If you’ve ever had to work with spreadsheets that you inherited from other people, chances are they were riddled with obsolete range names that do not point to valid addresses anymore. Getting rid of those one by one by pressing the delete button is tedious and you may accidentally delete a name too many in the process. Tracking range names down however is not too difficult using a bit of visual basic code. Read the rest of this entry »

In planning and manhour forecasting you will repeatedly have to count the number of workdays within a certain date interval. In case the dates are all fridays or mondays this is easy of course, but if they are not, you cannot just count weeks and multiply by 5. Counting workdays gets even more complex if you want to account for public holidays as well.

Counting workdays by user defined function in VBA

In MS-Excel you can easily automate the process of counting workdays by using Visual Basic. And because it runs so fast, the algorithm can be quite ‘dumb’ : just run by each date in the interval, decide if it is a workday and if it is, count it:
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In a previous post I addressed the issue of not designing a relief valve for liquid overfill in relation with the requirements for instrumental protection. Taking this subject a little bit further, there is also a relation between liquid overfill and design pressure.

Not taking this relationship into account during early design stages may lead to surprises at later stages as safety reviews may require corrective action to safeguard the design. What could have been an easy solution (selecting a slightly higher design pressure) will then no longer be an option as it would usually mean massive re-work and schedule impact.
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Travel PlanEven though you may have experience traveling, it is always a good idea to make a business travel plan. Many companies actually require you to submit some form of travel plan before you are even allowed to go on a business trip. But even if such a requirement is not imposed I’d still recommend to make one.

Why should I make a Business Travel Plan?

Think of it as a flight plan: no airline pilot is ever allowed to take off without one. So why should you?

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waterAPI standard 521 provides a possibility to take credit for operator response to avert relief. It says that a commonly accepted time range for the response is between 10 min and 30 min, depending on the complexity of the plant. In practice this criterion is often used to rule out liquid overfill as relief contingency for large vessels like for instance distillation columns. A ‘nice’ fringe benefit of this action that we do not have to account for liquid discharges to the flare system (at least not on paper that is!).

Is Operator Intervention Safe?

An ‘interesting’ situation will occur if the shut-off pressure of a charge pump significantly exceeds the design pressure of the downstream vessel while the installed relief valve is not sized for the pump capacity (taking credit for operator intervention). This would then mean that catastrophic failure would occur in case the operator “fails on demand” to stop the overfill.

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