at R400,00 (incl postage and VAT) per year; R945,00 per year for Africa/Overseas. We will post you an invoice on receipt of your fax.

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SubscriptionOn the Move

Changes are afoot at Goscor as Neil Wilson has been appointed CEO and Francois Otto is group financial man-ager of the Goscor group of companies. Anton Bothma has been appointed MD of Goscor Power Products.

Rockwell Automation has announced the appointment of Francois Retief to the position of managing director.

Anton BothmaFrancois OttoNeil Wilson

Francois Retief


Pumps Valves Systems

KSB Slurry Pumps – Ton after TonTake tons of solids, add liquid and shake vigorously – a recipe for slurry. Whatever the mineral, KSB slurry pumps can finesse the complexity of tar sands and phosphates or transport the glint of gold, copper and metal ores. Beyond mineral processing, KSB’s expertly engineered and robust pumps and valves can also support secondary operations like chemical processing or wastewater pumping.

KSB Pumps and Valves (Pty) Ltdwww.ksbpumps.co.za

LCC-MHard metal pumps for

LCC-R16 Bar rubber lined pumps

LSA-SPremium design hard

MDXMaximizes up-time inHard metal pumps for

general slurries16 Bar rubber lined pumpsfor general slurries

Premium design, hardmetal pumps for severe slurries

Maximizes up time in SAG, Ball mill circuits and cyclone applications


Suppliers of geared motors, industrial gears, frequency inverters, drive electronics, servo technology and services.

Naturally, as the leading drive-technology specialists, we consistently develop new products that are above all reliable, energy-efficient and produced cost-efficiently. Moreover, our know-how and experience allows us to go a step further than the rest – providing solutions that you can build on. That’s what we call Drive 360o – Seeing the big picture: from the system availability to problem-solving competence, achieving lower operating costs through energy-efficiency right through to finished systems. We can fulfill all your needs.

SEW-Eurodrive (Pty) LtdPO Box 90004 l Bertsham 2013Tel: +2711 248-7000Fax: +27 11 248-7289

www.sew.co.za

SEW-EURODRIVE - Driving the world

We don’t develop products we develop solutions.

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