DISCLAIMER: I am not an attorney and would not even play one on TV, but I have stayed at a Holiday Inn Express!
I was shocked to hear that a Harris County jury has returned a $61.5 million verdict against 3M for families devastated by the 2020 Watson Grinding explosion in West Houston. The explosion killed three (3) people and destroyed or damaged more than 450 surrounding homes and businesses. At trial, testimony showed that 3M failed to properly service the facility’s gas detection and alarm systems. I was NOT at this trial, but I am anxiously awaiting the details of how the jury came to find 3M at fault for this system not being in service at the time of the accident. Looking back at the CSB report, we can clearly see that Management knew the system had been disconnected and even discussed this issue weeks before the fatal accident. Management even changed to a different vendor to inspect and calibrate these detectors. I do NOT know if 3M was the original installer or if the company was hired later, as the CSB report does not mention 3M. Here are the pertinent parts of the CSB report that have me scratching my head as to how 3M could be liable…
The purpose of the gas detection system was to continually monitor the propylene and oxygen concentration inside the coating booths and, in instances of dangerous concentrations, provide local alarms when the prescribed parameters were exceeded, start up the booth’s exhaust fan (if not already operating), and stop the flow of these gases (both locally in the booth and remotely at the propylene and oxygen storage tanks located north of the coating building).
Six of the eight HVOF coating booths (Booths 4, 6, 7, 8, 9, and 10) were equipped with a wall-mounted gas detector,a as shown in Figure 12 below. These were installed in 2010 during the coating building rebuild following the 2008 incident. Each gas detector was originally configured to transmit a signal to the programmable logic controller (PLC), a type of computer control system, when its gas sensor(s) detected the pre-set concentration level of flammable gas or oxygen. Upon the receipt of a signal from one of the gas detectors, the PLC was originally configured to:
- Trigger alarms notifying employees that propylene had been detected inside a coating booth and to take appropriate action (evacuate);
- Automatically start up the booth’s exhaust fan to help remove flammable gas from inside the booth, if the fan was not already running;
- Automatically close the remote shutoff valve inside the individual coating booth where gas is detected; and
- Automatically close the remote shutoff valve at the propylene storage tank, thus shutting off the flow of propylene.
The alarms were both audible and visual. The audible alert consisted of a verbal message alerting employees of the hazard and directing employees to evacuate, alternating with a siren. Meanwhile, the visual alarm consisted of a flashing red beacon located outside of alternating coating booths. At the time of the incident, the automated gas detection alarm, exhaust fan startup, and gas shutoff system was not functional.
The CSB concluded that the Booth 4 automated gas detection alarm, exhaust fan startup, and gas shutoff system was not functional at the time of the propylene leak. Had the system been functional, it would have alarmed to alert employees, started up the exhaust fan, which would have removed the leaking propylene from
inside the booth, and remotely shut off the propylene storage tank, stopping the flow of propylene vapor and likely preventing the dangerous accumulation of propylene from Booth 4. Evidence indicated that Watson Grinding did not effectively respond to reports in 2013, 2016, 2019, and two weeks before the January 2021 explosion, of the gas detection alarm, exhaust fan startup, and gas shutoff system not being connected to the computer control system (a PLC).
Following the 2010 installation of the propylene automated gas detection alarm, exhaust fan startup, and gas shutoff system, Watson Grinding did not maintain engineering drawings and additional documentation on the system, did not maintain this system in working order, and did not train its employees on effectively using or maintaining the system. The CSB concludes that deficiencies in process knowledge and documentation at Watson Grinding significantly contributed to the incident.
In 2016, the individual who originally designed and installed this system visited Watson Grinding to conduct repair work on one of the robotic arms in a coating booth and noted that he found the gas detection system to be dismantled and disabled. The designer recommended that Watson Grinding conduct a proper assessment of all the coating booths to ensure safe operation. Watson Grinding did not follow the designer’s recommendation to conduct a hazard assessment of the coating booths.
In 2016, Watson Grinding hired a company, different from the original system designer, to improve the coating process. Engineering drawings were developed for the robotic coating system within certain booths. This effort did not include developing drawings for the automated gas detection alarm, exhaust fan startup, and gas shutoff system. In addition, this company did not conduct work to reconnect this system to ensure the automated alarms, exhaust fan, and gas shutoff would function in the event of a release. The CSB concludes that Watson Grinding did not maintain critical process safety information for the automated gas detection alarm, exhaust fan startup, and gas shutoff system. Such documentation is necessary to maintain the reliability of this critical safety system. The lack of this information contributed to this system not being functional on the day of the incident. Had the system worked, it should have prevented the accumulation of flammable propylene gas within the coating building.
Several years prior to the incident, Watson Grinding disabled the safety function of its automated gas detection alarm, exhaust fan startup, and gas shutoff system, essentially disconnecting it from the computer control system (a PLC), that should have automatically triggered the closure of the remote shutoff valve at the propylene storage tank. Gas sensor calibration contractors visited the Watson Grinding coating building in 2013, 2016, and 2019, and raised concerns in writing that the gas detection system was disconnected from the PLC. Watson Grinding management also had a discussion two weeks prior to the incident that the booths’ gas detectors were not connected and needed to be fixed. Watson Grinding did not address these issues prior to the incident.
In addition, Watson Grinding had no testing program in place to ensure the functional integrity of the automated gas detection alarm, exhaust fan startup, and gas shutoff system. As a result, once the propylene leak began inside Booth 4, the alarms did not activate, the exhaust fan did not start up, and the remote shutoff valve at the propylene storage tank did not close, allowing propylene to accumulate to explosive levels inside the coating building. The CSB concludes that a robust mechanical integrity program would have ensured that an effective inspection, testing, and preventive maintenance system was in place to maintain the integrity of the automated gas detection alarm, exhaust fan startup, and gas shutoff system. Such a program should have ensured a prompt response to reports and inspections about the non-working conditions of those systems.
CLICK HERE for the CSB Report