Lessons from Deepwater Horzon incident investigation by USCG

The US Coast Guard has released its investigation report on the Deepwater Horizon disaster. There are lessons to be learnt for us in the chemical processing industry. The key findings from the report are given below:
"Failure to Use the Diverter Line: When the drilling crew directed the uncontrolled well flow through the Mud Gas Separator (MGS), the high pressure exceeded the system’s capabilities and caused gas to discharge on the Main Deck. Alternatively, the crew could have directed the well flow through a “diverter line” designed to send the flow over the side of the MODU (Mobile Offshore Drilling Unit). Although the diverter line also may have failed under the pressure, had it been used to direct the flow overboard, the majority of the flammable gas cloud may have formed away from the Drill Floor and the MODU, reducing the risk of an onboard explosion.
Hazardous Electrical Equipment: At the time of the explosions, the electrical equipment installed in the “hazardous” areas of the MODU (where flammable gases may be present) may not have been capable of preventing the ignition of flammable gas. Although DEEPWATER HORIZON was built to comply with IMO MODU Code standards under which such electrical equipment is required to have safeguards against possible ignition, an April 2010 audit found that DEEPWATER HORIZON lacked systems to properly track its hazardous electrical equipment, that some such equipment on board was in “bad condition” and “severely corroded,” and that a subcontractor’s equipment that was in “poor condition” had been left in hazardous areas. Because of these deficiencies, there is no assurance that the electrical equipment was safe and could not have caused the explosions.
Gas Detectors: Although gas detectors installed in the ventilation inlets and other critical locations were set to activate alarms on the bridge, they were not set to automatically activate the emergency shutdown (ESD) system for the engines or to stop the flow of outside air into the engine rooms. The bridge crew was not provided training or procedures on when conditions warranted activation of the ESD systems. Thus, when multiple gas alarms were received on the bridge, no one manually activated the ESD system to shut down the main engines. Had it been activated immediately upon the detection of gas, it is possible that the explosions in the engine room area could have been avoided or delayed.
Bypassed Systems: A number of gas detectors were bypassed or inoperable at the time of the explosions. According to the chief electronics technician, it was standard practice to set certain gas detectors in “inhibited” mode, such that gas detection would be reported to the control panel but no alarm would sound, to prevent false alarms from awakening sleeping crew members. Similarly, the crew bypassed an automatic shutdown system designed to cut off electrical power when ventilation system safety features failed, possibly allowing flammable gas to enter an enclosed area and reach an ignition source. The chief electrician had been told that it had “been in bypass for five years” and that “the entire fleet runs them in bypass.”
Design of the Main and Emergency Power Sources: Although the arrangement of main and emergency generators on DEEPWATER HORIZON met IMO MODU Code requirements to have completely independent engine-generator rooms along with independent power distribution and control systems, it did not prevent a total failure of the main electrical power system, when the explosions and fire damaged multiple generators and their related power distribution and control equipment. The design did not adequately take into account that the proximity of the air inlets to each other created a risk that flammable gases could impact all six generators at once.
Crew Blast Protection: DEEPWATER HORIZON did not have barriers sufficient to provide effective blast protection for the crew. Although the barriers separating the Drill Floor from adjacent crew quarters met the standards of the IMO MODU Code, those specifications are only designed to slow the spread of fire, not to resist an explosion. They did not prevent personnel in the crew accommodations area from sustaining injuries.
Command and Control: Because of a “clerical error,” by the Republic of the Marshall Islands, DEEPWATER HORIZON was classified in a manner that permitted it to have a dual-command organizational structure under which the OIM was in charge when the vessel was latched on to the well, but the master was in charge when the MODU was underway between locations or in an emergency situation. When the explosions began, however, there was no immediate transfer of authority from the OIM (Offshore Installation Manager) to the master, and the master asked permission from the OIM to activate the vessel’s EDS. This command confusion at a critical point in the emergency may have impacted the decision to activate the EDS".

The full report is available in this link.