How to measure surface profile. Excellent webinar by SSPC & KTA

1. Determining Conformance to
Steel Profile/Surface Roughness/
Peak Count Requirements
William D. Corbett
KTA-Tator, Inc.

2. Webinar Content
• Review of industry
standards
• Review of
instrumentation and
measurement
acquisition procedures
• Content of Proposed
SSPC Standard

3. Learning Objectives/Outcomes
• Completion of this webinar will enable the participant
to describe:
 The industry standards for surface profile, surface roughness and
peak count measurement
 The instruments used to measure surface profile/ roughness and to
quantify peak count
 The proposed content of the SSPC standard, “Procedure for
Determining Conformance to Steel Profile/Surface
Roughness/Peak Count Requirements”

4. Industry Standards for Surface Profile,
Surface Roughness and Peak Count
Measurement
• ASME B46.1, Surface Texture (Surface Roughness, Waviness
and Lay)
• ASTM D4417, Standard Test Methods for Measurement of
Surface Profile of Blast Cleaned Steel
• ASTM D7127, Standard Test Methods for Measurement of
Surface Roughness of Abrasive Blast Cleaned Metal Surfaces
Using a Portable Stylus Instrument

5. Industry Standards for Surface Profile,
Surface Roughness and Peak Count
Measurement, continued
• ISO 4287, Geometrical Product Specifications (GPS) - Surface
Texture: Profile Method - Terms, Definitions and Surface
Texture Parameters
• ISO 8503, Preparation of steel substrates before application of
paints and related products - Surface roughness characteristics
of blast-cleaned steel substrates
 Part 4: Method for the calibration of ISO surface profile comparators and
for the determination of surface profile - Stylus instrument procedure
 Part 5: Replica tape method for determination of the surface profile
• NACE SP0287, Field Measurement of Surface Profile of
Abrasive Blast Cleaned Steel Surfaces

6. Proposed SSPC Standard
• Procedure for Determining Conformance to Steel
Profile/Surface Roughness/Peak Count
Requirements
• Draft #6b (May 21, 2012) in SSPC Standards
Review Committee (SRC)
• After SRC approval, SSPC Board must approve
• Timeline for approval is unknown at this time

7. Content of Proposed
SSPC Standard
Scope; Description; Referenced Standards; Definitions
Description of Instruments; Verification of Accuracy
Required Number & Location of Readings
Reporting
Conformance to the Specified Surface Profile Range
Appendix A: Calibration & Verification of Accuracy
Appendix B: Determining Compliance based on Process
Control Procedure
Appendix C: Additional Considerations when Measuring
Surface Profile

8. Instrumentation and Measurement
Acquisition Procedures
• Visual Comparators
• Depth Micrometers
• Replica Tape
• Stylus Instruments

9. Visual Comparators
• ASTM D4417, Method A
 5-10 X illuminated
magnifier
 Comparator Disc

10. Visual Comparators
• Three Comparator Discs
S: Sand
G/S: Grit/Slag
SH: Shot
• Stencil Code
Profile depth (2)
Abrasive Type (Sand)
Year reference (1970)

11. Visual Comparators
• Select Disc
• Attach Disc to
Comparator
• Examine Surface
• Select Segment(s)

12. ISO Visual Comparators
• Grit or Shot prepared
surfaces
• Used with 5-10X
magnifier
• Surface roughness
“graded” as:
Fine
Medium
Coarse

13. Depth Micrometers
Instrument sets on
peaks of the profile
while a conical-
shaped point
projects into the
valleys
Digital models
store and upload
data for analysis
(“paperless”)

14. Replica Tape
• Used in conjunction
with a spring-loaded
micrometer (analog or
digital)
• Compressible foam
attached to 2 mils of
polyester film (Mylar®)
• Digital version of
micrometer can upload
data (USB)

15. Replica Tape

16. Using HT Replica Tape
• Obtain measurement with X-Coarse replica
tape
If reading is 0.8-1.5 mils (red zone), record the
measurement using Coarse tape
If reading is 2.6-4.5 mils (blue zone), record the
measurement using X-Coarse tape
If reading is between 1.5-2.5 mils using X-Coarse,
obtain a second reading (same location) with the
Coarse tape
If the reading with the Coarse tape is also within
1.5-2.5 mils inclusive, average the two values

17. Portable Stylus Instruments
(ASTM D7127)
• Retractable arm with diamond
point stylus
• Arm is automatically retracted
• Rt: The distance between the highest peak
and the lowest valley within any given
evaluation length
• Rmax: The greatest distance between the
highest peak and lowest valley for any of the
five sampling lengths that comprise an
evaluation length
• Pc: The number of peak/valley pairs, per unit
of evaluation length, extending outside a
“deadband” centered around the mean line
over the sampling length

18. Frequency of Surface Profile
Measurements
• No. of readings indicated in ASTM standards
• No. of locations not indicated in ASTM
standards
• No. of locations may be indicated by the
project specification
• Proposed SSPC Standard provides no. of
locations to characterize the surface
 Primary purpose of this webinar

19. Number of Readings
(to determine location average)
• Based on Test Method (unless otherwise specified)
• ASTM D4417
 “Sufficient” number of readings for Method A
(visual comparator)
10 readings per “location” for Method B
(depth micrometer)
3 readings per “location” for Method C
(replica tape)
• ASTM D7127 (portable stylus instrument)
5 traces per “location”

20. Number of Locations
(to characterize the surface)
• Minimum of three 6” x 6” (15cm x 15cm) locations
Per surface preparation “apparatus”
Per work shift or 12-hour period (whichever is shorter)
• Optional method (Non-mandatory Appendix B)
Based on changes in process between acceptance of jobsite
standard & completion of production surface preparation

21. Surface Preparation “Apparatus”
• Individual Blast Pot
(multiple nozzles) [1]
• Individual abrasive
recycling/blast cleaning
units (multiple pots) [2]
• Individual centrifugal
units (stationary or
mobile) [3]
• Individual power tool [4]
1 2
3
4

22. Reporting
• Report:
Range of Location Averages (lowest
location average & highest location
average)
Surface Profile Measurement (per
“apparatus”)
• Example (based on replica tape):
Location 1: 4.5, 4.8, 4.1 mils; (4.5)
Location 2: 4.0, 5.0, 3.8 mils; (4.3)
Location 3: 3.5, 4.1, 4.8 mils; (4.1)
Range: 4.1-4.5 mils; Average 4.3 mils

23. Conformance to the Specified Surface
Profile Range
• The average of the “location averages” must
fall within the specified surface profile range
• Location averages and average surface profile
measurements outside of the specified range
are not acceptable
• The magnitude of the non-conforming surface
profile measurement areas must be determined,
marked and recorded

24. Non-
conforming
Location
OK
OK
OK OK
Non-
conforming
Location
OK
OK
OK
EndofPreparedArea
6” x 6” (15cm x 15cm)
areas
Chalk line
demarcating non-
conforming area

25. Appendix A: Calibration &
Verification of Accuracy (shop/field)
• Calibration of instruments (applies to ASTM
D4417 methods B&C; ASTM D7127)
• Calibration by manufacturer or approved
laboratory only
• Recalibration per manufacturer’s
recommended interval (typically annual)
• Obtain a dated Certificate of Traceability

26. Appendix A: Calibration &
Verification of Accuracy (shop/field)
• ASTM D4417
Method A (visual
comparator): visual for
damage
Microscopic examination
in a laboratory to
confirm depth of valley
relative to corresponding
peak (if necessary)

27. Appendix A: Calibration &
Verification of Accuracy (shop/field)
• ASTM D4417
Method B (depth
micrometer)
• Zero set (float glass plate)
beginning & end of shift
• Verify accuracy using
shim with cut-out/hole on
float glass plate
• Verify cone tip condition
using 10x magnifier
• Tips are replaceable (re-
verify accuracy upon
replacement)

28. Appendix A: Calibration &
Verification of Accuracy (shop/field)
• ASTM D4417
Method C (replica tape)
• Select appropriate tape
• Coarse (0.8-2.5 mils)
• X-Coarse (1.5-4.5 mils)
• X-Coarse Plus (4-5 mils)
• Recheck if in “overlap
area” of 1.5-2.5 mils
• Verify accuracy of
micrometer using
traceable shims

29. Appendix A: Calibration &
Verification of Accuracy (shop/field)
• ASTM D7127 (portable
stylus instrument)
Set gage parameters
(sampling & evaluation
length, deadband &
filter) per Standard
Verify accuracy using
standard (provided with
gage) prior to each use

30. Appendix B: Determining Compliance
Based on Process Control Procedure
• Based on establishing a process control prior to
production blast or power tool cleaning
• Within 15 minutes after start of surface preparation,
prepare sample area (min 2’ x 2’)
• Measure surface profile. If surface profile conforms,
document process control items

31. Appendix B: Determining Compliance
Based on Process Control Procedure
• A change in process during production requires re-
measurement
• Denote time of the change & location of surfaces prepared
prior to the change
• Obtain two measurements at random locations
 One in an area prepared prior to the change in process
 One in an area prepared after the change in process
• Document: Locations of tests; test method(s); test results;
conformance to specification
• The magnitude of the non-conforming surface profile
measurement areas must be determined, marked and
recorded (as described earlier)

32. 1 Worker performing abrasive blast cleaning
2 Blast nozzle type
3 Blast nozzle size
4 Number of nozzles operating from same compressor
5 Abrasive manufacturer
6 Abrasive type, hardness and physical shape (e.g., steel grit, steel shot, or ratio
of mix, or type of mineral abrasive, such as garnet, coal slag, etc.)
7 Abrasive size (sieve size)
8 Air pressure at nozzle
9 Blast hose length (as a range)
10 Blast hose diameter
11 Compressor size (CFM)
12 Air pressure at compressor
TABLE B1
PROCESS CONTROL ITEMS
FOR ABRASIVE NOZZLE BLAST CLEANING

33. 1 Worker performing power tool cleaning
2 Power tool type, model and manufacturer
3 Power tool media manufacturer
4 Type of media used (e.g. wire brush, coated abrasive disc, abrasive embedded
in matrix, wire bristle, impact tool)
5 Abrasive media size
6 Grade of media
7 Replacement/substitution of consumables (e.g., disc, wire brush, needles,
bristles)
8 Compressor size (CFM) if tool is air-powered
TABLE B2
PROCESS CONTROL ITEMS
FOR POWER TOOL CLEANING (SP 11, SP 15 only)

34. 1 Unit Operator
2 Blast wheel type
3 Wheel motor power
4 Wheel positioning
5 Control cage movement
6 Media flow rate
7 Abrasive manufacturer
8 Abrasive type and physical shape (e.g., steel grit, steel shot, or ratio of
mix, or type of mineral abrasive, such as garnet, coal slag, etc.)
9 Abrasive size (sieve size)
10 Configuration, orientation and size of piece being cleaned (if in shop)
TABLE B3
PROCESS CONTROL ITEMS
FOR CENTRIFUGAL BLAST CLEANING

35. Appendix C: Additional
Considerations
• Measuring surfaces prepared in the shop using
centrifugal blast cleaning units
Potential for variability due to wheel alignment
and configuration of item
• Measuring surfaces prepared using portable
centrifugal blast cleaning units
Potential for variability due to uneven distribution
of blast media

36. Appendix C: Additional
Considerations
• Measuring surface profile exposed by
waterjetting units
Profile may vary considerably. Additional
measurement locations may be required
• Measuring surfaces prepared using power tools
(SSPC-SP11; SP15)
Consider productive life of cleaning media;
Additional measurement locations may be required
Use ASTM D4417, Method B only

37. Appendix C: Precautions
• Determining surface profile on flame cut edges
Removal of carburization (hardening) may be
required prior to blast cleaning
• Effect of existing surface profile on newly
generated surface profile
– Existing profile beneath coating may exceed
specified profile for maintenance painting. Prepare
test area prior to production work
• Pitted steel: Measure in non-pitted areas

38. Summary
• During this webinar, we have described :
The industry standards for surface profile, surface roughness
and peak count measurement
The instruments used to measure surface profile/ roughness
and to quantify peak count
The proposed content of the SSPC standard, “Procedure for
Determining Conformance to Steel Profile/Surface
Roughness/Peak Count Requirements”

39. Determining Conformance to
Steel Profile/Surface Roughness/
Peak Count Requirements
William D. Corbett
KTA-Tator, Inc.
THE END