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4 GUIDELINES FOR MANAGING ABNORMAL SITUATIONS
the occurrence of an abnormal situation, identify its source, and take
corrective action quickly and efficien tly. However, in a dynamic process
control environment, the situation can develop and change rapidly, making
it difficult to determine the nature of the intervention that is required.
For optimal management of abnormal situations, the methodologies,
tools, processes, and training should be established prior to the occurrence
of such an event. This would help personnel recognize abnormal situations
so they can either safely restore normal operations as quickly and efficiently
as possible or take the process to a safe state, and subsequently to capture
lessons learned to prevent similar situations from occurring in the future.
1.3 THE BUSINESS CASE FOR MANAGING ABNORMAL SITUATIONS
The consequences of a failure to prov ide the right intervention during an
abnormal situation could ultimately lead to a major disaster such as a fire,
explosion, toxic release, leading to environmental damage, injury and
fatalities. Opportunities for early identification, allow corrective action to be
taken before the abnormal situation escalates.
Examples of abnormal situations in order of increasing significance and
consequences are included in this chapter. The relationship between
abnormal situations and process safety events is provided in Figure 2.1 in
Chapter 2.
Loss of product quality.
Reduction in operating efficien cy/ increased processing costs.
Deterioration of equipment (e.g., pump bearings, rates of
corrosion), potentially leading to damage to the pressure envelope.
Loss of containment of hazardous substances due to overpressure
or overfilling, potentially leading to major events such as fire,
explosion, toxic release, environmental damage, and fatalities.
Most of these conseque nces include a cost component such as lost
production, equipment damage, injuri es, or personnel costs including
investigation and rectification work; as well as indirect consequences, such
as damage to the environment, fines, and community complaints, even if
the situations are managed well. |
142
near-critical and super- critical processing
replacement of batch reaction processes with semi-batch or
continuous processes reducing the quantity of reactants present
use of processes that are less sensitive to critical operating
parameter variations
These possible choices of process technology and materials are not
always available for each final produc t desired; some of these choices
may not be viable in certain app lications and situations. However,
research personnel should thorough ly vet all possibilities using the
technology knowledge in their respec tive companies, other companies if
this can be arranged, and search th e literature diligently for as much
information as possible to reduce th e hazards and select the range of
inherently safest chemistry possible while achieving the desired product.
Where available and accessible, inform ation describing incidents or near
misses that involve the candidate process technologies should be
reviewed. Those technologies that have contributed to the root cause(s) of process safety incidents or near misses should be withdrawn from
consideration.
8.3.2 Types of Hazards Associated with Research Table 8.1 contains a representative list of the types of process safety
hazards and hazardous events that re searchers attempt to find and to
minimize in searching for the best chemistry.
Table 8.1. Types of Process Safety Hazards
Fires Flash fires
Pool fires
Jet fires
Solid fires (pyrophoric materials or flammable
metals) |
44 PROCESS SAFETY IN UPSTREAM OIL & GAS
It is a truism that what has not been identified cannot be prevented or mitigated.
HIRA activities should be translated into a risk register and action tracking system
for any needed follow-up activities. This is to ensure that no identified issue is
inadvertently neglected during progression through the design phases.
3.2.3 Pillar: Manage Risk
This pillar addresses many important topics for operational safety and management
of risks. These include operating proce dures, safe work practices, contractor
management, training, operational readine ss and conduct of operations. This pillar
also addresses asset integrity, management of change, and emergency management.
All these topics are important to process safety for upstream.
RBPS Element 8: Operating Procedures
These are written instructions for an activity that describe how the operation is to be
carried out safely, explaining the consequences of deviation from procedures,
identifying key safeguards, and addressing special situations and emergencies.
Operating procedures have improved substantially from the past approach of
simply taking start-up procedures from the design contractor. Now procedures are
designed with operating personnel engagement, are periodically updated based on
feedback and any modifications, and use modern layouts with graphics and
photographs to convey key safety messages. Risks from deviations are highlighted
– e.g., if equipment purging is required before start-up, the procedure should
highlight safety risks with shorter duration purging. Barrier management is an
important aspect of process safety and the procedures should highlight relevant
barriers potentially aff ected by the procedure.
RBPS Element 9: Safe Work Practices
Safe work practices are requirements estab lished to control hazards and are used to
safely operate, maintain, and repair equipment and conduct specific types of work.
They include control of work (job safety analysis (JSA), permits and oversight),
breaking containment, energy isolation, SIMOPS (see SIMOPS discussion in
Chapter 5) and other activities. These prac tices are used when developing detailed
procedures, ensuring that requirements ar e met and the appropriate safeguards have
been or will be implemented for the work.
In upstream facilities, there can be severa l parties involved in work – the owner
and its contractors. Interface documents di ctate what safe work practices are used
and specify who approves the work.
RBPS Element 10: Asset Integrity and Reliability
Asset integrity and reliability activities ensure that important equipment remains
suitable for its intended purpose throughout it s service lifetime. This includes proper
selection of materials; inspection, testin g, and preventative maintenance; and design
for maintainability. During the design stage, potential asset integrity problems can
be anticipated and significantly mitigated. |
Doerr, W.W., and Hessian Jr., R.T. (1991). Control toxic
emissions from batch operations. Chemical Engineering Progress, 87 (9),
57-62.
Doherty, M., and Buzad, G. (27 August, 1992). Reactive
distillation by design. The Chemical Engineer , s17-s19.
Donohue, M. D. and Geiger, J.L. (1994). Reduction of VOC
emission during spray painting operations: A new process using
supercritical carbon dioxide. In Preprints of Papers Presented at the 208th
ACS National Meeting , August 21-25, 1994, Washington, DC (pp. 218-219).
Center for Great Lakes Studies, University of Wisconsin-Milwaukee,
Milwaukee, WI: Division of Environmental Chemistry, American Chemical Society.
Dowell, A.M. (1996). Vent systems: life cycle & inherently safer
concepts. In International Conference and Workshop on Process Safety
Management and Inherently Safer Processes, October 8-11, 1996, Orlando, FL (Workshop F: Case St udies on Inherent Safety: Cost
Benefit Analysis; Life Cycle Cost).
Drexler, K. E. (1994). Mole cular manufacturing for the
environment. In Preprints of Papers Presented at the 208th ACS National Meeting , August 21-25, 1994, Washington, DC (pp. 263-265). Center for
Great Lakes Studies, University of Wisconsin-Milwaukee, Milwaukee, WI: Division of Environmental Chemistr y, American Chemical Society.
Drioli, E., and L. Giorno (1 January, 1996). Catalytic membrane
reactors. Chemistry and Industry , 19-22.
Dutt, S. (1996). Safe design of di rect steam injection heaters. In
The 5th World Congress of Chemical Engineering , July 14-18, 1996, San
Diego, CA, Vol. II (pp. 1107-1102). New York: American Institute of
Chemical Engineers. (
Edwards, D.W. and Lawrence, D. (1993). Assessing the inherent
safety of chemical process routes: Is there a relation between plant costs and inherent safety? Trans. IChemE. 71 , Part B, 252-258.
Edwards, D.W. and Lawrence, D. (1995). Inherent safety
assessment of chemical process routes. In The 1995 ChemE Research 475 |
104 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
CCPS 2003, Essential Practices for Managing Chemical Reactivity Hazards , Center for Chemical
Process Safety, John Wiley & Sons, Hoboken, N.J.
CCPS 2004, “CCPS Safety Alert; A Checklist for Inherently Safer Chemical Reaction Process
Design and Operation”, March 1, Center for Chemical Process Safety, of the American
Institute of Chemical Engineers, New York, NY.
Crowl 2019, Daniel A. Crowl and Joseph F. Louvar, Chemical Process Safety, Fundamentals with
Applications 4th Edition ., Pearson, NY.
CP, Cole-Parmer Technical Compatibility Data base, https://www.coleparmer.com/Chemical-
Resistance.
CSB, U.S. Chemical Safety and Hazard Invest igation Board, https://csb.gov/videos/reactive-
hazards/.
CSB 2002, “Hazard Investigation Improving Reac tive Hazard Management”, Report No. 2001-
01-H, U.S. Chemical Safety and Haza rd Investigation Board, October.
CSB 2009, “T2 Laboratories, Inc. runaway reaction”, Investigatio n Report, Report No. 2008-3-I-
FL, U.S. Chemical Safety and Hazard Investigation Board, September.
HSE 2009, “Designing and Operating Sa fe Chemical Reaction Processes”,
https://www.hse.gov.uk/pubns/books/hsg143.htm.
Johnson and Lodal 2003, “Screen Your Facilit ies for Chemical Reactivity Hazards”, Chemical
Engineering Progress , American Institute of Chemical Engineers, New York, NY, August.
Johnson 2003, R. W., S. W. Rudy, and S. D. Unwin, Essential Practices for Managing Chemical
Reactivity Hazards . Center for Chemical Process Safety, Hoboken, NJ USA: John Wiley & Sons.
LB, “Propylene Oxide Product Safety Bulleti n”, LyondellBasell, Houston, Texas, 2020.
NFPA, National Fire Protection Association, Quincy, MA, www.nfpa.org.
NFPA 704, “Standard System for the Identifi cation of the Hazards of Materials for
Emergency Response”
NFPA 491M “Manual of Hazard ous Chemical Reactions”
NFPA43 B “Storage of Organi c Peroxide Formulations”
NFPA 49 “Hazardous Chemicals Data”
NFPA 325 “Fire Hazard Properties of Flamma ble Liquids, Gases, and Volatile Solids”
NFPA 430 “Storage of Liquid and Solid Oxidizers”
NIH, https://webwiser.nlm.nih.gov/getHomeData
NOAA, CAMEO Chemicals, National Ocea nic and Atmospheric Administration,
https://cameochemicals.noaa.gov/.
|
5 • Facility Shutdowns 92
rapid temperature rise, the uncontrolled runaway exothermic
chemical reaction was already occurring
Relevant RBPS Elements
Process Knowledge Management
Training and Performance Assurance
LL2) The Standard Operating Proces s (SOP) did not require regular
lab sampling of flash bottoms in the residue treater as a safeguard
to identify if the concentration was too high [this had been identified
in the Process Hazards Analysis (PHA) ]. However, the SOP for the
start -up included sampling the liquid remaining in residue treater
from the prior run before restarting the unit and then before adding
new feed. The new shift did not kn ow that the lab had reported a
too high concentration in the residue treater before restarting the
residue treater.
Relevant RBPS Elements
Process Knowledge Management
Hazard Identification and Risk Analysis
Operating Procedures
(Note : Other Lessons Learned included addressing an ineffective
Operational Readiness Review (i.e., the Pre-Startup Safety Review)
and emergency response protocols (i.e., Emergency Management)
[50]) |
132
The shell and tube sides of liquid-to-liquid heat exchangers, and the
tubes of air-cooled heat exchangers can be designed to contain the
maximum attainable pressure on eith er side. Such a design eliminates
reliance on pressure relief devices or other active safeguards for overpressure protection, although these may still be necessary per regulatory requirements for heat ex changer shells which are designed
as pressure vessels. (Ref 7.5 Kletz 1998; Ref 7.6 Kletz 2010)
External sight glasses provide simple level detection and can
outperform other level devices when multi-layer process streams are encountered (such as a hydrocarbon- intermediate layer-water mixture
in a decanting vessel). However, they can be prone to external damage with the possibility of loss of cont ainment. Newer, armored sight glass
designs (whether external or built in to the face of the vessel) greatly
reduce the hazard of breakage while still allowing for reliable level
detection. In addition, there are new options available (surface coatings
and/or different glass formulations) to reduce or eliminate chemical
attack of the glass itself.
7.6 SIMPLIFIED PROCESS EQUIPMENT AND DESIGN
In addition to making process equi pment and designs more robust, they
can be simplifiedsimplified, eliminating needless complication, and
reducing the likelihood of failure (le ss is more!). Consider the following
examples:
Buildings containing compressors that process flammable gases should be open to natural vent ilation. This usually means that
the walls are eliminated and replac ed with partially open panels,
and high points are vented properly. Completely enclosing a flammable gas compressor and rely ing on a series of active
controls to detect and trip the machine when leaks occur is not as reliable. (Ref 7.5 Kletz 1998; Ref 7.6 Kletz 2010)
Oxidation processes usually re quire measurement of process
flow stream oxygen levels. For mixed gas streams, where other vapors or liquids are present, th is measurement can be difficult.
Complicated systems that scrub th ese other materials out of the
stream to be measured generally do not work well, so oxygen monitors provide inaccurate measurements. Sometimes a |
347
order to reach a well-ba lanced resolution when technological options
conflict.
Various means for measuring inherent safety characteristics are
available. These include the Dow Fire and Explosion and Chemical
Exposure Indices and the Mond Index. Several inherent safety indices
have also been developed by Khan and Amyotte, Heikkilä, and Edwards
and Lawrence.
13.9 REFERENCES
13.1 Boykin, R.F., Kazarians, M. and Freeman, R.A. (1986).
Comparative fire risk study of PCB transformers, Risk Analysis, 6 (4), 477-
488.
13.2 Center for Chemical Process Safety (CCPS 1989). Guidelines
for Chemical Process Quantitative Risk Analysis . New York: American
Institute of Chemical Engineers, 1989.
13.3 Center for Chemical Process Safety (CCPS 1992). Guidelines
for Hazard Evaluation Procedures, Second Edition With Worked Examples .
New York: American Institute of Chemical Engineers, 1992.
13.4 Center for Chemical Process Safety (CCPS 1993). Guidelines
for Engineering Design for Process Safety . New York: American Institute of
Chemical Engineers, 1993.
13.5 Center for Chemical Process Safety (CCPS 1995). Tools for
Making Acute Risk Decisions With Chemical Process Safety Applications .
New York: American Institute of Chemical Engineers, 1995.
13.6 Center for Chemical Process Safety (CCPS 1998). Guidelines
for Design Solutions to Process Equipment Failures. New York: American
Institute of Chemical Engineers, 1998.
13.7 Dow Chemical Company (1994a). Dow's Chemical Exposure
Index Guide , 1st Edition . New York: American Institute of Chemical
Engineers, 1994.
13.8 Dow Chemical Company (1994b). Dow's Fire and Explosion
Index Hazard Classification Guide , 7th Edition. New York: American
Institute of Chemical Engineers, 1994. |
LIST OF TABLES
Table 2.1. Process safety activities for new engineers ................................................................... 29
Table 3.1. Examples and sources of proce ss safety related regulations ..................................... 42
Table 3.2. Sources of process safety related codes and standards and selected examples .... 43
Table 3.3. Comparison of RBPS elements with U.S. OSHA PSM and U.S. EPA RMP elements .. 46
Table 4.1. Flammability properties ............................................................................................ ....... 63
Table 4.2. Minimum ignition energies for selected materials ....................................................... 63
Table 4.3. Examples of various types of explosions ....................................................................... 70
Table 4.4. Selected combustible dust properties ........................................................................... 72
Table 4.5. Ignition sources and control methods ........................................................................... 73
Table 5.1. Chemical Reactivity types and examples ....................................................................... 92
Table 5.2. Some Reactive Functional Groups .................................................................................. 9 2
Table 5.3. Example form to document screenin g of chemical reactivity hazards ...................... 97
Table 6.1. Example chemical exposure effects ............................................................................ 110
Table 6.2. Effects of oxygen depletion ........................................................................................ .. 113
Table 7.1. Safety data sheet sections and content ...................................................................... 124
Table 7.2. NFPA 704 hazards and rating ....................................................................................... 126
Table 9.1 Tier 1 Process Safety Even t Severity Weighting .......................................................... 151
Table 9.2. Typical Tier 3 and Tier 4 process safety metrics ........................................................ 153
Table 10.1. Asset life cycle stages including project phases ...................................................... 168
Table 11.1. Failure modes and design consider ations for fluid transfer equipment .............. 191
Table 11.2. Common failure modes and design co nsiderations for heat exchangers ........... 197
Table11.3. Common failure modes and design considerations for reactors ........................... 210
Table 12.1. Preliminary hazard identification study overview ................................................... 246
Table 12.2. Checklist analysis overview ....................................................................................... . 247
Table 12.3. What-If analysis overview ......................................................................................... .. 248
Table 12.4. HAZOP overview .................................................................................................... ...... 251
Table 12.5. FMEA overview ..................................................................................................... ........ 252
Table 12.5. Typical hazard evaluation objectives at different stages of a process life cycle .. 255
Table 13.1. Typical discharg e scenarios ....................................................................................... . 274
Table 13.2. Input and output for flash models ............................................................................ 277
Table 13.3. Input and output for evaporation models ............................................................... 278
Table 13.4. Input and output for pool spread models ................................................................ 279
Table 13.5. Input and output for neutral and positively buoyant plume and puff models .... 281
Table 13.6. Input and output for dispersion models .................................................................. 282
Table 13.7. Input and output for dense gas dispersion models ................................................ 286
Table 13.8. Types of fires and explosions ..................................................................................... 286
Table 13.9. Input and output for pool fire models ...................................................................... 287
Table 13.10. Input and output for jet fire models ....................................................................... 288
Table 13.11. Input and output for VCE models ............................................................................ 292
Table 13.12. Input and output for toxic impact models ............................................................. 295
Table 13.13. Effects of thermal radiation ..................................................................................... 295
Table 13.14. Selected overpressure levels and damage ............................................................. 297
Table 13.15. Typical industry building da mage level descriptions ............................................ 297
Table 13.16. Selected consequence analysis models ................................................................. 303 |
Piping and Instrumentation Diagram Development
66
Table 5.11 (C ontinued)
Case P&ID
Adding a pump’s driver control
FC FT
MPM
MCC115
HS
HSH/O/AS/SS/S command
Run status
Common trouble alarm
L/R status stopShutdown command
FV
FE
FO
Nonroutine condition
Considering a temporary strainer
(commissioning)A permanent strainer is already placed
Adding a nonreturning valve in case of reverse flow
FC FT
MPM
MCC115
HS
HSH/O/AS/SS/S command
Run status
Common trouble alarm
L/R status stopShutdown command
FV
FE
FO
Using the minimum flow line on a discharge
line with a control valve to protect the pump from flows lower than minimum flow of the pump
FC FT
FT
FEPM
MCC115
HS
HSH/O/AS/SS/S command
Run status
Common trouble alarm
L/R status stop
Shutdown command
FV
FEFC
FV
FOFO
M |
7 • Unscheduled Shutdowns 129
cause catastrophic failure of piping, valves, and other components,
“…often preceded by audible ‘hammering’ in…piping” [18, p. 2].
As the operations team restarted the ammonia refrigeration
system, an operator manually cleared an alarm that interrupted the
blast freezer evaporator’s defrost cycle, switching the evaporator
directly from its defrost mode to its refrigeration mode without
bleeding hot gases from the evaporator coil. The control system
continued with its normal sequence and subsequently released the
hot gases into the downstream piping containing low -temperature
liquid. The combination of hot gas and cold liquid created the
pressure shocks that ruptured the piping.
Incident i mpact : 14,600 kg (32,100 lbs) of anhydrous ammonia was
released, with the ammonia cloud drifting across a river (Figure 7.2).
More than 150 people reported exposure to the released ammonia,
with 32 people admitted to the hospital and four being placed in
intensive care.
Risk management system weaknesses:
LL1) The control system contained a programming error that
permitted the cycle interruption without addressing the potential
for the hot gas to be inadvertently released into the cold liquid -filled
system. “After an unintended interruption, process upset, or power
outage, refrigeration system operators can avoid the need for
manual intervention to the defrost cycle sequence by programming
the control system to automatically bleed any coil that was in
defrost prior t o the power outage upon restart [18, p. 10] .” Overall,
the company had a weak understanding of its refrigeration system
controls and of the potential for hydraulic shock. (See additional
resource on “water hammer” [20, pp. 171-174, 197].)
Relevant RBPS Elements
Process Knowledge Management
Hazard Identification and Risk Analysis
Operating Procedures
Training and Performance Assurance |
160
methods, as well as the variety of available PHA techniques (Ref 8.14
CCPS 2008). It is also appropriate to revisit the basic chemistry to study
alternate options that may be availa ble, given the unit operations that
are anticipated to be used in the process design.
8.4.1 Unit Operations - General There are a variety of ways of accomplishing a particular unit operation.
Alternative types of process equipme nt have different characteristics
that can be used to achieve a higher level of inherent safety, such as inventory, operating conditions, operating techniques, mechanical
complexity, and self-regulation. Self-regulation means that the
process/unit operation naturally moves itself toward a safe condition, rather than an unsafe condition wh en certain process parameters or
conditions reach a certain point, e.g., as the temperature of a reaction increases the reaction rate decrease s, thereby lowering the temperature
naturally. For the unit operation of re action, the designer could select a
continuous stirred tank reactor (CST R), a small tubular reactor, or a
distillation tower to process the reac tion, each of which has a different
impact on the instantaneous invent ory of materials in the process.
|
THE UPSTREAM INDUSTRY 21
2.2 EXPLORATION PHASE
2.2.1 Onshore
The exploration phase refers to drilling carried out where the primary information
available is from seismic surveys or from nearby wells. The terms conventional and
unconventional are sometimes used to describe reservoirs. A conventional reservoir
is one where buoyancy keeps oil and gas sealed beneath a caprock and these flow
easily into a wellbore for production. Unconventional reservoirs differ in that fluid
trapping mechanisms and other formation properties differ to conventional
reservoirs and require different means to produce. Examples include coalbed
methane, shale gas, tight gas, and tar sand s. The main process safety concerns with
well construction during exploration are a loss of well control leading to a blowout
event, a leak into subsurface water layers , or a leak from surface operations. Onshore
wells can have a direct safety and environmental impact to the public, depending on
their location. Offshore wells are primarily a safety issue for their workforce, but
there can be public safety and environmental impacts as well.
Exploration wells have the objective to determine the extent of the hydrocarbon
deposit and its composition (oil or gas), te mperature, pressure and potential flow
rate and other well characteristics. Information regarding local geology and
hydrocarbon pressure can also be gather ed to improve subsequent drilling and well
control decisions. Multiple exploration wells or appraisal may be needed to establish
the size of a reservoir and whether it is commercially viable.
Key factors in well control are the local ge ology and pore pressure of each strata
in the wellbore. Reservoir properties and how they affect casing requirements and
mud weight are described in more detail in Chapter 4.
Onshore wells can be economically viable with relatively smaller hydrocarbon
reserves than offshore wells. This is because the infrastructure required is usually
much less costly than offshore (i.e., a well pad is required but no jackets or floating
structures) and the workforce may be able to drive directly to the site without the
need for helicopters, marine transport, or offshore accommodations. However, some
onshore wells are in remote areas (arctic, desert, or jungle locations) and might
require helicopter transport. Accommodati on, if needed, is usually adequately
separated from the well construction activity.
While some wells may still be associated with conventional large deposits
which can be exploited using traditional vertical or directional drilling, the fastest
growing area onshore is for shale fields. Sh ale wells employ horizontal drilling once
the hydrocarbon formation is reached. High-pressure hydraulic fracturing or
fracking of the shale layer is used to open higher flow potential channels and release
the trapped oil and gas.
Another type of unconventional reserve is oil sands as may be found in
Venezuela or Alberta, Canada. Although these deposits are very large, the
technology to recover the oil is costly as it may involve mining or heat treating the |
5.2 Learning Models for Individuals | 57
Sections 5.2 and 5.3 will discuss a representative sampling of individual
learning models and corporate change models, highlighting the most useful
features to include in a new model for driving corporate learning from
investigated incidents. Specifically, Section 5.2 will describe learning models,
which tend to address work done by individuals (boxes II and III in Figure 5.2);
Section 5.3 will describe corporate change models, which tend to address
actions taken by the company (boxes I and IV).
5.2 Learning Models for Individuals
This section presents a representative selection of learning models for
individuals and small groups and identifies the characteristics of each model
that are useful for driving continuous process safety improvement.
5.2.1 Multiple Intelligences and Learning Styles Model
Research by the American psychologist Howard Gardner led him to identify of
eight independent forms of intelligence (Gardner 1995 and 2011) summarized
in Table 5.1. Each person has one or more of these intelligences, but generally
not all of them. Gardner showed that everyone learns best when learning
engages his or her specific forms of intelligence.
Table 5.1 Gardner’s Eight Forms of Intelligence
Intelligence Type Summary
Musical Attuned to tones, rhythms, and harmonies, often
has perfect pitch
Visual-spatial Able to visualize in the mind
Verbal-linguistic Attuned to reading, writing, telling stories; good at
memorizing
Logical-
mathematical Good at abstraction, logic, and numbers. Connects
cause and effect
Kinesthetic Control of physical motion, manual dexterity
Interpersonal Perceptive to other’s feelings, prefers to work in
groups
Intrapersonal Reflective, prefers to work alone
Naturalistic Recognizes how biological and physical systems
work together |
Ancillary Systems and Additional Considerations
387
Table 18.7 Win terization methods.
Examples
Minimizing exposed area ●Indoor equipment
●Underground and below frost line equipment
●Diaphragm seal (for fluid‐in instruments)
Internal free draining
No dead legs
Mechanical‐driven flow ●Recirculation by a fluid mover on emergency power
●Warm up system for spare item
OpenOpen
OpenCloseOperating
Thermal‐driven flow
(thermosiphon circulation)
Winterization insulation and
tracingW |
7. Developing content of a job aid 71
Table 7-1: Example task analysis as a table
Task
Description Tanker
driver Storage tank
technician Control room
operator Location
1 Prepare for
offloading N/A Communication
task Communication
task Storage
Control
Room
2 Connect road
tanker Action N/A N/A Offloading
bay
2.1 Connect
earth to road
tanker
grounding
point Action Checking task N/A Offloading
bay
2.2 Connect
hose from
vapor return to
tanker Action Checking task N/A Offloading
bay
2.3 Connect
hose from road
tanker to filling
point Action Checking task N/A Offloading
bay
3 Offload road
tanker Action N/A N/A Offloading
bay
4 Disconnect
road tanker Action N/A N/A Offloading
bay
5 Leave site Action Checking task Communication
task Offloading
bay |
104 | 3 Leadership for Process Safety Culture Within the Organizational Structure
desirable for all of us, but it is essential to leaders if they are to
lead.”
3.7 REFEREN CES
3.1 Chemers M., An integrative theory of leadership . Lawrence Erlbaum
Associates, Publishers, 1997.
3.2 Chin, R., Examining teamwork and leadership in the fields of public
administration, leadership, and management , Team Performance
M anagement, 2015.
3.3 Markwell, D, Instincts to Lead: On Leadership, Peace, and Education ,
Connor Court, Australia, 2013.
3.4 Bird, C., Social Psychology . New York: Appleton-Century, 1940.
3.5 Stogdill, R., Personal factors associated with leadership: A survey of
the literature , J ournal of Psychology, Vol. 25, 1948.
3.6 Mann, R., A review of the relationship between personality and
performance in small groups . Psychological B ulletin, Vol. 56, 1959.
3.7 Arvey, R., Rotundo, M., Johnson, W., Zhang, Z., & McGue, M., The
determinants of leadership role occupancy: Genetic and personality
factors . The Leadership Quarterly, Vol. 17, 2006.
3.8 J udge, T., B ono, J., Ilies, R., & Gerhardt, M., Personality and
leadership: A qualitative and quantitative review . J ournal of Applied
Psychology, Vol. 87, 2002.
3.9 Tagger, S., Hackett, R., Saha, S., Leadership emergence in
autonomous work teams: Antecedents and outcomes , Personnel
Psychology, Vol. 52,
http://onlinelibrary.wiley.com/doi/10.1111/j.1744-
6570.1999.tb00184.x/abstract, 1999.
3.10 Kickul, J ., Neuman, G., Emergence leadership behavior s: The function
of personality and cognitive ability in determining teamwork
performance and KSAs , J ournal of B usiness and Psychology", Vol. 15,
2000. |
9. Human Factors in equipment design 101
9.6 Example of poor equipment Human Factors
Figure 9-4 shows an image of two control screens for a set of filters and vessels.
Design issues with the panel include:
• The screens are mirrored images. The filters 1 to 4 are shown on the left
of top screen and filters 5 to 9 are on the right side of the top screen. On
the lower screen, filters 1 to 4 are shown on the right and filters 5 to 9
are shown on the left. This creates a potential for the operator to
confuse the filters between the two displays.
• The screens have no “mimic” of the connections between the filters and
vessels.
• The lower screen is very cluttered.
• The PSI indications are equidistant between the vessels at the bottom of
the lower screen, creating a potent ial to confuse which vessel the PSI
indicator relates to.
• Some of the indicated values obsc ure the vessel abbreviated names.
• The “FLOW In Out” labeling is not meaningful.
• Red text is used on the upper screen for RESET despite this not being a
warning.
• The gallons are shown in the upper sc reen as seven digit numbers such
as 3808998 which is harder to read than 3,808,998. |
132 | 4 Applying the Core Pr inciples of Process Safety Culture
being treated unfairly when public or media attention of them is
adverse. Once these biases are overcome the organization can
proceed to interface with the public and be a positive im pact on
their culture. If a facility has been a good corporate citizen, they
have a much better chance of being able to weather the
challenging tim es when an incident occurs. A good corporate
citizen can affect the culture of the public in the following ways: Supporting the local comm unity in tangible ways. This
includes both financial donations and volunteering.
Supporting the local schools by providing information
about which they are expert and the tim e of their
employees for presentations, tours, and other information
outreach . Being open with information about their risks and hazards
and not being afraid to dialogue about them.
Above all, being honest, credible, and consistent.
External Emergency Responders
Most facilities rely at least in part on outside emergency
responders. These may come from nearby facilities as part of a
m utual aid arrangement between plants or from public fire and
ambulance services. All emergency responders, regardless of
their origin, are motivated to respond quickly, hoping to limit
dam age, and to address the emergency aggressively. This stem s
from the public’s expectation of emergency responders to protect
them , and is codified in the legal principle of Duty to Act, which
m any see as requiring such aggressive response to emergencies.
This principle may or may not be written into the national or local
law, but its influence exists regardless. Emergency responders
should research how their national and local laws define a
responder’s duty to act both on- and off-duty. (Ref 4.13)
Experience has shown however that aggressive response may,
in many cases, be the worst option. This was reinforced by the •
•
•
• |
56
when the product purification ar ea shut down. This forced the
plant staff to solve the problems that caused the purification
area shutdowns. (Ref 3.22 Wade).
Another acrylonitrile plant that supplied by-product hydrogen
cyanide to various other units e liminated an inventory of 350,000
pounds by having the other units draw directly from the plant. This required considerable work to resolve many issues related
to acrylonitrile purity and unit scheduling. (Ref 3.22 Wade).
A central bulk chlorine system with large storage tanks and
extensive piping was replaced with several small cylinder
facilities local to the individual ch lorine users. The total inventory
of chlorine was reduced by more than 100,000 pounds. This is another example of conflicting i nherent safety strategies. The
use of a central bulk chlorine system reduces the need for
operators to frequently connect and disconnect chlorine
cylinders, a step where increased rates of human error and equipment wear, and failure are possible. But, the disadvantage is a large inventory that could be released if a leak occurs. The
use of several local cylinder facilities results in a greater likelihood of a leak because of the necessity to connect and
disconnect the cylinders more fr equently, but the maximum size
of the leak will be limited to the inventory of one cylinder. In such
cases the total risk must be analyzed and considered; the increased frequency of failure , combined with the reduced
consequences per event when us ing small chlorine cylinders,
must be compared to the combined frequency and consequences of using large bulk chlorine storage and delivery
systems. (Ref 3.22 Wade).
Debris from a fire and explosio n in a pesticide manufacturing
facility narrowly missed damaging a neighboring storage tank containing methyl isocyanate (MIC). Although the explosion was not related to MIC manufacturing , the company recognized the
hazards associated with storing la rge quantities of MIC in above-
ground storage tanks throughout the plant. The company embarked on a redesign of the MIC storage and handling processes at the plant, inco rporating IST/ISD techniques,
eliminating above-ground storag e, reducing overall stored |
6.2 Assess the Organization’s Pr ocess Safety Culture |221
participants with their contact information in case they wish to
com municate privately, or if they think of som ething else.
M oderate Focus Groups. The primary role of moderators is
to get participants talking to each other. Once the conversation
starts, the moderator should then ask probing questions to drive
the discussion to cover the desired topics. M oderators need to
quickly establish rapport with the entire group, and then m aintain
that rapport. If the m oderator cannot establish report, any results
received should be questioned. Moderators should not have a
stake in the outcome of their focus groups. Their sole
responsibility is to gather information and ideas from the
participants.
Successful m oderators: Treat everyone and their comments with respect and hold
participants to the same standard,
Make sure everyone participates equally and prevent any
participant from dominating,
Probe deeper into responses with phrases such as “Tell me
m ore about that… ”, “I can’t read the groups’ reaction. Help
m e out”, and “B oy, that got quite a rise out of everyone.
What is everyone reacting to?”), Validate what they think they hear with phrases like, “So, it
sounds like you are saying… ”,
Know when to remain silent to allow others to comment;
and
Know when to encourage discussions going down a
desired path.
Review records
A limited, though important, portion of the process safety
culture evaluation should involve reviewing records. This can be
particularly useful in detecting Normalization of Deviance . Records
that can reveal Normalization of Deviance include: •
•
•
•
•
• |
Piping and Instrumentation Diagram Development
342
control valve. This takes the place of the solenoid valve
and all the instrument tubing. If you are not sure how the interlock system works in this particular case, you can refer to the cause and effect diagram (shutdown key) using the identification number 49, and this will tell you what action will be taken. In this case it says SD, which means shutdown of the electric motor on the pump.
Let’s have a look at some other examples of SIS symbology.Figure 16.17 shows the SIS control of a fired heater. It
also shows the logic used for the safety function, through the use of an “or” function. This means that if we have low–low flow of product through the tubes or low–low flow of air to the heater, the SIS interlock will activate the pneumatic piston valve on the fuel line. This is a straight -
forward example, so you can imagine how crowded a P&ID would be if we opted to show all instrumentation lines and logic functions for the whole plant.
A variation of this symbology is shown in Figure 16.18.Instead of showing interconnecting lines and logic
functions, we can show the interlock symbols attached to the instruments. In order to see what the SIS control mechanism is, you would refer to number 214 in the shutdown key. Some people condense the symbology even further by combining the two diamonds of each instrument, as shown in Figure 16.19.
Figure 16.20 shows another example of SIS control
symbology.
If we read the logic behind this function, it shows that
if we have a low‐low level in the tank on the left, or a high‐high level in the tank on the right, the SIS will be activated. It does not show precisely what the SIS action will be, but an educated guess would be to shut down the
I
SIS
XV
Air FuelORFSLL
FSLL
Figure 16.17 SIS symbology on a fired hea ter.
I
II
III
SIS
214214214
SISSIS
XV
Air FuelFSLL
FSLLFigure 16.18 Var iation of SIS symbology on a fired
heater. |
176 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
Tools
Tools that may be used to support engineering project design and the
consideration of process safety in the design, include the following.
CCPS Guidelines for Integrating Process Safety into Engineering Projects . This book
addresses all engineering projects, whether upst ream or downstream, large or small. It is
based on a project life cycle approach. (CCPS 2019 a)
The Project Management Institute A Guide to the Project Management Body of Knowledge
PMBOK Guide , is a widely recognized resource fo r effective project management in any
industry. It is available in multiple languages (PMI 2017)
The Oil & Gas Engineering Guide. This book provides a comprehensive description of
engineering project activities, sequence, and docu mentation. It includes many illustrations and
would support an engineer in any discipline to improve their understanding of engineering
project execution. (Baron 2018)
ISO 17776:2016 Petroleum and natural gas industries — Offshore production
installations — Major accident hazard management during the design of new
installations. This document is directed toward larger projects but is applicable to smaller
ones as well. It is also relevant to onshore facilities. (ISO 17776)
Other tools include process simulators and cons equence modeling packages that allow design
alternatives to be quickly evaluated for their contribution to risk reduction.
Summary
An engineering project is typically a collaborati on of the efforts of many different engineers
frequently in different locations. The clarity and accuracy of engineering documentation is
crucial in making sure these engineers communica te effectively and avoid any errors in design.
This documentation evolves as the project engi neering details evolve. It continues into the
operation phase of a facility’s life and is used in management of change evaluating proposed
modifications to the existing facility.
The best time to include process safety consid erations in an engineering design is in the
development stages. Inherently safer design and the hierarchy of contro ls are concepts that
can be used to frame design decisions ensuring process safety is addressed. Building process
safety studies into a project execution strategy and verifying that action items resolved before
startup can support a successful project.
Other incidents
Other incidents involving problems in engineering design include the following.
Union Carbide MIC release, Bhopal, India, 1984
Space Shuttle Challenger, U.S., 1986
Space Shuttle Columbia, U.S., 2003
Air France Flight 447, Brazil, 2009 |
16. Task planning and error assessment 185
Table 16-2: Task planning tactics for potential high-risk situations
Type Potential situation Task planning tactic
Anticipated Adverse weather Define safe operating criteria (for
starting and stopping tasks).
Repeat of past equipment
faults or process trips Test equipment as a task pre-
requisite. Recommend additional
engineered safeguards.
Repeat of past faulty
instrumentation Use a second indicator to, for
example, measure pressure.
Un-
anticipated Novel equipment defects Draw attention to critical Hold or
Stop points where it may be
necessary to stop, regroup and
reassess the risks due to
unanticipated events.
Delays in prior tasks Define task pre-requisites.
Sudden absence of team
members Define team competence and
minimum number of staff as a task
pre-requisite and/or identify
replacement team members.
Latent Fatigue or stress Apply fatigue and staffing controls
as a task pre-requisite. See Chapter
15.
Understaffing or task
overload Define team competence and
staffing level as task pre-requisites.
See Chapter 15.
Poor process
documentation Verify clear and comprehensive
documentation as a task pre-
requisite. See Chapter 1.
Process equipment not fit
for purpose Advise team of equipment
limitations and devise safe system
of work.
Operational pressures or
delays Stipulate “Hold” or “Stop” points and
independent checks to mitigate
time pressures.
|
xxiv
Figure 8.2: Process Design Safe Operating Limits
Figure 8.3: Proper and improper piping design Figure 8.4: Operating Ranges and Limits Figure 8.5: An example of poor assignment of equipment identification
numbers
Figure 8.6: An illogical arrangement of burner controls for a kitchen
stove
Figure 9.1: Security Layers of Protection or Defense in Depth
Figure 9.2: Elements in a CCPS Se curity Vulnerability Assessment
Figure 10.1: Management leadersh ip is the foundation for process
safety management
Figure 10.2: Inherent Safety Review Preparation Figure 10.3: Inherent Safety Review Process
Figure 10.4: Applicability of inherently safer design at various stages of
process and plant development.
Figure 11.1: Plug Valve Operator Figure 11.2: Valve Gearbox Designs Figure 11.3: Inherent Safety-Based Management of Change Process
Figure 11.4: Inherent Safety-Based Incident Investigation Methodology
Figure 12.1: Example of Potential De sign Solutions for Reactor Failure
Figure 13.1 and 13.2: Examples of batch (top) and continuous (bottom)
process
Figure 13.4: Process safety system design solutions for a heat
exchanger failure scenario
Figure 14.1: Major Chemical A ccidents and Releases (MCAR)
Figure 14.2: ISO Stationary Sources MCARs Figure 14.3: County and Richmond ISO MCARs Figure 15.1: Initial Process |
255
(Ref 10.19 Overton). IS reviews at th e design stage of a new process are
most critical for the implementation of inherently safer alternatives.
IS reviews should be conducted ea rly in the development phase of a
new process and then reviewed throug hout the different project design
phases, including the follo wing, where applicable:
During the chemistry form ing (synthesis) phase for
product/process research and de velopment to focus on the
chemistry and process
During facilities design scopin g and development, prior to
completion of the design basis, to focus on equipment and
configuration
During the basic design phase of the project
However, the emphasis on the importance of early consideration of
inherently safer design (ISD) alte rnatives can lead engineers and
managers responsible for the operation of existing facilities to conclude
that ISD is not relevant to them. They have an existing plant with
established technology that is not ea sily or inexpensively changed. With
existing plants, it is often not economically feasible to apply new
inherently safer technology. If the proposed change in volves different
chemicals or significantly different operating conditions, then it is likely
that a major capital expenditure will be required to replace existing equipment (Ref 10.19 Overton).
But ISD is relevant to existing pl ants and processes. Opportunities
often exist to apply ISD principles to an existing plant, making it
inherently safer. Furthermore, t ools such as release consequence
modeling and quantitative risk analys is (QRA) can be beneficial to
understanding the potential benefits of ISD options, helping to gain
management support for implementing ISD modifications to existing facilities (Ref 10.15 Hendershot).
Additional guidance on conducting IS reviews at the following major
process life cycle stages is provided in Section D of the Contra Costa County Industrial Safety Ordinance (ISO) guidance document. See Chapter 14 for a detailed description of this ordinance and its application
(Ref 10.7 Contra Costa County):
Chemistry-forming phase |
DEVELOPING EFFECTIVE RECOM M ENDATIONS 293
12.4.5 Review Recommendations with Management
As shown in Figure 12.1, the next step is a presentation an d review with the
members of line management who have responsibility for operation of the
affected unit. Management may then approve, modify, reject, or implement
the recommendations. This is discussed further under section 4.2.9 –
Recommendation Responsibilities.
At this stage of review, it is often the case that the full incident
investigation report has not yet been written, and only the essential
recommendations have been developed. Line management will consider these key
recommendations as a priority, and the other, less critical
recommendations may not be reviewed with management until the report
has been drafted at a later time.
The investigation team should provide guidance to management on the
risk priorities of the various action s, including those that should be
implemented before restart, where ap plicable. However, management is
responsible for resourcing the recommend ations and assigning priorities for
the actions. This would typically be expressed in the form of a due date.
Where no specific due date is assign ed, there should be clear guidance
provided by management on the timing such as: “Before restart”, “During
next turnaround”, or “Before the year en d”. The definition of “priorities” (e.g.,
1, 2, 3 etc.) should be clearly specified, and will vary between organizations and investigations. A common way to a ssign priority is to consider the
consequences of continuing to operate without implementing the
recommendations. At times, it may be necessary to conduct a more through
risk assessment in order to prioritize the actions.
Once the recommendations have been made and accepted, they should
be communicated effectively thro ughout the organization. The
implementation of the recommendations is further discussed in Chapter 14.
12.4.6 Tracking and Closure of Recommendations
The progress and implementation of recommendations should be closely monitored using metrics as detailed in Chapter 15. This should include:
1. Leading indicator metrics assi gned and frequently reviewed (e.g.,
item priority, no action, in prog ress, due in 30 days, 30 days
overdue, closed, etc.).
2. Be tracked to completion with periodic management review. |
18 | 2 Learning Opportunities
2.2 Resources for Learning
You can learn about process safety incidents from a variety of resources that
are available in various formats. This section will cover the resources most
commonly used throughout the industry.
2.2.1 Process Safety Boards
Increasingly, countries are establishing process safety boards, quasi-
independent governmental or non-governmental bodies that investigate
incidents solely for the purpose of understanding root causes and
communicating findings and recommendations broadly. Table 2.3 lists some
of the better-known process safety boards. Some, like the US CSB and the
Dutch Safety Board (DSB), also produce high-quality, engaging videos to
enhance their communications. Nearly all the incident reports from these
boards have been indexed in the Appendix.
Table 2.3 Examples of Established Process Safety Boards
Country Board name
Brazil Agencia Nacional do Petróleo
Japan Association for the Study of Failure of Japan
Netherlands Dutch Safety Board (DSB)
UK COMAH Competent Authority of the Health and Safety
Executive (HSE)
USA Chemical Safety and Hazard Investigation Board (CSB)
2.2.2 Databases
In today’s world, information is at your fingertips. Databases offer a large array
of information that you can mine in a relatively short amount of time. Given
the efforts to compile and maintain such databases, there may be a fee
associated with their use. In addition to the databases developed by the
process safety boards listed above, other commonly used process safety
databases include:
• Analysis, Research, and Information on Accidents (ARIA 2020a)
• CCPS Process Safety Incident Database (CCPS 2020b)
• DECHEMA ProcessNet (DECHEMA 2020)
• Études de Prévention par l'Informatisation des Comptes Rendus
d'Accidents (INRS 2020) |
102 INVESTIGATING PROCESS SAFETY INCIDENTS
Team members who come from another part of the organization,
experienced contractors, and part-time staff may bring an unbiased, fresh,
objective perspective to the investigation. Some companies choose to avoid
selecting managers or supervisory personnel as team members, (at least
from the same site or unit), since they may inhibit open dialogue among
other team members and might bias the conclusions and recommendations.
The team leader should become familiar with each member’s
competencies and strengths. Team leaders should encourage team
members to admit when they require help or if they do not have the
competence needed for a task. Team members may not be forensic investigative professionals and should not
be expected to contribute beyond
their level of competence or experience. The team leader needs to be flexible
in making and modifying job assignments.
Team size is also a consideration. Some companies recommend the core
team consists of a minimum of two and a maximum of eight people for a
workable size group, but signif icant or complex incidents may involve more
personnel. However, large investigation teams are generally more difficult
to manage and may require a longer timeframe to reach consensus and
closure on findings and recommendations.
Some personal and technical characte ristics to consider when selecting
team members are provided below.
Select personnel with:
• Open, logical minds
• A desire to be thorough
• The ability to maintain an independent perspective
• The ability to work well with others
• Special expertise or knowledge regarding the technology or the
facility
• Experience in technical troubleshooting
• Data analysis skills
• Writing skills
• Interviewing skills
Avoid selecting personnel:
• With preformed opinions on important issues
• Who are difficult for th e team to work with
• Who identify causes of the inciden t before the investigation starts
• Who are too close to the incident, the |
| 157
5
ALIGN IN G CULTURE WITH PSMS
ELEMEN TS
Previous chapters have noted that process safety culture is an
essential factor in the success of a com pany’s or facility’s Process
Safety Management Systems (PSMS). In fact, culture influences
each elem ent in a PSM S and can m ake the difference whether that
elem ent succeeds or fails.
Com panies use a wide range of PSMSs that may be designed
based on regulations, trade group practices such as Responsible
Care®, quality standards such as ISO-9001, or company business
m anagement practices. Many companies follow the Risk B ased
Process Safety (RB PS) approach (Ref 5.1 CCPS), base their system
on it, or developed something similar. Since RB PS spans nearly all
considerations addressed by the PSMSs in use, this chapter will
use it to discuss the alignment of process safety culture with the
PSMS.
RB PS is based on 20 elements, organized into 4 foundation
blocks that link it to the quality principle of Plan-Do-Check-Act.
Figure 5.1 shows the organization of the 20 RB PS elements by
foundation block.
As discussed throughout this book, culture starts with senior
corporate leadership. It is then reinforced by leaders in all other
levels and functions.
Essential Practices for Creating, Strengthening , and Sustaining Process
Safety Culture , First Edition. CCPS . © 2018 AIChE . Published 2018 by
John Wiley & Sons, Inc. |
158 Human Factors Handbook
14.5 Managing competency gaps
14.5.1 Overview
Managing competency requires:
• Monitoring competency levels (com petent vs not yet competent).
• Developing processes to identify and address situations where the
development of competency does not meet the competency standards.
Consideration should be given to some subtle/transient group competency
elements, such as:
• Changes in workload due to start-ups/shut-downs/equipment
preparation;
• Additional skills needed across a team.
The aim of this process is to improve pe rformance, by helping people to reach
and remain at the required level of performance standards. In addition to building error-tolerant systems, setting people up to succeed. To achieve this, people
should receive regular performance feedback. Managers should view dealing with
performance gaps as a normal pa rt of their supervisory role.
It is important to investigate the causes of performance gaps to determine the
next steps of action. These actions could include:
a) Providing refresher learning opportunities.
b) Assigning individuals with an “on-the-job” mentor or coach.
c) Reviewing work conditions or job design.
d) Referring individuals to employee assistance services.
14.5.2 Understanding performance gaps
Prior to assessing the causes of performance gaps, it is
important to check the opportunities for learning. This
includes providing opportunities for transfer of
knowledge into the job environment, where the
knowledge may have been gained in the classroom or via a formal qualification. It is also important to check the
development of job competency.
Higher critical gaps in competency may require immediate intervention to
address the risk that the competency gaps present. Immediate correction of
competency gaps will have positive effect on human performance.
See Chapters 2 and 3
for more information
on Systems Approach
to understand other
factors that impact human performance. |
344 | Appendix F Process Safety Culture Assessment Protocol
of these system s and equipm ent can lead to or contribute to
a process safety incident, and hence deserve the same
consideration as the m ain process systems and equipment
that contain the hazardous materials of concern.
2. Is the PSMS driven by the “it cannot happen here? That is,
serious process safety incidents are not possible or so rare
that the PSM S can be designed and implemented with this
philosophy as a basis.
3. Is the PSMS (particularly the perform ance of PHAs) governed
by the “double jeopardy doesn’t count” philosophy? Double
jeopardy in this context m eans that more than one concurrent
failure should not be considered a credible cause of a process
safety scenario. Note that m ultiple latent (or unrevealed)
failures in place waiting for a single triggering initiating event
should not be treated as a double jeopardy situation.
4. Is the presence of other strong EHS related program s, such as
environmental programs or achievem ent of OSHA’s Voluntary
Protection Program (VPP) Star status used to lim it the scope or
applicability of the PSM S? Note that VPP program inspections
do not focus only on process safety but exam ine the full
spectrum of health and safety program s in a facility.
5. Is the PSM S a detailed set of m anagement system procedures
that represents a “paper only” program that sits on the shelf,
or has it actually been implemented and is it being used?
6. Are the scope and boundaries of PSM S extended to cover
other hazards that are not covered explicitly by regulation but
have been shown by incident history to represent significant
process safety risks? This is an extension of the philosophy of
not adopting a minim alist approach to process safety. An
exam ple of other process safety hazards are combustible dust
hazards.
7. Is there a system in place that ensures an independent review
of m ajor process safety-related decisions? Are reporting
relationships such that impartial opinions can be rendered? |
4 • Process Shutdowns 46
4.2 The process shutdown
The two transient operating modes for a process shutdown are the
shut-down beforehand (mode Type 3, Table 1.1) and the start-up afterward (Type 4, Table 1.1). A pr ocess shutdown may be referred to
as an “outage,” implying that the proc ess equipment is placed in a safe
state (“out of service” such as Lo ck Out, Tag Out {LOTO}) with the
affected equipment properly prepare d by operations and handed over
to other groups, such as engineering, maintenance, or contractors, as needed. This differs from a “turn around,” which implies a larger, more
complicated time where many process units or even an entire facility are undergoing major equipment-related work that stops production altogether (see Chapter 5). As was no ted in Chapter 3, there are usually
special additional handover proc edures between engineering,
operations, and maintenance for safe equipment ownership transfer.
These handover procedures are ad ministrative controls and are
designed and implemented to reduce mistakes, reducing the special
project shutdown-related risks that are associated with the process’s
hazardous materials and energies. Th e plans are designed to reduce
hasty decisions to get the process ba ck up and running quickly that
many place people in harm’s way.
These planned equipment outage times (the “shutdown”) include
product transitioning times which ma y require special procedures or
low product demand times which af fect the equipment scheduling
time. However, since additional planning may be needed for small engineering projects, this chapter provides a brief overview of the
types of projects requiring the diff erent type of transition, such as
when work is scheduled for au thorized changes through a
Management of Change (MOC) prog ram (i.e., changes to procedures,
equipment, or processes), or is scheduled for routine maintenance
activities which correspond to an equipment Inspection, Testing, and
Preventive Maintenance (ITPM) program [14] [21]. |
Piping and Instrumentation Diagram Development
204
temperature for the heat transfer media goes beyond this
number, using steam is not economical and possibly we need to use another more expensive heat transfer medium, like non‐water‐based heat transfer media. These heat transfer media could be a synthetic heat transfer material like Dowtherm
®.
11.5 Heat Exchangers:
Gener
al Naming
Heat exchangers can be named based on different criteria.
Heat exchangers can also be named based on their
types. The most common heat exchanger types are shell and tube heat exchangers, double pipe heat exchangers, plate heat exchangers, and spiral heat exchangers.
In a plant heat exchangers can be named based on
the service they are working on. A heat exchanger could be a “gasoline heat exchanger” or a “treated water heat exchanger, ” etc. It is very common to see the names rough heat exchanger and trim heat exchangers. Generally speaking where there are two heat exchangers in series and the first one is a process heat exchanger (as will be discussed in Section 11.8.1) and the second one is a utility heat exchanger, the upstream heat exchanger is named a rough heat exchanger and the downstream heat exchanger is named a trim heat exchanger. The reason is that the first heat exchanger brings the temperature close to the target temperature but not very close to the acceptable temperature. The second heat exchanger or trim heat exchanger brings the temperature within the acceptable range.
Heat exchangers can be named based on their func -
tions. They can be named any of these four: cooler, heater, condenser, or vaporizer.
Heat exchangers can also be named based on their
phase of the service fluids. They could be named liquid/liquid (L/L), liquid/gas (L/G), gas/gas (G/G).
A heat exchanger can be named based on the type
of energy source or energy sink. They can be named utility heat exchanger or process heat exchanger. A utility heat exchanger is a heat exchanger that uses a utility stream as a heat exchange media. The utility stream could be steam, hot/cold, cooling water, etc. However, in a process heat exchanger both streams are process streams. A process stream means any stream that is not a utility stream and is one of the streams from the process.
For example, a heat exchanger in a plant could be a
natural gas heat exchanger, which is an S&T HX, a heater, and a gas/gas heat exchanger, and it could be utility heat exchanger because the heating media is utility steam.11.6 Heat Exchanger Identifiers
As it was stated in Chapter 4, the identifiers of heat exchangers on P&IDs are heat exchanger symbols, heat exchanger tags, and heat exchanger call‐outs.
11.6.1
Heat Ex
changer Symbol
It has been seen that in some companies they mistakenly
use the PFD symbol of heat exchangers instead of P&ID symbols (Table 11.5).
In PFDs the symbol for heat exchangers doesn’t show
the type of the heat exchanger. This is acceptable as in the preliminary stage of a project the type of heat exchanger is not decided and the general symbol is used in PDF. However at the P&ID stage a more specific symbol should be used.
Table 11.6 shows symbols of different heat exchangers.There is always confusion in recognizing and differen-
tiating between different symbols of S&T HXs. That is the reason that plenty of companies recommend referring to the heat exchanger call‐out (rather than the symbol) to recognize the exact type of S&T HX.
11.6.2
Heat
Exchanger Tag
Not all companies use heat exchanger tags. If heat
exchanger tags are needed to be shown on the body of the P&IDs, they are generally placed inside of the heat exchanger unless there is not enough room or it causes confusion.
Table 11.5 PFD symbols for hea t exchanger types.
Heat exchanger
typeHeat exchanger symbol
Utility heat
exchangersHeater
Vaporizer
Cooler
Condenser
Process
heat exchanger
or |
Containers
163
Floating roofs were invented to store volatile liquids.
The first type of floating roof was the type later called
“external floating roofs. ” The external floating roofs have some fugitive gases that then pollute the air. After envi-ronmental regulations became stricter a fixed roof was installed on the floating roof and “internal floating roof tanks” came on to the scene.
Dome roof tanks are the tanks that have a fixed roof
but the type of their roof is not cone type but dome type.
Figure 9.31 shows different types of cylindrical tank
roofs on P&IDs.
9.17 Tank Floors
Floors of tanks can be of two main types: flat floors and sloped floors (Figure 9.32).
From a construction and also capital cost viewpoint
the best tank floor is a flat one and is the easiest floor to construct. However, in some cases, because of opera-tional reasons, the floor of a tank may need to be con-structed in a sloped form.
There are mainly two types of sloped floors: radially
sloped floors (double sloped) and diametrically sloped floors (single sloped).
Radially sloped floors are of two types: cone down and
cone up. Radially sloped floors are much cheaper than diametrically sloped floors. In fact, diametrically sloped floors are not very common in the industry for different reasons, including their high cost of construction. Diametrically sloped floor tanks are not very common for tanks with diameters more than 20–30 m.
The sloped floors allow easy material movement
within a tank and eventually easy removal of liquids or flowable solids. For example, silos almost always have a sloped floor to facilitate the removal of solids from the silo to the outlet nozzle. The type of sloped floor in silos is the coned‐on radial type. For complete drainage of a tank we need to have a sloped floor. This is especially important when the liquid content of the tank is flam-mable or toxic. In such cases before an operator enters for inspection or maintenance the tank should be com-pletely drained. In that case the tank may have a coned‐down floor or a cone‐up floor.
One important thing that is sometimes overlooked is
that even flat floor tanks will turn to cone‐up floor tanks after a while. The reason is if the weight of the shells on the tank is larger than the weight of floor sheets then the shells push the perimeter of the tank down and conse-quently the center of the floor goes up.
If the intention of a sloped floor is complete drainage
the drain valves should be on the side of liquid accumula-tion. This means that in a coned‐down arrangement the drain valves should be extended to the center of the tank inside of a sump. If the floor arrangement is cone up there should be multiple drain valves around the perimeter of the tank (Figure 9.33).
Arguably the most common tank floors after the flat
floor is the cone‐down type. Here we are going to shed more light on the angle of tank floors in the cone‐down cases.
The angle of cone‐down floors could be in a wide range.
It may start from less than 1° to a large value of 60°. For liquid in tanks, the floor cone‐down angle could be a num-ber from 1° to 5° for low viscosity liquids to a number from 10° to 15° for high viscosity liquids. For flowable solids in silos, the floor cone‐down angle could be a number from 45° to 60°. Interestingly the floor cone‐down angle would be a number around 0.5° if the plan is to have a flat floor Fixed Roof Internal floating roof External floating roof Domed roof
Figure 9.31 Tank r oofs.
Flat
Sloped
Radially sloped Diametrically sloped
Cone down Cone up
Figure 9.32 Tank floors .
Cone down
Cone up or fl atSide
Plan
Sump
Figure 9.33 Drain v alve arrangement for cone‐down and cone‐up
floors. |
KEY RELEVANCE TO PROCESS PLANT OPERATIONS 61
3.4.2.2 Normal Operations
Abnormal situations can also arise during normal operations.
Sometimes, these can be anticipa ted and provided for in advance
through specific procedures – for exam ple, in response to power failures
or other loss of utilities. Other co mmon situations include a pump trip
or a control failure.
The provision of sufficient, approp riately trained operators and field
personnel with adequate resource s and good communications should
ensure an appropriate response to th ese types of upsets. Training could
be provided using process simulators, similar in concept to that provided
to airline pilots. Some upsets may not be anticipated, however, as
detailed in Example Incidents 3.9 and 3.10. |
186 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
or toxic materials can create personnel hazards. A low boiling fluid can flash, so knowledge of
the vapor pressure/temperature is needed.
Example 1. The pump in Figure 11.5 was destroyed because the mechanical seal failed.
The light hydrocarbon being pumped was released ; it ignited and burned – causing extensive
local damage. No one was near the pump when the fire occurred, consequently no injuries
resulted (CCPS 2002 a).
Example 2. A 75 HP centrifugal pump was operated with both suction and discharge
valves closed for about 45 minutes. It was believed to be completely full of liquid. As
mechanical energy from the motor was transferred to heat, the liquid in the pump slowly
increased in temperature and pressure until finally the pump failed catastrophically (see Figure
11.6). One fragment weighing 2.2 kg (5 lb) wa s found over 120 m (400 ft) away. No one was in
the area consequently no injuries resulted (CCPS 2002 b).
Figure 11.5. Damage from fire caused by mechanical seal failure
(CCPS 2002 a)
|
22. Human Factors in emergencies 295
Table 22-5: Leadership in emergency situations
Leadership behavior Description
Coordinating tasks
and workload Taking responsibility for directing all team members’
efforts.
Setting goals and priorities according to situation
demands.
Planning and prioritizing activities to contain the
situation.
Communicating the plan clearly to all team members.
This includes communicating individual tasks, and
how team members’ efforts should be joined
together to contain the situation.
Centralizing
communication Directing relevant information and task “order”.
Receiving or obtaining all relevant information to
allow for effective decision-making.
Developing the team’s
understanding of the
situation Ensuring that all team members have a common
understanding of the situation. This is known as
shared situation awareness. It includes ensuring all
team members understand the problem, the issues,
the tasks, and the order that tasks are to be
completed in.
Managing stress Ensuring that individuals’ negative emotions (i.e.,
panic or anxiety) do not spread, and that each
individual maintains focus on their tasks.
Emergency situations are stressful due to time
pressure, awareness of hazards, and unsuccessful
attempts to contain the situat ion. It is the leader’s job
to manage this.
Teams function best with sound leadership during emergency situations.
Critical situations require the leader to direct, coach, support, and delegate.
Therefore, the leadership style must be matched to the situation and to the people
involved in the situation.
22.4.9 Delegating and communicating
Delegating and communicating are two no n-technical skills that are crucial in
emergencies. These skills are also vital for individuals assuming a leadership |
42 | 2 Core Principles of Process Safety
Table 2.2 (Continued)
Com m unication indicator Observed?
Positive indicators (Continued)
Is the emotional com mitment to process safety
communicated broadly?
Are images used to reinforce communications?
Are communications confirmed to ensure they were
delivered successfully?
Negative indicators
Are members of the organization afraid that they will face
retribution if they challenge bad ideas?
Does an us-versus-them mentality exist between shifts,
departments, or production areas, management vs labor,
employees vs. contractors, etc.?
Do leaders within groups or shifts dislike each other,
avoid each other, etc.?
Do some groups or stakeholders feel like they receive
insufficient comm unications?
2.5 M AIN TAIN A SEN SE OF VULN ERABILITY
Chernobyl, Ukraine, (Form er) USSR, April 26, 1986
Thirty-one people died when a nuclear reactor melted down.
More than two hundred suffered radiation poisoning and
radioactive contamination spread over the western Soviet
Union, Eastern Europe, and Scandinavia. The entire local
community had to be evacuated until the dam aged reactor
could be encased in concrete.
During an unauthorized trial, the cooling water level
decreased to the point that the recirculation pumps would not
operate. As a result, the core overheated and began to |
Hendershot, D.C. (1994). Chemistry—The Key to Inherently
Safer Manufacturing Processes. In 208th American Chemical Society
National Meeting, August 21-25, 1994, Washington, DC (Paper No. ENVR-
135).
Hendershot, D.C. (1995). Conflicts and decisions in the search
for inherently safer process options. Process Safety Progress, 14 (1), 52-
56.
Hendershot, D.C. (1995). Some thoughts on the difference
between inherent safety and safety. Process Safety Progress, 14 (4), 227-
28.
Hendershot, D.C. (1996). Conflicts and decisions in the search
for inherently safer process options. In G.F. Nalven (Ed.). Plant Safety
(pp. 58-62). New York: American In stitute of Chemical Engineers.
Hendershot, D.C. (1996). “The philosophy of inherently safer
chemical process design.” Presen ted at the 89th Annual Meeting and
Exhibition of the Air & Waste Mana gement Association, June 23-28,
1996, Nashville, TN (Session 27).
Hendershot, D.C. (1996). Case stud ies of inherently safe design.
In The 5th World Congress of Chemical Engineering : Technologies Critical to
a Changing World July 14-18, 1996, San Diego, CA (pp. 98-99). New York:
American Institute of Chemical Engineers.
Hendershot, D.C. (1996). How do you measure inherent safety
early in process development? In International Conference and
Workshop on Process Safety Ma nagement and Inherently Safer
Processes, October 8-11, 1996, Orlando, FL (Workshop F).
Hill, R.G. (July, 1995). Inherent safety. Safety & Health News , 4.
Hill, R.G. (April, 1995). On going work—Inherent safety. Safety
and Health News , 1.
Hodel, A.E. (March, 1993). Butyl acetate replaces toluene to
remove phenol from water. Chemical Processing, 53-56.
Hugo, P., and Steinbach, J. (1986). A comparison of the limits of
safe operation of a SBR and a CSTR. Chemical Engineering Science, 41 (4),
1081-1087. 480 |
109
containment due to overfilling, then it can be considered an inherently
safer design. For example, a prominent chemical company designed
their columns to withstand complete filling without cons equences, save
for processing delays. Designing the st ructure of a column at a high-level
hydrostatic load without completely filling it requires that active
safeguards be relied upon to prot ect the column against structural
failure.
The concept of inherent robustne ss also applies to designing
equipment to be impervious to th e corrosion mechanisms that are
present given the materials of constr uction and within the process, and
the operating conditions (i.e., temperature, pH, concentration, viscosity, etc.). The use of specialized alloys w ill eliminate certain types of corrosive
attack. As with the pressure example above, if use of the specialized alloy or material of construction virtually eliminates the possibility of loss of
containment due to corrosion/erosion, then it can be considered an
inherently safer design. Fiberglass rein forced plastic (FRP), high density
polyethylene (HDPE), and steel piping lined with Teflon, PFA, Kynar (PVDF), or other elastomers have increasingly been used in applications where corrosion is particularly se vere. However, the use of FRP and
HDPE always results in a loss of robustness with respect to temperature and pressure resistance. Lined piping systems often contain many flanges, increasing the likelihood of flange leaks. Therefore, these
possibly competing inherent robustness goals (strength and corrosion resistance) must be carefully analyzed and balanced. In these instances, the design becomes a passive safeguar d/layer of protection rather than
an inherently safer one.
The same concept of inherent robustness can be applied for
equipment handling combustible dusts, as the risk of explosion may be
high. The maximum overpressure resu lting from a deflagration of a
combustible dust or flammable vapor in air initially at atmospheric pressure can range from 6 to 9 bar ga uge. It may be feasible to build
process equipment and structures that are strong enough to contain this type of event. When designing a sy stem for combustion containment,
factors such as highly reactive materials, oxygen or other oxidant enriched atmospheres, and congested geometry inside vessels or pipelines that could result in tr ansition to detonation must be |
22 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
occur. Managing risk helps a company or a fa cility deploy management systems that help
sustain long-term, incident-free, and profitable operations.
Learning from experience involves monitoring, and acting on, internal and external
sources of information. Despite a company’s best efforts, operations do not always proceed
as planned, accidents and near misses occur. A near miss is an event in which an accident (that
is, property damage, environmental impact, or human loss) or an operational interruption
could have plausibly resulted if circumstances had been slightly different. Organizations must
be ready to turn their mistakes, and those of others, into opportunities to improve process
safety efforts.
The twenty elements are described in more detail in the following sections. As a new
engineer or someone new to proc ess safety, some of these elem ents will have a more direct
impact on you than others, but all have some impact. For example, learning about the Codes
and Standards that affect your process and locati on will be an important part of your first few
years in industry, whereas you may not be invo lved in Stakeholder Outreach. Nevertheless,
the effort expended by the organization on stak eholder outreach may have a direct impact on
how you will have to approach pr ocess safety at your locale.
Pillar: Commit to Process Safety
The aim of the first pillar is to ensure that th e foundation for process safety is in place and
embedded throughout the organization.
RBPS Element 1: Process Safety Culture
Process safety culture is a commonly held set of values, norms, and beliefs. It can be stated
as “How we do things around here,” “What do we expect here,” and “How we behave when no
one is watching.”
This element describes a positive enviro nment where employees at all levels are
committed to process safety. It starts at the highes t levels of the organization and is shared by
all. Process safety leaders nurtu re this process. Process safety culture is differentiated from
occupational safety culture as it addresses less frequent major incident prevention cultures as
well as occupational safety.
Process safety culture highlights the necessary role of leadership engagement to drive the
process. Safety culture should not be thought of as a passive outcome of a specific work
environment, rather it is somethin g that can be managed and improved.
RBPS Element 2: Compliance with Standards
Regulations, codes, and standards document learnings and good practices. Compliance
requires identifying, developing, and implementi ng them as appropriate. Standards should be
developed for both new construction and exis ting operations. These can be internal and
external standards, national and international codes and standards, and local, state and
federal regulations and laws.
Requirements issued by regulators and consensus standards organizations may need
interpretation and implementation guidance. The element also includes proactive
development activities for corporate, consensus, and governmental standards. |
DETERM INING ROOT CAUSES 221
The basis for logic tree construction lies in the application of logic gates
(Other symbols are used to explai n the overall syst em structure and analysis
boundaries.) The most important logic gates are the OR-gate and the AND-
gate. (Other gates are used occasionally).
Figure 10.5 Generic Logic Tree Displaying the AND-Gate
The AND-gate is such that the output occurs only if all the input events
occur . Event A and Event B and Event C must all occur for the output event
to happen. A generic logic tree with an d AND-gate is shown in Figure 10.6.
Figure 10.6 illustrates an AND-gate: fuel, oxygen, and an ignition source
must be present for a fire to occu r. If any of these components were missing,
the fire would not occur. These conditions are necessary and sufficient for
the fire to occur.
Figure 10.6 Generic Logic Tree for a Fire
|
1. Introduction
1.1 OBJECTIVES, INTENDED AUDI ENCE, AND SCOPE OF THIS BOOK
1.1.1 Objectives
The primary objective of this book is to provide a tool that can be used
by any industrial company that handles hazardous chemicals to better
understand inherent safety concepts and provide guidelines on how to
implement them. The goal of this book is to provide practical guidelines
for illustrating and emphasizing the merits of integrating research,
development, and design into a comp rehensive approach that balances
safety, capital, and environmental conc erns throughout the life cycle of
the process. The authors ho pe that this book will help influence the next
generation of engineers, chemis ts, and current practitioners and
managers in the field of chemical processing.
Inherent safety is a powerful and effective means of reducing
hazards and risk, versus managing risk by adding layers of protection. A
hazard eliminated is one that then doesn’t need to be addressed, which
may have many direct and indirect benefits. Responsible companies
understand the concept and apply it wherever and whenever it may be
useful throughout the life cycle of the process. Companies who have an
internal motivation to apply inhere nt safety routinely to the fullest
capacity “as a way of doing business” recognize that doing so is
beneficial.
In 1996, the Center for Chemical Process Safety (CCPS) published the
first edition of its inherent safety concept book. Lessons learned in the
ensuing years, combined with the fact that inherently safer design (ISD)
was becoming more widely accept ed, prompted CCPS to update the
concept book in 2009. In the subsequent years, inherent safety has been
of greater interest to industry, gove rnment, and the public as a concept
to reduce hazards. In fact, several governmental entities have mandated
consideration of inherently safer de sign for certain facilities. In the
United States, for example, specific regulations exist now for Contra
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482 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
5. Determine the heat addition and heat removal capabilities of the pilot plant or
production reactor.
Don’t forget to consider the reactor agitator as a source of energy – about 2550
Btu/hour/horsepower. Understand the impact of variation in conditions on heat transfer
capability. Consider factors such as reactor fill level, agitation, fouling of internal and
external heat transfer surfaces, variation in the temperature of heating and cooling media,
variation in flow rate of heating and cooling fluids.
6. Identify potential reaction contaminants.
In particular, consider possible contaminants which are ubiquitous in a plant environment,
such as air, water, rust, oil and grease. Think about possible catalytic effects of trace metal
ions such as sodium, calcium, and others commonly present in proc ess water. These may
also be left behind from cleaning operatio ns such as cleaning equipment with aqueous
sodium hydroxide. Determine if these materi als will catalyze any decomposition or other
reactions, either at normal conditions or at the maximum adiabatic reaction temperature.
7. Consider the impact of possible deviat ions from intended reactant charges and
operating conditions.
For example, is a double charge of one of th e reactants a possible deviation, and, if so,
what is the impact? This kind of deviation mi ght affect the chemistry which occurs in the
reactor – for example, the ex cess material charged may react with the product of the
intended reaction or with a reaction solvent. The resulting unanticipated chemical
reactions could be energetic, generate gases, or produce unstable products. Consider the
impact of loss of cooling, agitation, and temperature control, insufficient solvent or
fluidizing media, and reverse flow into feed piping or storage tanks.
8. Identify all heat sources connected to th e reaction vessel and determine their maximum
temperature.
Assume all control systems on the reactor heating systems fail to the maximum
temperature. If this temperature is high er than the maximum adiabatic reaction
temperature, review the stability and reactivi ty information with respect to the maximum
temperature to which the reactor contents coul d be heated by the vessel heat sources.
9. Determine the minimum temperature to wh ich the reactor cooling sources could cool
the reaction mixture.
Consider potential hazards resulting from too much cooling, such as freezing of reaction
mixture components, fouling of heat transfer surfaces, increases in reaction mixture
viscosity reducing mixing and heat transfer , precipitation of dissolved solids from the
reaction mixture, and a reduced rate of reacti on resulting in a hazardous accumulation of
unreacted material.
10. Consider the impact of higher temperature gradients in plant scale equipment
compared to a laboratory or pilot plant reactor.
Agitation is almost certain to be less effective in a plant reactor, and the temperature of
the reaction mixture near heat transfer surfac es may be higher (for systems being heated) |
DETERM INING ROOT CAUSES 219
investigation methods such as a checklist or HAZOP. The inductive methods
may also benefit from use of th e fact/hypothesis matrix tool.
10.5 BUILDING A LOGIC TREE
As previously discussed, the logic tree is a systematic mechanism for
organizing and analyzing the elements of the inciden t scenario. It is a
deductive approach, looking backward in time to examine preceding events
necessary to produce a specified result. This section illustrates building a
logic tree using a simplified fault tree approach and includes the key steps
of the methodology and tips for success ful use. Examples are also provided
to illustrate the application of the logic tree approach.
Standard symbols from systems theo ry are often used to construct the
logic tree diagram. The diagram often takes the form of a qualitative fault
tree, showing the incident as the top event and th e various branches using
conventional AND- and OR-gates. Some investigators have simplified
development of the logic tree by not distinguishing between AND-
conditions and OR-conditions on the first pass through th e tree. Instead,
they use a “universal gate” and determine its status as the investigation
progresses. Other techniques use only AND-gates. Other similar methods
(such as causal tree) will be somewhat different in terms of symbols and the
look of the tree, but the basic concep ts are the same. Various proprietary
software programs are available to facilitate development of logic trees.
The trees in this sectio n will be drawn from top to bottom. Some similar
techniques are drawn from left to right or right to left. In a systematic way,
the logic tree provides a structure for thoroughly considering possible
multiple causes. Each of the succeeding lower levels is developed by
repeatedly asking “Why?” until a level is reached that allows examination of
a management system or a small segment of it. Th e particular management
system would then be scrutinized for deficiencies that caused or contributed
to the incident. Identi fying deficiencies provides a foundation for
recommended improvements and preventive action.
Many deductive investigation techni ques use logic tree diagrams. A
partial list of these methods includes fa ult tree analysis (FTA), causal tree
method (CTM), and Why Tree. These methods are described in Chapter 3. |
KEY RELEVANCE TO PROCESS PLANT OPERATIONS 67
Example Incident 3.12 – Loss of Site Power Supply ( cont. )
The site had identified critical power supplies and provided UPSs and
several self-starting backup genera tors for when the power supplies
failed. The generators were tested on a monthly basis, but the test did
not include synchronization to the site systems. When they were
required, several of them failed to synchronize and tripped out,
resulting in loss of critical power supplies to the control system for a
high-integrity steam generator. Once that was lost, steam supplies to
critical turbine-driven machinery fa iled, leading to loss of compressed
air for the instrumentation system.
Each of the outlet valves from the 12 crackers was motor-driven with
a manual handle in case of failure of the motor drive, as was the
situation here, although each one re quired over 100 turns before the
valve could be closed. Operators st arted to close these valves, once
they realized that the cracker tubi ng was rupturing, to prevent the
reverse flow of hydrocarbons. Howe ver, there was not enough time,
or enough staff, to close all 12 valves before the major, uncontrolled
fires were burning in the crackers.
Lessons learned in relation to abnormal situation management:
Services Failure: The site thought that they had adequately
prepared for this type of situat ion via the HIRA process, however,
the backup systems failed when they were required.
Procedures: There were procedures in place to test backup utility
services, although these did not fully simulate emergency
conditions of total power loss. Th e backup to the backup (manual
closure of valves) was impractical due to lack of time and labor
availability.
|
2 • Defining the Transition Times 18
Table 2.1 Definitions for the modes of operation.
The operating mode when the process is operating between its start-up
and shut-down phases (its transient operating modes) and within its
normal operating conditions (its standard conditions).
For a Continuous Process (an open, steady-state system)
The time when the process conditions, such as the flow rates,
temperatures, and pressures, are not changing over time - when the
process is at the normal operating conditions and within its standard
operating limits.
For a Batch Process (a closed, unsteady-state system)
The time when the process conditions, such as temperatures,
pressures, and concentrations, are changing over time - when the
process is at the normal operating conditions and within its standard
operating limits.
Abnormal Operations
(Mode)The operating mode that occurs during normal operations when there
is a process upset and the process conditions deviate from the normal
operating conditions.
The operating mode that occurs after abnormal operations, when
either:
1) a shut-down is activated due to a significant process upset that
exceeds the safe operating limits during abnormal operations.
2) an emergency shut-down occurs due to a loss event with the loss of
containment of hazardous materials or energies during normal
operations.
The time associated with simultaneous or adjacent activities, such as
drilling and operations or construction and operations, not normally
carried out together.
Note 1: This may introduce novel hazards not anticipated in prior HIRA
studies for the facility and bring together staff not familiar with all the
risks and how these are managed for the other activity. A formal
SIMOPS plan and staff training is usually required to address these
aspects safely.
Note 2: SIMOPS includes work associated with an engineering project
or maintenance activity on equipment or processes that are not
operating yet (i.e., are in their construction or commissioning stage) or
have been taken out of operations for a scheduled inspection, test, or
preventive maintenance (ITPM) activity.Normal Operations
(Mode)
Emergency Operations
(Mode)
Simultaneous
Operations (SIMOPS) |
62 PROCESS SAFETY IN UPSTREAM OIL & GAS
any problems with subsea BOPs and to enable functioning of the BOP (by manually
turning valves) when built-in redundant systems have failed.
4.1.7 Well Completions
Well completion equipment is designed to withstand all expected loads throughout
the well life. During completion activities, the wellbore is filled with a dense
completion fluid to maintain sufficient hydrostatic pressure. Many completion
sequences provide for removing the heavy weight mud so that the well is perforated
through tubing in a clean fluid.
The BOP is removed and replaced with a wellhead valve assembly termed a
Christmas tree. The wellhead includes a surface safety valve that terminates flow if
required. Offshore wells often install a sub-surface safety valve (SSSV), typically
30 m (100 ft) below the seabed, a regulatory requirement in the US. Onshore sour
gas wells may also employ SSSVs. SSSVs are not considered a permanent barrier.
They may be used as a temporary barrier in combination with a mechanical barrier
(e.g., plug or back-pressure valve) for BOP or Christmas tree removal.
The annular space between the productio n tubing and the casing is sealed,
normally using a mechanical sealing devi ce to prevent hydrocarbons from flowing
up the annulus.
4.1.8 Well Workovers or Interventions
Workovers and interventions are similar activities with the aim to maintain, restore
or increase productivity of a well or en sure well integrity. A workover usually
requires a drilling or completion rig with all its equipment to be placed over the
wellbore, whereas an intervention uses equi pment that may not require a rig. Both
activities require tools of various types to be inserted into the well to do the required
work.
A loss of well control is possible during well workovers or interventions. Dense
fluid is used as the primary safety barrier during workovers. If the Christmas tree is
removed, a BOP is installed. This prov ides the two safety barriers required.
Alternative arrangements are employed if coiled tubing is used in a workover.
Explosive charges are used in some workover activities for cutting or creating
entry points for hydrocarbon production or removing obstructions within the well
and formal explosives safety practices are required.
4.1.9 Depleted Wells
When reservoirs have insufficient hydrocarbon reserves or have been depleted by
production, the wells are plugged and abandoned. Wells that are to be left and
returned to for later production are temporarily abandoned. In a temporary
abandonment, a barrier is not required to extend across the full section of the well
and include all annuli. |
8. Format and design of job aids 89
Figure 8-7: An example of icon and color coding
Operating limit: The maximum operating pressure is 5
bar.
Caution : Corrosive liquid may drip from the hose. Care
must be taken when disconnecting flexible hose from the
road tanker.
Warning : Entry of oxygen into the vessel enables auto-
ignition of heated flammable gas. An inert nitrogen gas
blanket must be maintained. Control vessel level at all
times to ensure liquids do not exceed 70% level.
Hold point: Stop work after inserting the second blind into
the manifold. Ask the team leader to verify the blinding.
Operating rule: The recirculation pump must be
operating before turning on the heating elements.
Information: The purpose of the procedure is to ensure
safe isolation of the tank prior to entry.
|
Piping and Instrumentation Diagram Development
36
also based on the plot plan of the plant. A typical intercon-
necting P&ID sheet is shown in Figure 4.24.
4.4.5 Detail P&IDs
The l
ast part of a set of P&IDs is the detail P&IDs.
When some items are removed from the main P&IDs for the sake of legibility and put on other P&IDs, those
are the detail P&IDs. Therefore, each sheet of the detail P&ID should be referred from one or more main P&IDs.
The systems shown on detail P&IDs comprise
sy
stems that have any of the following features or a
combination:Table 4.7 Differ ent services of network P&IDs.
Distribution or
collection networkUtility or nonutility networkContinuous flow or intermittent flow
Utility distribution P&IDs Distribution Utility Continuous flow or
intermittent flow
Utility collection P&IDs Collection Utility Continuous flow or intermittent flow
Relief and blowdown P&IDs Collection Nonutility Intermittent flow
Fire water distribution P&IDs Distribution Can be considered as
utility or nonutilityIntermittent flow
Sewer collection system P&IDs Collection Utility Intermittent flow
Blanket gas distribution P&IDs Distribution Utility Intermittent flow but very frequent
Vapor recovery unit P&IDs Collection Utility Intermittent flow but very frequent
Figure 4.21 A Utilit y Generation P&ID. |
116 | 4 Applying the Core Pr inciples of Process Safety Culture
daily, such as potential conflicts of interest, wrongful use
of resources and mism anagem ent of contracts and
agreements.
Characteristics of Ethical Organizations
Ethics experts have identified several characteristics com mon
to highly ethical organizations: (Refs 4.6, 4.4):
They are led by people committed to process safety and
ethics for its own sake, not solely for compliance - Establish
an Imperative for Safety .
They see their activities in terms of a purpose that
m em bers of the organization highly value, which includes
ethics and process safety. They also see leaders act
consistently and credibly with that purpose. And purpose
ties the organization to process safety. Establish an
Imperative for Safety, Provide Strong Leadership. They are obsessed with fairness. Their ground rules
emphasize that in any relationship, the other persons'
interests count as much as their own. Workers see leaders
acting fairly and know they can follow instructions without
fear of m istreatment. Foster Mutual Trust. They keep communication channels open, especially
upward. Leaders and supervisors then act responsively,
even to bad news. This helps ethical issues to surface
before they become a crisis. Leaders also encourage peers
to communicate on sensitive issues including those of
process safety and ethics and other critical areas. Foster
Mutual Trust, Defer to Expertise. Responsibility is individual rather than collective. Each
person assum es personal responsibility for their actions in
support of the organization. The organizations’ ground
rules mandate that individuals are also responsible to
them selves. Provide Strong Leadership. •
•
•
•
• |
Table C-1 continued
HF Competency Performance/ Knowledge
Criteria Level 1 - Operator Level 2 - Supervisor* Level 3 - Manager**
Non-technical skills
Agile Thinking Understands the concepts of
agile thinking Can describe the concept of
agile thinking and how this
concept links to other non-
technical skills (e.g., decision-
making) Can recognize the
importance and need for
application of agile
thinking in dynamic,
rapidly evolving
situations Is able to lead discussion on
the concept of agile thinking
and its contribution to
effective emergency
management
Is able to apply agile thinking
in rapidly changing; evolving
situations Can identify situations when
agile thinking is required Can recognize the need
for application of agile
thinking
Is able to apply agile
thinking in emergencies
to control the situation if
current course of action
is not effective Is able to assess the need for
agile thinking in evolving
situations
Is able to apply lead agile
thinking in emergencies to
control the situation if
current course of action is
not effective
|
DETERM INING ROOT CAUSES 259
The following example illustrates the importance of correcting
weaknesses that led to human error by an individual:
Structured root cause analysis un covers the underlying reasons for human
error and consequently provides gu idance on suitable corrective actions.
Humans make errors, so it is impo rtant to design sy stems that detect and
correct an error before it leads to a serious consequence. Chapter 11
provides extensive informat ion related to human factors that is applicable to
root cause analysis.
10.11 SUM M ARY
The success of the cause analysis is a direct function of the quality of available
and discovered information as well as the perceptiveness of the incident
investigation team. The goal of th e cause analysis is to find the information
needed to determine cost effect ive and practical preventive measures.
Simple and minor incidents may be sa tisfactorily investigated using the
5 Whys methodology, providing its i nherent weaknesses are understood and
appropriately managed. It may also be used to supplement other techniques.
For more complex events, the use of more structured methods, such as
the logic tree and predefined tree tec hniques, can ensure that multiple
underlying root causes can be found. By applying the iterative loop, testing
the facts, and syst ematically applying quality control tests, incident
investigators can uncover the multiple underlying causes that could
otherwise result in future incidents.
If a component fails because of a human error, “counseling”
the worker may prevent him or her from performing the same
error again, but what of the other members of the operating
crew? Conditions that led to the original failure remain, so others are still prone to committing the same error. Many
repeat occurrences could be avoided if the correct information
and reasons for those errors are uncovered by the investigation team and (1) corrected and/or (2) communicated to others who
might also be at risk of committing them. |
Table B.2. Generic Severity (S) Rankings
Category Low
(1) Medium
(2) High
(3) Very High
(4)
Health &
safety impacts Minor injury or
health
effect Moderate injury or
health
effect Major injury or
health
effect; offsite public impacts Fatality offsite,
multiple
onsite injuries or fatalities,
Asset damage (replacement cost) Low Medium Moderate High
Business interruption (days unavailable or $) Low Medium Moderate High
Environmental impact (remediation damages) Low Medium Moderate High
458 |
412 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
Forest 2018, “Don’t Walk the Line – Dance it!”, Process Safety Progress , Volume 37, No. 4,
December.
IChemE, https://icheme.myshopify.com/collect ions/bp-process-safety -series/products/bp-
process-safety-series-set- of-16-books-paperback.
Leveson 2005, Leveson, Nancy G, “Software System Safety”,
http://web.archive.org/web/20101108055426/http: //ocw.mit.edu/courses/aeronautics-and-
astronautics/16-358j-system-safety-spr ing-2005/lecture-notes/class_notes.pdf.
OSHA, https://www.osha.gov/OshDoc/data_Hu rricane_Facts/confine d_space_permit.pdf.
Shigenaka 2014, “Twenty-Five Years After the Exxon Valdez Oil Spill: NOAA’s Scientific
Support, Monitoring, and Research”, NOAA Office of Response and Restoration, Seattle, WA.
Wermac, http://www.wermac.org /valves/valves_c ar_seal.html
|
370
misunderstanding or lack of apprec iation of the impacts of some IS
modifications - may create a barrier to both common expectations, and
to an accepted definition of “feasib ility” between the public and industry.
Any move in an inherently safer direction is likely to be a positive risk reduction move and should be encouraged.
14.2.2 New Jersey Toxic Catastro phe Prevention Act (TCPA) and
Prescriptive Order for Chemical Plant Security This section focuses on a regulation for inherently safer studies in the
state of New Jersey (NJ), USA, prov iding another regulatory framework
that can help companies evaluate ther e IS options. The first discussion
covers the IS requirements of the NJ Toxic Catastrophe Prevention Act
(TCPA), covers its Prescriptive Order for Chemical Plant Security, covers
its specific regulations defining “fea sible” IS studies, discusses results
after implementing the Prescriptive Order, and some lessons learned
from this approach.
New Jersey is the United State’s most densely populated state. It has
a large number of chemical and petrol eum facilities, and is also a locus
of pharmaceutical, biotechnology, an d other life-science industries.
These and other industrial plants that produce or use hazardous chemicals are clustered in the Dela ware and Passaic River valleys, and
around the well-developed transporta tion corridor linking the New York
and Philadelphia metropolitan regions.
The combination of critical chemical infrastructure in close proximity
to high population centers has prov ided an incentive for the state to
enact particularly stringent programs to reduce the risk of release - both
accidental and intentional - from su ch facilities. The NJ state Toxic
Catastrophe Prevention Act (TCPA) regulation (Ref 14.11 TCPA) was
adopted in 1987 in the wake of the Bhop al incident to protect the public
from catastrophic accidental rele ases of extraordinarily hazardous
chemicals, and was the United State’s first holistic, multi-element process safety regulatory program. The success of the TCPA program
influenced the enactment of the two titles in the Clean Air Act of 1990 that authorized US OSHA’s PSM Standard and EPA’s RMP Rule.
NJ Toxic Catastrophe Prevention Act . New Jersey enacted the Toxic
Catastrophe Prevention Act legisl ation in 1985 (Ref 14.16 NJSA) and |
10 • Risk Based Process Safety Considerations 208
Table 10.3 Examples of good operat ional discipline for changes,
emergency response, and in cident investigations.
(Adapted from [49, p. Table 1])
Table 10.4 Examples of good operatio nal discipline for monitoring
effectiveness.
(Adapted from [49, p. Table 1])
Process Safety
SystemRBPS Element Examples of Good Operational Discipline During Transient Operations
Management
of ChangeIdentifying and responding quickly to proposed changes during the transition
times; evaluating the risks associated with the change; properly approving and
authorizing changes; effectively communicating changes; and effectively
documenting changes
Operational
ReadinessFollowing and completing safe work procedures before resuming operations (e.g.,
permit to work; job safety analyses; hot work, electrical isolation, etc.); performing
operational readiness / pre-start-up safety reviews; and effectively managing and
documenting handovers
Emergency
ManagementCreating contingencies to the emergency response plan if events occur during
transition times; resourcing response teams adequately if special conditions need
to be addressed during the transition time
Incident
InvestigationIdentifying and evaluating incidents, including near misses, that occur during the
transition times; resourcing investigation teams adequately; identifying causal factors (e.g., incipient and latent; systemic); identifying systemic or cultural issues; proactively evaluating unexpected events; sharing and implementing learnings from incidents at other locations (within and external to company)Change
Processes Safely
Manage Incident
Response and Investigation
Process Safety
SystemRBPS Element Examples of Good Operational Discipline During Transient Operations
Measurement
and MetricsIdentifying, tending, and tracking leading and lagging indicators for the transition
times; addressing and sharing the findings (within and external to company, as
appropriate)
AuditingScheduling audits that include the transient operating mode procedures;
documenting, addressing, and sharing findings (within and external to company, as
appropriate)
Management
Review and
Continuous
ImprovementScheduling area management reviews during the transition times; documenting,
addressing, and sharing findings (within and external to company, as appropriate)Monitor Process
Safety Program
Effectiveness |
343
Performance
Factor > x 10 = x 5 = x 3 = x 1 =
SAFETY 10 100 50 30 10
Performance Factor > x 3 = x 5 = x 1 = x 10 =
ENVIRONMENT 7 21 35 7 70
Performance Factor > x 3 = x 10 = x 2 = x 1 =
OPERABILITY 5 15 50 10 5
Performance Factor > x 1 = x 9 = x 10 = x 3 =
DESIGN 3 3 27 30 9
Performance Factor > x 7 = x 5 = x 10 = x 1 =
OTHER 3 21 15 30 3
SUM 178 258 197 106
13.7 MEASURING INHERENT SAFETY CHARACTERISTICS
Current efforts to measure the inherent safety of processes and operations are still in development stage and are primarily focused on
basic process technology and route selection. These measures have
been used occasionally in industry an d there is, as yet, little data that
relates the application of these indi ces to process safety outcomes in
chemical processing. |
RISK BASED PROCESS SAFETY 21
Figure 2.4. RBPS structure
(CCPS 2021)
Commitment to process safety is the cornerstone of process safety excellence.
Organizations generally do not improve withou t strong leadership and solid management
commitment. All involved should commit to proce ss safety in order to create a strong process
safety culture.
For process safety, management needs to reco gnize that process safety is not the same
as occupational safety and move beyond occupational safety programs. A company’s
commitment to process safety is demonstrated by its actions.
Organizations that understand hazards and risk are better able to allocate limited
resources in the most effective manner. Industrial experience has demonstrated that
businesses using hazard and risk information to plan, develop, and deploy stable, lower-risk
operations are much more likely to enjoy long-term success.
Managing risk focuses on four issues: (1) prudentl y operating and maintaining processes
that pose the risk, (2) managing changes to th ose processes to ensure that the risk remains
tolerable, (3) maintaining the integrity of eq uipment and assuring quality of materials,
fabrications, and repairs, and (4) preparing for, responding to, and managing incidents that do
|
EQUIPMENT FAILURE 233
API RP 580, “Risk-Based Inspection”, Americ an Petroleum Institute, Washington, D.C.
API RP 581, “Risk-Based Inspection Methodology” , American Petroleum Institute, Washington,
D.C.
API RP 939-C, “Guidelines for Avoiding Sulfid ation (Sulfidic) Corrosion Failures in Oil
Refineries”, American Petroleu m Institute, Washington, D.C.
API RP 941, “Steels for Hydrogen Service at Elevated Temperatures and Pressures in
Petroleum Refineries and Petrochemical Plants”, American Petroleum Institute, Washington,
D.C.
API STD 617, “Axial and Centrifugal Compress ors and Expander-Compressors”, American
Petroleum Institute, Washington D.C.
API STD 620, “Design and Construction of La rge, Welded, Low-pressure Storage Tanks”,
American Petroleum Institute, Washington, D.C.
API STD 650, “Welded Steel Tanks for Oil Storage” , American Petroleum Institute. Washington,
D.C.
API STD 651,“Cathodic Protection for Abovegr ound Petroleum Storage Tanks”, American
Petroleum Institute, Washington, D.C.
API STD 660, “Shell-and-Tube Heat Exchangers”, American Petroleum Institute, Washington,
D.C.
API STD 674, “Positive Displacement Pumps-Controlled Volume for Petroleum, Chemical, and
Gas Industry Services”, American Pe troleum Institute, Washington, D.C.
API STD 685, “Sealless Centrifugal Pumps for Pe troleum, Petrochemical, and Gas Industry
Process Service”, American Petrol eum Institute, Washington, D.C.
API STD 2000, “Venting Atmospheric and Low-Pr essure Storage Tanks”, American Petroleum
Institute, Washington, D.C.
API STD 2350 “Overfill Prevention for Storage Tanks in Petroleum Facilities”, American
Petroleum Institute, Washington, D.C.
Berg, J. “The Case for Double Mechanical Seals”, Chemical Engineering Progress , June 2009.
BHN, https://www.bnhgastank.com/mounded-bullets-lpg.html.
Bouck, Doug, “Distillation Re vamp Pitfalls to Avoid”, Chemical Engineering Progress , February
2014.
Britton, L.G., Avoiding static ignition ha zards in chemical operations , Center for Chemical
Process Safety, John Wiley & Sons, Hoboken, N.J.,1999.
Buncefield 2008, “The Buncefield incident, 11 December 2005: the final report of the major
incident investigation board”, U.K. Health and Safety Executive.
(http://www.hse.gov.uk/comah/buncefield/miib-final-volume1.pdf)
CCPS CRW, Chemical Reactivity Worksheet 4.0,
https://www.aiche.org/ccps/resour ces/chemical-reactivity-worksheet . |
6 • Recovery 108
In addition to the automatic controls monitored by and controlled
by the BPCS during normal and abnormal operations, there are alarms
that let the operations team know if there is something that requires an administrative action on their part. These administrative controls
may be as simple as acknowledgin g the panel alarm or the response
may involve ensuring that someone visually checks or adjusts
components or equipment in the field, such as opening or closing a manual valve. The administrative controls include the normal operating procedures, as well as special procedures during the transient operation modes: normal process start-up and shut-down,
emergency process shut-down, an d start-up after an emergency
process shut-down. If the situation is new and there is no specific
procedure for the situation, then th ere should be a situation-response
management system in place to addr ess the issues safely that might
arise. Typically, the facility’s ch ange management system is used to
address such temporary operations [14] [21].
Since the normal operating procedures can include general
troubleshooting guidance, it is essent ial that they are well written, up-
to-date, and effectively implemented (refer to Section 3.3). However, it
is impossible to write a procedure for every potential, unpredictable deviation that might (and sometimes do) occur, whether the deviation occurs during a normal process st art-up, normal operations, or when
normally shutting the process down. This poses a problem for writing
effective troubleshooting guides, as operating procedures for normal
operations can be prescriptive, step-by-step instructions for specific tasks when operating the process wi thin its safe operating limits.
Procedures can be written for the normal equipment and process
start-ups and process shut-downs, the transient operating modes,
since the changing, transient operating conditions and their associated hazards and risks are (or should be) understood. For this reason, only |
Fundamentals of Instrumentation and Control
245
because very few people use a DCS for this function.
In the layer of regulatory control, the majority of shapes are circles to show control by DCS. There are diamond shapes here as well, to illustrate that some unit opera-tions are controlled by PLC integrated with the DCS. These could be equipment packages bought from manu-facturers with their own dedicated PLCs.
In the regulatory control layer, it becomes the respon-
sibility of the I&C practitioner to integrate the PLC “islands” into the rest of the DCS.
13.6 ICSS Elements
Primary and final elements vary, depending on the type of action and function of the control system, as shown in Table 13.4.
(Primary and final elements will be discussed later but
in a nutshell, the primary element is the sensor and the final element could be a valve or control on an electric motor)
The BPCS is discussed in this chapter and Chapters
14 and 15. In Chapter 16 alarms and SISs will be discussed.13.7 Basic Process Control
S
ystem (BPCS)
It is important to understand that BPCS control is not an add‐on to a given process, but rather an integral part of it. A good understanding of the process is essential for a good control system.
The first question that needs to be answered is whether
we need to implement a control system for a certain piece of equipment or not. Why should we bother to install a control system at all?
We have to install a control system for all elements,
except for elements that meet the following three requirements:
1)
Where t
here is no fluctuation. In the case of a fully
closed circulating water system, for example, there is
typically no fluctuation. An example of this would be a completely closed system, such as an HVAC system where the flow rate doesn’t change.
2)
Where
fluctuation does exist, but it is not impor -
tant (i.e. it is tolerable) in the process. Sometimes we might have fluctuation in a flow to a storage tank – but variations in flow to a storage tank are typically not considered important to a process. On the other hand, a fluctuation in flow to a reactor or a distillation tower would be a critical factor in a process.
3)
Where t
he equipment is self‐controlled. There are not
many pieces of equipment that are self‐controlled.
In chapter 14, various complicated loop systems are
discussed, but we don’t use these complex systems if we don’t really need to. The best control system is a single‐loop system.
Let’s start our discussion about control loops with a
simple daily life example of control.
Figure 13.4 shows Bill preparing to wash the dishes.
The first thing he needs to do before filling the sink is to
Safety Interlock
Regulatory Control
Figure 13.3 Imag inary layers of control.
Table 13.4 Con
trol system elements.
BPCS SIS
Action Regulatory Process discrete Safety discrete
Name Control loop Discrete control loop SIF loop
Schematic
Primary element Sensor (sensitive toward a range) Sensor or switch (sensitive toward a point)
Final element Control valve or
VSD on electric motorSwitching valve orstart‐up/shutdown switch on electric motor |
7 • Unscheduled Shutdowns 128
continuous process containing the same material; and 4)
incorporate this information in the operating procedures, safe work
practices, and training.
Relevant RBPS Elements
Process Knowledge Management
Hazard Identification and Risk Analysis
Operating Procedures
Safe Work Practices
Training and Performance Assurance
Incident Investigation
LL2) Systems were not in place to prevent isolation valve leakage,
including corrosion and erosion evaluations.
RBPS Element
Asset Integrity and Reliability
LL3) Systems were not in place to alert residents and nearby
facilities surrounding the facility during an emergency.
RBPS Element
Emergency Management
7.6.3 Incidents occurring during the start-up after an unscheduled
shutdown
C7.6.3 -1 (Introduced in Chapter 2) – Millard Refrigerated Systems,
Ltd. [18]
Incident Year: 2010
Cause of the shut -down activated for an unscheduled shutdown:
Power outage; duration 7 hours
Cause of the start-up incident: Failure of a roof- mounted pipe due
to hydraulic shock upon restart after the power outage. Hydraulic
shock is “an abnormal transient condition [a rapid deceleration of
liquid] that results in a sharp pressure rise with the potential to |
206 Human Factors Handbook
• Isolating the wrong part of the system or working on the wrong system,
such as due to poor or no labelling.
• Improvising an unsafe isolation, such as having inadequate or
inaccessible blind points, or failing to note blind points on process diagrams.
• Failing to test the system state, such as not testing:
o Pressure levels.
o Residual content.
o Purging effectiveness.
• Failing to identify an interlock holding back the hazard.
• Failing to secure isolation, such that it may be mistakenly removed.
• Working around an isolation in order to “get the job done”.
• Miscommunicating or not communicating important information, so that one team is unaware of maintenance work being done by another team.
• Failing to make a new shift aware that equipment was not in a safe state.
• Commencing work too early, such as due to miscommunication, before
a system is fully isolated.
• Forgetting to remove isolation.
While isolation is a frequent and highly practiced task, it can sometimes present
increased risk of error. For example:
• It may involve working on unfamiliar equipment.
• People who don’t usually work on the system may complete the isolation.
• Equipment or piping changes that were not properly addressed in a management of change process.
• Equipment in the field may be difficult to access and may have poor lighting.
• Equipment may have been modified since the last time it was isolated. If this is not checked, the isolation procedure may be wrong.
• People may forget specific steps or execute an action incorrectly,
especially if they are fatigued, distracted, or time pressured.
As shown by the incident in Table 17- 4, experience alone does not ensure
correct performance. Even an experien ced operator makes mistakes. It is
important for everyone to check fo r zero energy – no exceptions. |
170 | 13 REAL Model Scenario: Internalizing a High-Profile Incident
similar number of hexane spills into containment dikes. Luckily, none of the
spills had caught fire.
Samir and Abishek quickly worked out simple ways to address the obvious
reasons for the spills. They assigned a longstanding Chana employee, Manoj,
to make the engineering changes, such as interlocking tank inlet valves on high
level, and adding an educator/lift system for emptying rainwater from dikes,
removing the manual drain valves that were always being left open. They also
invited Rakesh, an experienced process safety engineer, to interview for a new
position focused on training and procedures, implementing Medjool’s policies,
and improving overall hazard identification and risk analysis efforts.
Rakesh’s interview occurred in late 2017, not long after the CSB released
its report on the refinery fire in Baton Rouge, LA, USA (See Appendix, Index
Entry C31). During his plant tour with Manoj, Rakesh pointed out the wide
diversity of equipment used to perform essentially the same role; a key factor
in the Baton Rouge fire had been an older valve different from the current
plant standard. Rakesh also noted that the isobutylene used at the Baton
Rouge facility had similar physical and hazardous properties to the hexane
used in the Chana plant.
At the conclusion of the interview, Samir offered Rakesh the position,
effective the next morning. His first assignment would be to see what else he
could learn from the Baton Rouge incident and recommend modifications or
additions to Chana’s hexane spill improvement plan.
13.2 Seek Learnings
Rakesh started by summarizing the key findings from Baton Rouge:
Baton Rouge, LA, USA,2017
The plant used two types of gearboxes to operate
its manual valves. Operators regularly experienced
problems with both kinds of gearboxes, either gears becoming stripped
or connection pins shearing off. When pressed for time, operators would
sometimes remove the gearbox to open the valve with a wrench. With
either type of valve, this could be done safely. However, the older design
gearbox had two possible ways to remove the gearbox. One way was safe,
but the other involved removing the bolts that also secured the valve
bonnet. The safe way could have been verified with a simple Job Safety
Analysis (JSA), but none was done. See Appendix
index entry C31 |
22. Human Factors in emergencies 281
Employees require relevant knowledge, procedural competence, and skills to
perform well in emergency situations. More
information on skills is noted in the SRK model.
Other skills or abilities required to manage
emergency situations include:
• Cognition – see Chapters 18 and 19 for
more information on cognitive heuristics.
• Effective use of non-technical skills.
22.3 Supporting human performance in emergencies
22.3.1 An example of effective operator action
A refinery explosion occurred on the 21s t June 2019 at the Philadelphia Energy
Solutions refinery (see Figure 22-3). Th e consequences could have been much
worse without prompt action by the control room operator.
At 04:00 am propane and some hydrofluoric acid escaped after an elbow joint
fractured in a hydrofluoric acid alkylation unit. The leaking vapor formed a ground
hugging vapor cloud around parts of the unit. Two minutes later the cloud ignited
causing a massive fire.
The control room operator quickly took steps to prevent the release of
additional hydrofluoric acid by rapidly dr aining the unit’s hydrofluoric acid to a
vessel designed to hold the acid in the event of an incident.
Hydrofluoric acid when released under pressure can form a toxic aerosol cloud
and travel for miles. This aerosol can immediately penetrate skin and cause
deaths. By draining the hydrofluoric acid, the operator greatly reduced the scale
of the accident. There were no serious injuries, due, in part to the operator’s quick
actions. See Chapter 3 for more
information on Skills,
Rule and Knowledge -
based (SRK)
performance model.
Human factors contributing to error in emergency situations include:
• Stress
• Information overload
• Haste
• Inadequate communications
and/or instructions
• Inadequate procedures
• Difficult operational
interface • Poor communications
channels
• Inadequate control
• Poor definition of
responsibilities
• Inadequate training
• Poor cooperation |
277
• When purchasing new equipment, are acceptable
models available that operate at lower speeds, pressures, temperatures or volumes?
• Are workplaces design ed such that employee
seclusion is minimized?
• Are food and beverages offered at the workplace
appropriate to minimize negative impact and maximize positive impact?
• Are all power tools de-energized when not in use for extended periods?
Simplify • Are all lights, sprinkle rs, accesses/exits, ventilation
ducts, electrical installati ons and machines clear of
piled materials?
• Are equipment and procedures designed such that they cannot be operated incorrectly or carried out incorrectly?
• Are machine controls located to prevent unintentional activation while allowing easy access for stopping the machine?
• Are all machines, equipment and electrical installations easily isolated of all sources of power?
• Is the workplace designed for consideration of human factors (i.e. an ergonomically designed workplace)?
In most PSM/RBPS programs human factors is addressed in the PHA
element by analyzing both human erro r potential in the formulation of
PHA causes and by addressing human factors engineering issues in the
equipment and operations. Human fact ors are also an important aspect |
50 Human Factors Handbook
aids. This is the user consultation step in Figure 5-1.
Supervisors, managers, and other staff should routinely verify in the field that
job aids and procedures are practicable and can be used as intended. Infrequent
and inconsistent verification can lead to large discrepancies between what
supervisors and managers think is occurring within the operation and what is
actually being practiced by the workers in the field.
Up to date
All job aids should be kept up to date with changes in processes, equipment,
risk analyses, and legislation or regulations to ensure an efficient and safe
sequence of actions. All outdated job ai ds must be removed from the work place
to avoid confusion. This is a requirement of the CCPS “Guidelines for Risk Based
Process Safety” Management of Change element [5].
5.4.2 Overview of Human Factors aspects of developing a job aid
Figure 5-1 provides an overview of how to achieve the attributes cited in section
5.4.1. The approach aims to ensure that the task is properly understood and that
the instructions and advice in job aids are practical as well as correct. This requires
a combination of analysis, engagement with users and validation in developing a
job aid including the following.
• Chapter 1 explains how to select a type of job aid.
• Sections 7.2 and 7.3 of Chapter 7 explain the use of task analysis, task
walk-throughs and Hazard Identification and Risk Analysis.
• Section 7.4 of Chapter 7 outlines user engagement.
• Section 7.5 of Chapter 7 covers operational and technical validation.
• Section 7.6 of Chapter 7 outlines keeping job aids up to date.
• Chapter 8 summarizes Human Factors guidance.
Safety culture
The underlying culture of the organization should promote and reward the use
of job aids and procedures. The CCPS guid e “Process Safety Leadership from the
Boardroom to the Frontline” provides advice on organizational safety culture. |
CONSEQUENCE ANALYSIS 297
Table 13.14. Selected overpressure levels and damage
(CCPS 1999) (Clancy 1972)
Pressure Damage
psig kPa
0.15 1.03 Typical pressure for glass breakage
1.0 6.9 Partial demolition of houses, made uninhabitable
2.5 17.2 50% destruction of brickwork houses
3 20.7 Heavy machines (3000 lb) in indu strial building suffe red little damage;
steel frame building distorted and pulled away from foundation
10 68.9 Probable total destruction of buildings; heavy machine tools (7000 lb)
moved and badly damaged; very heavy machine tools (12,000 lb) survive.
Building Damage Levels (BDL) are used as a criterion for the evaluation of existing
buildings to limit the hazards to which occupa nts are potentially exposed. New buildings are
designed for their intended location. BDLs are defined for various types of building
construction including masonry buildings and pr e-engineered metal buildings. Selection of a
BDL includes an implied estimate of the occupa nt vulnerability. Building damage increases as
the severity of the blast load increases. BDLs ar e categorized into damage states ranging from
minimal damage to collapse as listed in Table 13. 15 and illustrated in Figures 13.13 and 13.14.
Table 13.15. Typical industry building damage level descriptions
(Baker 2002) (CCPS 2012)
Building Damage
Level (BDL) BDL Name Damage Description
1 Minor Onset of visible damage to reflected wall of building
2A Light Reflected wall components sustain permanent damage requiring
replacement, other walls and roof have visible damage that is
generally repairable
2B Moderate Reflected wall components are collapsed or very severely
damaged. Other walls and roof have permanent damage
requiring replacement
3 Major Reflected wall has collapsed. Other walls and roof have
substantial plastic deformation that may be approaching
incipient collapse.
4 Collapse Complete failure of the building roof and a substantial area of
walls
|
7 • Unscheduled Shutdowns 135
established, resulting in confusion and inefficient management of
the emergency.
Relevant RBPS Elements
Process Safety Culture
Process Safety Competency
Stakeholder Outreach
Training and Performance Assurance
Emergency Management
LL2) Although the plant was designed to withstand significant
earthquakes, the company’s risk assessments did not adequately
address the severe magnitudes that hav e occurred in the Pacific’s
“ring of fire” and had underestimated the impact of a tsunami that
could result from such an earthquake. The design of the plant left
the Fukushima plant vulnerable to the simultaneous critical back -up
equipment failure (i.e., the loss of main power supply, the diesel
generator, and the battery back -up).
Relevant RBPS Elements
Compliance with Standards
Process Knowledge Management
Hazard Identification and Risk Analysis
Risk Management Strengths:
LS1) Although the Fukushima Daiichi plant suffered the nuclear
meltdown, another nuclear power plant, the Onagawa Power Plant
[77], located north of the Fukushima plant, also suffered from a
tsunami that hit the plant after the same earthquake. However, the
design of this plant prevented the common -cause failure that
occurred on the critical back -up e quipment at the Fukushima power
plant. The Onagawa power plant, operated by a separate power
company with a different safety culture, was able to perform a safe
shut -down with relatively minor d amage. In addition, the Onagawa
power plant had been built wit h a more robust back- up energy
supply system such that they maintained control of their reactors
during the emergency. |
A.4 Report References | 217
Health Safety Executive (HSE) of the UK Safety Alerts and Notices—
Offshore (Continued)
(See: www.hse.gov.uk/offshore/notices/sn_index.htm)
Code Investigation
HA5 'Single line components' in the hoisting and braking systems of
offshore cranes
HA6 Weldless repair of safety critical piping systems
HA7 Testing of HVAC dampers (Not Indexable)
HA8 Potential catastrophic failure of pressure-balanced cage-guided
control valves and chokes
HA9 Ensuring adequate safety during davit lifeboat drills, testing and
maintenance on UK offshore installations (NOT INDEXIBLE)
HA10 Interlocks for drill floor machinery
HA11 Explosion protected electrical heaters
Health Safety Executive (HSE) of the UK Safety Bulletins - COMAH
(English)
(See: www.hse.gov.uk/comah/alert.htm)
Code Investigation
HB1 Explosion and Fire: Chevron Pembroke Refinery, 2 June 2011
HB2 Safety Alert to operators of COMAH oil/fuel storage sites & others
storing hazardous substances in large tanks
HB3 Corrosion Fatigue Failure of Tubes in Water Tube Boilers
HB4 Failure of Residual Pressure Valves (RPV) manufactured by Ceodeux
Indutec for Transportable Gas Cylinders
HB5 Failure of Residual Pressure Valves (RPV) manufactured by Ceodeux
Indutec for Transportable Gas Cylinders - Clarification regarding
14mm plugs PDF
HB6 Explosion in a urea ammonium nitrate (UAN) Fertiliser Transfer
Pump
HB7 Safety Alert: Rupture of an (atmospheric) crude oil storage tank PDF
HB8 To operators of COMAH oil/fuel storage sites
HB9 TAV 'checkable' level switches - User safety checks and switch
testing
|
316 INVESTIGATING PROCESS SAFETY INCIDENTS
Figure 14.1 Flowchart for Implementation and Follow-up
Responsible managers should prio ritize, monitor, and document
progress of all actions through to completion to ensure that the corrective
and preventive actions are achieving th e intended results. Inevitably, some
actions may result in changes to local management systems and equipment,
and a rigorous Management of Change (M OC) procedure should be adopted
t o e n s u r e t h a t a l l potential consequences of implementing the
|
APPLICATION OF PROCESS SAFETY TO OFFSHORE PRODUCTION 113
Incident: P-36 Incident, March 15, 2001
The P-36 FPU was located off Brazil, produ cing oil and gas in deep water. A
design safety concept was for all hydrocarbons to be located on the topsides,
with none located in the four vertical columns or the two submerged pontoons.
However, drain tanks were located in tw o of the columns to receive separated
water before discharge. One of these tanks was taken out of service for extended
maintenance and all the tank connections were isolated correctly using blind
flanges, except one which used only a block valve for isolation.
On March 15, a loud “bang” was noted in the column and an emergency
response team was sent to investigate. As the column had been designated a
“safe place”, no special precautions were taken by the team. When they started
their entry, a flammable cloud in the column ignited and 11 crew members were
killed. The blast also sheared the main cooling water line and the rig started to
flood. Since the cooling water also supplied the firewater system, it was by
design not easy to isolate the incoming water. The rig was evacuated and after
five days, even with salvage efforts, the FPU eventually sank.
Investigation showed that, over a period of time, the drain tank block valve
leaked slowly, and a mixture of water and some oil flowed into the isolated drain
tank. As the relief valve had also been isolated, the internal pressure rose and
eventually a pressure burst occurred – this was the loud bang. The ruptured tank
released flammable vapor that was ignite d by the entering emergency team. The
primary result of the Petrobras investigation was a recommendation to
implement a system of Operational Excellence to ensure that all maintenance
work including isolations was conducted correctly. Several technical
improvements were also im plemented across Petrobras.
Reference: Barusco (2002) The Accident of P-36 FPS
RBPS Application
Safe Work Practices : Maintenance work isolations were not performed
correctly. Had the drain tank been fully isolated with blind flanges, then the
incident would not have occurred.
Process Knowledge Management : The response team did not understand the
potential for a designated “safe place” to become unsafe as there was a process
vessel in the leg. Emergency teams should carry out gas testing before entering
confined spaces.
pipelines on the seabed. Production and export risers are susceptible to collision by
vessels (such as supply vessels or crude shuttle tankers in the case of an FPSO) or
to dropped objects. Either can cause a ri ser leak or rupture and can result in
environmental pollution. If th e hydrocarbons reach the su rface and ignite, a fire on
the sea surface occurs that ca n impact the facility. An exam ple of a riser rupture due
to collision is the Mumbai High incident (refer to Table 1-1). A means to protect
against riser collision is by locating risers on the inner side of the platform legs. |
10 GUIDELINES FOR MANAGING ABNORMAL SITUATIONS
Figure 2.1 Relationship of Abnorm al Situations to Process Safety
Management of abnormal situations is inherently re lated to process
safety performance and the avoidance of process safety incidents. The
relationship in Figure 2.1 demonstr ates that abnormal situations may
progress from challenges to protecti on layers (barriers) to a minor
incident, and ultimately to a major in cident if the abnormal situation is
not managed in a timely manner. Furthermore, since abnormal
situations can occur without warning, the timescale of such situations
does not permit activities such as planning, training, and procedure
development, to respond to them as they occur. Consequently, process
safety elements and principles should be applied to address abnormal
situations before an incident occurs.
A number of process safety elements are key to the management of
abnormal situations. The most important of these elements for safe
operation are:
Hazard Identification an d Risk Analysis (HIRA) to identify,
understand, and predict what abnormal situations can occur (CCPS
2007a, 2008b, 1999, 2010),
Operating Procedures for transient and normal operation to
ensure operations personnel have access to safe operating limits,
consequences of deviation from sa fe limits, troubleshooting, and
actions required to correct a deviation to prevent abnormal
situations progressing to a proc ess safety incident (CCPS 2007a,
1996),
Training and Performance Assurance to build competency
(knowledge, skill, ability) in oper ating procedures, control systems,
recognizing warning signs, trou bleshooting, and understanding
|
288 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
the flammable mass is determined by identi fying the cloud volume between the upper and
lower flammable limits. Identify the dimensio ns of the flammable cloud (from dispersion
modeling) and use this to determine conseque nce zone. Dense gas models are important for
this estimate as they tend to be wider and sh orter and show the potential impact inside the
process facility. Gaussian models can be misleading.
Jet Fires
Jet fires typically result from the combustion of a material as it is being released from
pressurized process equipment. Jet fires are highly turbulent and are often two-phase burning
mixtures. The main concerns are direct imping ement and local radiation effects. One method,
the API (1996) method was origin ally developed for flare therma l analysis but is now applied
to jet fires arising from accidental releases. Fl are models apply to gas releases from nozzles
with vertical flames. For accidental releases, the release hole is typically not a nozzle, and the
resulting flame is not always vertical. The fraction of energy converted to radiant energy versus
convective energy is determin ed empirically based on limited experimental data. The view
factors and atmospheric transmissivity are de termined using published correlations. The
pressurized jet focuses the fire also yielding hi gh heating where direct contact occurs. It also
imparts a mechanical force on surfaces it contacts. Jet fire thermal flux (outside the flame
envelope) can be over 300 kW/m2 (95,163 BTU/hr/ft2). Firewalls suitable for jet fires are rated J
followed by minutes (e.g. J-15). This heat and fo rce from direct impact can be challenging for
firewalls. ISO 22899 “Determination of the resistance to jet fire fires of passive fire protection
materials” specifically addresses this topic.
Table 13.10. Input and output for jet fire models
Input for jet flame model Input for point source model
Input for jet flame model
flame height (based on
reaction stoichiometry and
molecular weight)
view factor formulas
humidity data
total energy generation rate
(based on mass flow rate of
combustible material)
view factor formulas
humidity data
Output: The received thermal radiation at target locations
Physical Explosion
When a vessel containing a pressurized gas ruptures, the resulting stored energy is released.
A steam drum burst is a well-known example. Th is can also apply to pressurized hydrocarbon
vessels where the relief system has not functioned correctly. A BLEVE event, discussed in the
next section, is another example. This ener gy can produce a shock wave and throw a small
number of large vessel fragments for hundreds of meters. If the contents are flammable it is
possible that ignition of the released gas co uld result in additional thermal consequence
affects. The total energy from the bursting vessel is distributed to the fracturing of the vessel,
generation a shock wave, and throwing of the fragments. Exactly what proportion of available
energy goes to which is difficult to determine. Several methods use the calculated equivalent
amount of TNT energy to estimate shock wave e ffects. In general, vessels of pressurized gas |
247
Provide NFPA hazard ratings or equivalent
Characterize combustible dust hazards (MIE, Kst, etc.)
8.Define process conditions (p ressure, temperature, etc.).
9.Estimate quantities used in each process system (tanks, reactors,
etc.).
State plant capacity basis
Estimate quantities of wastes/emissions
Table 10.1: Inherent Safety Review Team Composition
Product
Development Design
Development Design
Stage
PHA Operations
Industrial
Hygienist/ Toxicologist √ √ √ √
Chemist √ √ √ √
Process Engineer √ √ √ √
Safety Engineer √ √ √ √
Process Technology Leader √ √ √ √
Environmental Scientist/ Engineer √ √ √ √
Control Engineer √ √ √ |
References 169
[25] CCPS, Incidents That Define Process Safety, Hoboken, NJ, USA: John Wiley
& Sons, 2008.
[26] State of New Jersey, "Toxic Catastrophe Prevention Act Program,
Consolidated Rule Document (Revisi on 10)," New Jersey Administrative
Code 7:31-4.2, p. 51, Trenton, NJ, USA, 2016.
[27] State of California, "Process Safety Management for Petroleum
Refineries," California Code of Regulations 5189.1(e)(3)(C), p. 5,
Sacramento, CA, USA, 2017.
[28] International Institute of Ammonia Refrigeration, "Guidelines for IIAR
Minimum Safety Criteria for a Safe Ammonia Refrigeration System
(Bulletin No. 109)," Washington, DC, USA, 1997.
[29] International Electrotechnical Commission, "IEC 61508, Standard for
Functional Safety of Electrical/E lectronic/ Programmable Electronic
Safety-Related Systems," Geneva, Switzerland, 2010.
[30] National Fire Protection Association,, "ANSI/NFPA 70, National Electric
Code," Quincy, MA, USA, 2020.
[31] OSHA, "Akzo-Nobel Chemicals - Limits of a Process," 28 February 1997.
[Online]. Available: https://www.osha.gov.
[32] CCPS Monograph, "Assessment of an d Planning for Natural Hazards,
Third Edition," New York, NY, USA, 2019.
[33] J. B. Babcock and W. M. Bradshaw, "The Right People – Key to a Successful
Hazard Review," in AIChE Spring National Meeting Proceedings , Atlanta, GA,
USA, 2005.
[34] U.S. Chemical Safety and Hazard Investigation Board, BP America
Refinery Explosion, Washington, DC, USA, 2007.
[35] British Broadcasting Corporation, "On This Day 1 November 1986," 1
November 1986. [Online]. Available: www.news.bbc.co.uk.
[36] T. Kletz, An Engineer’s View of Human Error, Third Edition, Boca Raton, FL,
USA: CRC Press, 2001. |
130 | 9 REAL Model Scenario: Chemical Reactivity Hazards
and then follow up with a message to all personnel. As he stood there, Phillip
stopped next to him. Phillip’s promotion to VP of operations had happened
about the same time as Jason’s promotion. “It looks like you’re about to send
me an email,” Phillip said. “I heard about the call you got. Stop by my office at
two today and we’ll talk about it.”
When Jason arrived at 2 p.m., the marketing communications director,
Sarah, was in Phillip’s office. Phillip explained that he had asked Sarah to help
refresh the messaging around the reactivity standard. Sarah explained that
people get used to seeing signs and eventually don’t see them. She showed
them a communication plan she’d developed to deliver the message in
different ways at intervals over the next three years. The plan factored in the
different ways that individuals learn. It included videos of related incidents
that shift teams and other work groups could play at safety meetings, as well
as a simulation, a sign contest, a new e-learning module, and a workshop. At
the end of the three-year period, they would repeat the plan.
Remembering the strategy his predecessor Roger had used, Phillip asked
each of his leadership team members to take responsibility for a part of the
communication plan. He personally volunteered to organize the sign contest.
Judging took place at the plant’s pre-Mardi Gras shrimp and crawfish boil.
Phillip held up the signs submitted by 12 teams, one at a time, for everyone to
see and offered positive comments on each one. After careful deliberation, he
declared every sign a winner, and said that the plant would use them in
rotation, one per month. He closed by announcing the new e-learning module,
workshop, simulation, and videos.
But he left the “10 or 10” sign by the front gate. Over the next three years,
although the number of disasters prevented continued to rise, he never had
to change the “since” year and reset the number to 0.
9.9 References
If so indicated when each incident described in this section was introduced,
the incident has been included in the Index of Publicly Evaluated Incidents,
presented in the Appendix.
Other references are listed below.
9.1 CCPS (1995). Guidelines for Chemical Reactivity Evaluation and Application to
Process Design. New York: AIChE. |
376 INVESTIGATING PROCESS SAFETY INCIDENTS
• Asset Integrity & Reliability
• Contractors Managements
• Emergency Management
• Hazards Identification and Risk Analysis
• Management of Change
• Operating Procedures
• Safe Work Practices
• Conduct of Operations
• Process Safety Culture
Findings and Recommendations
Causal Factors :
i Piping Integrity
The carbon steel piping in the ca talyst preparation area and the
isopentane feed lines to the area was weakened by external corrosion. The
lines were Schedule 40, carbon steel lines which are suitable for this service.
However, the lines were 12 years old. Physical evidence indicates that the
failure most likely occurred at an elbo w in the Kettle No. 3 exit piping.
Pressure data from the system indicates the fa ilure occurred when the
system pressure was 120 psig, which is below the pressure rating for the
vessel. Inspections of remaining parts of the catalyst mix and isopentane
feed lines revealed deterioration of in sulation and missing parts of the
external shield (designed to prevent wa ter from getting into the insulation).
Corrosion under insulation especially in a heat affected zone is consistent with
a failure in the kettle exit piping. (Asset Integrity & Reliability)
ii Asset Integrity Management Program
The existing asset integrity managemen t program did not appear to cover
the catalyst preparation area. While record s were found for inspections of the
Reactor systems and the isopentane st orage area, no inspection records
were found for the catalyst preparat ion area. Interviews suggest these
inspections were delayed by the budget crunch. (Asset Integrity & Reliability)
iii Fire Pumps Integrity
The No. 1 diesel fire water pump was inoperable because it h a d
overheated during an outside a gency annual performance test 1.5 months
prior to the incident. The pump probably had problems prior to the test,
but overheating may not have been detected in monthly maintenance tests
because the 5- minute run time may not have been sufficient to find the
overheating. |
OTHER HAZARDS 143
References
AGU, American Geophysical Union, https: //blogs.agu.org/landslideblog/2010/12/19/the-
outcome-of-a-study-of-the-kolo ntar-tailings-dam-failure/.
AP Photo/Rossiiskaya Gazeta Newspaper, Sayano-Shusensk aya hydroelectric plant in
southern Siberia.
ASCE, American Society of Civil Engineers, https://hazards.atcouncil.org/#/.
ASCE 2014, “Flood Resistant Design and Construc tion”, ASCE/SEI 24-14, American Society of
Civil Engineers.
ASCE 2016, “Minimum Design Loads and Associated Criteria for Buildings and Other
Structures”, ASCE /SEI 7-16, American Society of Civil Engineers.
ATC, Applied Technology Council, https://hazards.atcouncil.org/#/.
CCPS Glossary, “CCPS Process Safety Glossary ”, Center for Chemical Process Safety,
https://www.aiche.org/ccps/resources/glossary .
CCPS 1995, Guidelines for Safe Storage and Handling of Reactive Materials , Center for Chemical
Process Safety, John Wiley & Sons, Hoboken, N.J.
CCPS 1998, Guidelines for Safe Warehousing of Chemicals , Center for Chemical Process Safety,
John Wiley & Sons, Hoboken, N.J.
CCPS 2003 Guidelines for Fire Protection in Chemical , Petrochemical, and Hydrocarbon Processing
Facilities , Center for Chemical Process Safety , John Wiley & Sons, Hoboken, N.J.
CCPS 2018, Guidelines for Siting and Layout of Facilities , Center for Chemical Process Safety,
John Wiley & Sons, Hoboken, N.J.
CCPS 2019, Monograph: Assessment of and planning for Natural Hazards , Center for Chemical
Process Safety, John Wiley & Sons, Hoboken, N.J.
CCPS 2020, Monograph: Risk Based Process Safety During Disruptive Times , Center for Chemical
Process Safety, John Wiley & Sons, Hoboken, N.J.
CSB, 2018, “Organic Peroxide Decomposition, Re lease, and Fire at Arkema Crosby Following
Hurricane Harvey Flooding”, Investigation Repo rt, Report No. 2017-08-I-TX, U.S. Chemical
Safety and Hazard Investigation Board.
FEMA, Federal Emergency Management Ag ency, https://www.fema.gov/flood-zones.
FM Global 2016, Property Loss Prevention Data Sheet 1-11 “Fire Follo wing Earthquake”, FM
Global, Hartford, Connecticut.
FM Global 2020, Property Loss Prevention Da ta Sheet 1-29 “Roof Deck Securement and
Above-Deck Roof Components”, FM Global, Hartford, Connecticut.
FM Global 2020 a, Property Loss Prevention Data Sheet 1-34 “Hail Damage”, FM Global,
Hartford, Connecticut. |
414 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
Key Points:
Process Safety Culture – A poor safety culture will have consequences.
It can lead to incidents, bad press coverage, and failure to receive new
operating permits. It could be much worse. Process safety should be
valued and seen as important by all.
Stakeholder Outreach – Work together to prevent incidents. It is
important that local planners understand the hazards of neighboring
facilities and that enforcement agencies identify shortfalls in compliance.
Stakeholders communicating with each other can create a mutual
understanding on managing risks .
Emergency Management – Do the responders understand the
hazards? Inform your local emergenc y responders of the risks on your
site so that when they respond to help you, you do not put them in
harm’s way.
Description
West Fertilizer Company (WFC) stored and handled ammonium nitrate (AN) in a fertilizer
building along with several other fertilizers including diammonium phosphate, ammonium
sulfate, and potash. The fertilizer building was a wood frame building. AN was stored in two
plywood bins. Figure 20.2 shows an overview of the building layout.
In addition to receiving and storing the va rious fertilizers, West Fertilizer also made
fertilizer blends, delivered, and sometimes applie d the fertilizers. West Fertilizer also stored
and handled anhydrous ammonia in two pressurized storage tanks.
When the facility was first built, 1962, it wa s surrounded by open land. Over the years the
t o w n g r e w a n d W F C c a m e t o b e s u r r o u n d e d b y residences and schools (Figure 20.3). This
contributed to the high impact of this incide nt. Most of the fatalities and injuries occurred
within 457 to 610 m (1,500 to 2,000 ft) of the explosion (CSB 2013).
|
Piping and Instrumentation Diagram Development
192
from very low flow rates during the reduced flow rate
conditions in a processed plant. However, such a thing doesn’t need to be placed in reciprocating pump arrange-ments. The reason is not that there won’t be any mini-mum flow experienced in a process plant. The reason is that reciprocating pumps are generally insensitive toward the low flow rate. This means reciprocating pumps still work fine even when the flow rate to them is very low. However, it should be mentioned that it is not the case that reciprocating pumps work fine even when the flow rate is very tiny in comparison to the size of the reciprocating pumps. When the flow rate is very tiny they start to lose their efficiency. However, this doesn’t force us to provide a minimum flow protection pipe for them as this very low flow rate is much lower than the low flow rate that can be experienced in process plants.
A typical P&ID representation of reciprocating pumps
is shown in Figure 10.31.
10.7.1.2 Rotary Pumps P&ID Piping
For rotary pumps, there is no need to install a pulsation dampener in the discharge site or suction site of rotary pumps. This is because rotary pumps don’t generate pul-sation even though they are part of positive displacement pumps.
Similar to reciprocating pumps, in rotary pumps
the flange sizes in the suction site and discharge site could be the same, smaller, or larger than pipe flanges. Therefore, having a reducer, and enlarger, or nothing in the suction and/or discharge sites of rotary pumps would be acceptable.
Rotary pumps need a pressure safety device on their
discharge side. This is because of the same logic as for reciprocating pumps. However, some companies decide to take a less conservation approach and do not install a pressure safety device on the discharge side of rotary pumps. Their logic is that because rotary pumps have an internal pressure safety device they don’t really need another external pressure safety device on their dis -
charge site. However, the companies that are more conservative believe that the internal pressure safety device of rotary pumps cannot relieve us from putting another pressure safety device on the discharge side of rotary pumps. The reason is that the set point of the internal pressure safety device cannot be fully in the control of the designer and also that the pressure safety device is only to protect the rotary pump and not nec -
essarily the discharge piping. Therefore, it makes sense to disregard the internal pressure safety device and put another pressure safety device on the discharge site of rotary pumps.
There is a need to put a check valve in the discharge
site of rotary pumps. This is similar to centrifugal pumps and dissimilar to reciprocating pumps.
There is no need for a minimum flow protection pipe
for rotary pumps. The logic is the same as for reciprocat -
ing pumps.
There are some cases where a spillback pipe between
the discharge side of a PD pump can be supplied with an isolation valve. This pipe loop is very similar to a minimum flow protection pipe; however, the pipe size is different and also this has an isolation valve like a gate valve rather than what we have in a minimum flow protection pipe, which may have a control valve. The purpose of this pipe loop is to facilitate a start‐up of PD pumps.
If destination is sensible to pulsation
No check va lve
Has internal check va lveIf long suction pipeDampenerPSV
No min. /f_lo wFigure 10.31 P&ID arr angement of a reciprocating
pump. |
76 Guidelines for Revalidating a Process Hazard Analysis
unaware of a particular damage mechanism, unfamiliar with actual
operating practices, or simply rushed. Regardless, any strong
indication of multiple or systemic deficiencies in the PHA virtually
dictates the Redo approach. Furthermore, any scenario-specific
analyses (e.g., LOPA, bow tie) rela ted to previous incidents will have
to be Updated to include any newly identified scenarios with
significant consequences.
• Did the PHA team identify the loss scenario, but misjudge the
likelihood of the cause(s)? The team may have underestimated the
frequency of equipment failures or human errors that could result
in process safety losses. If true for the actual incident, were the
causes of other potential scenar ios similarly underestimated? If
not, an Update can remedy the error; if so, all the risk evaluations
may need to be Redone .
• Did the PHA team identify the loss scenario, but misjudge the
severity of the consequences? The team may have underestimated
the quantity of material that could be released, the likelihood of
ignition, or the number of people who could be affected. If true for
the actual incident, were the consequences of other potential
scenarios similarly underestimated? If not, an Update can remedy
the error; if so, all the consequence estimates and risk judgments
likely need to be Redone .
• Did the PHA team identify the loss scenario, but misjudge the
capability of the safeguards, probability of safeguard failures, or
independence of multiple safeguards? Did the PHA team list (and
rely on) vague safeguards such as “procedures,” “training,” or
“maintenance?” If the actual incident involved deficiencies or
breakdowns in the engineered and/or administrative controls, then
are the claimed safeguards against other scenarios also
questionable? If not, an Update can remedy the error; if so, the
scenario frequency and risk judgments likely need to be Redone.
When applying these questions to a review of incidents in a given process,
it is typically the number and/or severity of incidents or PHA-related deficiencies
that determines the revalidation approach . Learnings from a single incident or
failure can usually be incorporated by the Update approach. Systemic issues
usually will require a Redo of the PHA or at least a Redo of the portions involved
in the identified issues. |
E.34 Normalization of Ignorance |323
E.34 N orm alization of Ignorance
A com pany was created by chem ist and chemical
engineer to manufacture a high value chem ical.
While both were experienced researchers, neither
had experience developing, designing, and operating processes
involving chemical reactions. They hired three recent chem ical
engineering graduates to operate the plant.
The plant operated without incident for three years, although
there were several batches with significant exotherms that were
difficult to control. One day, a m ore serious exotherm took place.
Suspecting a problem with the cooling system, the
owner/engineer and an operator/engineer went to investigate.
B efore they could determ ine the problem, the reactor vessel
burst, killing both and dam aging property in a 400-meter radius.
Debris from the blast was found m ore than 1.5 km away. The CSB
investigation team (Ref E.4) found that no reactive chem ical
testing had been conducted during the design of the plant, the
relief valve was not sized to handle the runaway reaction case, and
the cooling system was significantly undersized and had no back-
up.
CSB also noted that none of the com pany’s employees had any
knowledge of or exposure to reactor design or reactive chem ical
hazards. They noted that chem ists and engineers are taught
about preventing reactive chemical hazards prim arily as in-
com pany training in larger com panies having a reactive chemical
program ; few degree program s addressed this subject. Noting an
overall academ ic culture that neglected process safety, CSB
recomm ended that the undergraduate chemical engineering
curriculum requirements be changed.
While this was clearly a wise recommendation, what other
culture factors might CSB have explored in this investigation? Actual
Case
History |
156 PROCESS SAFETY FOR ENGINEERS: AN INTRODUCTION
Exercises
List 3 RBPS elements evident in the Petrobras P 36 sinking summarized at the beginning
of this chapter. Describe their shortcomings as related to this accident.
Considering the Petrobras P 36 sinking, what actions could have been taken to reduce
the risk of this incident?
Considering the BP Texas City explosion describe d in Chapter 2, was this a Tier 1 or Tier
2 PSE? Suggest a Tier 3 metric and a Tier 4 metric that could have been measured to
indicate an incident such as this was becoming more likely.
Considering the MIC release in Bhopal, India described in Chapter 6, was this a Tier 1 or
Tier 2 PSE? Suggest a Tier 3 metric and a Ti er 4 metric that could have been measured
to indicate an incident such as this was becoming more likely.
A facility experiences an increasing number of “small” releases (less than 25 kg) of
butane. Is this a process safety event? If so, what Tier is it?
An accidental release of 636 liters (4 barrels) of gasoline at a gasoline station results in a
fire causing $50,000 damage. No one is injured. Is this a process safety event? If so,
what Tier is it?
Propane is relieved through a pressure relief valve to the flare system. Estimates of the
quantity put the release at 2268 kg (5000 lbs). Is this a process safety event? If so, what
Tier is it?
A maintenance technician is working on the ammonia refrigeration system in the
refinery methyl ethyl ketone unit and inadvertently causes a release of 4.5 kg (10 lb) of
ammonia. He immediately begins coughing and his eyes are irritated and burning. He is
kept in the hospital overnight for observation. Is this a process safety event? If so, what
Tier is it?
An offshore drilling platform uses diethylamine as a corrosion inhibitor. A leak occurs in
the diethylamine piping releasing 1500 kg (3307 lb) that flows into the sea. No one is
injured. Is this a process safety event? If so, what Tier is it?
A blowdown drum overflows, and 28,769 liters (7600 gallons) of a pentane/hexane
mixture rain out onto the ground in an area where no buildings or people are present.
The overflow is stopped, and no one is injured. Is this a process safety event? If so, what
Tier is it?
References
ANP 2001, “Analysis of the Accident with the Platform P-36, Report of the ANP / DPC
Commission of Investigation”, Agencia Nacional do Petroleo, Gas Natural e Biocombustiveis,
July,
http://www.anp.gov.br/images/EXPLORACAO _E_PRODUCAO_DE_OLEO_ E_GAS/Seguranca_Op
eracional/Relat_incidentes/Analysis_of_t he_Accident_with_the_Platform_P-36.pdf.
API RP 754, “Process Safety Performance Indi cators for the Refining and Petrochemical
Industries” 3rd Edition, American Petroleum Institute, Washington, D.C., US, 2021.
CCPS Glossary, “CCPS Process Safety Glossary ”, Center for Chemical Process Safety,
https://www.aiche.org/ccps/resources/glossary . |
PREPARING THE FINAL REPORT 307
Equipment damage information
Lab analysis reports
Engineering analysis reports
Witness interviews
Timeline
If a map is used, it should focus on the area of inte rest, and should
minimize the amount of nonessential information shown.
Medical evidence is usually omitted from incident investigation reports
due to the need to respect and protec t medical information. Names of
injured and other participants are also frequently omitted for privacy
reasons. Descriptions such as Operat or 1, 2, or 3 can be substituted.
It is a good documentation prac tice to include the reasons for
eliminating other possible causes and alternate scenarios. This can be
extremely useful and enlightening to su bsequent investigators or analysts
who may follow years later.
13.5 REPORT REVIEW AND QUALITY ASSURANCE
13.5.1 Reviewing the Report
All members of the incident investigation team should review and reach
consensus on the content of the report before it is finalized. All report content
should be reviewed and checked for accu racy. An example checklist is shown
in Table 13.3. Reviews may be needed by management and legal teams for protection of company intellectual proper ty and other legal rights. It may be
appropriate for investigation team members to sign the final report
depending on local practice. This is an indication of personal endorsement
of the
team consensus.
Many companies have an incident invest igation report approval process.
The level of approval is often tied to th e categorization of the incident, which
typically corresponds with the actual or potential severity of the incident. Generally, higher severity categorizati on requires a high er management level
review and approval.
|
6 • Recovery 114
process. Effective proc ess safety and risk management programs are
the subject of considerable guidance today, noting that the knowledge
of how to identify, design, implemen t, and sustain the technologies for
these programs continues to evolve . Additional guidance for applying
and auditing these RBPS elements for an effective overall process safety and risk management program is provided in other resources [40].
|
Table C-1 continued
HF Competency Performance/ Knowledge
Criteria Level 1 - Operator Level 2 - Supervisor* Level 3 - Manager**
Non-technical skills
Stress Management Understands impact of stress
on performance Can describe basic concepts
of stress management Can recognize the
impact of stress on
safety and performance Is able to identify the causes
and consequences of stress
Is able to mitigate stress in
self and others Can identify signs of stress Can recognize the
effectiveness of stress
mitigating techniques Is able to assess - detect
signs of stress in the
workforce and apply
appropriate stress mitigating
strategies
Teamwork Understands contribution of
effective teamwork in
emergency situations Can describe the role of
teamwork in normal and
emergency situations Can recognize the
impact of teamwork on
performance in normal
and emergency
situations Can lead discussion on
importance of highly
performing teams
Is able to work effectively as
part of a team, in normal and
abnormal situations and
process upset conditions Can identify characteristics of
a highly performing team Can apply techniques
(e.g., other non-technical
skills, such as
communication,
leadership, decision-
making) to enhance
teamwork Can assess team’s
effectiveness and identify
solutions for improvements
|
62
310, www.aiche.org/rapid/about-rapid
3.11 The Institution of Chemical Engineers and The
International Proces s Safety Group. Inherently Safer Process Design .
Rugby, England: The Institution of Chemical Engineers, 1995.
3.12 Kletz, T.A., Cheaper, Safer Plants, or Wealth and Safety at
Work . Rugby, Warwickshire, England: The Institution of Chemical
Engineers, 1984.
3.13 Kletz, T.A., Plant Design for Safety, Rugby, Warwickshire,
England: The Institution of Chemical Engineers, 1991.
3.14 Kletz, T., Amyotte, P., Process Plants – A Handbook for
Inherently Safer Design , 2nd Ed., CRC Press, 2010.
3.15 Lutz, W.K., Take chemistry and physics into consideration
in all phases of chemical plant de sign. Process Safety Progress 14 (3),
153-162, 1995a.
3.16 Lutz, W.K. Putting safety into chemical plant design . Chemical
Health and Safety , 2 (6), 12-15, 1995b.
3.17 Reay, D, Ramshaw, C., and Harvey, A., Process
Intensification, 2nd. Ed., Elsevier, Ltd., 2013
3.18, Scheffler , N. E, “Inherently Safer Latex Plants,” Process Safety
Progress 15, no. 1 ( 1996): 11–17.
3.19 Siirola, J.J. “An industrial perspective on process synthesis.” In
Foundations of Computer- Aided Process Design, American Institute of
Chemical Engineers Symposium Series, 91 (304):222-223, 1995.
3.20 Stankiewicz, A. and Moulijn , J., editors, Reengineering the
Chemical Processing Plant: Process Intensification, CRC Press, 2004
3.21 United States Chemical Sa fety and Hazard Investigation
Board (CSB), FINAL REPORT, Valero Refinery Propane Fire , 7/9/2008
3.22 Wade, D.E. Reduction of risks by reduction of toxic material
inventory. In J.L. Woodward (Ed.). Proceedings of the International
Symposium on Preventing Major Chem ical Accidents, February 3-5,
1987, Washington, D.C (2.1-2.8.) New York: American Institute of
Chemical Engineers, 1987. |
39
4
Examples of Failure to Learn
“The past can't hurt you anymore, not unless you let it.”
—From V is for Vendetta by Alan Moore
The Index of Publicly Evaluated Incidents prepared for this book (see
Appendix) illustrates how often companies fail to learn from past incidents.
Figure 4.1 shows that of the 441 incidents in the index, 13 primary and
secondary findings were repeated in more than 100 incidents. (Primary
findings are those that contributed most to the incident; secondary findings
are those that contributed less but still may have learning potential.) Three of
these findings—Hazard Identification and Risk Analysis (HIRA), Culture, and
Safe Design—repeated in more than 180 incidents. As large as they are, these
numbers may be understated, since the indexing process intentionally limited
the number of findings that would be indexed for each incident.
Figure 4.1 Most Repeated Findings from 441 Indexed Incidents
Driving Continuous Process Safety Improvement From Investigated Incidents By CCPS and EI
© 2021 the American Institute of Chemical Engineers |
RISK ASSESSMENT 313
Figure 14.2. Illustration of a plugged settling leg prepared for maintenance
(Bloch 2019)
After the incident, a physical examination of the DEMCO® valve revealed that it was open
at the time of release, and that air hoses whic h supplied the air pressure to open or close the
|
88 | 3 Leadership for Process Safety Culture Within the Organizational Structure
organization’s leaders do not fully understand what process
safety culture means. Only the senior leader can align the
leadership team to achieve the corporate vision of process
safety excellence . To be most effective, the PSMS must be fully
integrated into the way business is conducted, not used as an
occasional touchpoint or box to check.
Ensure Technical Competence
Individuals at all levels having process safety responsibilities
should be technically competent in the relevant process
technology, the specific process safety com petence required for
their job, and the PSMS in general. All such individuals should
know the hazards of their process, the critical safeguards required
to operate the process within the organization’s risk tolerance,
and their responsibilities in maintaining those safeguards.
Process safety specialists should be able to accurately interpret
how process safety regulations and other form al requirements
apply to the facility’s operations.
Technical com petence is a hallmark of high reliability
organizations (Appendix D), and gaps in com petence are
important warning signs of a potential catastrophic incident. (Ref
3.16). Technical com petence will be discussed further in section
5.2.
Ensure Management Com petence In addition to possessing technical com petence as noted
above, m anagers should know how to manage. M anagement
skills do not come autom atically upon promotion to a
m anagement role. While an individual’s personality traits m ay
help them succeed in a management role, specific m anagem ent
skills m ust be taught, learned, and practiced. Management skills
particularly relevant to process safety include: |
Table 12-1: Competency Gap Analysis and Training Needs Analysis template
Competency
standards Process control room supervisors should be able to successfully manage a simulated emergency response in
three tests (out of a possible 10 scenarios), & display appropriate skills such as task delegation, & effective
communication.
Competency
current
level Knowledge of emergency response procedures
in various situation: Basic application: Level 2 Skills
Delegation: Awareness: Level 1
Communication: Basic application: Level 2
Competency
required Knowledge of emergency response procedures
in various situations: Skilled application: Level 3 Skills
Delegation: Skilled application: Level 3
Communication: Skilled application: Level 3
Learning
needs Increase knowledge of emergency response
procedure: Move from Level 2 to Level 3 Improve delegation skills: Move from Level 1 to Level 2 to Level
3
Improve communication skills: Move from Level 2 to Level 3
Learning
objectives Improve knowledge of emergency procedures by
attending training, & completing required
assessments, within next four weeks.
Effectively manage emergency response in a
series of simulated exercises, by using correct
emergency procedures suitable for each
scenario. Improve non-technical skills us ed during emergencies by
attending training, & completing required assessments,
within next six weeks for Level 2, & within next 12 weeks for
Level 3.
Demonstrate effective & efficient communication &
delegation skills during em ergency response simulation
exercises.
“Bridging
the gap”
training Classroom-based training; Walk-through
procedures; Simulation training/case studies Classroom training on Non -Technical Skills; Simulation
training
Learning
evaluation Direct questioning; Open questions; A “show me
how” observation Quiz; Case studies; Observation |
General Rules in Drawing of P&IDs
23
Figure 4.2 P&ID orien tation.
Figure 4.3 Keeping the rela tive size of equipment on the P&IDs. |
EVIDEN CE IDEN TIFICATION , COLLECTION & M ANAGEM ENT 145
circumstances of the incident. It is not po ssible to offer a prescribed priority. In
general, historical paper data such as procedures, mainte nance records, and
drawings are less fragile than people and physical data. The team should
identify time-sensitive data as one of its first tasks, prioritize the data, and
implement measures to collect or preserve the data.
If the team includes enough member s, the data collection tasks can be
assigned to individuals. For exampl e, some team members can perform
personnel interviews, while others identify and preserve physical data (and its
associated position data), or gather electronic and paper data. For a major
event, this type of approach may be required.
Figure 8.2. Forms of Data Fragility
Taking the individual investigator’s skills and experience into
consideration when assigning data collectio n tasks allows the team to
progress more rapidly. Some examples of time-sensitive data are outlined
below.
• Data stored in software files may be very fragile. Process computer
system records are sometimes structured such that the level of detail
diminishes over time. Therefore, the team may need to assign a high
priority to preserving this data. Computers may have a battery
backup that will preserve memory data for a finite time when power
is lost. Data on disk or flash memory may be lost or corrupted on
restart.
|
22 | 2 Learning Opportunities
• American Fuel and & Petrochemicals Manufacturers Conferences (AFPM
2020).
• IChemE Hazards Symposium (IChemE 2020c)
• International Symposium on Loss Prevention and Safety Promotion in
the Process Industries (EFCE 2019).
2.2.5 Other Resources
Many other resources can help you learn from incidents. Consulting
companies, insurers, and manufacturers will, with varying degrees of
anonymity, publish papers in journals and conferences describing incident
investigations and their findings and recommendations. When you attend
regularly scheduled process-safety training, you not only keep your skills up to
date, but often you can get a closer look at specific incidents.
Virtual events allow you to glean information across the globe—without
having to travel. Virtual learning opportunities include webinars, e-Learning
modules, and micro-learning opportunities. We can also anticipate advances
in virtual immersive learning experiences with technologies such as virtual-
and augmented-reality.
2.3 References
2.1 Associação Brasileira de Normas Técnicas (2018). Atmosferas Explosivas.
Place of publication: Associação Brasileira de Normas Técnicas.
2.2 AFPM (2020). Technical Papers. www.afpm.org/data-reports/technical-
papers (accessed May 2020).
2.3 AIChE (2020a). Process Safety Progress. AIChE/Wiley, aiche.onlinelibrary.
wiley.com/journal 15475913 (accessed May 2020).
2.4 AIChE (2020b). Proceedings of the AIChE Spring Meeting and Global
Congress on Process Safety. New York: AIChE.
2.5 AIChE (2020c). Proceedings of the Ethylene Producers’ Conferences.
epc.omnibooksonline.com (accessed May 2020).
2.6 AIChE (2020c). Proceedings of the Safety in Ammonia Plants and Related
Facilities Symposium. waiche.org/ammonia (accessed May 2020).
2.7 ARIA (2020). The ARIA Database. www.aria.developpement-
durable.gouv.fr/the-barpi/the-aria-database/?lang=en (accessed June
2020).
2.8 ARIA (2020). The BARPI. Subscription via www.aria.developpement-
durable.gouv.fr/the-barpi/?lang=en (accessed June 2020). |
164
of short residence time and is particularly useful for reactive or unstable
materials.
Solids Handling . The handling of solid materials frequently has the
potential for producing dust clouds that can lead to explosion hazards
(if the combustible dusts have the n eeded properties to support dust
explosions). Dusts also present pote ntial industrial hygiene hazards.
Handling solids in the form of larger particle size granules or pellets,
rather than a fine powder, reduces the potential for worker exposure
and also increases the minimum expl osive concentration and decreases
the residence time that the dust w ill be suspended in the air, thus
reducing the hazard of dust explosions.
If the solid is unoxidized and hence combustible, the dust explosion
hazard can be greatly reduced or ev en eliminated by using a larger
particle size material. However, it is important to remember that particle
attrition can occur during handling and processing, resulting in the generation of small particles that can become suspended, increasing
dust explosion hazards. The sequence of size reduction steps or even
the required particle size must be studied to minimize the number of
processing steps that involve very sm all particles. Another option would
be to change the form to a shape le ss prone to dust generation, such as
pellets, beads, prills, etc. Handling of so lids as a wet paste or slurry rather
than dry solids or powders can also reduce hazards, reducing worker
exposure and dust explosion hazards, such as with dyes (Ref 8.10 Burch).
For example, using wet benzoyl peroxide instead of the dry form reduces the hazards of this extremely reac tive material (Ref 8.84 Yoshida).
It may even be possible to eliminat e solids handling by processing in
a solution. However, this may require an assessment of the hazards of a toxic or flammable solvent in a process compared to the hazards of the solvent-free process. Additionally, hy brid mixtures of solid material
dusts with flammable gases and liqui ds are generally more hazardous
than the dust by itself (Ref 8.22 CCPS 2004), (Ref 8.15 CCPS 2017).
Inherently safer approaches to dust explosion hazard control also
include building equipment and structures strong enough to contain an explosion. A more thorough discussi on of dust explosion hazards and
their control have been published by CCPS (Ref 8.11 CCPS 1999) (Ref 8.27 |