profile measurement web in ar
TRANSCRIPT
Determining Conformance to Steel Profile/Surface Roughness/ Peak Count Requirements
William D. CorbettKTA-Tator, Inc.
Webinar Content
• Review of industry standards
• Review of instrumentation and measurement acquisition procedures
• Content of Proposed SSPC Standard
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”
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
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
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
Content of Proposed SSPC Standard
Scope; Description; Referenced Standards; DefinitionsDescription of Instruments; Verification of AccuracyRequired Number & Location of ReadingsReportingConformance to the Specified Surface Profile RangeAppendix A: Calibration & Verification of AccuracyAppendix B: Determining Compliance based on Process
Control ProcedureAppendix C: Additional Considerations when Measuring
Surface Profile
Instrumentation and Measurement Acquisition Procedures• Visual Comparators• Depth Micrometers• Replica Tape• Stylus Instruments
Visual Comparators
• ASTM D4417, Method A 5-10 X illuminated
magnifier Comparator Disc
Visual Comparators
• Three Comparator DiscsS: SandG/S: Grit/SlagSH: Shot
• Stencil CodeProfile depth (2)Abrasive Type (Sand)Year reference (1970)
Visual Comparators
• Select Disc• Attach Disc to
Comparator• Examine Surface• Select Segment(s)
ISO Visual Comparators
• Grit or Shot prepared surfaces
• Used with 5-10X magnifier
• Surface roughness “graded” as:FineMediumCoarse
Depth MicrometersInstrument
sets on peaks of the profile while a conical-shaped point projects into the valleys
Digital models store and upload data for analysis (“paperless”)
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)
Replica Tape
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
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
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
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”
Number of Locations (to characterize the surface)
• Minimum of three 6” x 6” (15cm x 15cm) locationsPer 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
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
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
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
Non-conforming Location
OK
OK
OK OKNon-conforming Location
OK
OK
OK
End of P
repared A
rea
6” x 6” (15cm x 15cm) areas
Chalk line demarcating non-conforming area
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
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)
Appendix A: Calibration & Verification of Accuracy (shop/field)
• ASTM D4417Method 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)
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
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
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
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)
1 Worker performing abrasive blast cleaning 2 Blast nozzle type 3 Blast nozzle size 4 Number of nozzles operating from same compressor5 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
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 B2PROCESS CONTROL ITEMS
FOR POWER TOOL CLEANING (SP 11, SP 15 only)
1 Unit Operator2 Blast wheel type3 Wheel motor power4 Wheel positioning5 Control cage movement6 Media flow rate7 Abrasive manufacturer8 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 B3PROCESS CONTROL ITEMS
FOR CENTRIFUGAL BLAST CLEANING
Appendix C: Additional Considerations• Measuring surfaces prepared in the shop using
centrifugal blast cleaning unitsPotential for variability due to wheel alignment
and configuration of item
• Measuring surfaces prepared using portable centrifugal blast cleaning unitsPotential for variability due to uneven distribution
of blast media
Appendix C: Additional Considerations• Measuring surface profile exposed by
waterjetting unitsProfile 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 requiredUse ASTM D4417, Method B only
Appendix C: Precautions
• Determining surface profile on flame cut edgesRemoval 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
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”
Determining Conformance to Steel Profile/Surface Roughness/ Peak Count Requirements
William D. CorbettKTA-Tator, Inc.
THE END