Std

SURFACE PREPARATION & COATING

1. INTRODUCTION .

1.1.ScopeThis specification covers the minimum requirements for surface preparation, priming, painting & inspection relating to new construction projects.

1.2 Applicable International standardsThe following standards and standard forms are referred in this specification and shall be used.

SIS 05 59 00 -Swedish standard pictorial surface preparation standard for Painting Steel Surfaces.

BS 4232 - Surface Finish of Blast-Cleaned Steel for painting.

SSPC - System and Specifications Steel Structures Painting Council.

BS 410 - Specification for Test Sieves.

2. DEFINATIONS .

Cure -The hardening of recently applied paint by chemical reaction, solvent evaporation, oxidation, heat curing ect.

High build -Describes a paint that can be applied to a surface in thick coats (of more than 100 micron thickness) without the paint sagging.

Passivated -The resistance to corrosion of a steel surface has been increased by the formation of an adherent nonreactive surface layer of a ferrous salt such as ferrous phosphate. This is normally achieved by treating the steel in a phosphoric acid solution.

Phenolic -A paint in which the resin incorporates the hydroxyl derivative of benzene and produced as a distillate from coal tar.

Ester-based -A paint in which the resin is a compound of an alcohol (glycol) and an acid (usually long-chain, e.g., linolenic or stearic).

Pot-Life -The length of time following induction that 2 Pack paint remains in an applyable condition as per manufacturer’s instruction.

NOTE: An ambient temperature in excess of that for which the pot-life has been stated will substantially reduce pot-life.

of 21Prepared By :- M T MULLA.


Shelf-Life -The period of the time stipulated by the paint manufacturer between manufacture and use during which the paint shows no marked deterioration.

Thinners -The solvents for cleaning, painting equipment, or for mixing with paint in small quantities if a decrease in paint viscosity is require.

Thixotropic -The property of a paint to decrease in viscosity when stirred and conversely increase in viscosity when left standing.-The property is important to maintain good pigment dispersion within a paint and to prevent pigment sedimentation.

3. PAINTING MATERIALS.

3.1 StoragePaint that has exceeded its marked shelf life shall not be used. Additionally shall not be used if it has thickened to such extend that more than 5% by volume. (10% by volume for primers) of the correct thinner is required to bring it to application consistency.

3.2 Preparation for use

31. Homogenizing.Mixing of painting and coating materials is critical and should be carried out under close supervision to ensure correct results. The drum should be opened and the bulk of the liquid portion poured into a clean drum of similar size with an open top. Stirring shall then break up the residual stiff or lumpy paste with a wide strong wooden paddle. If the residue cannot be worked into a smooth and uniform paste by this treatment, the paint shall not be used. If the residue can be worked into a smooth and uniform paste by this treatment, the liquid portion originally poured off shall be replaced in small quantities while stirring with a power driven stirrer moving with a figure-of-eight (8) motion.

When the paint appears to be completely uniform, it shall be ‘boxed’ by pouring repeatedly from one drum to the other. Before use, the paint shall be strained through 100-mess metal gauze to BS-410 to remove any skin or small lumps.

Only thinner supplied, recommended or approved by the paint manufacturer for the particular paint type shall be used.



Where coatings are being used containing metallic or heavy pigments that have a tendency to settle, a power driven stirrer shall be used in a pressure pot, or fitted in the supply drum for an airless spray pump.

32. Mixing of Two component paints.Paints, which are supplied as two components in separate containers, shall be mixed together immediately before use and shall be applied within the time limits specified by the manufacturer. The methods of preparing these types of paints before use shall be as follows.

1) Oil based aluminum paints are supplied as powder or paste and vehicle, packed in separate container in the correct proportions for mixing. Mixing shall be carried out thoroughly and a quantity only sufficient for 1 day’s work shall be mixed. Oil based aluminum paint, unused for more than 48 hours after mixing, loses luster and becomes grayish in color. It is then unsuitable for use as a finishing coat. The epoxy ester based aluminium paint is supplies ready mixed.

2) Epoxy resin based paints, high-build epoxy paints and coal-tar epoxy paints are supplied as two components in separate container in the correct proportion for mixing. These components shall be mixed in the correct proportion since curing takes place by chemical reaction. Once mixed, the paint shall be used within the time limits (Pot life) specified by the supplier. When the base material is thixotropic, it shall be stirred thoroughly in order to reduce its viscosity before adding the curing agent.

3) Wash primer (Phenolic modified wash primer) is supplied as two separate components. The hardener or accelerator is acidic and normally supplied in plastics, glass or stoneware bottles. After mixing, this material shall be used within specified Pot life.

4) Zinc silicate paints and graphite stack paints are supplies as separate powder and vehicle in the correct proportions for mixing. They shall be mixed thoroughly before use and stirred frequently during application.

5) Product from different manufacturers shall not be used in the same coating system, although in maintenance painting, this may be permitted at the discretion of the company, when new system are to be applied over existing sound coating.

3.2.3 Thinning.Brushing paints, with the exception of emulsion paints, are manufactured to the correct consistency for use.



Thickening is usually due to prolonged storage. If thickening prevents proper application by brush, not more than 5% by volume of thinner shall be added. For oil-based primers, containing red lead thinning by up to 10% by volume shall be acceptable. For enamels, which are applied by spraying, special enamel thinners shall be used. On all occasions thinners recommended or approved by the paint manufacturer shall be used.

Emulsion paints normally require thinning with up to 10% by volume of clean fresh water. The addition of more water than 10% to obtain a satisfactory brushing consistency shall be avoided.

Gasoline, kerosene or gas oil shall not be used to paint.

4. EQUIPMENTS.

4.1 Compressors.Air compressors shall comply with the safety regulations in chapter 9.0 of this specification. The compressed air supply used for blasting shall be free from water and oil. Adequate driers separators and traps shall be provided and these shall be kept emptied of water and oil. Accumulation of water and oil shall be removed from the air receiver by regular purging.

Air compressors shall not deliver air at a temperature greater than 110 o C.

4.2 Blast cleaning equipments.All blasting equipment shall comply with the safety regulations in chapter 9.0 of this specification. Blasting equipment shall be earthed and conductive hoses used to prevent build-up of static electricity.The blasting abrasive shall be discharged with a pressure at the nozzle (measured with a hypodermic pressure gauge) of 700 kPa(g) (100 psi) and shall not under any circumstances fall below 550 kPa(g) (80 psi).

Tungsten Carbide venturi nozzles shall be used and discarded when wear reaches 50%.

The blasting operators hood or headgear shall be ventilated by clean cool air served through a regulator/filter to prevent blasting residues from being inhaled by the operator.

Ventilation shall meet the requirements laid down in BS 4275.

4.3 Abrasives.Abrasives that may be used in blast cleaning are:-

- Child Iron Grit or Shot.



- Steel Grit or Shot.- Copper slag.- Aluminium oxide.- Glass bead.

High Silica sand and other material containing free Silica shall not be used.

Abrasive shall be free from oil, grease, moisture and salts and shall not be rusty, noticeably worn or dull when compared with fresh material.

Abrasive specified as non-reusable shall be no account is reused without prior approval of the company.

4.4 Spraying Equipment.The spraying equipment to be used shall meet the recommendations and instruction set forth by the paint manufacturer for each specific paint or coating system. For airless spray the correct tip range and fluid pressure setting shall be used.

An adequate moisture trap shall be placed between the air supply and pump or pressure pot feed to the gun. The trap shall bleed off continually any water or oil from the air supply.

Suitable working regulators and gauges shall be provided for the air supply to the pump or pressure pot.

Spraying units shall be earthed and precautions taken to prevent build-up of static electricity.

4.5 Scaffolding, Staging and Accessibility.Fixed scaffolding or staging shall be used to provide adequate access for surface preparation and painting and shall comply with the safety regulations and in accordance with chapter 9.0of this specification. Operator shall be able to stand up with body and arms free of scaffolding or staging and the structure being worked on.

The contractor shall provide all rigging and scaffolding equipment needed to complete the work in accordance with the specification.

Scaffolding shall not be removed until after the final inspection of the coating.

5. SURFACE PREPARATION.

5.1 Solvent Cleaning.When solvent cleaning is specified, this shall be in accordance with SSPC: SP-1 ‘Solvent Cleaning’ of the Steel Structure Painting Council (USA). Solvent



cleaning shall normally be carried out prior to blast or power tool cleaning. Any traces or smudges of oil or grease discovered on the blast cleaned surface shall be removed by solvent washing and the whole area shall be re-blast.

All boltholes shall be solvent-cleaned prior to blast cleaning.

All surfaces to be painted, which do not require blast cleaning, or power tool cleaning shall be cleaned down thoroughly by scrubbing with 2% approved emulsifier or diluted ammonia solution, followed by washing down with copious amount of potable water. A high-pressure cleaning unit is particularly effective in this application.

Acid washes, or other cleaning solution, or solvents shall be used on metal surfaces after they are blast or power tool cleaned prior to paint application. This includes inhibitive washes intended to prevent rusting.

5.2 Blast Cleaning.

5.2.1 Environmental Conditions.Blast cleaning shall not be conducted when the temperature of the surface is less than 3 0C above dew point of the surrounding air or when the relative humidity of the air is greater than 80%.

It is essential to ensure that no condensation occurs on blasted surface. To prevent dust and abrasive contamination, blast cleaning shall not be done in open areas close to painting operation or wet coated surface. Blast cleaning shall be permitted only during daylight hours, except that rough blasting shall be allowed during the night providing that the surface is given a light blasting to the specified standard in daylight thereafter.

When blast cleaning is in enclosed spaces, such as tanks and vessels, adequate ventilation shall be provided. The direction of ventilation shall normally be away from the blast site, i.e. in tanks from bottom to top.

5.2.2 Blast Cleaning Techniques.Maximum speed and the most effective cleaning is obtained by systematic, even blasting. Blasting the work in squares may be helpful.

Blast cleaning shall overlap by a minimum of 25mm into any adjacent coated areas. Any surface not primed and/or wetted by rain or moisture shall be blasted again prior to being painted.

Wet abrasive blast cleaning shall not be allowed without prior permission of the company.



5.2.3 Prior to Blast Cleaning.Grease oil, etc, shall be removed by means of solvent cleaning (see 5.1) or by high pressure water jetting or steam cleaning with, if necessary, an alkaline cleaning agent. Excessive rust scale shall be removed using impact-cleaning tools.

When using high pressure water jetting to clean a lined or coated surface, the nozzle pressure must be controlled to prevent coating damage, and should generally be less than 7000 kPa (1000 psi).

All bolts holes shall be solvent cleaned prior to blast cleaning. All sharp ages shall be removed or rounded off.

To prevent damage during blast cleaning valve steams, gauges, nameplates, area to be welded, etc, shall be protected using suitable covers of adhesive masking tape. Such items and area shall remain protected until the painting is completed.

5.2.4 Grade of Surface Finish.Mill scale, rust, corrosion products, paint or any other foreign matters shall be removed by blast cleaning to one of the grades specified.

For each painting and coating system the grades of surface finish by blast cleaning shall be specified using the Swedish Standard SIS 05 59 00 (1967), as shown in Table-1 and cross-reference to other national and professional standards is also given in Table-1.

TABLE 1 - Surface Finish International Standards

ISO 8501-01 SIS05 59 00

BS 4232 SSPC INDIAN IS-1477-1971 CLEAN

BARE METALEXTENT OF

RESIDUEGENERAL DESCRIPTION FOR QUALITY

OF BLASTING.

SA 3 1st QUALITY SSPC SP-5 WHITE METAL FULL SURFACE NIL BLAST CLEANING TO PURE METAL.VERY THOROUGH REMOVAL OF MILL SCALE,

RUST, FOREIGN MATTERS.

SA 2.5 2nd QUALITY SSPC SP-10 NEAR WHITE METAL 95% SURFACE MAX. 10% IN

UNIT AREA VERY THOROUGH BLASTING, REMOVAL OF MILL SCALE, RUST, FOREIGN MATTER

TO THE EXTENT THAT ONLY SLIGHT TRACES ARE REMAINING AS STAINS IN

THE FORM OF SPOTS AND STRIPS.

SA2 3rd QUALITY SSPC SP-6 COMMERCIAL 80% SURFACE MAX. 10% IN UNIT AREA THOROUGH BLAST CLEANING.ONLY

LIMITED MILL SCALE AND RUST ARE REMOVED.



5.2.5 Degree of Roughness.The require degree of surface roughness or peak to valley height after blast cleaning depends on the type of paint to be applied. Surface roughnesses of 30 to 80 microns usually require.

5.2.6 Post Blasting Cleaning.A dry abrasive blast cleaned surface shall be brushed with clean brushes made of hair, bristles or fiber, blown off with compressed air(free from oil and moisture)or vacuum cleaned to remove all traces of blast cleaned products from the surface or from pockets and corners.

No surface shall be blast cleaned which cannot be painted within the same working day. Any time constraints between blasting and the application of paint coatings as specified by paint manufacturers shall be strictly applied. Should delay between blasting and painting cause flash rusting of the steel surface, that surface shall be given a sweep blasting before painting proceed.

5.3 Power Tool Cleaning.Power tool cleaning shall be carried out to a visual standard in accordance with Swedish Standard SIS 05 95 00 St 3.

Metal surface for which blast cleaning is specified but which because of their location cannot be open blasted shall be prepared wherever practicable by vacuum blasting. Where this is not possible such areas shall be 100% power disc sanded using a cross technique to provide good adhesion. Where welds occur within these areas a Jason needle gun shall be used to prepare them.

Power tool cleaning shall extend to a minimum of 25mm into adjoining coated areas.

Areas prepared for painting by power and hand tool cleaning shall be primed within four hours and never left unprimed overnight.

Needle gun shall have needles of small cross section. When using a needle gun the profile of the surface shall not exceed 50-micron differential and no sharp edges, craters, etc, shall be left on the metal surface. All rough peaks shall be removed.

5.4 Pickling.

5.4.1 General.Pickling shall be carried out preferably under controlled workshop condition. The surface produced shall be in accordance with SSPC-SP 8. The minimum requirements for the process shall be: -



- Immersion in a warm dilute sulphuric acid or phosphoric acid bath to remove mill scale and rust.

- Washing in a bath of warm water to remove all traces of sulphuric acid. This water wash may be omitted when phosphoric acid is used.

- Immersion in a bath of hot dilute phosphoric acid to provide a passivated surface suitable for painting.

- Rinsing in fresh water between 21 0C and 50 0C.

Contents of all acid bath shall be discarded when the concentrations fall below that indicated specifically for each bath or if accumulation of sediment causes staining of the work.

The pickling process is detailed in the following.1) Descaling bath

The descaling bath shall consist either of sulphuric acid or phosphoric acid.- Sulphiric acid bath: - The bath shall contain a solution of sulphuric

acid of 5% to 15% by Weight in water. An inhibitor shall be used to prevent undue attack on the steel. The temperature shall be maintained at 50 0C to 65 0C. Acid from the treated material shall be allowed to run back into the bath. The sulphuric acid in the bath shall be discarded when the concentration of dissolved iron reaches approximately 70 grams per liter.

- Phosphoric acid bath: - The bath shall contain a solution of phosphoric acid of 10% to 20% by weight in water. The temperature shall be maintained at 60 0C to 85 0C and a suitable inhibitor shall be incorporated. The concentration of phosphoric acid should be maintained by regeneration or the solution changed whenever the concentration drops below 7% by weight and/or the iron content exceed 30 grams per liter.

2) Intermediate water wash bath.The water bath shall be maintained with clean fresh water at a temperature of 60 0C to 65 0C. The steel shall be dipped twice in the water bath before being passed into the final (phosphoric acid) bath. The total acidity of the water bath, expressed as H2SO4, shall not exceed 1gram per liter. This intermediate water wash can be omitted when a phosphoric acid descaling bath is used.

The chloride concentration of all wash waters should be limited to a maximum of 500 ppm.

3) Dilute phosphoric acid bath.The bath shall contain a concentration of approximately 2% of free phosphoric acid initially, and shall be maintained at a concentration of 1.5% to 2% by weight by occasional addition of phosphoric acid.



The iron content shall not be allowed to exceed 0.5% by weight. The temperature shall be maintained at not less than 85 0C. Immersion time shall be 3 to 5 minutes.

The appearance of treated steel leaving the final phosphoric acid bath shall be free from any powdery deposit on the surface and shall be dull gray in colour. A brown colour indicates that the temperature of the final bath is too low.

4) Final water rinse bath.This water bath shall be maintained with clean fresh water at a temperature between 21 0C and 50 0C.

5.4.2 Protection after pickling.Unless otherwise specified a coat of oil based red lead type primer shall be applied, preferably by brush, as soon as the pickled steel is dry.

For pickled tank plates, the steel shall be primed as described above, with the exception of approximately 50mm margins around the edge, which shall be painted with an approved lead free primer. The material shall then be stacked under cover in such a way that there is free access of air to the paint coating. Packing or assembly shall not be take place until the primer is hard enough to handle.

5.5 Chemical Cleaning.Chemical cleaning is subjected to prior consultation with and approval of the company.

6. COATING APPLICATION.

6.1 Environmental Condition during Coating.

6.1.1 Weather Conditions.Cleaning, surface preparation, or coating work shall not be undertaken in unsuitable environmental conditions, includes:-- High wind speeds (greater than 15 knots).- Airborne dust or sand.- Rain, fog, mist or when there is free moisture on the prepared surface.- Steel temperature/air temperature less than 5 0C.- Steel temperature less than 3 0C above due point of the surrounding air

or relative humidity greater than 80%.- Where there is likelihood that weather condition will change within 2

hours such that the above conditions apply.The company shall reserve the right to stop the work when such conditions prevail.



6.1.2 Weather Protection.Where environmental circumstances and/or contractors program and/or construction methods require weather protection of all or part of the structure to be painted, the contractor shall provide and equipment such as tents, heating burners, ventilation, and equipment for dehumidification, scaffoldings, screening, etc.

6.1.3 Ventilation.When painting is carried out in enclosed spaces, adequate ventilation shall be provided. The capacity of the ventilation shall be sufficient to keep the concentration of solvent vapor in the air below 10% of the lower explosion limit at all areas within the workspace. This is considered adequate for personnel health protection, avoidance of explosion hazards and to ensure adequate evaporation of solvent from the paint.

Direction of ventilation shall be from top to bottom to withdraw vapors, which are heavier than the air, where access at the bottom of the space is not available, suction ducts shall be suspended from the roof with opening near to the bottom of spaces served.

6.2 Application Technique.

6.2.1 General.Application of coatings shall be in accordance with the manufacturer’s recommendations. Application of primer shall normally be by brush or by airless spray, except in the case of stripe coats, which shall be by brush only. Brush marks shall be avoided as these indicate low DFT in the valley of the marks.

Each coat shall be allowed to dry for at least the time recommended by the manufacturer.

Paint shall not be applied within 50mm of an edge prepared for a field weld and care shall be taken to ensure this by masking off. On completion of finish coating the plant identification marks, flow direction arrows, pipe identification color bands, etc, shall be applied as requested and directed by the company.

6.2.2 Protection of Equipment.The contractor shall protect all equipment and structures, and any other areas required by the company from mechanical damage from paint droppings or over spray.

Equipment or structure to be protected shall include the following. of 21

Prepared By :- M T MULLA.


Valve spindles, gauge glasses, nameplates, giving makers specification, etc, on vessels, motors, etc, motors, cables, stainless steel pipe work, gratings, near by vehicles or buildings or any other area of the structure not being painted at that particular time. Special attention shall be paid to protecting equipment that operating at the time of painting.

6.2.3 Airless Spray.All liners and pots shall be thoroughly cleaned before any addition is made of new materials. The spray gun shall be held not closer than 450mm from the work surface and not further than 600mm, and shall always be held at right angle to it. Even, parallel passes shall be made, each pass overlapping the other by 50%.

Large surface shall be ‘cross coated’ by receiving passes in two directions at right angles to each other. The gun shall not be operated continuously but will be triggered before and after each pass to obtain the correct spray pattern and avoid runs and sags. Spray width adjustment on the gun and readjustment of atomizing pressure at the regulators shall be made until the desire spray pattern is obtained.

Each coat shall be applied uniformly and completely over the entire surface. Great care shall be taken to avoid areas of low DFT and ‘misses’. All runs and sags shall be brushed out immediately, or the paint shall be removed and the surfaces resprayed.

Before spraying each coat, all areas such as corners, angles, edges, welds, flanges, brackets, bolts, nuts and interstices shall be given a brush coat to ensure that these areas have at least the minimum specified film thickness.

Paint spraying from a single boatswains chair shall not be permitted.

6.2.4 Brush.Coating shall be brushed on to all areas, which cannot be adequately spray coated, e.g., difficult access, complex shape, etc.

Surface not accessible to brush shall be painted by company-approved means to ensure a uniform paint film of adequate thickness.

6.2.5 Roller.Application by roller shall only be done on large flat or slightly curved surfaces where application by spray is not possible. This method is not suitable for painting rough areas of crevices.

7. INSPECTION. of 21



The contractor shall ensure that qualified personnel inspect all painting working line with the following requirements.

7.1 Environmental Conditions.

7.1.1 Steel Temperature.The surface temperature of the steel at a representative area shall be checked before application of any coating, and shall be within the range specified by the paint manufacturer. Inspector may extend the minimum and maximum recoat intervals for low surface temperature and reduce for high surface temperatures.

The inspector to measure steel temperature may commonly use two methods, namely a battery operated thermocouple or thermistor with digital read out, or a contact thermometer that is simply clamped to the surface with a magnet.

With both instruments time must be allowed for the device to reach a stable temperature.

7.1.2 Air Temperature.The contractor shall measure air temperature and relative humidity at least twice daily and before coating or blasting operation start. Measurement shall be done using a sling Hygrometer.

The due point shall be determined using the approved chart. All results shall be recorded and submitted to the inspector.

7.1.3 Ventilation.Before and during blasting and coating work in enclosed spaces, adequate ventilation shall be established. During coating operations the vapour concentration shall be monitored at regular intervals using approved equipment and should never exceed 10% of lower explosion limit.

The TLV (Threshold Limit Valve) or MAC (Maximum Allowable Concentration) of the product being used must be known. Ventilation shall be such as to maintain, wherever practical, a safe atmosphere below the TLV.

7.2 Surface Preparation.Before any surface preparation commences, the surface shall be inspected to ensure it is free of oil and grease, other foreign matter and any substrate defects.



After surface preparation, the surface shall be visually inspected and the degree of cleanliness and surface character evaluated with standard or comparators.

7.2.1 Blasting Abrasive Quality.If there is any doubt about the quality of the blasting grit, the contractor shall provide a specification covering sieve grading, chemical analysis and physical properties. If such a specification is not available, the contractor shall take samples, of minimum 1 kg each, from each batch of abrasive and arrange for analysis by an independent third party. Such analysis shall include: -- Sieve grading.- Physical and chemical analysis.

Specification and/or analysis results shall be submitted to the company for comparison with accepted values. If the abrasive has been wetted by salt water, rain or condensation, or if its moisture content is considered too high, it shall not be further used. The inspector shall reject any blast cleaning done with such abrasive.

7.2.2 Surface Contamination and Cleanliness.The contractor shall ensure that dust or dirt has been removed from the surface prior to painting.

Contamination of the blasted surface by large embedded abrasive particles, which cannot be brushed off using a stiff brush, shall not be accepted. If such contamination is detected, no further blasting shall be performed, using the same batch of abrasive. Tightly adherent embedded fine particles, however, need not be a cause for rejection.

Work may be allowed to continue using a different batch, make or type of abrasive approved by the company.

Removal of contamination by wire brushing shall not be allowed.

When using copper slag abrasive under high ambient temperature condition, the visual standard SA2.5 may not be obtained due to embedded fine particles causing a different shade. If there is any doubt on the acceptability of the prepared surface the company shall be requested to provide a dedicated visual standard for SA2.5 using copper slag under these conditions.

7.2.3 Residual Mill scale and Corrosion Products.Standard of preparation shall be established by visual comparison of the steel surface with the appropriate photographic standard included in Swedish Standard SIS 05 59 00.



Visual examination will normally indicate the presence of residual mill scale. If required by the inspector, a copper sulphate test shall be carried out.

7.2.4 Surface Profile.Contractor shall measure the surface profile after blasting using an optical method or needle probe. Approved methods using a profile comparator are Keane Tator or Rugotest no.3.

7.3 Coating Materials and Applications.

7.3.1 Materials.Coating materials records shall be maintained by the contractor and made available to the company. These records shall include, but not be limited to information on the: -- Type of coating system.- Batch numbers (which shall relate to paint production date).- Manufacture/expiry date.- Numbers and sizes of paint containers or coating packages.- Quantity of coating materials consumed during each day.

7.3.2 Wet Film Thickness (WFT).The contractor shall, at all stages of paint application, as required by the inspector measure the WFT as often as necessary to obtain the specified Dry Film Thickness (DFT). WFT shall be determined using an appropriate comb gauge.

7.4 Dry Film Thickness Inspection.After the film is sufficiently dry or cured the contractor shall perform an examination.

7.4.1 Visual Inspection.After each coat the coating shall be inspected visually. The paint system applied should have the correct shade, degree of gloss and evenness and be free from thickness after drying/curing and free from cracks, holidays, runs, sags, wrinkles, patch ness, brush or roller marks or other defects that may deleterious to the quality of the coating.

Finishing coat shall be even in colour and gloss.

7.4.2 Dry Film Thickness (DFT).DFT shall be measured after each coat at randomly chosen location. The density of measuring points shall be at the discretion of the inspector but



shall normally be once every 4 square meters for large areas and once every 1 square meter for small areas or structures.DFT shall be measured using a magnetic pull-off gauge or an electronic instrument working on magnetic flux or eddy current principles. The instrument’s working range shall be adequate for the specified coating thickness and shall cover a minimum of 150% of the expected DFT.

The instruments which shall be checked or calibrated before each set of measurements using a substrate of similar material and thickness to the work, and shims of the expected coating thickness, shall have an accuracy of better than + 10%.

Records shall be kept of all DFTs measured. Average, minimum and maximum values shall be reported.

DFTs of each paint film shall be within + 25% of the specified thickness. The total DFT shall never be less than the specified total DFT.

If coating is performed over existing paint layers, DFT of the existing coating shall be measured before application so that the thickness of the new layer of coating may be determined.

DFT of different layers of a paint system may be measured using a paint inspection gauge utilizing calibrated cutters and microscope. This however is a destructive test and nor suitable for production painting.

7.4.3 Pinhole Detection (Wet Sponge Method).Pinhole detection shall be conducted on all conventional thin film and coal tar epoxy coating system using a method approved by the company.Refer to the system specification for details. Pinhole detection is carried out after the final coat has been applied and fully cured/dried.

The wet sponge method shall be used.

For tanks and vessel internals, 100% of the surface shall be tested. Special attention shall be paid to welds, edges and irregular surface.

For external surfaces, random inspection, which shall be representative of the entire surface, shall be conducted.

7.4.4 Holiday Detection (High Voltage Spark Test).Holiday detection shall be conducted on all heavy-duty systems including FBE, GRE, heavy coal tars, asphalts and polyurethylene coatings. A high voltage (spark) detector shall be used. The type of brush shall be suitable for the surface to be inspected. The voltage setting shall be according to the manufacturer’s recommendations or as



given in the system specification. Normally 100% of the surface shall be tested. Special attention shall be paid to welds, edges and other irregular surfaces.

7.4.5 Degree of Cure.An indication regarding the cure of two component materials such as zinc silicates or epoxies can be obtained by solvent swabbing. The curing test shall consist of rubbing the laminate surface for one minute with a clean rag soaked in a suitable solvent. If cure is complete the surface shall not be softened as indicated by scratching it with fingernail. The test shall be conducted at a number of representative places on the surface.

7.5 Reporting.All inspection results shall be recorded daily, at site a standard ‘Daily Painting Record’ together with all inspection/repair report shall be recorded.

8. SAFETY .

8.1 General.When paints containing volatile solvents are applied in enclosed or confined spaces, two hazards exist: Fire & Explosion hazards and Toxic hazard. Precautions must be taken to eliminate these dangers.

8.2 Fire and Explosion Hazard.When the following factors are presents, there is a high risk of creating a fire or an explosion; they are: -- When the concentration of vapour in air is between the lower explosion limit

(LEL) and the upper explosion limit (UEL).- When a flammable liquid, in contact with air (open container) is at a

temperature above its flashpoint.- When there is a source of ignition with high enough temperature and energy

to initiate the explosion reaction.These conditions shall be avoided at all times during the handling and application of paints or coatings.

8.2.1 Ventilation and Extraction.Adequate ventilation and extraction must be provided in the workroom to prevent a potentially flammable concentration of vapours by maintaining the concentration of vapour in air at no more than 10% of the Lower Explosion Limit. The use of solvents with a flashpoint below the working temperature is prohibited.

Booths and similar enclosures should be designed, installed and maintained to prevent any vapours, over spray and droplets escaping into



the general atmosphere of the workplace. The exhausts from such booths should be designed to minimize external environmental pollution.

All booths and ducts shall be fire resistant structures and shall be subjected to regular cleaning to prevent the accumulation of solid paint residues.

8.2.2 Source of Ignition.All potential sources of ignition shall be strictly controlled. Smoking shall be prohibited in all areas where paint is stored, handled or used.

Sparks, hot surfaces, flames and all other sources of ignition must be absolutely prevented. Flameproof lighting and electrical equipment must be used, spark proof tools and clothing shall be used, all hot work in adjacent compartments shall be prohibited.

8.2.3 Storage.Special storage precautions are necessary for products with a flashpoint below 32 0C. Storerooms shall be separated from workshops and constructed to company approved standards. The amount of paint stored in the workshop or working area shall be limited to one working day’s requirements. All containers of paint and thinners not in use shall be kept securely closed. Paint stored in workshops shall be kept in bins or cupboards of fire resistant materials.

8.2.4 Cleanliness.Strict attention to cleanliness shall be observed. All places where dry paint deposits can accumulate shall be cleaned regularly and any brushes used shall be of non-ferrous metal or non-sparking material. All scrapings and sweepings must be placed immediately in metal container with suitable covers, wetted down and removal from the building.

All spillages shall be cleaned up as they occur by absorption into sand, earth or other suitable inert material. Any rags or other combustible materials used for minor cleaning or any other work area cleaning must be deposited immediately after use in a metal container having a suitable cover, wetted down and removed without delay to a safe place outside the building. If combustible material is used to protect floors or other surfaces from paint drips or spillages, it should be removed daily and deposited in a safe place for disposal.

8.2.5 Firefighting Equipment.Adequate fire prevention and firefighting equipment shall be provided and maintained in all areas where paint is used, handled or stored. Guidance regarding the type and amount of equipment to install shall be obtained the PDO safety department.



8.3 Toxic Hazards.

8.3.1 General.Application of paint containing a high proportion of solvents may, in poor conditions of ventilation, result in high atmospheric concentrations of solvent vapour. Overexposure may cause adverse physiological effects. Certain paints may give rise to additional specific hazards, which shall be indicated, on the label and in the manufacturers literature. Particular care must be taken when handling and using paints containing heavy metals, e.g., lead, and precautions taken to protect against skin contact and fume inhalation.

8.3.2 Inhalation.Inhalation of fumes, dust or sprays during surface preparation, application of paint and sanding processes shall be avoided. Employees shall be protected against the inhalation of dust, fumes or sprays during any of the above activities by the provision of adequate ventilation at all times and where appropriate, local extraction and dust masks or respirators. A cartridge respirator should be worn, and fitted with a vapour/particulate cartridge designed for paint spray and light fume protection. In some cases a higher degree of protection from an air-line breathing apparatus may be advisable, and where this is so it will be stated in the manufacturer’s technical literature and marked on paint and solvent containers. For dry sanding operations a cartridge respirator shall be worn. In the open air, work or operations down wind of the spraying area shall be restricted as necessary or personnel protection devices worn.

When working in workshop areas, spraying shall be confined, so far as possible, to spray booths which are designed, installed and maintained to prevent any vapours escaping into the general atmosphere of the workplace.

In an emergency resulting in personnel injury or sickness, the patient shall be moved to a fresh air location as quickly as possible and kept warm until medical attention arrives. In case of unconsciousness the patients breathing should be checked and artificial respiration given when breathing stops.

8.3.3 Ingestion.Accidental ingestion (swallowing) of paint may cause irritation of the mouth, throat and digestive tract, resulting in vomiting and abdominal pain. Significant absorption of paint containing a high proportion of solvents may cause drowsiness or loss of consciousness.



Ingestion of paint must always be avoided. Food should not be brought into, stored, prepared or consumed in workshop or work areas where paint is handled or stored. Receptacles and utensils, which could be used for food or drink, should also be excluded. Washing facilities should be provided and their use encouraged before food is consumed or handled.

In an emergency, vomiting shall not be induced because of the risk of the introducing solvents into the lungs by inhalation of vomit. This cans result in severe lung damage. The spontaneous vomiting occurs, the patient shall be turned on to his face if unconscious.

8.3.4 Skin Contact.Some substance used in paint may cause irritation after repeated or prolonged contact with the skin and in certain cases there is a risk of dermatitis.

Operatives with a history of skin sensitivity should not be employed in processes where skin contact cans occur. Prolonged or repeated contact with the skin should be avoided. Barrier cream shall be provided and used gloves and overalls shall be worn.

8.3.5 Eye Protection.Splashes of paint products will irritate the eyes and goggles shall be worn whenever possible to prevent this occurrence. Emergency treatment shall consist of irrigation of the eyes with copious amount of clean water until medical attention has been obtained.

8.4 Safe working Conditions in confined areas.Safe working is of the greatest importance, but especially so during the application of internal tank coatings.

The following principal measures will ensure safe working.1) Blast Cleaning.

When voice communication between the blast cleaner and blast operator is not practical a reliable system of communication by signals shall be established. The blast cleaner shall be provided with an air-fed helmet and ear protection.

A safety valve control operating by a ‘dead mans handle’ principle shall be provided for the blast cleaner.

All blasting equipment shall be electrically earthed to the mass of the tank, vessel or structure being cleaned.

All scaffolding shall be provided with safety rails. of 21



2) Painting.All mixing of paints shall be performed outside the confined area.

Exhaust and fresh air ducts and fans shall be provided. The fresh air shall be directed to the bottom of the tank and exhaust duct shall be close to the bottom of the tank.

All spraying equipment shall be electrically earthed to the mass of the structure being painted.

Warning signs shall be provided around the structures being painted indicating that spraying is in progress.

A supervisor shall be in continuous contact with painters and shall have his own safety outfits.

Unauthorized personnel shall not enter the tank or vessel during spraying.

All hoses shall be checked regularly for damage.

Safety lights and other electrical equipment shall be suitably certified for use in hazardous areas likely to be encountered during paint spraying.

Painters shall be provided with lifelines, where necessary.

3) Drying.A fresh dry air supply shall be provided. The end of the exhaust duct shall be installed close to the bottom of the tank.


Std

Documents

Transcript of Std