Factory : Office:
Plot Nos: B-3/3 to B-3/12, 3rd Floor, Mahan Terrace,
Sachin Udyognagar Sahakari Mandali Limited Adajan Road, Surat - 395009 Sachin, Surat- 394230, Gujarat, India Gujarat, India
Ph+Fax: 91 261 2390471 Ph: 91 261 2686085, 3063000
E-mail:[email protected] Fax: 91 261 2681175
_____________________________ __________________________
(Inspection Engineer)
(QC Manager)
CONTENTS
I. PURPOSE
II. SCOPE
III. REFERENCE DOCUMENTS
IV. SIGNIFICANCE OF SURFACE PREPARATION
V. PAINTING
VI. COATING REPAIR PROCEDURE
VII. INSPECTION
VIII. SAFETY CAUTIONS
I PURPOSE
The purpose of this document is to follow proper procedure to carry out the activities in sequence for surface preparation, painting at shop as well as at field and also touch/repair painting on damaged portions.
II SCOPE
This manual covers the standards procedure for blasting and painting of pressure vessel.
III REFERENCE DOCUMENTS
1) Paint manufacturer’s instruction & safety data sheets. 2) CLIENT Specification no:-9294-VW-SG-001 Rev-03.
3) Technical Data Sheets for Paint system / Touch-up Paint system as per Paint Manufacturer’s recommendations
IV SIGNIFICANCE OF SURFACE PREPARATION
All surfaces to be painted shall be cleaned and prepared before application of and contoured. Sharp edges shall be rounded, chamfered. Oil, grease, loose, rust and loose mill scale, if present, shall be removed by suitable methods.
REFERENCES:
A. Painting manufacturer’s Date sheets B. CLIENT standards.
SURFACE PREPARATION METHOD
A. BLAST CLEANING
I. Blast cleaning is the ideal surface preparation method for suitable to prepare surface for painting. All the other forms of surface preparation have their limitations.
II. In blast cleaning an abrasive is directed at high velocity against the surface. The abrasive material shall be approved by Client before being used.
III. Copper Slag (Abrasive) shall be dry, clean, and free from containments and of a type and size adequate to give required Surface finish.
IV. Compressed air for blasting shall be free from oil and water.
V. The surface to be painted shall be cleaned by Copper slag blasting to a degree of SA 2.5.
VI. Blasting operation shall not be carried out on surface that are wet and also when the surface temperature of the steel and structural is less than 3°C above the due point of surrounding air or when relative humidity of air exceed 85%.
VII. Surfaces where abrasive blasting is not accessible, surfaces are to be cleaned by Wire brush grinding to obtain the required surface finish.
V PAINTING:
1. Painting shall be carried out as per approved paint manufactures specifications. 2. Primer shall be applied after completion of blast cleaning within 4 hours.
3. Paint application log shall be maintained.
4. Coatings and Primers shall be received in the original containers bearing the manufacturer’s name, brand name, product designation, batch no, shelf life and date of manufacture. Corresponding test certificates to be collected.
5. All paint materials shall be stored as per manufacturer’s recommendation. 6. All Painting material shell is stored clean, dry and far from work place.
7. All paint shall be stirred thoroughly prior to use. Stirring up will also become necessary repeatedly during application to prevent settling of Pigments.
8. Primer shall be applied by brush, roller or spray gun. A smooth uniform film shall be applied to the surfaces to be coated. At no place, the film shall be less than the specified thickness, thick paint or detrimental brush marks are not acceptable.
9. Paint shall be applied only to dry, clean, adequately prepared surfaces under favourable conditions and in accordance with the paint manufacturer’s instructions. 7. To maintain the required dry film thickness for primer consecutive single coat.
Consecutive coats will be applied only after the previous coat dried.
8. The temperature of the substrate must be a minimum of 3°C above the dew point during coating. The substrate temperature shall be a minimum of 5°C and a maximum of 60°C during coating application.
STEPS IN PAINTING SYSTEM:
i) Application of Primer
The Primer should be applied as per the painting specification
1.) Ethyl Silicate Inorganic Zinc Rich of 75 µm as per painting specification no:- 9294-VW-SG-001 Rev-3 Table 1 (Item- Equipment in Ferritic Steel)to be applied after blasting on all Heater panels, Stacks & all supporting structures.
2.) Epoxy Polyamide cured zinc chromate primer (2 x 35 µm) as per painting specification no:- 9294-VW-SG-001 Rev-3 Table 1 (Item-Structural Steel) to be applied on other structural Steel like Handrails, Platforms & Ladders.
The painting system for steel surface is designed to give dual action. Corrosion inhibition Barrier protection
ii) Significance of Primers
This is the corrosion inhibitive coat applied to restrict corrosion at steel surface. This contains various anti-corrosive pigments like Zinc-silicate & Zinc Dust. If this coat is not applied, the painting system will provide only a barrier, like a plastic sheet. In case of mechanical damage or rupture in the paint film during its life corrosion will start on & shall creep in to the surface causing peeling off of paint immediately. Besides primer helps & improve adhesion of second coat as well. Hence for steel surface primer coat is very important & essential.
iii). Application of paint:
The following precautions are suggested during paint application: a) Shall not apply paint when temperature falls below 10°C.
b) Shall not apply paint when humidity is above 85% or during fog, mist or rain.
c) Primed Surface shall be over coated after the recoat ability time specified in the data sheet of the paint manufactured.
d)All the primers and finishes are supplied with brushing consistency. Thinner should be added only if the viscosity increases due to temperature change during application. Normally addition of thinner is restricted up to 5-10% by volume in case of brush application. In case of spray application, only recommended thinner shall be used to bring the paints to spraying consistency.
e) Blast cleaned surfaces shall be coated with primer within maximum 3-4 hours. If relative humidity is over 75% this should be reduced to 1-2 hours for better performance.
f) All the two packed primers and paints should be used up within the pot life mentioned in data sheets.
g) Application of paint is recommended at ambient temperature. The substrate should be at ambient temperature.
h) Epoxy polyamide MIO of 150 µm as per painting specification no:- 9294-VW-SG-001 Rev-3 Table 1 (Item- Equipment in Ferritic Steel)to be applied on the primed surface of heater panels as Intermediate. Aliphatic polyurethane (1x50 µm) as final coat to be applied on the Intermediate coat, colour code as per Table 3 RAL no:-7035 for Furnace casing and RAL no:- 9006 for stack & flue duct(In field).
i) 2 pack Polyamide cured Epoxy finish of (2 x 35 µm) as per painting specification no:- 9294-VW-SG-001 Rev-3 Table 2 (Item- Structural Steel)to be applied on the primed surface of platforms, Ladders & Handrails as final coat, colour code as per Table 3 RAL no:- 1021.
j) For Stack the intermediate and final coat should be silicon acrylic aluminium paint of 25 micron each.
VI COATING REPAIR PROCEDURE AT SITE FOR ALL SHOP PAINTED ITEMS
1) All shop painted items shall be checked for DFT of coating as per the specifications & condition of coating for uniform coverage and damages during transportation. 2) In case of shop applied primer/coating is in acceptable condition the surface shall be
thoroughly rubbed down/ cleaned by emery paper and remove oil, grease by solvent and wash the surface with fresh water and dry it with compressed air & proceed with the field painting system.
3) The compatibility of shop and field paint coating shall be ascertained as per paint manufacturer’s painting system.
4) Any size and type of paint damage/deterioration shall be repaired/ repainted as per approved procedure.
VII INSPECTION:
Inspection shall be carried out in stages as per approved Quality Control plan & Section 11.3 of painting Specification (no:-9294-VW-SG-001 Rev-03.). Dry film thickness, humidity and final DFT shall be inspected. Profile measurements for blasted surface shall be carried with surface profile gauge.
The dry film thickness of coat shall be checked by means of a calibrated Elcometer- dry film thickness gauge. Re calibration will be done after expiry of the certificate. Periodic and continuous field checks on workmen shall be made to ensure that the correct procedure and paint is applied according to the specifications prescribed. Defective work shall be corrected as and when identified.
A Painting log shall be maintained & format of same shall be as attached Annex1.
VIII SAFETY PRECAUTIONS:
1.PPE shall be used during blasting operation & painting. 2.Paint material shall be kept away from hot work areas. 3.Material Data Sheets shall be made available at all times. 4.Required permits shall be obtained during work progress.
_____________________________ __________________________
(Inspection Engineer)
(QC Manager)
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