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ANNUAL SUMMARY REPORT ON MOLTEN METAL INCIDENTS IN 2018
October 2019
For the year 2018, 170 reports were received on incidents occurring world-wide as compared to
181 reports received for 2017 and 195 reports for 2016. The attached figures summarize the
reports for 2018 as well as the data for the years 1980 thru 2018.
SUMMARY POINTS:
• For 2018, there were 170 explosion incidents reported, which is comparable to the
historically high number of incidents reported the previous three years.
• There were 148 Force 1 explosions, 20 Force 2 explosions and two Force 3 explosions
reported in 2018. The two Force 3 incidents were both in China. The information
regarding these incidents was taken from government investigation reports and other
Chinese documents, translated into English.
• There were a total of 26 reported injuries, including 8 fatalities, 4 serious and 14 minor
injuries. The two Chinese Force 3 explosions accounted for all 8 fatalities, 2 serious and
2 minor injuries.
• Both Chinese Force 3 explosions occurred during steady state billet casting.
• Excluding the two Force 3 incidents in 2018, there were 14 injuries (2 serious and 12
minor) in 168 incidents. This would be the second lowest total number of injuries since
the beginning of the reporting program in 1981, with only 2017 being lower at 8 injuries.
• Incidents, injuries, and injury rate data were investigated in greater depth for Melting,
Casting and Transfer operations, with injuries and injury rates showing a downward
trend over the last 6-8 years for Casting and Transfer, notable considering the increase
in reported incidents over the past 4 years. Melting injuries have been very low over
the past 10 years (<4) with the exception of 2015 when there was one Force 3 incident
causing 35 Minor injuries.
• As noted in the past, this lower injury frequency can be attributed at least partially to:
1) the increased use of primary and secondary PPE; 2) improvements in PPE materials
and design; 3) an increased focus on hands-free casting operations that remove
personnel from high risk casting operations and 4) possibly increased training and
hazard awareness.
• The 8 fatalities are the highest number since 2007 when there were 19 fatalities, also
the result of a Force 3 explosion in China. For the 9 years prior to 2018 there had been
only two reported Fatalities and 4 in the last 10 years.
• This large number of fatalities in 2018 increased the average yearly fatality rate from
2.5 to 2.7 for the entire reporting period from 1981 through 2018.
• The two Force 3 explosions in 2018 are the most reported in a year over the last 10 years
with 5 years reporting one Force 3 and five years reporting zero Force 3 incidents. The
5 year and 10 year average incident rates increased to 1.0/yr. and 0.7/yr. from the
previous rates of 0.6/yr. for both the 5 and 10 year averages.
• As noted the previous two years, the Force 2 explosions continued to be high at 20; 18
in 2016 and 24 in 2017 as compared to the years 2012 through 2015, which averaged 7
per year.
• As is typical of previous years, in 2018 Reduction process plants experienced the highest
number of incidents as compared to Extrusion, Rolling and Other: 87 incidents with 7
minor injuries and one serious injury.
• Most explosions occurred during the Casting operation (71), as compared to Melting
(46), which historically has had the highest total number of incidents. Starting in 2003,
however, this trend was reversed and now total Casting incidents (1375) have passed
total Melting incidents (1336).
• Most Casting explosions occurred at Start-up, as has been the norm; 55 of the 66
incidents which had this information provided. Five Force 2 and 0 Force 3 explosions
during Start-up. The only 2 Force 3 explosions occurred during Steady-State, these were
the Chinese incidents. Termination had one Force 2 incident.
• Most Casting incidents occurred when casting either DC slab or billet; 41 total. Sow or
mold casting accounted for 29 explosions.
• Most injuries were during Casting (6 Minor, 2 Serious and 8 Fatal), with 12 of the 16
occurring in the two China incidents. Transfer operations accounted for 8 injuries (7
Minor and one Serious). Of note, is that there was only one Melting injury, but it was a
Serious injury.
• As typical of past years, most Melting explosions occurred due to wet or contaminated
scrap, 30 of the 46 incidents with 9 being Force 2. The second highest reason for Melting
explosions was related to tools and drain or skim pans; one Force 2 of the 9 reports.
• There were 40 Transfer operation incidents, all Force 1, almost the same rate as Melting
with 46 explosions. For Transfer explosions, this is almost double the incident rate
experienced the last four years, which averaged 22/yr. Transfer operations accounted
for 7 Minor and 1 Serious injury, while Melting had only one Serious injury.
EXPLANATION & DISCUSSION OF CHARTS AND DATA:
The Aluminum Association classifies molten metal explosions according to Force level, with
Force 1 being the least severe and Force 3 being the most severe. Table 1 below provides
information on the criteria used for rating Force level. Figures 1 through Figure 38 display
various charts and tables as described in the discussion below and are provided after the
discussion.
Table 1: Explosion Rating Force Criteria
LOW SEVERE
Figure 1 displays by year from 1981 thru 2018 the total number of reported incidents, 3886. The
170 explosions reported in 2018 are in the same range of total explosions as in the past three
years. From 2015 through 2018 there was decided upward trend averaging 180 reported
incidents over this timeframe. This rate is higher than the years 2000 through 2007, which
averaged 145 incidents per year.
Figures 2 thru 7 provide Force Level data for the years 1981 thru 2018 in various formats,
including the number of incidents and rates. Figure 2 displays the reported incidents each year
for all three Force Levels. In 2018 there were 148 Force 1, 20 Force 2 and 2 Force 3 explosions.
Figure 3 shows the data for only Force Levels 2 and 3 and Figure 4 displays only Force Level 3.
Both Figure 3 and Figure 4 include the average number of explosions per year for this time frame.
The two Force 3 explosions in 2018 is the first time since 2007 with more than one Force 3
explosion; 2007 had four Force 3 incidents. The average number of Force 3 explosions over the
last 5 and 10 years (1.0/yr and 0.7/yr respectively) continues to show a much lower level
compared the 3.1/yr. average for the entire reporting history from 1981 through to 2019. The
notable downward trend of Force 2 explosions observed in Figure 5 starting around 2008 and
Guidelines Force 1 Force 2 Force 3
Property
Damage None Minor Considerable
Light Minimal Flash Intense
Sound Short cracking Loud Report Painful
Vibration Short and sharp Brief rolling Massive
structural
Metal
Dispersion <15 feet >15 to 50 feet >50 feet
continuing through 2014 was reversed starting in 2016 and has continued through 2018 with an
average of 21/yr. over the past three years.
Figures 6 and 7 display a comparison of all three Force Levels for the entire reporting history
from 1981 through 2018 in two different formats: 1) bar graph and 2) pie chart. Force 1 incidents
account for 75.3% of all incidents, while Force 2 incidents account for 21.7% of the total
compared to 3.0% for Force 3.
Both Force 3 explosions occurred in China with extensive damage to the facilities and numerous
fatalities and injuries to personnel. The information regarding these incidents was taken from
government investigation reports and other Chinese documents, translated into English. One
incident involved 5 Fatalities and 1 Serious injury, while the other had 3 Fatalities, 1 Serious and
2 Minor injuries. Both explosions occurred during steady-state billet casting and were related to
extensive metal bleed-outs into the casting pit. One bleed-out was the result of a broken cable
used to lower and raise the casting table. Indirect causes were reported to be related to
maintenance, worker fatigue, production standards, safety management and inadequate
training. The other explosion involved an undetected trough or launder leak upstream of the
casting table which flowed into the casting pit. Indirect causes included long work hours,
inadequate training, procedures and unrecognized risks. It was notable that the documentation
for both explosions did not mention casting pit water levels or protective pit coatings.
Figures 8 thru 12 provide in various formats injury incident data (Minor, Serious and Fatal) for
the years 1981 thru 2018. The Figure 8 bar chart shows Minor, Serious and Fatal injuries for each
year. In 2018 there were 8 Fatalities, 4 Serious and 14 Minor injuries. As noted above, the two
China Force 3 explosions accounted for 8 Fatalities, 2 Serious and 2 Minor injuries. For the 9
years prior to 2018 there had been only two reported Fatalities and 4 in the last 10 years.
When not including the two Force 3 incidents for 2018, there were 14 injuries (2 Serious and 12
Minor) in 168 incidents. This would be the second lowest total number of injuries since the
beginning of the reporting program in 1981, with only 2017 being lower at 8 injuries. As noted
in the past, this lower injury frequency can be attributed at least partially to: 1) the increased use
of primary and secondary PPE 2) improvements in PPE materials and design, 3) an increased focus
on hands-free casting operations that remove personnel from high risk casting operations and 4)
possibly increased training and hazard awareness.
From 1981 through 2018, there is now a total of 1583 Minor, Serious and Fatal reported injuries
with Figure 9 showing the total injuries in these three categories. The Figure 10 pie chart breaks
this down into percentages: 69.7% Minor, 24.1% Serious and 6.82% Fatal. Unlike recent previous
years, the % of Minor injuries decreased compared to the Serious and Fatal injuries due to the
two Force 3 incidents.
Figure 11 looks at the % of injuries for each injury category per the total number of reported
incidents. This indicates that for each 100 incidents reported there is a 28.4% rate for Minor
injuries, a 9.8% rate for Serious injuries and a 2.6% rate of a Fatality. Since explosions are typically
more likely to be reported when there is an injury of some degree, these numbers are certainly
inflated compared to the situation if all explosions were reported, but this does provide an
indication of the potential rate of an injury per incident.
Figure 12 displays data only related to Fatalities for the reporting program from 1981 through
2018. As indicated above, there have been only two Fatalities reported over the previous 9
years, which is well below the average of 2.7 fatalities per year. Last year this average rate was
2.5/yr.
Figures 13 thru 32 provide more detailed information regarding the 170 reported explosions in
2018 along with similar charts comparing this yearly data with the entire database from 1980
thru 2018.
Figure 13 shows the 2018 data by Force Level for each of the four major categories of operations:
Melting, Casting, Transfer and Other. This can be compared to the same data for the years 1980
thru 2018 in Figure 14. In 2018, most explosions occurred in Casting (71), compared to Melting
(46), Transfer (40) and Other (11). All Other explosions occurred in the Reduction Process.
Shown in Charts 1 & 2 below are: 1) Annual Incidents by the Four Major Categories of Operation;
and 2) Annual Incidents for Melting and Casting. This specific data is only available for the years
1990 through 2018, excluding 2011. Historically Melting and Casting have been the operations
that have had the highest number of explosions. Since the beginning of the program Melting has
always had the highest total up until this year; now total Casting incidents (1375) have passed
total Melting incidents (1336). From the second plot it can be more easily seen that starting in
2003 the trend was reversed with Casting having a higher frequency than Melting.
Chart 1
0
20
40
60
80
100
120
1990 1995 2000 2005 2010 2015 2020
Annual Incidents by Operation1990 - 2018
Melting Casting Transfer Other
Chart 2
In the past, there has typically been a higher percentage of Force 2 and Force 3 explosions in
Melting compared to all the other process categories and in 2018 the data was in this direction
as well, with 12 Force 2 and zero Force 3 Melting explosions compared to 7 Force 2 and 2 Force
3 Casting explosions, no Force 2 or Force 3 Transfer explosions and one Force 2 in the Other
category. The majority of Force 2 and Force 3 explosions for the entire reporting period
continues to be related to the Melting operation by a wide margin as shown in Figure 14.
As discussed above with Figures 8 through 12, there appears to be a downward trend with
injuries. The incident data was investigated further and is newly presented in this year’s report
in Figures 15 through 20. These graphs provide Injury and Incident data for each Melting, Casting
and Transfer operations in two different formats: 1) Injuries and Incidents; and 2) # Injuries per
Incident or Injury Rate. The data is displayed by year from 1990 through 2018, excluding 2011.
Unfortunately, the data is not available for program years prior to 1990 and 2011. In general, the
data shows an expected up-swing in incidents in the early 2000’s and the last 4 years as is seen
previously in Figures 1 and 3. There appears to be a general downward trend in Injuries and
Injuries per Incident, however, over the last 6 to 8 years, especially when considering the
increase in reported incidents over the past 4 years. A downward trend can be observed
especially for the Casting and Transfer operations. Melting injuries and Injury Rate have been
very low for the last 9 years (< 0.05) with the exception of 2015 (>0.7), which had 35 Minor
injuries resulting from one Force 3 explosion when a furnace bled-out into a casting pit. For the
Injury per Incident Rate charts a best fit line is provided along with R2 values, which are very low
due to the scatter in the data. It is a positive sign that the Injury per Incident Rate is trending in
this direction. There are probably a number of reasons for this trend including improvement with
primary and secondary PPE materials, design and use, movement toward ‘hands-free’ casting
removing personnel from the casting pit during cast starts, and increased training and hazard
awareness.
0
20
40
60
80
100
120
1990 1995 2000 2005 2010 2015 2020
Annual Melting & Casting Operation Incidents1990 - 2018
Melting Casting
Figure 21 provides 2018 data regarding the type of charge materials involved in 46 Melting
incidents. As in the past, wet or contaminated scrap was the leading cause of Melting explosions,
with 21 Force 1 and 9 Force 2 incidents in this category. The next highest charging category was
wet tools and drain / skim pans with 9 explosions, followed by 7 incidents due to wet alloy
additions including Mg, Si, Mn and salt flux. There were also 6 incidents due to wet primary sows.
Figure 22 provides a compilation of the Melting explosion data over the years 1980 thru 2018 for
the various types of charging material involved. Wet or contaminated scrap continues to be the
reason for most of the Melting explosions. The second highest area is related to wet alloying
materials. The majority of Force 2 and Force 3 Melting explosions have been related to Scrap
charging. The majority of other Force 2 and Force 3 explosions are related to charging various
types of sows (primary and RSI) and t-bar.
Figure 23 provides a breakdown of the 71 Casting incidents in 2018 in two different ways: by
stage in the process and by type of casting process. As mentioned above, Casting had the highest
number of explosions in 2018. With the increased level of reports over the last 4 years the
Casting incidents have increased significantly with an average of 85 incidents / yr. over the past
4 years compared to 34 incidents / yr. over the previous 10 years. There were 6 Force 2 and 2
Force 3 explosions in 2018, with the two Force 3 China explosions discussed above. As typically
seen in the past, most of the explosions occurred during Start-up (55), with 7 during Steady-State
and 4 during Termination. There were 4 Casting incidents that did not have the casting stage
indicated on the report. The majority of the Casting incidents (41) occurred when casting DC
Billet or Slab. This included 5 Force 2 explosions and 2 Force 3 explosions. The balance of the
explosions (29) occurred with sow or mold casting, 26 Force 1 and 3 Force 2.
Figure 24 shows DC Casting incidents by drop segment for years 1980 - 2018. The historical data
is similar to the 2018 data shown in Figure 23 in that most explosions occur during Start-up,
followed by Steady-state and then Termination.
Figure 25 provides the major causes of the 75 Casting incidents in 2017. They are listed by cast
stage for DC casting and also for mold or sow casting. For DC casting, the main issues were related
to wet equipment, wet starting blocks, butt-curl control and bleed-outs or bleed-overs. Details
of the causes of the 2 Force 3 China billet explosions are discussed above. The main sow and
mold casting incidents were due to wet or cracked molds, and wet equipment. Unfortunately
there were 9 Casting incidents with No Reason for the explosion provided.
There were 40 Transfer explosions in 2018 as shown in Figure 13, Force 1. Figure 26 indicates
that 19 incidents, almost 50%, were related to wet equipment / refractory and 11 were due to
wet tools. This was followed by 9 resulting from wet or rusty drain or skim pans.
Figure 27 provides a bar chart showing the equipment involved in 798 Transfer explosions for
the years 1980 thru 2018. As in the past, Drain Pan explosions are related to the highest number
of Transfer explosions, followed by Trough and then Crucible that were wet or damp.
Injuries by Operation (Melting, Casting, Transfer and Other) resulting from the 170 explosions
in 2018 is shown in Figure 28. The highest number of injuries occurred in Casting with a total of
16. The two China Force 3 billet casting explosions discussed above accounted for 12 of the 16.
Transfer operations had 8 Injuries, with only one in Melting and one in Other (Reduction). In
2017 there were only reported 8 Injuries, with 18 Injuries in 2016 and 57 Injuries in 2015.
Figure 29 provides Injury by Operation data for 1980 thru 2018. The highest number of Minor
and Serious injuries has occurred in the Casting Operation. The Melting Operation accounts for
the highest number of Fatalities, also the highest number of Force 3 explosions as seen in Figure
14. It should be noted that a significant number of injuries have occurred in Transfer Operations,
with 7 Fatalities occurring even from this typically rather straight forward procedure.
Figures 30 and 31 provide incident data vs. the type of Process Plant (Reduction, Extrusion,
Rolling and Recycling) for 2018 and for 1980 thru 2018 respectively. In 2018, more than half (87
of the 181 explosion incidents) were reported by Reduction facilities. All but two of these were
Force 1, the other being Force 2. Rolling accounted for the nest highest at 47, 38 Force 1 and 9
Force 2. Next was Recycling with 21 incidents, 13 Force 1 and 8 Force 2. Of note is that 38% of
the Recycling incidents were Force 2. Extrusion accounted for 15 incidents, including 1 Force 2
and 2 Force 3. As shown in Figure 31, a majority of the explosions reported from 1980 thru 2018
occurred in Reduction facilities; the second highest were reported from Rolling facilities.
The main causes of the 2018 Reduction facility explosions are broken down in Figures 32 and 33.
They are listed by Melting, Casting and Transfer / Reduction incidents. Melting incidents were
related to wet charges and wet tools. The primary reason in the Casting was cracked, wet or
rusty molds for primary casting. Wet equipment and tools, wet sample molds and wet, rusty or
cracked drain pans were the major categories under Transfer and Reduction incidents.
Figure 34 is a bar chart providing 2018 Reduction plant injury information for the 6 Minor and
one Serious Injuries. Transfer operations accounted for 5 of the 7 injuries including the one
Serious injury. The primary reason for the injuries were unpreheated hand tools which resulted
in 4 Minor and 1 Serious injury: one Casting, 3 Transfer and one Reduction.
Rolling plant injuries are shown in Figure 35, which included one Serious and 4 Minor. The
Serious injury occurred from melting wet scrap. The two Minor Casting injuries resulted from
bleedouts resulting from excessive curl and high metal temperature. The two Minor Transfer
injuries were due to wet refractory and equipment.
Figure 36 displays information regarding 13 Casting injuries in Extrusion operations. 12 of the
13, which included 8 Fatalities, were from the two Force 3 China billet casting explosions
discussed above. The other Minor injury was due to a Force 1 start-up explosion due to wet
equipment.
Figure 37 summarizes the 2018 injury data by type of Process Plant and Figure 38 shows this
same data for 1980 thru 2018.
The last page of the report after the Figures provides an Aluminum Association Molten Metal
Incident Report Form or you can link to the form at:
https://www.aluminum.org/resources/electrical-faqs-and-handbooks/safety
RTR – October 31, 2019
ALUMINUM ASSOCIATION
MOLTEN METAL INCIDENT REPORT
Date of Incident: Predominant Plant Activity: SELECT ONE:
(month/year)
Explosion Force – Mark One: Force 1 Characterization: Force 2 Characterization: Force 3 Characterization: For definition of force, click arrow to see a description
Alloy Metal Temperature °F °C Approximate Amount of Metal Involved lbs kilograms
OPERATION:
Charging / Melting Type of Furnace SELECT ONE:
Furnace Capacity lbs mt % Full
Materials Charged
Outside Storage? Yes No Preheat? Yes No Preheat Time/Temp: hrs °F °C
Transfer Type SELECT ONE:
Casting Type SELECT ONE: Type of Product being Cast:
SELECT ONE:
Stage of Operation: SELECT ONE:
Other Describe
Number of Injuries by Type: Minor Severe Fatal
Provide a brief description of the incident and its root cause(s):
.
_________________________________________________________________________________________________________
_________________________________________________________________________________________________________
_________________________________________________________________________________________________________
If Charging/Melting Incident, please
select appropriate Primary and
Secondary cause(s):
Other
Other
If Contaminations (other than moisture) was
selected, please specify:
SELECT ONE:
If Transfer Incident, please select
appropriate Primary and Secondary
cause(s):
PRIMARY CAUSE:
SECONDARY CAUSE:
If Casting Incident, please select appropriate
Primary and Secondary cause(s):
PRIMARY CAUSE:
SECONDARY CAUSE:
If Bleed-out/Bleed-over is selected above, describe
reason for Bleed-out or Bleed-Over:
If Explosion due to Bleed-out/Bleed-over was selected
above, where was the location of Explosions:
SELECT ONE:
If Metal Level Control Problem was selected above,
please specify location of problem:
SELECT ONE:
Please return to:
Curt Wells
Director, Regulatory Affairs
The Aluminum Association.
1400 Crystal Drive, Suite 430
Arlington, VA 22202
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