Tank Lifting. Tank Foundation. Tank Relocation. Alan Watson A.P.I. ...

Alan Watson

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Tank Lifting. Tank Foundation.

Tank Relocation.

Website: arwatson.com E-Mail: [email protected]

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A.P.I. 650 and 653 only give general guide lines to the type of foundation Number of different types, evaluated on the basis for:

• Risk • Cost

• Constructability • Schedule

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What to look for around tank to show Faulty Foundation

Grass, moss growing out from under the tank

Tree’s growing from under the tank

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Tank floor laid on river stone

Tank shell has edge settlement

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Tank is below ground

Water lying around ring wall foundation

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Ground outside foundation cracked

Water lying around tank

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Timber railway ties laid under shell holding moisture

Foundation around tank is uneven

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Concrete foundation has large cracks

Tank floor annular plate is starting to delaminate

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Tank shell is flattening out at the top of the tank

Floating roof jams on the way up

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Tank is not level

Insulation holding moisture

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Tar laid on top of annular hiding corrosion

Bottom shell course bulges out

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Foundation Failure Causing Underside Corrosion

Concrete ring wall slopes under tank

Poorly constructed or inadequate foundation material

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Moisture held in the foundations

Welding of the tank floor not to any code

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Concrete Ring Walls and Grout

If the steel tank floor is in contact with concrete, the moisture in the concrete and the galvanic action between the dissimilar metals will, over a period of time, cause the steel to corrode at an accelerated rate.

Double Bottom Method

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Developed in the 1980’s as the only viable secondary containment method, has failed in a number of cases

With the old steel floor and a new steel floor spaced apart with sand or concrete, the oxygen and moisture makes a perfect battery cell and the new floor becomes the sacrificial anode.

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The new steel floor corrodes out at a rate 4 times faster than the old floor.

C.P.must be designed and installed by experienced contractors or it may result in increasing the rate of corrosion of the tank floor.

Any change in the amount of moisture in the foundation material will cause the resistivity of the material to change and this may result in the C.P. breaking down.

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In some cases, where oil impregnated fiber board or oil sand has been used, nature has done its work and eaten the oil out of the sand. This can reduce the resistance of the sand and this condition has proven to accelerate corrosion.

NDT (Non-Destructive Testing) inspection has limitations and flaws and cannot inspect 100% of the tank floor. It cannot inspect the critical zone around the shell to annular weld, lap joints, under the roof columns, around tank sumps. Sometimes packed rust shows up as good metal

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We have identified that many of the problems with aboveground storage tanks start at the foundations. Tank’s not properly founded are bound to fail.

Tank Foundation

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When built on good foundations tanks have lasted 50 and more years

Difference in Settlement between Center and Periphery EEMUA 159

Tank Shell Tank Bottom

Shell settlement

Settlement at center 30% greater than at Shell

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Remove moisture = no corrosion

Air Steel

If all 3 elements are present then corrosion can occur

Corrosion Triangle

Remove air = No corrosion

Moisture Steel

If all 3 elements are present then corrosion can occur

Corrosion Triangle

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New Tank Foundation Construction with Liner

EEMUA 183

9. Main Conclusions and Recommendations -Codes and standards covering the design and construction of storage tanks are based on over 100 years of experience. There is no need to question the integrity of the tank structure as a as a primary container, provided it is properly designed and built to recognised standards. -Effective prevention of ground and ground water pollution from storage tanks depends on the design and construction of a good foundation, a properly construction tank bottom and regular, effective inspection.

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Alan Watson is working on re-writing API 650 APPENDIX “B” “RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION OF FOUNDATIONS FOR ABOVEGROUND OIL STORAGE TANKS” If you have any suggestions please contact him at [email protected]

All accidents are preventable

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Safe Methods & Procedures

Tank Lifting

Tank Lift Engineering

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Tank lifting work is started after thorough professional engineering evaluations are performed. The evaluations are accomplished with very conservative safety factors built in.

Wind Forces

Wind Uplift

Calculations are in accordance with: • Local codes and practices • Knowledge of the tank’s original construction SiesmicForces

• A.P.I. tank construction standards and details • Local wind conditions Vertical Shell Compression

Allowable Air Bag Pressure Tank Perimeter Supports

Radial Shell/Floor Compression

Radical Shell/Floor Compression

Vertical Shell Compression

Air Bag Support Timbers Ground Bearing Pressure

Tank Lifting Engineering

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Wind Forces

Wind Uplift

Tank Stress • Maximum air bag pressure • Calculated floor sag SiesmicForces

• Required number of perimeter supports


Allowable Air Bag Pressure





Tank Perimeter Supports


Wind Forces

Wind Uplift

Foundation load • Proven ground bearing pressure and shear strength SiesmicForces

• Minimum number of tank supports








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Wind Forces

Wind Uplift

Wind Velocity • Skidding • Tank overturning

SiesmicForces

• Sty overturning Vertical Shell Compression







Additional cribbing system installed before any personnel can go under a lifted tank

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Water in the foundation will weaken the soil. It may not support the load under the lifting jacks

Job Safety Analysis: On the Job Safety; For Everyone; Everyday; All the time House keeping; Follow written procedures; ask for assistance, if needed ASSESS the risk; What could go wrong? What is the worst thing that could happen if something does go wrong?

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Air bag Technology

Correction of the tank rim settlement Repair/replacement of tank floor plates Restore/change the tank floor profile Reconstruct tank foundation

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No welding required on tank

Air bags can be move to balance tank weight

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100% under floor visual inspection

No limit in size

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All internal fixtures can remain in place

Tank lifting equipment is portable

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Tank can be lifted completely external

Tanks that have leaked can be safely lifted

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Tank suction can be overcome by increasing the number of air bags

Tank can be moved and rotated

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Laying new steel floor

Tank floor inspection made easier with plenty of light

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An added benefit of tank lifting, is the ease at which a tank can be relocated once the tank is in the air. This can save the tank operators thousands of dollars and months of downtime.

Tank Relocation

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Moving tanks for tank farm upgrade

Moving tanks to give better utilization of the land

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Joining tank farms together to maximize terminal facilities

Tank moved to make building a new foundation easier and more cost effectively

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Moving tank to sell land for a profit

Returning leased land back to the owner

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Relocation of tank to a new site.

Questions? Contact: Alan Watson Washington Office: 4016 E Maryland St. Bellingham, WA 98226 Phone: USA 360-734-9157 Fax: USA 360-752-1779

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