1. William D. Corbett KTA-Tator, Inc.
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 Stencil Code 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 mils (red zone), record the measurement using Coarse tape
If reading is mils (blue zone), record the measurement using X-Coarse tape
If reading is between mils using X-Coarse, obtain a second reading (same location) with the Coarse tape
If the reading with the Coarse tape is also within 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”1 2
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] 3 4

22. Reporting Report: Example (based on replica tape):
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: 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. Chalk line demarcating non-conforming areaOK
6” x 6” (15cm x 15cm) areas OK
End of Prepared Area
Non-conforming Location
Non-conforming Location OK OK OK OK
Chalk line demarcating non-conforming area OK

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 ( mils)
X-Coarse ( mils)
X-Coarse Plus (4-5 mils)
Recheck if in “overlap area” of 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. PROCESS CONTROL ITEMS FOR ABRASIVE NOZZLE BLAST CLEANING
TABLE B1
PROCESS CONTROL ITEMS FOR ABRASIVE NOZZLE BLAST CLEANING 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

33. FOR POWER TOOL CLEANING (SP 11, SP 15 only)
TABLE B2
PROCESS CONTROL ITEMS
FOR POWER TOOL CLEANING (SP 11, SP 15 only) 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

34. FOR CENTRIFUGAL BLAST CLEANING
TABLE B3
PROCESS CONTROL ITEMS
FOR CENTRIFUGAL BLAST CLEANING 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)

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