Entities QA / QC & Testing

Group Coating Application

Status Supplement of IP
Version English

Inspection and Testing Procedure

MEASUREMENT Dry Film Thickness

0 Oct 01th, 2021 All Approved AAA Technical Dept Technical Dept
Rev Date Page Description Prepare by Endorsed by Approved by

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1. SCOPE

1.1. This method describe the apparatus ( Elcometer 456 ) and procedure for measuring
Nominal Dry Film Thickness of other coating ( Zinc, alkyd, epoxy, Polyurethane, Glass
flake, fusion bonded epoxy, galvanize, including Passive Fire Protection, etc ) on the
steel.

1.2. This procedure applicable for internal and External Surface.

2. REFERENCES

2.1. THE SOCIETY OF PROTECTIVE COATING ( SSPC )

2.1.1. SSPC PA 2 – 2012

Paint Application Specification No.2 Measurement of Dry Paint Thickness With Magnetic
Gage

2.1.2. SSPC PA 3 - 96

Safety in painting application

2.2. ASTM G 12 - 83

Standard Test Method for Nondestructive Measurement of Film Thickness of Pipeline

Coating on steel.

2.3. ASTM 1186 - 93

Standard Test Methods for Nondestructive Measurement of Dry Film Thickness of

Nonmagnetic Coatings Applied to a Ferrous Base.

3. PRECAUTIONS

3.1. The accuracy of measurement of a coating thickness may by affected by a number of

factors. The following precautions should be observed.

3.1.1. Calibration
The instrument should be calibrated prior to use, re - calibrated after each hour and
re checked at the of the work period.
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3.1.2. Substrate thickness

For each instrument, three is a critical thickness of metal substrate below which the
accuracy of the instrument cannot be assured. Since this thickness depends on the
booth measuring frequency of the probe system and the electrical conductivity or the
magnetic permeability of the substrate, its value should be determined
experimentally, unless it is specified by the manufacturer of the test instrument.

3.1.3. Edge effect

Measurement should not be taken close to an edge, hole or inside corner of a test
specimen unless the instrument is calibrated for such measurement

3.1.4. Surface profile and roughness

Measurement are influenced by the surface topography of the substrate and of the
coating. Rough surface and the anchor pattern of a surface profile can cause both
systematic and random error

3.1.5. Curvature

Measurement is affected by curvature of the specimen. The influence of curvature

varies considerably, depending on the make and type of the instrument, but always
becomes more pronounced as the radius of curvature decreases. Measurement
made on curved test specimen will therefore not be valid unless the instrument is
specifically calibrated for such measurement.

3.1.6. Foreign Particle

The probes of the coating thickness gauge need to make contact with the test
surface. The instrument therefore sensitive to any foreign material that prevent
intimate contact between the probe and surface of the coating. The probe tip should
be checked periodically for cleanness and foreign particles remove using plasticine
or similar material.

3.1.7. Soft Coating

Soft coating may be deformed by the probe. Valid measurement on the test
specimens may only be possible with the use of special probes or fixture ( WHEN,
softness of the film is caused by the degree of cure, it may be necessary defer
testing )
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3.1.8. Surface Contamination

Sticky, greasy, tacky material, or other type of contaminant, may cause a build - up
on the probe, so care should be taken that such material.

3.1.9. Probe pressure

Excessive pressure on the probe may damage a coating. Care should be taken to
ensure that magnetic instrument probes are held vertically and that the coating is not
damaged by the probe when determining measurement.

3.1.10. Electromagnetic fields

Instrument may not operate correctly in the presence of the strong electromagnetic
fields. Inaccurate result may be obtained where strong filed are present, e.g. near
aluminium smelter pot lines or in vicinity of electric welding activities.

3.1.11. Magnetic properties of pigment

The magnetic effect of certain pigment and extenders, such as micaceous iron oxide (
MIO ) and red iron oxide, can affect the accuracy of measurement obtained from some
instrument.

3.1.12. Temperature effect

Extremes of temperature may influence both the readings obtained from the instrument
and deformation properties of the coating being measured.

4. DEFINITIONS OF READING AND MEASUREMENT

4.1. Gage reading = Gage reading

4.2. Spot reading 3 gage reading

4.3. Area reading

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5. POINT READING

5.1. When determining a reading at a point on the coating, single reading is sufficient. How
ever, suspect or disputed readings the mean of five separate gauges readings taken
within the area of a 1,5 inch and / or 4 cm diameter should be record.

1.5 inch
4cm

5.2. Make five ( 5 ) separate spot measurements average of three reading

5.3. Means of area reading in this procedure maximum 10 M2 with five spot reading

5.4. SSPC PA2 requires a minimum of three gauge readings to be taken per spot
measurement and five spot measurements over 10m2 ( ~100ft2 ).

5.5. The average measurement for each such 100 square foot area shall not be less than
specified thickness. No single spot measurement in any 100 square foot area shall be
less than 80 percent of the specified thickness.

5.6. For structure not exceeding 300 square feet in area, each 100 foot area should be
measured.

5.7. For structure not exceeding 1.000 square feet in area, three 100 square foot area shall
be randomly selected and measured.
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5.8. Measurement method

Sample point Mandatory to record

5.9. Measurement method on Steel Structure including Beams

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Measurement on beam and girder

5.10. Measurement on Edge Substrate see 5.9 sketch point 12 & 2 and point 8 & 6 see
Appendix 6 SSPC – PA2

Measurement on edges substrat

5.11. Sample Edge NOT available

Steel Structure sharp edges below 5 mm

5.12. For structure exceeding 1.000 square feet in area, the first 1.000square feet shall be
measured state in section 4.5 and for each additional 1.000 square feet of area
increment there of, one 100 square foot area shall be randomly selected and
measured.
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5.13. If nominal dry film thickness for any 100 square foot area section 4.5 and 4.6 is not in
compliance with the requirement of section 4.2 then each 100 square foot area shall
be measured.

6. TESTING AND MEASUREMENT RELATED TO CONSTRUCTON TYPE

6.1. Numerical example reading and testing See Appendix 1 SSPC - PA 2.

6.2. Methods for Measuring Dry Film Thickness on Steel Beams (Girders See Appendix 2
SSPC PA 2

6.3. Methods for Measuring Dry Film Thickness for a Laydown of Beams, Structural Steel,
and Miscellaneous Parts after Shop Coating See Appendix 3 SSPC - PA 2 .

6.4. Method for Measuring Dry Film Thickness on Coated Steel Test Panels See 4 Appendix
SSPC - PA 2.

6.5. Method for Measuring Dry Film Thickness of Thin Coatings on Coated Steel Test Panels
that Have Been Abrasive Blast Cleaned See Appendix 5 SSPC - PA2.

6.6. Method for Measuring the Dry Film Thickness of Coatings on Edges See
Appendix 6 SSPC - PA2
6.7. For edge area less than 5 mm shall determine related to gage probe possibility attach
and prior coating completed application mandatory to carry out according to SSPC - PA
guide 11 Edge protection.

6.8. For edges exceed 5 mm or more mandatory to measure and recorded see point 5.9 in
this procedure.

7. RECOMMENDED FILM THICKNESS PIPELINE COATING’S

7.1. Method for Measuring Dry Film Thickness on Coated Steel Pipe Exterior See Appendix
7 SSPC - PA2.

7.2. For standard corrosion protection, a DFT of 0.75 mm minimum to 1.25 mm maximum (
750 microns to 1250 microns, 30 mils to 50 mils ), is recommended.
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7.3. Number and Location of Spot Measurement - pipe spools

Pipe Diameter Circumferential Spot Interval Spacing

Measurements
Up to 12 in (30 cm) 4 evenly spaced 10 feet (3 meters) apart
14 to 24 inches (36-60 cm) 6 evenly spaced 10 feet (3 meters) apart
Greater than 24 inches (60 cm) 8 evenly spaced 10 feet (3 meters) apart

Circumference = pi x diameter

Example: 10 pieces of 48” long x 9” diameter pipe on a cart or rack

4’ x (3.14 x 0.75’) = 9.4 sq. feet per pipe section.9.4 sq.

feet per pipe section x 10 pipe sections = 94 sq. ft

8. THICKNESS LIMIT

8.1. Some paints are especially sensitive to high or low film thickness. In all cases, limitation
on maximum or minimum film thickness specified in the manufacture’s instruction shall
be followed.

8.2. IF the coating thickness NOT specified and / or stipulated in General specification
associated to Inspection level.

8.3. Inspection Level 3 must be taken.

8.4. For burial pipe inspection recommendation as per SSPC PA 2 - 2012 is level 2

9. ACCEPTANCE CRITERIA

9.1. Single gage reading NOT accepted means of reading see section 4.

9.2. Acceptance Criteria according to thickness level agreement

9.3. Acceptance criteria related type and construction geometry must according to Appendix
1 - 7 per SSPC PA 2 - 2012

9.4. IF the owner no state and / or declare inspection level all parties shall agree according
to Level # 3 SSPC PA 2 with high and low 120 / 80 % for Industrial according to ISO
12944 - 2 Exclude Marine Vessel
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9.5. For marine Vessel and / or marine Facilities shall following to inspection level # 2 as
specified of maximum 120 % or following to level # 3.

9.6. Marine Performance Standard for Protective Coatings for Dedicated Seawater Ballast
Tanks in all types of Ships and Double - Side skin spaces of bulk carriers following to
IMO MSC 215 with maximum average low thickness 90 % and minimum of high
thickness achieve 10 % from specified thickness.

9.7. Example High and Low reading

120 % Average Minimum high

(Inspection level # 3)

20 % Minimum High

Specification = 100 % Coating Thickness

20 % Maximum low

80 % Maximum Average
(Inspection level # 3)

9.8. Acceptance level # 2 for burial Pipe

Max 20 % High
(Inspection level # 2)

Specified
Coating Thickness

UN ACCEPTED MUST BUILD UP

Low thickness
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9.9. Wet Film Thickness calculation

DFT = Measured WFT x % Volume Solids,

DFT = Measured WFT x % volume solids ÷ (100% + % thinner added)

10. SAFETY

10.1. Provide safety access to inspection areas at all time make sure the ladder,
scaffolding are in good repair and are secure, no missing handrail or steps include with
fall protection.

10.2. For internal vessel and or confined space should make sure proper ventilation
before take reading point measurement.

10.3. If more than 2m ( 6 ft ) in height should be securely tied off with safety harness

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