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Analysis of Chemical Plant Heat Exchanger Explosion

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00:00:17.930 00:00:17.940 00:00:19.630 00:00:19.640 June 13th 2013 the Williams guys Mar 11
00:00:26.019 00:00:26.029 2016 and fire that killed two workers
00:00:33.369 00:00:33.379 the Chemical Safety Board launched an
00:00:35.869 00:00:35.879 investigation and issued a case study in
00:00:39.080 00:00:39.090 it the agency describes a number of
00:00:41.450 00:00:41.460 process safety management program
00:00:43.640 00:00:43.650 deficiencies at Williams which set the
00:00:46.490 00:00:46.500 stage for the incident in particular the
00:00:49.910 00:00:49.920 CSB found that the heat exchanger that
00:00:52.070 00:00:52.080 failed was completely isolated from its
00:00:54.530 00:00:54.540 pressure relief valve when pressure
00:00:56.360 00:00:56.370 inside the heat exchanger dangerously
00:00:59.030 00:00:59.040 increased there was nothing to stop a
00:01:01.399 00:01:01.409 catastrophic rupture our case study on
00:01:05.359 00:01:05.369 the explosion at Williams describes an
00:01:07.580 00:01:07.590 ineffective process safety management
00:01:09.590 00:01:09.600 program at the plant at the time of the
00:01:11.870 00:01:11.880 incident
00:01:12.410 00:01:12.420 we urge other companies to learn from
00:01:15.140 00:01:15.150 our investigation to incorporate our
00:01:17.300 00:01:17.310 recommendations at their facilities and
00:01:19.219 00:01:19.229 to assess the current state of their
00:01:21.709 00:01:21.719 process safety culture so that a similar
00:01:24.200 00:01:24.210 accident can be averted
00:01:32.740 00:01:32.750 the Williams guys maar olefins plant is
00:01:35.899 00:01:35.909 located in guys Mar Louisiana the plant
00:01:38.719 00:01:38.729 produces ethylene and propylene these
00:01:41.569 00:01:41.579 are chemicals used in the petrochemical
00:01:43.940 00:01:43.950 industry to make a variety of products
00:01:46.429 00:01:46.439 including plastics and antifreeze within
00:01:49.760 00:01:49.770 the Williams process is a distillation
00:01:51.950 00:01:51.960 column called the propylene fractionator
00:01:54.800 00:01:54.810 it separates a mixture of propane and
00:01:57.590 00:01:57.600 propylene heat exchangers called
00:02:00.200 00:02:00.210 reboilers supply heat to the
00:02:02.630 00:02:02.640 fractionator to boil the propane and
00:02:05.179 00:02:05.189 propylene mixture which is essential to
00:02:07.490 00:02:07.500 the separation process the reboilers are
00:02:10.370 00:02:10.380 shell and tube heat exchangers hot water
00:02:13.339 00:02:13.349 flows through the tubes heating and
00:02:15.920 00:02:15.930 vaporizing propane that flows through
00:02:18.620 00:02:18.630 the shell and back to the propylene
00:02:21.080 00:02:21.090 fractionator the water that flows
00:02:23.120 00:02:23.130 through the tubes contains a small
00:02:24.979 00:02:24.989 amount of oily tar which condenses into
00:02:27.770 00:02:27.780 the water earlier in the process over
00:02:30.020 00:02:30.030 time the oily tar from the water builds
00:02:32.780 00:02:32.790 up on the walls of the reboiler tubes
00:02:34.729 00:02:34.739 this buildup is called fouling fouling
00:02:38.690 00:02:38.700 reduces the efficiency of the reboilers
00:02:41.289 00:02:41.299 periodically the reboilers must be shut
00:02:43.819 00:02:43.829 down to clean the tubes the original
00:02:46.640 00:02:46.650 propylene fractionator design had both
00:02:49.340 00:02:49.350 reboilers running simultaneously but in
00:02:52.640 00:02:52.650 that configuration the fractionator had
00:02:55.160 00:02:55.170 to be shut down when a reboiler fouled
00:02:57.590 00:02:57.600 and needed cleaning to prevent shutdown
00:03:00.770 00:03:00.780 of the propylene fractionator each time
00:03:03.170 00:03:03.180 the reboilers needed to be cleaned in
00:03:05.830 00:03:05.840 2001 new valves were installed on each
00:03:09.590 00:03:09.600 reboiler to allow for operation of only
00:03:12.259 00:03:12.269 one at a time the other reboiler is on
00:03:15.440 00:03:15.450 standby clean and ready for use but
00:03:18.740 00:03:18.750 unforeseen at the time these valves
00:03:20.870 00:03:20.880 introduced a serious hazard they
00:03:23.210 00:03:23.220 isolated the standby reboiler from its
00:03:25.789 00:03:25.799 protective pressure relief valve located
00:03:28.280 00:03:28.290 on top of the fractionator On June 13
00:03:31.599 00:03:31.609 2013 during a daily meeting with
00:03:34.759 00:03:34.769 operations and maintenance personnel
00:03:37.270 00:03:37.280 the Williams plant manager noticed that
00:03:39.580 00:03:39.590 the water flow rate through the
00:03:41.080 00:03:41.090 operating reboiler had dropped gradually
00:03:44.140 00:03:44.150 over the past day the operation
00:03:46.690 00:03:46.700 supervisor informed the group he would
00:03:48.700 00:03:48.710 try to identify the problem he went into
00:03:51.310 00:03:51.320 the plant to evaluate the water flow
00:03:53.440 00:03:53.450 rates the operation supervisor informed
00:03:56.140 00:03:56.150 several personnel that fouling within
00:03:58.720 00:03:58.730 the operating reboiler could be the
00:04:01.000 00:04:01.010 problem and they might need to switch
00:04:02.949 00:04:02.959 the reboilers he attempted to meet with
00:04:05.410 00:04:05.420 his manager so they could get the
00:04:07.030 00:04:07.040 necessary maintenance and operations
00:04:08.949 00:04:08.959 personnel involved who would perform the
00:04:11.470 00:04:11.480 work but his manager was not available
00:04:13.810 00:04:13.820 the operation supervisor returned to the
00:04:16.810 00:04:16.820 field the CSB determined that at 8:33
00:04:20.110 00:04:20.120 a.m. the operation supervisor likely
00:04:23.830 00:04:23.840 opened the water valves on the standby
00:04:26.050 00:04:26.060 reboiler hot water began flowing inside
00:04:28.870 00:04:28.880 the valves blocking the reboiler from
00:04:31.780 00:04:31.790 its protective pressure relief valve
00:04:33.580 00:04:33.590 remained closed but unknown to the
00:04:36.640 00:04:36.650 operation supervisor the standby
00:04:39.100 00:04:39.110 reboiler contained flammable liquid
00:04:41.230 00:04:41.240 propane that had accumulated during the
00:04:43.600 00:04:43.610 16 months the reboiler was out of
00:04:46.150 00:04:46.160 service the hot water quickly heated the
00:04:48.880 00:04:48.890 liquid propane confined inside of the
00:04:51.520 00:04:51.530 reboiler and pressure dangerously
00:04:54.100 00:04:54.110 increased just three minutes later the
00:04:56.430 00:04:56.440 reboiler violently ruptured
00:05:00.029 00:05:00.039 propane exploded from the reboiler and
00:05:02.700 00:05:02.710 ignited to create a massive fireball the
00:05:06.480 00:05:06.490 explosion killed the operations
00:05:08.159 00:05:08.169 supervisor and an operator working
00:05:10.350 00:05:10.360 nearby 167 williams employees and
00:05:14.219 00:05:14.229 contractors reported being injured
00:05:17.059 00:05:17.069 during its investigation the CSB found
00:05:20.609 00:05:20.619 that prior to the explosion the standby
00:05:23.159 00:05:23.169 reboiler had been out of service for
00:05:24.929 00:05:24.939 over a year
00:05:26.100 00:05:26.110 isolated from the process by closed
00:05:28.469 00:05:28.479 block valves but during this 16 month
00:05:31.799 00:05:31.809 period liquid propane unintentionally
00:05:34.889 00:05:34.899 entered the shell of the reboiler
00:05:36.389 00:05:36.399 perhaps through a mistakenly open valve
00:05:38.879 00:05:38.889 or a leaking back valve the CSB
00:05:42.389 00:05:42.399 determined that when the Operations
00:05:44.129 00:05:44.139 Supervisor opened the hot water valves
00:05:46.559 00:05:46.569 to the standby reboiler the propane
00:05:48.600 00:05:48.610 liquid crap inside was heated and
00:05:50.939 00:05:50.949 expanded in volume to completely fill
00:05:53.760 00:05:53.770 the reboiler shell this caused pressure
00:05:56.399 00:05:56.409 to dramatically increase until that we
00:05:59.519 00:05:59.529 boiler ruptured when identifying
00:06:01.589 00:06:01.599 overpressure protection requirements for
00:06:04.110 00:06:04.120 heat exchangers engineers should
00:06:06.389 00:06:06.399 evaluate the scenario that caused the
00:06:08.369 00:06:08.379 williams explosion the hot side of the
00:06:10.829 00:06:10.839 heat exchanger was operated while the
00:06:13.230 00:06:13.240 cold side was blocked in in this
00:06:15.779 00:06:15.789 scenario
00:06:16.409 00:06:16.419 just having a pressure relief valve
00:06:18.659 00:06:18.669 available could have prevented the
00:06:20.639 00:06:20.649 explosion the CSB discovered that in the
00:06:23.610 00:06:23.620 12 years leading to the incident a
00:06:25.769 00:06:25.779 series of process safety management
00:06:27.749 00:06:27.759 program deficiencies caused the reboiler
00:06:30.719 00:06:30.729 to be unprotected from overpressure when
00:06:33.959 00:06:33.969 Williams installed the process block
00:06:35.820 00:06:35.830 valves on the reboilers in 2001 they
00:06:38.730 00:06:38.740 perform the management of change review
00:06:40.709 00:06:40.719 to identify how this action affected the
00:06:43.589 00:06:43.599 safety of the process the CSB found
00:06:46.110 00:06:46.120 however that Williams did not identify
00:06:48.059 00:06:48.069 that the new valves could isolate the
00:06:50.790 00:06:50.800 reboilers from their protective pressure
00:06:52.679 00:06:52.689 relief valve companies are required to
00:06:56.459 00:06:56.469 conduct a management of change review
00:06:58.199 00:06:58.209 before making equipment changes so they
00:07:01.170 00:07:01.180 may consider the impact of that change
00:07:03.119 00:07:03.129 on the safety of the process but the CSB
00:07:06.179 00:07:06.189 discovered that Williams conducted the
00:07:08.040 00:07:08.050 management of change review after the
00:07:10.259 00:07:10.269 process was already operating with the
00:07:12.300 00:07:12.310 new
00:07:12.620 00:07:12.630 valve we concluded that williams
00:07:14.990 00:07:15.000 conducted the delayed management of
00:07:17.510 00:07:17.520 change to meet regulatory requirements
00:07:20.060 00:07:20.070 at that point rather than to use it as a
00:07:22.670 00:07:22.680 tool to identify and control new process
00:07:25.820 00:07:25.830 hazards that was a serious missed
00:07:28.190 00:07:28.200 opportunity to identify the new
00:07:31.040 00:07:31.050 overpressure hazard that was introduced
00:07:33.320 00:07:33.330 to the process by the new valve after
00:07:36.710 00:07:36.720 the 2001 reboiler valve installation
00:07:39.050 00:07:39.060 williams also performed a pre startup
00:07:41.660 00:07:41.670 safety review as required by regulations
00:07:44.390 00:07:44.400 but the CSB found that williams
00:07:47.180 00:07:47.190 reviewers did not respond to key process
00:07:50.330 00:07:50.340 safety questions on the form one of
00:07:52.820 00:07:52.830 those questions asked are pressure
00:07:54.890 00:07:54.900 relief systems in place and operational
00:07:56.980 00:07:56.990 that answer was left blank even though
00:08:01.040 00:08:01.050 the pre startup safety review document
00:08:03.410 00:08:03.420 was incomplete and there were questions
00:08:05.390 00:08:05.400 that were not answered management
00:08:07.850 00:08:07.860 approved the form and the end result was
00:08:10.670 00:08:10.680 b3 boilers were put into service without
00:08:13.130 00:08:13.140 adequate overpressure protection the CSB
00:08:16.280 00:08:16.290 found that in the following 10 years
00:08:18.710 00:08:18.720 Williams performed three process hazard
00:08:21.560 00:08:21.570 analysis or PHAs in 2001 2006 and 2011
00:08:27.590 00:08:27.600 none of the PHAs sufficiently identified
00:08:31.250 00:08:31.260 or controlled the reboiler overpressure
00:08:34.430 00:08:34.440 hazard an internal recommendation from
00:08:37.070 00:08:37.080 the 2006 PHA stated consider locking
00:08:40.969 00:08:40.979 open at least one of the manual valves
00:08:44.180 00:08:44.190 associated with each of the propylene
00:08:46.490 00:08:46.500 fractionated reboilers while that
00:08:49.160 00:08:49.170 recommendation was marked as complete
00:08:51.610 00:08:51.620 CSV found that it was not implemented as
00:08:54.950 00:08:54.960 intended a process valve on the
00:08:57.470 00:08:57.480 operating reboiler was locked open but a
00:09:00.830 00:09:00.840 process valve on a standby reboiler was
00:09:03.650 00:09:03.660 not locked open even though the PHA
00:09:06.620 00:09:06.630 recommended that valves on both reboiler
00:09:09.770 00:09:09.780 should be locked open so that the
00:09:12.050 00:09:12.060 reboiler had an open path pressure
00:09:14.240 00:09:14.250 relief and the CSB found that Williams
00:09:17.990 00:09:18.000 failed to develop a procedure for
00:09:19.640 00:09:19.650 activities performed on the day of the
00:09:21.829 00:09:21.839 incident as following in the quench
00:09:23.720 00:09:23.730 water system was a known issue
00:09:25.610 00:09:25.620 William should have had a written
00:09:27.380 00:09:27.390 procedure to assess falling and switch
00:09:29.990 00:09:30.000 the reboilers furthermore the company
00:09:32.090 00:09:32.100 could have established a routine
00:09:33.380 00:09:33.390 maintenance schedule to prevent
00:09:35.000 00:09:35.010 extensive fouling in the first place one
00:09:37.640 00:09:37.650 of the key lessons from this incident is
00:09:39.680 00:09:39.690 the importance of detail when
00:09:41.900 00:09:41.910 implementing process safety programs if
00:09:44.329 00:09:44.339 a critical detail is overlooked in an
00:09:47.210 00:09:47.220 MOC in a PSS are a safeguard evaluation
00:09:51.440 00:09:51.450 or a PHA a significant hazard can be
00:09:55.130 00:09:55.140 missed and this can lead to a major
00:09:57.740 00:09:57.750 incident sometimes years later at
00:10:00.590 00:10:00.600 Williams the overpressure hazard was
00:10:03.860 00:10:03.870 overlooked in that very first MOC and
00:10:07.220 00:10:07.230 that contributed to the explosion that
00:10:09.740 00:10:09.750 occurred 12 years later to prevent
00:10:12.530 00:10:12.540 future incidents and further improve
00:10:14.690 00:10:14.700 process safety at the guys Mart plant
00:10:16.790 00:10:16.800 the CSB recommended that Williams
00:10:19.130 00:10:19.140 conduct safety culture assessments that
00:10:21.950 00:10:21.960 involve workforce participation and
00:10:24.110 00:10:24.120 communicate the results in reports that
00:10:26.630 00:10:26.640 recommend specific actions to address
00:10:29.180 00:10:29.190 safety culture weaknesses develop a
00:10:31.910 00:10:31.920 robust safety indicators tracking
00:10:33.949 00:10:33.959 program that uses the data identified to
00:10:37.070 00:10:37.080 drive continual safety improvement and
00:10:39.519 00:10:39.529 perform comprehensive process safety
00:10:42.380 00:10:42.390 program assessments to thoroughly
00:10:44.449 00:10:44.459 evaluate the effectiveness of the
00:10:46.220 00:10:46.230 facility's process safety programs in
00:10:49.699 00:10:49.709 its case study the CSB encourages
00:10:52.340 00:10:52.350 companies from across the country to
00:10:54.199 00:10:54.209 review and incorporate the safety
00:10:56.360 00:10:56.370 lessons and recommendations from the
00:10:58.790 00:10:58.800 Williams guys Mart plant investigation
00:11:00.949 00:11:00.959 within their own facilities many of the
00:11:03.890 00:11:03.900 incidents that the CSB has investigated
00:11:05.960 00:11:05.970 could have been prevented if an
00:11:08.300 00:11:08.310 effective process safety management
00:11:09.710 00:11:09.720 program had been in place at the
00:11:11.630 00:11:11.640 facility managers must implement and
00:11:14.300 00:11:14.310 then monitor these programs and
00:11:16.490 00:11:16.500 encourage a strong culture of safety to
00:11:19.160 00:11:19.170 protect workers and the environment for
00:11:23.780 00:11:23.790 further information about the CS B's
00:11:25.760 00:11:25.770 Williams guys mar plant investigation
00:11:28.040 00:11:28.050 please visit CSB gov

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