Shop-fabricated Tanks

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

johncornell@storagetanks.info

www.storagetanks.info

Phone: (814) 436-7453

Cell: (814) 706-7514

H.I.R. Technical Serviceswww.storagetanks.info