Planning to Avoid Failure Storage Tanks

safety
TANK STORAGE • September/October 105
Accidents involving storage
tanks are unfortunately not
as uncommon as people
in the industry would like.
The oldest and most
significant event occurred in
January 1919 at an alcohol
factory in Boston, US1
when a
tank exploded and dumped
9.5 million gallons of molasses.
In January 2005 an occurrence
in Buncefield2
, UK saw a 22
tank storage park for jet fuel
completely destroyed by fire.
More recently, in Venezuela
last year3
, a storage tank farm
was also wiped out by fire.
An overall look at past
incidents shows that events
occurred via different
causes, marked by a string
of major accidents. These
accidents combined spurred
the US community to create
regulations and standards
such as API 653, which seek
to ensure co-existence
with these facilities.
A study by James Chang
and Cheng-Chung Lin, shown
through this ‘cause and
effect’ diagram (top right),
took in accidents in storage
tanks between 1960 and
2003. It provides an overview
of accidents that occurred
more frequently at refineries
and storage terminals,
facilitating an understanding
of the causes and regularity
of accidents in storage tanks.
It shows that accidents
involving fire and explosions
made up 85% of cases and,
of those, approximately
33% are caused by lightning
and 30% by human error
or poor maintenance.
Other causes included
damage from leaks in pipes
or valves connected to
tanks, natural disasters and
other static energy causes.
The study also indicated
the refining industry, where
external floating tanks are
more apparent, suffered the
majority of these events as
they usually have greater
operational complexity and
large stocks of product, such
as crude oil, naphtha and
petrol. These products also
appear in other studies as
figuring heavily in accidents,
contributing to large losses
due to their combustibility.
Despite an advent of
technical legal agencies,
associations and entities
related to engineering, such
as the Brazilian Association of
Technical Standards (ABNT),
American Petroleum Institute
(API), American Society of
Mechanical (ASME) and
National Fire Protection
Association (NFPA), and the
subsequent standards and
recommendations for projects
levied, accidents involving
storage tanks still occur.
So learning from the
past is important because
similar events could be
prevented in the future via
good engineering practice
to ensure minimum use of
these recommendations,
codes and standards.
Planning to
avoid failure
Diagram showing the causes of accidents involving storage tanks4
Causes of Accidents QTD %
Lightning 80 33,1
Hot Work 32 13,2
Poor operation 29 12,0
Equipment failure 19 7,9
Sabotage 18 7,4
Crack/Rupture 17 7,0
Piping rupture/leak 15 6,2
Static electricity 12 5,0
Open flame 8 3,3
Nature disaster 7 2,9
Runaway reaction 5 2,1
Total 242 100%
Cause of tank accidents4

safety
106 September/October 2013 • TANK STORAGE
Understand the whole process
The provocation of the
technical community
comes with a suggestion
to develop best practices
among professionals that
somehow align directly
with storage tanks and their
managers, performers and
operators. To do this it would
be necessary to develop a
training plan and based on
the main standard documents
relating to storage tanks.
It is important to
understand and apply the
standard documents fully as
single acts of expertise do not
eliminate all vulnerabilities.
That requires a multidisciplinary
forum to discuss, evaluate
every step from investment
plans to the tank’s retirement,
including the findings of
regular inspections, service
changes, the discovery of
any new techniques and
methods of maintenance,
inspection or repairs,
investments into emergency
assistance resources,
patrimonial security and
training for all staff involved.
To safely manage a
storage area in petrochemical
refineries and similar, it requires
knowledge from project
design to construction,
operation, inspection
and maintenance of the
terminal. To do that, those
responsible for those units
should use API 2610.
This standard covers issues
like site selection, the spacing
between tanks, pollution
prevention and waste
management, safe operation,
fire prevention and protection,
levees, mechanical systems,
transferring of products,
corrosion protection,
structures, needs of
nearby communities,
relocation, removals and
decommissioning.
Keeping control
Operational control for
level checks should receive
special attention during
storage tank usage, especially
when it involves product
moving through a pipeline,
to aid protection against
spillages. The API 2350
covers overfill protection
for all surface storage tanks
that hold flammable or
combustible liquid products.
The management of
product will need constant
logistical evaluation,
particularly if tanks see a
change of stored product
over time. Any overpressure
or vacuum, usually resulting
from modification of
calibration parameters in
ventilation devices, need
to be addressed. When this
occurs it is important to check
the behaviour of the fluid and
its vapour pressure in relation
to the type of tank roof using
API 2000 and API 520.
Emergency reponse
An operations team, together
with site security members, can
guide their management’s
actions when responding to an
emergency using NFPA 25 as
a reference for maintenance
inspection and system testing,
including cooling systems,
hydrants, foam cameras
and combat vehicles. The
publications API 2021, NFPA 11,
NFPA 30 and NFPA 600 are the
recommended documents for
training the staff responsible
for those actions.
Reliability
The technical experts, who
seek integrity and availability
of storage tanks, have API 581
which brings a methodology
for preparing a proposal
for inspection based on
risks and consequences
for their company.
For cases related to
detection techniques for
inspection, maintenance,
repairs and alterations, API
653 covers details used in
soldered, riveted and vertical
tanks (excluding refrigerated
tanks). Tanks that do operate
at temperatures between 5°C
and -198°C, are more suited
to the criteria in API 625.
Healthy atmosphere
As discussed, atmospheric
discharges are a constant
concern for the safety of
storage tanks because
they have been identified
as frequent causes of
accidents throughout the
world, especially in external
floating roof tanks. Four
recommendations which
aim to stop this problem
are NBR 5419, API 545, API
2003 and NFPA 780.
However, these documents
do not provide actions to
avoid or eliminate any natural
manifestations on tanks. Site
managers should ensure
that recommendations for
maintaining the sealing
or ventilation systems with
flame arresters, as well as
tank groundings, are met. It
should be noted the sealing
of the systems, to avoid
flammable emissions, is of
great importance in the
fight against lightning.
The static age
Static energy is another
phenomenon which causes
accidents in tanks, usually with
catastrophic consequences.
This type of accident mostly
occurs when sampling
activities of flammable liquids
takes place while opening
or closing hatches or values.
It is vital to incorporate
appropriate practices to
ensure activities like avoiding
metallic shocks, using glasses
and sampling gauges for
non-conductive material.
Conclusion
The research and studies of
accidents involving storage
tanks across the world have
become known by the
technical community via the
media, conferences and
congresses. After analysis
it can be concluded that
most incidents could have
been avoided if good
engineering practices were
used on design, construction,
maintenance and operation,
with a well-executed security
programme part of it too.
References
1
Catastrophic Tank Failures:
Highlights of Past Failures along
with Proactive Tanks Designs John
R. Cornell and Mark A. Baker, P.E.
2
The Buncefield Investigation:
Third progress report
Written by Taf Powell, Buncefield
investigation manager and
member of Buncefield Major
Incident Investigation Board
3
Explosion kills 24 at
Venezuela’s biggest refinery
Written by Abdul Ahad Sunday,
26 August 2012 – Reuters, 2012
4
A Study of Storage Tank
Accidents, James Chang
and Cheng-Chung Lin,
a) API 2610 - Design, Construction,
Operation, Maintenance,
and Inspection of Terminal
and Tank Facilities
b) API 2350 - Design, Construction,
Operation, Maintenance,
and Inspection of Terminal
and Tank Facilities
c) API 2550 - Measurement
and Calibration of Upright
Cylindrical Tanks by the
Manual Strapping Method
d) API 2000 - Venting
Atmospheric and Low-pressure
Storage Tanks, Sixth Edition
e) API 520 - Sizing, Selection,
and Installation of Pressure-
relieving Devices in Refineries.
f) API 2021 - Fighting Fires
in and Around, Flammable
and Combustible, Liquid
Atmospheric Storage Tanks
g) NFPA 25 - Requirements for Less
Frequently Performed Fire Sprinkler
System Inspections and Tests
h) NFPA 11 - Standard for
Low-, Medium-, and High-
Expansion Foam
i) NFPA 30 - Flammable and
Combustible Liquids Code
j) NFPA 600 - Standard on
Industrial Fire Brigades
k) Book Aboveground Storage
Tanks – Philip E. Myers
l) Philip E. Myers Complete
Guide API 2350 – Tank Storage
Magazine - Volume 8, Issue 5
m) Bruce Kaiser Controlling
Lightning Damage at Transfer
Stations – Tank Storage
Magazine - Volume 8, Issue 3
n) Orlando Costa The Use
of Code API 653 Integrity of
Storage Tanks 9th. COTEQ -
International Conference on
Equipment Technology.
For more information:
This article was written by
technical equipment and integrity
inspector Orlando Costa and
engineer equipment and integrity
inspector Paulo Valença of
Braskem Petrochemical, Unib-Ba

Planning to Avoid Failure Storage Tanks

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