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0Steel Structures Painting Council
<br />SURFACE
<br />White Metal Blast
<br />Cleaning
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<br />1. Scope
<br />1.1 This specification covers the requirements for
<br />White Metal Blast Cleaning of steel surfaces by the use of
<br />abrasives.
<br />2. Definition
<br />2.1 A White Metal Blast Cleaned surface, when
<br />viewed without magnification, shall be free of all visible
<br />oil, grease, dirt, dust, mill scale, rust, paint, oxides, cor-
<br />rosion products, and other foreign matter.
<br />2.2 ACCEPTABLE VARIATIONS IN APPEARANCE
<br />THAT DO NOT AFFECT SURFACE CLEANLINESS as
<br />defined in Section 2.1 include variations caused by type of
<br />steel, original surface condition, thickness of the steel,
<br />weld metal, mill or fabrication marks, heat treating, heat
<br />affected zones, blasting abrasive, and differences in the
<br />blast pattern.
<br />2.3 When painting is specified, the surface shall be
<br />ghened to a degree suitable for the specified paint
<br />system.
<br />2.4 Immediately prior to paint application the surface
<br />shall comply with the degree of cleaning as specified
<br />herein.
<br />2.5 SSPC-Vis 1 or other visual standards of surface
<br />preparation may be specified to supplement the written
<br />definition.
<br />'NOTE: Additional information on visual standards is
<br />available in section A.4 of the Appendix.
<br />3. Blast Cleaning Abrasives
<br />3.1 The selection of abrasive size and type shall be
<br />based on the type, grade, and surface condition of the
<br />steel to be cleaned, type of blast cleaning system
<br />employed, the finished surface to be produced (cleanli-
<br />ness and roughness), and whether the abrasive will be
<br />recycled.
<br />3.2 The cleanliness and size of recycled abrasives
<br />Shall be maintained to insure compliance with this
<br />specification.
<br />3.3 The blast cleaning abrasive shall be dry and free
<br />of oil, grease, and other harmful materials at the time of 6.2.2 Dry abrasive blasting using a closed cycle, recir-
<br />use. culating abrasive system with compressed air, blast noz-
<br />3.4 Any limitations or restrictions on the use of zle, and abrasive, with or without vacuum for dust and
<br />'Notes are not requirements of this specification.
<br />� National Association of Corrosion Engineers
<br />�uae� Endorsement, October 31, 1984
<br />SSPC-SP 5
<br />March 1, 1985
<br />specific abrasives, quantity of contaminants, or degree of
<br />embedment shall be included in the procurement docu-
<br />ments (project specification) covering the work, since
<br />abrasive embedment and abrasives containing con-
<br />taminants may not be acceptable for some service re-
<br />quirements.
<br />'NOTE: Additional information on abrasive selection is
<br />available in Section A.2 of the Appendix.
<br />4. Reference Standards
<br />4.1 If there is a conflict between the cited reference
<br />standards and this specification, this specification shall
<br />prevail unless otherwise indicated in the procurement
<br />documents (project specification).
<br />4.2 The standards referenced in this specification
<br />are:
<br />SSPC-SP 1 Solvent Cleaning
<br />SSPC•Vis 1 Pictorial Surface Preparation Standards
<br />for Painting Steel Surfaces
<br />5. Procedure Before Blast Cleaning
<br />5.1 Before blast cleaning, visible deposits of oil or
<br />grease shall be removed by any of the methods specified
<br />in SSPC-SP 1 or other agreed upon methods.
<br />5.2 Before blast cleaning, surface imperfections such
<br />as sharp fins, sharp edges, weld spatter, or burning slag
<br />should be removed from the surface to the extent required
<br />by the procurement documents (project specification).
<br />'NOTE: Additional information on surface imperfections is
<br />available in Section A.5 of the Appendix.
<br />6. Blast Cleaning Methods and Operation
<br />6.1 Clean, dry, compressed air shall be used for
<br />nozzle blasting. Moisture separators, oil separators, traps
<br />or other equipment may be necessary to achieve this re-
<br />quirement.
<br />6.2 Any of the following methods of surface prepara-
<br />tion may be used to achieve a White Metal Blast Cleaned
<br />surface:
<br />6.2.1 Dry abrasive blasting using compressed air,
<br />blast nozzles, and abrasive.
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