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IN T E R L I N E TA N K L I N I N G SY S T E M S

Recommended Working Procedures

Installation of a lining system is the most effective method of protecting steel tanks andvessels from corrosion and preventing product contamination. There are three essentialelements to a correct tank lining:-

• Selection of the appropriate lining system• Suitable film thickness specification• Correct installation

The procedures contained in this document have been compiled to provide guidance onachieving both the mandatory standards for surface preparation and for lining application.Any proposed deviations from these recommendations should be discussed and agreed withInternational Protective Coatings before the project is commenced.

The responsibility for achieving the standards detailed in this document to carry outinstallation in accordance with good lining practice rests with the contracting companycarrying out the work. Under no circumstances does the responsibility become the burdenof International Protective Coatings or any associate company thereof, whether thatcompany or associate is represented on site or not.

GENERAL

REQUIREMENTS FOR

TANK LINING

• Tanks must be structurally sound. Tank lining is intended to mitigate corrosion, preventproduct contamination and give assurance against leakage. No tank lining, includingfibre glass systems, afford structural strength to the tank.

• Contractors selected by the client for tank lining application should be made familiarwith the procedures required and be able to demonstrate competence to the client’ssatisfaction.

NEW CONSTRUCTION The preferred manufacturing procedure for new tanks is that internal surfaces should becoated with a preconstruction primer prior to fabrication. The primer should then beremoved after erection and hydrostatic testing. Benefits of this procedure are:-

• Reduced potential for steel contamination from soluble salts either from corrosion orhydrostatic testing.

• Easier to achieve specified blast standard as recommended on individual product datasheets.

TANK CONDITION

PRE-CONTRACT

Before the start of treatment it is essential that internal tank surfaces are clean, dry and in acondition suitable for surface preparation and application of the lining system. Thefollowing minimum requirements apply:-

• Tanks must be structurally sound and gas free.

• All inlet pipes must be blanked off.

• Surfaces should be de-sludged and residues removed from the tank. Oil or grease mustbe removed from all surfaces to be lined.

• Heavy scale or other debris must be removed from all surfaces, including the roof. Forheavily scaled or contaminated surfaces rough cleaning by sweep blasting may be

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required.

• Corroded steel that is heavily contaminated may require additional cleaning, e.g. steamcleaning or high pressure fresh water washing, before surface preparation starts.

• Any hot work or welding must be completed before surface preparation commences.

• Tanks are often subjected to hydrostatic testing and if this is carried out using salt orbrackish water then this test must be followed by fresh water washing. In theseconditions the maximum allowed salt contamination is 20 p.p.m. Where coatings as areused for storage of aqueous media at high temperatures (e.g. distilled water up to 90ºC)then a lower salt contamination level of 10 p.p.m. is recommended to prevent prematurefailure due to osmotic blistering. International Protective Coatings will recommend asuitable test procedure.

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HEALTH & SAFETY Some tank linings contain volatile flammable organic solvents which can form explosivemixtures with air and additionally can contain materials which may necessitate personalprotection against potential health hazards. A summary of the main precautions to be takenincludes:-

• Attention to the dangers of explosion or fire.• Provision of adequate ventilation.• Ensure that tanks and surrounding areas are flame and spark free.• Provide painters or operatives with the correct respiratory protection.• Ensure correct protective clothing is worn to avoid skin contact.

• The safety advice provided is applicable to the surface preparation, application of thelining and inspection. It is not intended to be comprehensive and is a guide based onaccumulated knowledge of the hazards involved, the proposed use of safety equipmentand evolved safety procedures.

• Full details of the H&S requirements for each material are given on individual ProductHealth & Safety Data Sheets.

General Site Requirements

Prior to any work being carried out there are a number of conditions which must be met.

a) Cleanliness

Any contaminants which may come in contact with the steel (even before surfacepreparation comments) can compromise the performance of a tank lining system, andas such all effort must be made to keep the working area clean. It is good workingpractice to establish a clean area around the entrance to the tank where clean footwearcan be put on prior to entering the vessel. If clean footwear is not readily availablethen disposable overshoes can be worn for short periods. Cleanliness must bemaintained throughout all stages of the application.

b) Weather Shelters

Weather shelters should be made available to cover application equipment duringmixing and application of material.

c) Power Source

Generator and sufficient fuel for entire contract to power all the equipment required forthe application, i.e. compressors, lighting etc.

d) Paint Storage Facility

Certain paint products have a minimum or maximum storage temperature and facilitiesshould be made available to store the materials at the correct temperature prior tomixing and application.

e) Dehumidification

Surfaces to be lined must have a temperature at least 3ºC above the dew point,immediately following blasting and priming, and during lining application, and mustalso remain in this condition during curing of the lining. To achieve this requirementdehumidification may be necessary.

As a guide, relative humidity levels of 40-60% give optimum installation conditions,although some lining applications may be carried out between 25% and 80% relativehumidity. The requirement for dehumidification is dependent on prevailingenvironmental conditions and the actual lining being applied, Consult InternationalProtective Coatings product data sheets for recommendations.

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When dehumidification is being used, provision must be made for continuous 24 houroperation to maintain the environment at the required levels throughout the contract.

f) Ventilation

During the blast cleaning operation, ventilation is necessary to allow adequatevisibility for safe working. Flexible ventilation trunking should be used to allowextraction of the dust immediately adjacent to where blasting is being carried out.

Ventilation should be maintained during lining application and while solvent isreleased during drying of the lining. The air movement should be sufficient to preventthe vapour concentration exceeding 10% of the Lower Explosion Limit.

Values shown below can act as a guide to the ventilation requirements for theapplication of Interline 850 according to specification. The figures are the absoluteminimum number of air changes and the number (where applicable) is based on atypical application rate of 500m2 (5300ft2) coated per hour.

This example is offered to demonstrate typical figures at a given application rate for atypical system. Similar details are available for all of our products, for furtherinformation please consult International Protective Coatings.

Diameter (m) Tank Construction Minimum Air Changes/Hour

10 3.50

20 3.00

30 1.75

50 0.60

100

Floating Roof(2m from Floor)

0.20

10 0.70

20 0.60

30 0.40

50 0.20

100

Cone Roof(10m High)

0.10

• To minimise dry-spray formation caused by excessive air movement the ventilationlevel may be reduced during application – paint application rate should then be adjustedto ensure 10% of Lower Explosion Limit is maintained.

• As with all processes, the ventilation equipment must be electrically safe duringoperation. Abrasive dust and solvent vapour should not be reintroduced to the tank. Apositive pressure greater than normal atmospheric should be maintained inside the tank.Provision should be made for 24 hour surveillance of ventilation equipment.

g) Heating

All linings must only be installed when steel temperatures are above the minimumtemperature indicated on specification and product data sheets.

If heating is necessary to satisfy the lining specification, it should be by means of aheat exchange system incorporated into the dehumidified air supply, i.e. air admitted tothe tank should not pass directly through a combustion chamber. Provision should be

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made for 24 hour surveillance of heating equipment.

h) Lighting

Lighting during blasting and lining installation must be electrically safe and providesuitable illumination for all work. Ideally, lighting should be by powerful spotlightswith background lighting on at all times in the interest of safety. Powerful, hand-heldspotlights should be provided for inspection work.

STEELWORK

PREPARATION

To provide a surface which will ensure optimum lining performance, preparation isrequired to remove surfaces which have a sharp edge. These include, but are not limited to,plate edges, weld spatter, plate laminations, weld undercuts, or gas cut surfaces.

INSTALLATION OF

STRIKER PLATES• Prior to the application of the lining system, it is recommended that precoated striker

plates are installed under any tank equipment that could cause mechanical damage tothe lining system, namely column roof supports, floating roof legs, roof drainagesystems or internal pipework.

• Installation of these striker plates is done before the general surface preparation tominimise the contamination from the roof during the jacking operation to install theplates.

• Striker plates are to be made from appropriate gauge plate and be of sufficient size as tofit existing plates. If striker plates do not exist, the plates shall be of sufficient size toextend 15cm (6 inches) in all directions from the roof support base.

• The new plates shall be blasted on both sides to Sa2½ ISO 8501-1:1988 (SwedishStandard SIS 05 59 00) or SSPC SP10. These plates shall be primed on both sides withthe specified Interline primer masking off a 50cm (20 inches) area on all sides at theleading edge on top.

• For GRP systems, the top face shall have the full specified Interline system applied.

The completed plate is ready for installation to the tank bottom.

• Raise the support column to allow installation of precoated striker plate. When thesupport column has been raised, apply an even coat of an appropriate Interline caulk tothe bottom side of the precoated plate and to the prepared area underneath the supporton the tank floor. Centre the plate under the support column and lower the jack.Remove excess caulk. (See Diagram A).

ABRASIVE BLAST

CLEANING

General

• The standard of blast cleaning for tank linings is higher than that required for coatingssubject to atmospheric service. The two common standards specified are to SSPC andISO 8501-1:1988.

• As a general principle, where products are recommended for immersion or aggressiveatmospheric conditions the blasting standard required will be to Sa2½ (ISO 8501-1:1988) or SSPC SP10, dependent upon the operational standards agreed with the client.

• In some areas of very aggressive service Sa3 (SSPC SP5) may be specified. Alwaysconsult the individual data sheets for minimum surface preparation standards.

• If advice on any other standard of surface preparation is required, please consultInternational Protective Coatings.

• Where the substrate is heavily corroded or pitted, it may be necessary to fresh waterwash areas after abrasive blasting, then reblast, to reduce levels of soluble corrosion

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products a maximum salt contamination level of 30 mgm2 is permissible. If rapid re-oxidation is occurring, this treatment should be carried out. When lining hot watertanks operating at temperatures in excess of 65ºC, fresh water washing after initialblasting must be carried out, followed by reblast to the specification standard.

Compressed Air

• Air used for blasting must be clean, oil free and dry. The pressure should be at least7kg per cm2 (100lbs per inch2) at the nozzle.

Abrasive

• Abrasive used for blasting should be dry and free from dirt, oil, grease or contaminationand have content of water soluble matter not exceeding 0.05%.

• The abrasive must be capable of producing the standard of cleanliness and surfaceprofile specified.

• For tank lining a sharp angular profile is required, consult individual product data sheetsfor minimum required profile. This can be achieved by hard angular abrasive ofparticle size 1-1.5mm(0.04-0.06 inches) using an efficient blast cleaning technique.Procedures to be adopted by the contractor for blast cleaning should be agreed withInternational Protective Coatings.

• Iron or steel abrasives are not recommended for in-situ open blasting. This is to preventcorrosion occurring at sites where spent abrasive is deposited and not fully removed.

Automatic Floor Blasting

• Automatic blasting using centrifugal wheel machines is recommended for floorblasting. The abrasive selected must be from blended shot and angular abrasive toachieve the specified profile and standard.

Cleaning

• Before initial blast inspection, the bulk of the spent abrasive should be removed. Anysubstandard areas should be identified and repaired. All marking paint, chalk etc., mustbe removed after rectification.

• Following inspection of the blast profile and standard, remaining traces of abrasive anddust should be removed from all areas. Industrial vacuum cleaners fitted with brushesshould be used – sweeping alone is not acceptable. Blowing down with compressed airis not recommended due to the potential of contamination.

• Cleaning should be carried out on any area on which debris or dust can collect, to avoidcontaminating surfaces to be coated including scaffolding, underside of loweredfloating roofs, support columns etc.

• The steelwork for lining application should be rechecked after the final cleaning processis finished.

HOLDING PRIMERS • Linings should always be applied to blasted surfaces with a visual appearance inaccordance with the specified standard.

• Under practical conditions, a holding primer is often used to aid the blastingprogramme. Holding primers must be compatible with the lining system and applied atthe specified film thickness to avoid introducing a weakness into the system.

• If practical, normally in small vessels only or in larger tanks where small areas will beblasted and then coated after a short period, the blast standard may be maintained by useof dehumidification only. If maintaining standard by this method the standard mustmeet the requirements stipulated in the individual product data sheets.

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NON-WELDING

STEEL REPAIR

Prior to the application of a GRP system, perforations in steel floor plate up to 2 cm (1inch) in diameter, not repaired by welding, can be patched with steel plate of 6mmthickness and of a size to extend a minimum of 7cm (3 inches) beyond the perforation in alldirections. The following technique should be used:-

• Abrasive blast clean and prime the steel plates to the specified standard.

• Attach plate to floor with a recommended Interline caulking compound, placing thesteel patch centred over the perforation and covering the edges. See Diagram B.

STRIPE COATING • Stripe coating is an essential part of good working practice, and as such should formpart of any lining specification. The number and sequence of stripe coats arehighlighted in the detailed product specification sheets.

• Stripe coats are applied to areas where it is difficult to get the required coverage,including but not limited to:-

Ø Plate edgesØ WeldsØ PipesØ LaddersØ Difficult access areas

• Stripe coats are normally applied to a specified film thickness range via a combinationof narrow angle airless spray and brush methods. Overcoating intervals for the stripecoats should be strictly adhered to as per the individual product data sheet. (SeeDiagram C).

Caulking

• Caulking is a specialised form of stripe coating where material (formulated for higherfilm thickness) is airless spray applied to give a smooth transition between irregularsurfaces. This is to help with the uniform application of the lining system. Caulking isessential to help in the good application of glass reinforced linings where the surface tobe laminated must have uniform transitions, particularly in weld overlap plates, chimeangles and repaired areas. to enable good rollering to eliminate air entrapment and togive good glass wetting in the laminate.

• Caulking is typically carried out on lapped plate seams, the angle between the verticaland horizontal plates, column supports and on deeply pitted areas. (See Diagrams D &E).

LINING APPLICATION • All linings should be applied in accordance with system specification sheets andproduct data sheets.

• The majority of linings are applied by using airless spray. Brush or roller may be usedfor application of stripe coats or touch-up coats only.

• Available air pressure and capacity of spray equipment should be at least 5kg per cm2

and 1.4m3 per minute (80 p.s.i. and 125 c.f.m.). International Protective Coatingsrequest the use of the highest available ratio pump to ensure optimum delivery ofproduct.

• Airless spray equipment should be in good working order. Pump ratios of 45:1 orgreater should be used as a minimum. Output pressures and the correct tip sizes as

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stipulated on product data sheets should be used.

• Some International Protective Coatings products require the use of twin feed applicationequipment, which needs certain specialised arrangements to ensure the successfulcompletion of the lining installation.

CURING In order for any lining to perform as expected, sufficient cure time must be allowed beforeplacing into service. The length of time required is dependent on the coatings intended, in-service use, ambient temperature, and relative humidity. Consult International ProtectiveCoatings for details.

The recommended temperature and humidity as specified on individual product data andsystem sheets must be maintained over a 24 hour basis throughout the cure cycle. As aguideline, a minimum temperature of 10ºC should be maintained for a minimum of 7 days.This value will change depending upon the material to be stored and InternationalProtective Coatings should be consulted.

A typical cure schedule is shown below for Interline 910. This is the time required toachieve resistance to gasoline.

Cure Schedule @ Different Ambient Temperatures.

0

10

20

30

40

50

3 4 5 6 7 8Cure Time (Days)

Tem

per

atu

re (

°C)

Similar graphs for other products and stored material combinations are available, pleaseconsult International Protective Coatings for details.

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tech.enquires@uk.akzonobel.comwww.international-pc.com

Subject to Standard Terms and conditionsPlease consult Technical and Safety Datasheets prior to using any Product

DIAGRAM ASTRIKER PLATE