Embed Size (px)
Citation preview
How to Write Paint Specifications
A.S.KhannaCorrosion Science & Engineering
IIT Bombay
What do we mean by Paint Specification
• Protecting a surface with a paint coating that takes care of the requirements of a user
• Requirements– Chemical Resistance
• Resistance to chlorides, acids, alkalies, solvents
– Mechanical Properties• Impact, scratch, abrasion, bond strength
– Weathering properties• Resistance to UV, rains, snow
– Heat Resistance• Highest Temperature a paint can resist
– Low Temperature resistance• Lowest temperature a paint can resist
Selection Criteria
• Location
– Environment
• Mild, Urban, Coastal
• Onshore
• Offshore
– Mud line
– Silent water Zone
– Splash Zone
Selection Criteria … contd• Surface Finishing Requirements
– New Surface
– Old Surface• Whether possibility of complete Cleaning
• Partial cleaning
• Application Technique– Brush
– Roller
– Air Spray
– Airless Spray
• Life of Coating– Long Life
– Short Life
• Cost
Type of paints
• Conventional Solvent based Paints
– Requires more time to dry
– High DFT in several coats
– Large recoating intervals
– Chances of malpractices – tempering of resin ./ solvent composition
• Modern paints
– Solventless Paints
– High DFT in single coat
– Modified by Glassflake enhance life by several folds.
Ensuring Proper Raw Materials
• Initial Checking of the composition of the paint- resin, hardener, thinner etc.
– Volume solid
– Viscosity
– Density
• Batch Testing of Each Batch
Performance tests– pre Qualifications
• Chemical Resistance
• Weathering
• Mechanical Properties
• Special Tests – if any
Qualified Personal
• It is now very important to properly check the staff who are going to take the job:– Technical Qualification of applicators / Surface
preparation
– Qualified Supervisor
– Qualified Inspectors
• Their role must be specified and data collected must be properly arranged and checked.
Coating Conditions
• Proper Humidity
• Proper Temperature
• Free from salt deposition
• Free from contamination by salt aerosols etc.
Environment
Category as per
(ISO-12944-2)
Surface Preparation
Required as per ISO 8501
Coating System No. of
Coats
DFT in
(μm)
C 3
Non-immersion
Medium Corrosion
( Temperature up to 120oC)
St 2 Medium durability
Primer : MIO based alkyd
Top Coat : Modified Alkyd ( with urethane)
1
1
50
50
Long Durability
Primer: Epoxy Mastic
Top Coat – 2 Pack Aliphatic PUR
1
1
50
100
Sa 2.5 Medium Durability
2 coats of Alkyd
Long Durability
Primer – Zn-rich
Top Coat -2 pack Aliphatic PUR
2
1
1
150
50
80
C 4
Non-immersion
( High Corrosion)
Sa 2.5 Medium Durability
Primer: Zn-rich epoxy
Intermediate: Epoxy MIO
Top Coat: 2 pack Aliphatic PUR
1
1
1
50
60
50
Long Durability
Primer: Inorganic Zn- Silicate
Intermediate: Epoxy MIO
Top Coat: 2 pack Aliphatic PUR
1
2
1
50
150
50
C 5
Non-immersion
Very High Corrosion
( Temperature up to 120oC
Sa2.5 Medium Durability
Primer: Inorganic Zn- Silicate Intermediate: Epoxy MIO
Top Coat: 2 pack Aliphatic PUR
1
2
1
50
150 (2x75)
50
Long Durability
Primer: Inorganic Zn- Silicate
Intermediate: high Build Epoxy MIO
Top Coat: 2 pack Aliphatic PUR
1
2
1
50
160 (2x80)
50
C 3
Non-immersion
Medium Corrosion
( Temperature up to 400oC
Sa2.5 Medium Durability
Aluminum Coating 2 250
Long Duration
Primer: Inorganic Zn- Silicate
Top Coat : Silicon Based Coating
1
2
50
200
C 3
Non-immersion
Medium Corrosion
( Temperature up to 600oC
Sa 2.5 Medium Durability
Primer - Silicon Based
Top Coat : Polysiloxane
1
2
50
250
Immersion
Service
Tanks for fuel, oil,
crude, chemicals
and process water
Sa 2.5
Solvent Less Epoxies 1 500
Immersion
Service
Sewage lines,
water treatment
facilities
Sa 2.5
Glassflake Epoxies
or
Combination of Glassflake and
Reinforced epoxies
1 or 2 1000 or more
Immersion
Service
Splash Zone in
Sea Water
Underwater
Sa2.5
HA 2
Polyester Glassflake
Water Repellent Epoxies
1
2
1000
2x400
Immersion
Service
Water Jetties
Sea Water
Sa 2.5 Glassflake Epoxy
Or Novolac Epoxy 1 or 2 1500-2000
Immersion
Service
Freshwater
Treatment
facilities, locks
and gates
Sa 2.5 Solvent less Epoxies 1 1000
Underground
Structures
Gas Pipelines
Water Pipelines
Sa 2.5
External
Oil & Gas
3 layer PE ( FBE Primer, Adhesive and
PE)
Water Pipelines
Coal tar or Tar Epoxy, tar-urethane
Liquid Epoxy, Elastomeric PU
3
1
2000 – 3000
3000-5000
700-1000
Quality Control for Protective Coatings Projects
A.S.Khanna
Corrosion Science & Engineering
IIT Bombay
Definition• QC gathers and documents the information that verifies that the work performed meets the minimum standards as required by specifications.• Quality assurance (QA) on the otherhand is to protect the against failures of quality control. It is process to verify that quality work was performed actually as claimed on the basis of QC.• The quality programme assures and controls the QA and QC as per industry standards.• The QC manager is a qualified person, appointed by top management to assure the quality of coating, which is evaluated on annual basis and recommendations of the corrective measures if any.• QA and QC inspector is the qualified person appointed by QC manager to perform individual inspections and verify the work being performed as per specifications, can introduce corrective measures or stop work, if not going as per specifications
Standards & Guidelines
1. SSPC-QP1 Standard Procedure for evaluating painting contractor( field application to complex industrial structures)
2. SSPC-QP3 Standard Procedure for evaluating Shop Painting Applicators.
3. SSPC-QP5 Standard Procedure for evaluating qualifications of coating and lining inspection companies .
Pre-Job Review
1. Contract & Specification review.
2. QC and inspector Requirements
3. Inspection Plan
4. Document control
5. Pre-job conference
QC and inspector Requirements
1. Formalised training & Certification of the inspector.
2. Experience in the type of structure to be inspected.
3. Availability of inspection equipments to the inspector.
4. Records of all inspection equipment used by inspector.
5. Standards & Procedures to show conformance with
The specifications be available with the inspector.
6. Approved copies of materials supplier technical data sheets, application instructions and material safety.
Inspection Plan
• Prior to the start of work,
•Immediately following the surface preparation.
• Immediately prior to the coating & lining application.
• Following the application of each coat
•Following the curing of coating or lining.
•Final inspection and sign off
Daily Inspection Activities
1. Revision Log2. Technical resource availability3. Calibration verification4. Daily work log5. Daily inspection report6. Corrective Actions7. Photographic Records8. Management review
Technical resource availability• SSPC Painting Manual Vol. 2, systems & specifications
• SSPC PA2, Measurement of DFT
• SSPC visual standards
• ASTM protective coating inspection standards for field and shop applications.
• Updated material supplier technical data sheets.
• Standard procedures SSPC, NACE, ASTM, API, ISO
Calibration verification
• Equipment type & serial number
• Required frequency & calibration method.
•Record of calibration data.
• Signature and date of person performing calibration verifications.
Daily inspection report
• Weather and site condition.
• Pre-surface condition & cleanliness
•Surface Preparation monitoring.
• Post surface preparation cleanliness and profile.
•Coating material preparation & application
• Physical film properties, DFT measurement
•Verification of corrective actions prior to final approval.
• Record of equipments used for measurement
