15. Tank Lifting Engineering

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All accidence are preventable


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Safe Methods & Procedures

Tank Lifting


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EEMUA Publication No. 159: 2003,3rd Edition Volume 2

Appendix C: Typical Repair Solutions

C.1.1 Application

J acking is a very important technique for makingrepairs or modifications to tank foundations andbottoms.

Tanks are jacked up by using hydraulic jacks or air-

bags, which lift the tank 6 8ft above the foundation,and supported on timber stacks.

The 6 8ft free height allows small earth-moving

equipment to operate under the tank.

C.1 Tank Jacking


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More specifically, jacking is often used to:

correct unacceptable foundation settlement

install a high density polyethylene (HDPE)

membrane under the entire tank together witha leak detection system or leak detection andmanagement system

remove contaminated soil caused by bottom

leakages, and restore the foundation


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ensure safe replacement of the tank bottom if thefoundation is contaminated

install a cathodic protection system under thetank bottom.

inspect the tank bottom for underside corrosion; ifnecessary, the underside of the tank bottom

can be blasted and coated after theinspection;


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Hydraulic jacks.

High capacity (up to 60 tons per jack) but heavy to

move around.

Lifting lugs need to be welded to the outside of the

shell, or the jacks welded to the tank

Large excavations are required to position the jacks

directly under the shell.Such large excavations are undesirable.

C.1.2 Types of Jacks


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C.1.2 Types of Jacks

Air-bags.

High capacity (up to 74 tons per air-bag) easy tohandle and move around.

Air-bags require a small excavation under the shell,about 2in high, to insert an empty bag.

Usually, two excavations are required to lift part ofthe shell to allow the insertion of additional air bagsat adjacent locations.


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C.1.7 General Requirements

The general requirements for ensuring a safe andsuccessful jacking operation are:

Selection of an experienced jacking contractor.

J acking contractor to perform site survey includinglevel measurements.


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J acking contractor to submit detailed methodincluding calculation of overturning stabilityunder wind conditions.

Special attention should be given to tanks with

corroded shell plates, i.e. more jacking pointsmay be required to reduce vertical bendingstresses.

In addition, the contractor should demonstrate bymeans of calculations that the tank integrity

(shell and roof structure) will be maintainedduring jacking.


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Tank Lift Engineering


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Tank lifting work is started after thorough

professional engineering evaluations are performed.

The evaluations are accomplished with veryconservative safety factors built in.


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Air Bag Support Timbers

SiesmicForces

Allowable Air Bag Pressure

Tank Lifting Engineering

Wind UpliftWind Forces

Tank Perimeter Supports Ground Bearing Pressure

VerticalShellCompressionRadicalShell/FloorCompression

Vertical Shell Compression Radial Shell/Floor Compression

Calculations are in accordance with:

Local codes and practices

Knowledge of the tanks original construction

A.P.I. tank construction standards and details

Local wind conditions


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SiesmicForces




Tank Perimeter Supports Ground Bearing Pressure



Tank Stress

Maximum air bag pressure

Calculated floor sag

Required number of perimeter supports


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SiesmicForces




Tank Perimeter SupportsGround Bearing Pressure



Foundation load

Proven ground bearing pressure and shear strength

Minimum number of tank supports


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SiesmicForces




Tank Perimeter SupportsGround Bearing Pressure



Wind Velocity

Skidding Tank overturning

Sty overturning


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Procedure & Job Safety Analysis

Client Safety Standards

Client safety standards will be reviewed prior to the

start of work and are to be followed.Additionally, all necessary work permits shall beobtained from client personnel prior to the start of

work each day.

Job Safety Analysis

Prior to each phase of work, a job safety analysisshall be performed. See Individual Tank Specificdocuments.


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Procedure & Job Safety Analysis

Pre-lift

Fill out Individual Tank Specific documents.

The individual tank specific documents include site

specific, heath, safety and environment requirements

The sheets required for toolbox meetings and thesheets required for job safety analysis.


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Job Tasks Potential Hazards Recommended Action or Procedure

Inspect and mark out Fall Care when walking around Tank

Cut and Weld Caught Welding leads, grinder, electric leadsare laid out safely. Use proper cutting

/ welding PPECrane Caught Inspect all rigging equipment prior to

each use.

Do not exceed the capacity of the

equipment.Never lift loads over people

Use tag lines to control all loads.

Know the capacity of riggingequipment and weight of load that you

are picking up.

All hooks must have a safety latch.

Use the right communications withcrane operator and rigger.

Job Safety Analysis


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Job Tasks Potential Hazards Recommended Action or Procedure

Install timbers Caught & Fall Keep timbers stacked and storedwhen not using. Tripping hazard

Be aware of pinch points, wear gloves

Proper lifting techniques, bend theknees

Install airbags andplates

Hydraulic J acks

Caught 2 men to move bags and steel plates

Proper lifting techniques, bend the

knees

Airbag hosesHydraulic hoses

Fall Keep hoses tidy tripping hazard

Job Safety Analysis


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Tool Box Meeting

Topics:

PPE Steel toe footwear

Hard hats Eye protectionHand protection Fall protectionHearing protection Respiratory protection

Discuss:

Health & Safety issues

Previous days work

Work that we are hoping to achieve today

Changes in working conditions


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On the Job Safety; For Everyone; Everyday; All

the time

House keeping; Follow written procedures; ask forassistance, if needed

Job Safety Analysis:

ASSESS the risk;

What could go wrong?

What is the worst thing that could happen ifsomething does go wrong?


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ANALYSE how to reduce the risk;

Do I have the necessary Training and Knowledge todo this job safely?

Do I have the proper Tools

Do I have Personal Protective Equipment?


ACT to ensure safe operation;Take necessary Action to ensure the job is donesafely


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Do not proceed unless

EVERYTHING IS SAFE


If you THINK that it is SAFEDont do it

Do it when you KNOW that it is SAFE


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Air bag Technology

Correction of the tank rim settlement


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Repair/replacement of tank floor plates

Restore/change the tank floor profile

Reconstruct tank foundation


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No welding required on tank


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Air bags can be move to balance tank weight


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Tank can be lifted completely external


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100% under floor visual inspection


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No limit in size


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All internal fixtures can remain in place


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Tank lifting equipment is portable


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Tank can be lifted completely external


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Tanks that have leaked can be safely lifted


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Tank suction can be overcome by increasing

the number of air bags


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Tank can be moved and rotated


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Laying new steel floor


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Tank floor inspection made easier with

plenty of light


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An added benefit of tank lifting, is the ease atwhich 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.


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Removing last airbag from under tank

15. Tank Lifting Engineering

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