SSPC: The Society for Protective Coatings
Procedure for Determining Conformance to
Steel Profile/Surface Roughness/Peak Count Requirements
B3 Additional Requirements for Process Changes
B3.1 If there is a change to any of the items listed inTables B1, B2, or B3 (as applicable) during surface prepara-tion, the time that the change took place and the location ofthe surfaces or the identity of the pieces prepared before thechange shall be identified.
B3.2 Unless otherwise specified in the contract docu-ments, two measurements shall be taken at randomlyselected locations on the prepared surface(s) of the struc-
ture (or on a minimum of two of the prepared pieces) uponcompletion of surface preparation. One measurementshall be taken on the structure’s surface(s) prepared (or on
one of the pieces prepared) before the process change.The second measurement shall be taken on the preparedsurface(s) of the structure (or on one of the pieces prepared)
after the process change. The location of the tests, thetest methods used, the test results and whether the resultsconformed to contract requirements shall be documented.
B3.3 If the process changes more than once duringsurface preparation, an additional measurement per the aboveprocedure each time the process changes shall be taken.
B4 Non-Conforming Surface Profile:
STEP 1: Determine location averages atregular intervals in four equally spaceddirections radiating outward from thenon-compliant 15 x 15 cm (or 6 x 6 inch)
location. If there is no space to takereadings in a given direction, then noreadings need to be taken. Determineadditional location averages in each
direction until two consecutive locationaverages are compliant in each directionor until there is no space to take additionalmeasurements in that direction. Determine
a single location average on repeatingstructural units or elements of structuralunits until location averages on twoconsecutive units (or elements) in each
direction are compliant or until there are nomore units or elements to test.
STEP 2: Acceptable location averages are asdefined by the specification for minimumand maximum values. Use removablechalk or other specified marking material
to identify the extent of the non-conformingsurface profile.
STEP 3: Record the extent of the nonconformityusing readily identifiable structuralmembers or permanent structural details.
NONMANDATORY APPENDIX C: Additional Consid-
erations When Measuring Surface Profile
C2.1 Determining Surface Profile/Peak Count onSurfaces Shop-Prepared Using Stationary CentrifugalBlast Cleaning Units: A centrifugal blast machine is
comprised of one or more spinning wheels that throw abrasiveblast media at a conveyed part that moves parallel to the blastmachine. Various parameters, including dwell time and rate
of travel, can affect the degree of cleaning and blast profileachieved. A key parameter that can affect the uniformity of theblast profile depth is the positioning of the adjustable wheels.
Improperly aligned wheels may not achieve a uniform blastprofile because some areas could be partially or completelymissed. In some cases the blast media may strike the surface
at an oblique angle resulting in a lesser profile depth. In orderto account for the potential variability in the surface profile,the profile should be measured at representative unique loca-
tions. For example, U-shaped sheet piles have three uniquelyoriented surfaces on each side. Each of the three surfacesshould be evaluated for compliance to the specified blast
profile separately. The values should not be averaged. If anyone surface is non-compliant, the machine should be adjustedand the piece reblasted and checked for compliance on each
surface. The procedure should be repeated until the specifiedprofile is achieved. Caution should be exercised in re-blastingas steel surfaces can be compromised by over blasting causing
surface failures in the grain structure of the steel surface.
C2.2 Determining Surface Profile on Surfaces CleanedUsing Portable Centrifugal Blast Cleaning Units: A portablecentrifugal blast machine uses one or more spinning wheels
that throw abrasive blast media at a surface as the blastmachine is moved parallel to the surface. Various parameters,including dwell time and rate of travel, can affect the degree of
cleaning and blast profile achieved. A key parameter that canaffect the uniformity of the blast profile depth is the distributionof blast media across the width of the cleaned surface. Improp-
erly distributed media may not achieve a uniform blast profilebecause some areas could be partially or completely missed.In order to account for the potential variability in the surface
profile, the profile should be measured at representative loca-tions across the width of the blast path.
C2.3 Determining Surface Profile on Surfaces CleanedUsing Waterjetting Units: Information about the surfacepreparation history and the effects of long-term exposure may
not be available for previously coated surfaces that have beencleaned by water jetting. The newly exposed profile couldchange significantly within a small area. Therefore, it may be
necessary to determine additional location averages of surfaceprofile or surface roughness and peak count to ensure that theprofile consistently meets the stated requirements.
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C2.4 Determining Surface Profile on Surfaces Cleanedto SSPC-SP 15 or SSPC-SP 11: When power tool cleaningto SSPC-SP 15 or SSPC-SP 11, the designed service life of
the cleaning media may end before the specified or defaultminimum surface profile required is achieved. The frequency
of determining additional location averages of profile or surfaceroughness and peak count should be increased to reflect the
productive life of the media being used. The designed servicelife of the power tool cleaning media used should be consideredwhen specifying the frequency for determining compliance.
C2.5 Precautions Regarding Determination of SurfaceProfile
C2.5.1 Determination of Surface Profile on Flame Cut
Edges: When steel is cut using oxy-acetylene torches, theheat that is generated during the cutting process hardens thecut edge. This is known as carburization or case-hardening
(surface hardening) of the steel. Subsequent abrasive blastcleaning of these surfaces will typically yield a shallower
surface profile depth due to the increased hardness of thesurface. Removal of the hardened surface using grinders priorto abrasive blast cleaning will typically resolve the problem.
Surface profile readings and location averages should beobtained in these areas to verify compliance with projectrequirements.
C2.5.2 Effect of Existing Surface Profile on NewlyGenerated Surface Profile: Steel surfaces with existingcoating that must be removed may already have an existing
surface profile. During surface preparation, the new surfaceprofile combined with the existing surface profile may exceedthe specified maximum surface profile for maintenance
operations. A representative area of the structure should beevaluated to determine the surface profile yield before produc-tion abrasive blast cleaning begins so that adjustments to the
abrasive, equipment or other factors (or the project specifica-tion requirements) can be made.
C2.5.3 Determining Surface Profile on Pitted Steel:Surface profile readings taken on pitted areas of steel can yieldfalse high values (even with visual techniques). Surface profile
readings should be obtained from non-pitted areas when thesteel surfaces contain pits. If the steel is 100% pitted, a testpanel should be created to evaluate the surface profile.