English subtitles for clip: File:Updated BP Texas City Animation on the 15th Anniversary of the Explosion.ogg
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1 00:00:07,720 --> 00:00:13,700 March 23rd, 2005. The BP refinery in Texas City, Texas. 2 00:00:14,110 --> 00:00:18,980 Several units at the refinery had been shut down for lengthy maintenance projects, 3 00:00:18,980 --> 00:00:25,220 which required nearly a thousand contractors to be on site, along with BP employees. 4 00:00:26,300 --> 00:00:34,120 BP had positioned a number of portable trailers, close to process units, for the use of contractors, and other maintenance workers. 5 00:00:34,930 --> 00:00:41,820 Over the period of months, BP had located ten trailers for workers servicing the Ultracracker Unit, 6 00:00:41,840 --> 00:00:48,350 including a double-wide, wood frame trailer, that contained eleven offices, and was regularly used for meetings. 7 00:00:49,040 --> 00:00:57,340 Though these trailers were located near the Isomerization Unit (ISOM), the occupants were not warned the ISOM unit was about to start up, 8 00:00:57,620 --> 00:00:59,940 a potentially hazardous operation. 9 00:01:01,820 --> 00:01:04,960 At 2:50 am, on March 23rd, 10 00:01:04,960 --> 00:01:14,330 overnight operators began introducing flammable liquid hydrocarbons, known as raffinate, into 170 ft (52 m) tall raffinate splitter tower, 11 00:01:14,330 --> 00:01:18,210 used to distill and separate gasoline components. 12 00:01:19,580 --> 00:01:25,570 Near the base of the tower, there was a single instrument that measured how much liquid it was inside. 13 00:01:26,590 --> 00:01:34,590 It transmitted this information to both the Satellite Control Room, and the Central Control Room, located away from the ISOM unit. 14 00:01:34,740 --> 00:01:40,860 But this level indicator was not designed to measure liquid above the 9 ft (274 cm) mark. 15 00:01:41,490 --> 00:01:47,330 During normal operation, the tower was only supposed to contain about 6 and one half feet (200 cm) of liquid. 16 00:01:47,360 --> 00:01:55,350 But during startups, operators routinely deviated from written procedures, and filled the tower above the 9 ft (274 cm) mark, 17 00:01:55,350 --> 00:02:01,100 concerned if the liquid level fluctuated too low, it would case costly damage to the furnace. 18 00:02:02,210 --> 00:02:10,710 At 3:09 am, as the liquid neared the 8 ft (244 cm) mark, a high-level alarm activated, and sounded in the control rooms. 19 00:02:11,030 --> 00:02:16,030 But a second high-level alarm, slightly further up the tower, failed to go off. 20 00:02:16,630 --> 00:02:23,810 By 3:30 am, the level indicator showed the liquid had filled the bottom 9 ft (274 cm) of the tower, and the feed was stopped. 21 00:02:24,660 --> 00:02:30,180 The CSB later estimated that the liquid was in fact at the height of 13 ft (396 cm). 22 00:02:30,320 --> 00:02:36,000 The operators could not know the actual level, because the indicator only measured up to 9 ft (274 cm). 23 00:02:36,690 --> 00:02:42,360 The Lead Operator had been overseeing the startup from the Satellite Control Room within the ISOM unit. 24 00:02:44,060 --> 00:02:50,870 At 5:00 am, he briefly updated the Night Board Operator in the Central Control Room, about the startup activities. 25 00:02:51,090 --> 00:02:56,710 The Lead Operator then left the refinery early, an hour before the end of the shift. 26 00:02:57,730 --> 00:03:06,020 A new Board Operator arrived in the control room around 6:00 am to start his 30th day in a row working on 12-hour shift. 27 00:03:06,260 --> 00:03:12,030 He spoke briefly with the departing Night Shift Operator and then read the logbook to prepare for the startup. 28 00:03:13,170 --> 00:03:19,360 But the logbook did not clearly indicate how much liquid is already in the tower and the equipment, 29 00:03:19,770 --> 00:03:25,560 and it left no instructions on routing of the liquid feed and products when the startup resumed. 30 00:03:26,330 --> 00:03:32,580 Instead the Control Board Operator only found a one-line logbook entry, that said: 31 00:03:32,580 --> 00:03:36,630 "ISOM – Brought in some raff to unit, to pack raff with." 32 00:03:37,300 --> 00:03:41,270 At 7:15 am, the Day Shift Supervisor have arrived. 33 00:03:41,630 --> 00:03:50,150 Because he was more than an hour late, he received no formal briefing from personnel on the night shift about conditions in the ISOM unit. 34 00:03:51,340 --> 00:03:55,330 At 9:51 am, operators resumed the startup. 35 00:03:55,610 --> 00:04:02,150 They began recirculating the liquid feed, and adding more liquid to the already overfilled tower. 36 00:04:02,160 --> 00:04:10,320 As new feed was added, startup procedures called for regulating the liquid level in the tower, using the automatic level control valve. 37 00:04:10,510 --> 00:04:15,780 But the board operators and others has received conflicting instructions on routing the product. 38 00:04:16,220 --> 00:04:23,650 As the result, this critical valve was left closed for several hours, blocking the flow of liquid from the tower. 39 00:04:25,040 --> 00:04:32,290 A few minutes later, operators lit burners on the furnace to begin heating up the feed, part of the normal startup process. 40 00:04:33,420 --> 00:04:42,750 While the startup was underway, the Day Supervisor left the refinery on short notice, just before 11:00 am, to attend to a family medical emergency. 41 00:04:43,230 --> 00:04:49,400 Contrary to BP's own procedures, no experienced supervisor was assigned to replace him. 42 00:04:50,160 --> 00:04:55,410 This left a single control board operator, now without a qualified supervisor, 43 00:04:55,410 --> 00:05:01,000 to run three refinery units, including the ISOM unit, which needed close attention. 44 00:05:02,230 --> 00:05:11,290 The refinery had eliminated a second board operator position, following corporate budget cuts in 1999, after BP acquired Amoco. 45 00:05:12,520 --> 00:05:21,480 As the startup continued, the tower steadily filled with liquid, reaching a height of 98 ft (30 m), shortly before noon. 46 00:05:21,480 --> 00:05:24,990 More than 15 times the normal level. 47 00:05:26,020 --> 00:05:34,630 But the improperly calibrated level indicator told operators in the control room that the liquid was 8.4 ft (256 cm), and gradually falling. 48 00:05:36,070 --> 00:05:42,010 Furthermore, the control panel was not configured to clearly warn operators of the growing danger. 49 00:05:42,260 --> 00:05:49,640 It did not display flows into and out of the tower on the same screen, nor did it calculate the total liquid in the tower. 50 00:05:51,190 --> 00:05:56,550 Meanwhile, the maintenance contractors, who were not involved in the operation of the ISOM unit, 51 00:05:56,550 --> 00:06:02,710 left their work trailers to attend a company lunch, celebrating a month without a lost time injury. 52 00:06:03,330 --> 00:06:11,670 At 12:41 pm, an alarm activated there's a rising liquid compressed the gases, remaining in the top of the tower. 53 00:06:12,800 --> 00:06:21,740 Unable to understand the source of the high pressure, operators opened the manual chain valve, to vent gases to the unit's emergency relief system. 54 00:06:22,160 --> 00:06:27,890 A 1950s era blowdown drum that vented vapor directly into the atmosphere. 55 00:06:28,890 --> 00:06:34,420 Operators also turned off two burners in the furnace, to lower the temperature inside the tower, 56 00:06:34,420 --> 00:06:36,820 believing this would reduce the pressure. 57 00:06:37,830 --> 00:06:41,500 Nobody knew, the tower was dangerously full. 58 00:06:43,390 --> 00:06:47,900 The operators did become concerned about the lack of flow out of the tower, 59 00:06:47,900 --> 00:06:53,370 and began opening the valve to send liquid from the bottom of the tower to storage tanks. 60 00:06:53,940 --> 00:06:55,710 But this liquid was very hot. 61 00:06:56,020 --> 00:07:05,140 As it flowed through the heat exchanger, it suddenly raised the temperature of the liquid entering high up the tower by 141°F (61°C). 62 00:07:06,000 --> 00:07:08,370 It was now about 1:00 pm. 63 00:07:08,560 --> 00:07:16,010 Contract workers, unaware of the startup and the looming danger, returned from lunch, and began a meeting in the double-wide trailer, 64 00:07:16,460 --> 00:07:19,940 in the corner room, closest to the blowdown drum. 65 00:07:21,780 --> 00:07:29,200 Over the next few minutes, the hot feed entering the tower caused the liquid inside to start to boil, and swell. 66 00:07:29,410 --> 00:07:39,150 Liquid filled the tower completely, and began spilling into the overhead vapor line, exerting great pressure on the emergency relief valves, 155 ft (47 m) below. 67 00:07:39,720 --> 00:07:47,500 At 1:40 pm, the three emergency valves opened, sending nearly 52 000 gallons (197 000 liters) of flammable liquid 68 00:07:47,500 --> 00:07:50,540 to the blowdown drum on the other end of the ISOM unit. 69 00:07:50,790 --> 00:07:58,060 Liquid rose inside the blowdown drum, and overflowed into a process sewer, setting off alarms in the control room. 70 00:07:58,280 --> 00:08:01,990 But the high-level alarm on the blowdown drum failed to go off. 71 00:08:02,950 --> 00:08:08,018 None of the operators knew of the catastrophe unfolding in the ISOM unit. 72 00:08:08,760 --> 00:08:18,153 As flammable hydrocarbons overfilled the blowdown drum, operators nearby saw a geyser of liquid and vapor erupt from the top of the stack. 73 00:08:18,640 --> 00:08:27,569 The equivalent of nearly a tanker truck full of hot gasoline fell to the ground, and began forming a huge flammable vapor cloud. 74 00:08:28,510 --> 00:08:35,175 The vapor cloud expanded in just 90 seconds, engulfing the unit, and the nearby trailers full of workers. 75 00:08:35,476 --> 00:08:42,689 About 25 ft (8 m) from the base from the blowdown drum, two workers were parked in a pickup truck with the engine idling. 76 00:08:43,033 --> 00:08:47,938 As flammable vapor entered the air intake, the diesel engine began to race. 77 00:08:48,246 --> 00:08:51,507 The two workers fled, unable to shut off the engine. 78 00:08:52,070 --> 00:08:57,667 Moments later, witnesses saw the truck backfired, and ignited the vapor cloud. 79 00:08:58,523 --> 00:09:01,544 Powerful explosions swept through the area. 80 00:09:02,100 --> 00:09:08,449 The blast pressure wave accelerated through the ISOM unit, causing heavy destruction, and igniting fires. 81 00:09:09,780 --> 00:09:14,498 The workers in the trailers were right in the path of the explosions. 82 00:09:15,060 --> 00:09:18,000 The fires continued to burn for hours. 83 00:09:19,320 --> 00:09:26,301 12 of the 20 occupants of the double-wide trailer were killed, along with 3 workers in the trailer nearby. 84 00:09:27,286 --> 00:09:34,203 180 workers were injured, many with serious burns, fractures, or other traumatic injuries. 85 00:09:35,220 --> 00:09:38,843 The wooden-metal frame trailers were blown apart from the blast. 86 00:09:39,741 --> 00:09:43,680 Firefighters struggled to rescue the injured, and recovered the victims. 87 00:09:44,430 --> 00:09:52,781 15 large chemical storage tanks were damaged, and the ISOM unit remained shut down for more than two years. 88 00:09:53,790 --> 00:10:02,916 The disaster at BP Texas City was the most serious refinery accident ever investigated by the CSB.