Bayer Crop Science: Ready or Not, Start it Up

Under pressure to get production going, the plant had to resume production without adequate preparation. One key omission leads to the explosion.

Company procedures called for a PSSR (pre-startup safety review) to be run for the methomyl unit before it was restarted. This was a complex process that was supposed to prove that all the equipment and safety devices were in order, allowing the unit to run correctly and safely.

This was no simple restart. Bayer had replaced the DCS during the outage, installing a completely new system to replace a platform that had been running for more than 20 years. The plant was under pressure to get the unit running again because the demand for Larvin (the specific pesticide product) was seasonal and orders had to be filled within a critical time frame. Methomyl, a key ingredient of Larvin, was being pulled from inventory, but there was not enough to fulfill demand so production needed to get started without delay. Consequently, Bayer had operators, engineering staff and contractors working around the clock to finalize all the installations, calibration and checking.

Who’s checking what?

The individuals performing many of the specific PSSR functions were not operators or people that were familiar with the process. Working through the eight pages of PSSR instructions, the team incorrectly identified some items as being complete or “not applicable” that in fact were applicable and had not been completed. Other things that were correctly identified as incomplete had no dates for follow-up. The PSSR related specifically to the new DCS was also incomplete and had critical errors.

While this was going on, the control room operators were trying to understand the new control system, but there was no formal training to prep them for this huge change. They were trying to learn, as best they could in the time available, how the system worked by observing operators at one of the other units in the plant. This attempt at OJT by watching a much different process did not prepare the operators for what lay ahead.

The startup procedure for the methomyl unit called for a solvent flush and nitrogen purge before the startup. This eliminated water from the system, and also helped verify instrument calibrations, proper equipment operating sequences and that the new DCS was performing as expected. Given the amount of piping changed to accommodate the new residue treater vessel, along with the new control system and its associated instrumentation, this was a hugely critical step.

Most of the job is not enough

Plant technicians did most of the job, but not all. They performed the solvent run through most of the unit, but not as far as the residue treater. In many respects this was the most direct cause, not because it would have identified some mechanical problem hiding in the system, but for the simple fact that the solvent used needed to remain in the residue treater to be in place and heated to the correct temperature when the “flasher bottoms” (methomyl-contaminated solvent) began to reach the treater. Instead, operators began pumping the flasher bottoms with an excessively high level of methomyl into an empty vessel where the decomposition process quickly got out of hand. A runaway exothermic reaction ensued and the tank exploded.

This should not have been possible because the control system was designed to prevent adding methomyl into the vessel unless there was enough MIBK (methyl isobutyl ketone) solvent in the vessel, at the correct temperature. Operators deliberately bypassed this safety measure, with the knowledge of supervisors, which led to the explosion.


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The detrimental impact sleep apnea has on the lives of countless sufferers is a very serious matter. Fortunately, with a bit of knowledge and research, it is possible for just about anyone to learn effective techniques for managing the condition. Review the ideas below for some useful information about battling sleep apnea successfully.

One way to improve your sleep apnea is to shed excess weight that you are carrying. Being overweight or obese places pressure on your neck, which can compress your windpipe as you sleep. Losing just 25 pounds can make a difference in your symptoms, and losing enough weight can eliminate the disorder altogether.

If you have sleep apnea, be sure to ask your doctor every five years if you should have a follow-up sleep study. As your weight and health change, your CPAP pressure may need to be adjusted. The most accurate way to reassess your needs is to have another sleep study with CPAP so the appropriate pressure can be determined.

If you have sleep apnea, be sure to ask your doctor every five years if you should have a follow-up sleep study. As your weight and health change, your CPAP pressure may need to be adjusted. The most accurate way to reassess your needs is to have another sleep study with CPAP so the appropriate pressure can be determined.

People who do not have a partner sleeping with them may not know they suffer from sleep apnea. If you wake up with a dry or sore mouth, wake up out of breath, have morning headaches, insomnia, and/or go to the bathroom frequently during the night, you may have sleep apnea and should talk to a doctor.

Keep your bedroom in prime shape for sleeping. Insomnia and sleep apnea are often connected. This makes keeping an environment in which you sleep at the right temperature, lightness level and sound level important for helping you get a good night of rest. The right environment also means leaving your stresses outside the bedroom to ensure you are relaxed enough to fall asleep.

If you have been diagnosed with sleep apnea, it is important to avoid drinking alcohol. Alcoholic beverages will relax the muscles in your throat, which makes it more likely that they will block your airway during your sleep. At the very least, avoid any alcoholic beverages in the evening before you get ready for bed.

A great way to know if you are experiencing severe apnea is to keep a sleep journal. Write down all the times that you wake up in the night and also record how you feel in the morning. This will help you to have a record to see your progress.

People who use alcohol, sedatives, and sleeping pills are far more likely to suffer from sleep apnea. This is because these drugs will relax the throat and cause their breathing to be impaired. Using these drugs before bedtime is more likely to cause sleep apnea than using these drugs during the day.

Learning more about sleep apnea is important because knowledge can help put your mind at ease. Take the information you have learned in this article and talk to your doctor about it. He or she can then better help you more easily when you know more about this disorder yourself.
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