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Shop-fabricated Tanks
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A Case Study on an Unusual Site with Shop-Fabricated Tanks.
by: John Cornell, Senior Tank Specialist
Mr. John R. Cornell
21 Years Storage Tank Experience Around The Globe
Senior Tank Specialist for H.I.R. Technical Services
API-653 and STI-SP001 Certified Tank Inspector
Current job
Official Contracted Training Provider for API on Both
Introductory and Advanced Level Tank Training
Programs.
Exclusive Training Provider for PHSMA, DOT Part
195, Breakout Tanks.
H.I.R. Technical Serviceswww.storagetanks.info
The Right Approach
Purpose of Presentation
Relate experience to new inspectors .
Challenge inspectors to bridge the gap between
standards.
Can we only use one inspection standard?
Help the tank owner.
Sources
API 653.
STI SP001.
API- 575 and others.
The Inspection Doesn’t Start Here…
It starts here…
How old is the tank?
What has been or is
currently being stored in
the tank?
What construction code
was the tank built to?
Internal or External
inspection required?
Radiation
Fire hazards
Etc..
What is the tank configuration?
Horizontal or Vertical axis?
What kind of roof?
Cone roof, Formed head, …
What type of roof access is available?
Vertical ladder, Spiral stairway, none?
Other questions…
Is the tank clean?
Other questions…
Choosing the inspection standard
I could keep going & going & going…
Choosing the inspection standard
API-653 works for:
Choosing the inspection standard
API-653 and STI-SP001 works for:
Choosing the inspection standard
Don’t use API-653 for these, unless you
want to.
Case Study: The Ugly Tank
Age: Unknown.
Operating Temp: >200° F.
Design Standard: Unknown.
Bottom: Cone down.
Bottom: Unsupported.
Should we use API-653
API-653:
Temp: Up to 500° F
(260°C).
Bottom must be uniformly
supported.
Covers tanks built to API 650 and API 12C..
may apply to any steel tank constructed in
accordance with a tank specification.
Can we use API-653
“API 653 was intended to inspect tanks constructed in
accordance with API 650 or API 620 as well as other
large field-erected tanks, while API 12R1 was
designed for production tanks.”
Phil Myers, P.E.
The New STI SP001 Tank Inspection Standard and
Compliance with The New EPA SPCC Rule for
Petroleum Storage Tanks, July 22, 2004
API-620: Does permit bottoms to be
sloped.
Question: Can API-653 inspector,
inspect API-620 tanks. Yes, under
limited conditions.
Should we use STI-SP001
STI-SP001:
Temp < 200° F (93.3°C).
Tank may be on legs.
ELEVATED AST – an AST which is not in
contact with the ground.. Examples of
elevated tanks are tanks constructed on
grillage or grating, or tanks on supports.
The inspection started at the bottom
API-653 approach
Remember, API -
653 minimums are
based on a fully
supported bottoms.
API-653 approach
Remember, API - 653 minimums are
based on a fully supported bottoms.
API-653, Table 4.4…..050”
API-653, 4.3.2.1(old “t” =/> 60%)
Take-away: The thickness of corroded
(Shell / Wall) may be reduced by 40%.
.375” x .60% = .225”
API-650 calls it a shell, API-620 calls
everything a wall..
STI SP001 approach
Category 1 ASTs - The remaining AST
shell thickness shall not be less than
25% of the original “t”.
.375” x 25% = .0938”
How thick should the cone be?
API-653, Table 4.4…..050”
653, 4.3.2.1(old “t” =/> 60%)
Plates may be reduced by 40%.
.375” x .60% = .225”
STI-SP001 - The remaining AST shell
“t” shall not be less than 25% of the
original “t”.
.375” x 25% = .0938”
Required Floor / Cone Thickness
So for the floor
portion of the tank
inspection, we
instructed the
inspector to follow
the perceived
requirements of
API-653.
Floor welds need to be inspected
STI-SP001, 8.3.2
Inspect the welds
for cracking by
visual inspection or
other means.
API-653, 4.3.8
Deterioration of
welds… must be
evaluated …
Lessons learned - Coned Tanks
Both API-653 and STI-SP001 have
limits.
Use all available standards as tools..
Think about this..
Are you trying to pass the tank
or
Are you trying to fail the tank
Now onto the shell
Ultrasonic Thickness Readings
API-653:
Insulated tanks need to have insulation
removed only to the extent necessary to
determine the condition of the exterior
wall of the tank or the roof.
No particular guidance was given to our
inspector…
Ultrasonic Thickness Readings
STI-SP001:
Readings must be concentrated in areas
where corrosion is likely to occur.
Direct guidance for the inspector to seek out
and find the areas at which accelerated
corrosion may be located.
Ultrasonic Thickness Readings
API-653 / STI-SP001 Hybrid
Combination:
Remove the insulation as required to
determine the condition of the tank’s
exterior and take additional readings in
areas where internal corrosion is likely to
occur.
There was already enough insulation missing
on this tank that no addition insulation needed
to be removed.
Shell Inspection Results
Shell Inspection Results
14,000
Gallon
Roof Hazards – Falling over
Fact: Many tank inspectors do not have
training in fall protection.
www.api-u.org/eLearning/FallProtectionIntro.html
Roof Hazards – Falling over
A man was killed when he
fell from the top of a storage
tank.
There were no guardrails or
other safety devices on the
tops of the tanks,
the victim was not using
any fall protection
equipment.
Roof Hazards – Falling overEmployers should follow the OSHA
guidelines for personal protective
equipment.
Owners, consider devices such as
nonskid surfaces and railings on top of
the tanks, and the
surfaces on top
should be kept free
of oily residue.
Roof Hazards – Unsafe Ladders
Check the ladder and stairways for loose
treads or missing bolts and etc..
Roof Hazards – Unsafe Treads
Check the ladder and stairways for loose
treads or missing bolts and etc..
Topside Corrosion
API-575, 7.2.9 Tank Roof Inspection
Hammer testing is not a recommended
method of establishing roof plate integrity for
personnel loading.
Check for corrosion as you go.
API Document 1972, Pre-653
1) All roofs should be hammer tested.
2) Regardless of the external appearance of
the roof.
3)The hammer testing should be done with a
full swing of the arm.
Underside Roof Corrosion
STI SP001:..It may be necessary to check the
plate thickness with a hammer test to verify its
adequacy.
Check for corrosion as you go.
API-653 permits any area on a tank roof
to corrode to a average thickness of not
less than .09” thickness in any 100
square inch area.
Experience shows that there can be
isolated thin spots.
Check for corrosion as you go.
Experience shows that there can be isolated
thin spots.
Floating Roof Inspection Hazards
This session will discuss approaching the inspection with safety in mind by reviewing:
Both Internal and External floating roofs.
and
How various designs will alter the inspections report.
Entry into confined space occurs
when the vertical plane of a shell
manhole is broken.
Are you trained to be in here?
Shows a floating roof from the top of
the cone roof looking in thru the roof
hatch.
External Floating Roof Access
Need more tank training?
Go to: www.api-u.org
Inspection of Fiberglass and Plastic Tanks.
Introduction to API 620, 650 and 653.
Advanced Tank Training.
API-12F and 12R1.
Questions???
John R. Cornell
H.I.R. Technical Services
701 North Perry Street, Suite 301
Titusville, PA 16354
www.storagetanks.info
Phone: (814) 436-7453
Cell: (814) 706-7514
H.I.R. Technical Serviceswww.storagetanks.info