Another Top 10 Interesting Things Engineers Do

Oil & Gas projects often run for a few years before the first barrel gets sold and it is quite common to see engineers who work in the early days being transferred to other projects, locations, role change or quitting. When this happens, it becomes the headache of the next engineer to pick up from where the previous engineer left off. Here are some instances that give the unsuspecting engineer a reason to scratch his/her head!! 

• Temperature Sensors in Baffles Spaces: This is a good idea if you are the control room engineer who thinks he/she is only getting paid to read the newspaper at work. Process equipment with baffles are often prone to solid debris like sand, epoxy, glass coatings or other particulate matter accumulating thereby masking the sensor's ability to read the temperature correctly. If at the commissioning stage, process lines were not purged properly, one could also add cigarette butts to the debris list that precludes the temperature trends from being recorded correctly at regular intervals.
• Using Thermo-couples for Control: Tuning a controller with noisy data can be a pain in the neck. If you are the chap who likes to meddle around with controller set points frequently to adjust for drift, one might as well save some money installing a thermocouple instead of an RTD (Resistance Thermometer Detectors). After all, as they say, listen to your elders, what was good for my grandfather is good for me!! Its not really the thermo-couple, but the thermo-well that decides the reliability and response time. If you have enough debris accumulating to give you slow rising temperature trend, then get rid of the smart transmitter and hook it up directly to the DCS with some back patting for doing some direct material productivity!!   

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• Relying Excessively on Orifice Plates for Measurements: Orifice plates are geometrically less complex than a Dunkin Donuts' Donut. But they are lousy. When Engineers give a damn about noise, rangebility not following the square root law, change in the meter coefficient, Reynolds number, density and composition, then its called plumbing and not engineering. Kindly take the money purse and shop for alternatives like Coriolis meter or magnetic flow meter or vortex flow meter.    
• Polarity of the Agitator's Motor: You like Blending?? One can argue that in whichever direction an impeller is rotating in an agitator, it will eventually blend the concoction to homogeneous uniformity. But if the polarity of the electric motor that is mounted on top of the agitator is reversed, Then.. Time to take out the money purse again to buy a new set of Seals and Seal Packing for the agitator setup.    
• Installing Pressure Gauges prior to Plant Startup: Unless you managed to pull down wool over your employer's eyes about holding stocks with the supplier's company, installing pressure gauges and electrodes that can go bust during construction or water batching is not a good idea for your pockets.    
• Equalization Lines without Purge or Steam Tracing: Something is wrong when you see liquid coming out with vapour from vapour lines and liquids with vapours coming out of liquid lines. Provide purge and steam tracing wherever necessary.    

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• Field Mounted Switches: Installing limit switches on valves can be necessary at times, because limit switches tell you whether the valve or instrument is functioning correctly or not. But if one starts guessing what should be the trip settings for field mounted pressure or temperature gauges, especially on critical equipment, make sure you are far away in the Bahamas. Don't bother to do a root cause analysis when you get back, because the evidence will also vaporize with the rest of the plant!!    
• Putting Faith in Controller Reset Action: In controller terminology, 'Reset' Action means anticipating changes by measuring the initial rate of change for accurate control. So if a sudden change occurs in the set point (SP), the process variable (PV) also shoots up excessively. In the case of a control valve, if the valve opening % shoots up, the integral action is switched off for a while until the output response (valve opening) falls within an acceptable range. Personally I would say, avoid using reset action excessively, otherwise you could end up looking like the Church-goer who asked "Who is Jesus Christ" at the end of the Sermon when the Padre finished reading out the entire Bible.    
• Insufficient Derivative action in pH and Temperature Controllers: Exothermic reactions produce heat and hence these vessel temperatures have to be brought down by cooling with a water jacket. To do so, water coolant controllers need derivative (D) action in addition to proportional (P) and integral action (I) to allow the controller to bring the process back to its intended state. If not included... Think again!! when your exothermic reaction temperature runs away you can watch the temperature trends on the trend recorder also running away fast like Julia Roberts in the movie 'Runaway Bride' !!!    
• Installing Analyzers: If you'd like to rate yourself as a creative, intelligent and loves adventure sports, get rid of the Coriolis Density Meter. They are reliable and accurate but can get boring after installation. Instead try doing some window shopping for other types of analyzers that like air conditioning, winter heating or ventilation. Ensure that there is no phone installed in the analyzer house, otherwise those pesky operators would frequently keep calling to ask what the heck is going wrong. Besides not only the dead time and analyzer cycle trends are soothing to watch, the analyzer house is a convenient excuse when your boss asks you where the heck you were!!

References: [1], [2], [3],[4]

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About the Author

Vijay Sarathy holds a Master’s Degree in Chemical Engineering from Birla Institute of Technology & Science (BITS), Pilani, India and is a Chartered Engineer from the Institution of Chemical Engineers, UK. His expertise over 16 years of professional experience covers Front End Engineering, Process Dynamic Simulation and Subsea/Onshore pipeline flow assurance in the Oil and Gas industry. Vijay has worked as an Upstream Process Engineer with major conglomerates of General Electric, ENI Saipem and Shell.