MechChem Africa April 2017

⎪ Minerals processing, metallurgy and materials ⎪

The characteristics of environmental factors

The degree to which factors are few in number and similar to one another.

Simple

Complex

The degree to which factors remain stable or are in a continual process of change.

Static

Low

Moderately low

Dynamic

Moderately high High The extent of perceived uncertainty affecting decisions.

Figure 3: Perceived uncertainty compared to decision environment characteristics.

shouldworkwell. It has in thepast. It requires understanding by client bodies. It is neither fun nor simple. If you want simple answers to complex circumstances, take some of your moneydown to the casino. Infrastructure en- gineering is not theplace togambleon simple answers, evenwhen the questions posed are simple to express. q

up of bio films on product contact surfaces. Whilst the focus had always been struc- tural integrity, the hygienic welding of joints introduced new challenges. These hygiene requirements, which provemore demanding to achieve than structural integrity, are in addition to other operational requirements. The approach to engineering choices

world is a far from simple place. Operational circumstances, economic, political and cul- tural systems that affect outcomes are highly complex. They have a myriad of interacting variables. The relationships between those variables are shifting constantly. For any de- cision there are normally between four and seven significant variables. These need to be identified,thencontrolled,influencedorsimply monitored (in the case of exchange rates, for example). The perceived uncertainly associated with decision environment characteristics is shown in Figure 3. The significant operating circum- stances govern the decision environment and these may or may not be static and time dependent. A balance within the context of the significant variables enables reasonableas- sessment andunderstandingof associated risk. Conclusions The first thing to take from this article is that nobodyknows exactlyhowamaterial or design will react over time. Sure, there will be lots of people making guesses. It is even certain that some of those guesses will turn out to be right. Anewguruwill beborn,whowill havehisor her time in the sununtil their nextmajor prediction fails miserably. It has always been so. The second thing to take away from this article is that there is often no need to make absolute predictions at all. Engineers all need the skill to identify the full set of predicted operating conditions that affect choices, com- binedwith the ability toworkout a strategy for when the situation changes. The engineering concern is not to predict with certainly but to recognise fairly soon if significantchangeshaveoccurred.Astrategyfor deviations is required. An example of this is the food and beverage sector, which made invest- mentdecisionsinthe1980sbasedonfunctional compliance. In the early 2000s new legislation related to health has emerged alongside the sustainability criteria. This limits acceptable bacteria and spore counts in the final product. Bacteria are directly associated with the build- integrity, the issue of hygienic joints introduced new fabrication challenges to allow the systems to be cleanable and eliminate bacterial entrapment areas. Sanitary piping is stainless steel high purity tubing for biopharmaceutical, food and beverage facilities. Whilst the focus had always been structural

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April 2017 • MechChem Africa ¦ 33