1、SSPC-SP 7/NACE No. 4January 1, 20071SSPC: The Society for Protective CoatingsJoinT SurfaCe PreParaTion STandardSSPC-SP 7/naCe no. 4Brush-off Blast CleaningThis The Society for Protective Coatings (SSPC)/NACE International (NACE) standard represents a consensus of those individual members who have re
2、viewed this document, its scope, and provisions. It is intended to aid the manufacturer, the consumer, and the general public. Its acceptance does not in any respect preclude anyone, whether he has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes,
3、or procedures not addressed in this standard. Nothing contained in this SSPC/NACE standard is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protect
4、ing anyone against liability for infringement of Letters Patent. This standard represents current technology and should in no way be interpreted as a restriction on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictab
5、le circumstances may negate the usefulness of this standard in specific instances. SSPC and NACE assume no responsibility for the interpretation or use of this standard by other parties and accept responsibility for only those official interpretations issued by SSPC or NACE in accordance with their
6、governing procedures and policies which preclude the issuance of interpretations by individual volunteers.Users of this SSPC/NACE standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this sta
7、ndard prior to its use. This SSPC/NACE standard may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this SSPC/NACE standard are also res
8、ponsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard.CauTionarY noTiCe: SSPC/NAC
9、E standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with technical committee procedures. SSPC and NACE require that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication. The user
10、 is cautioned to obtain the latest edition. Purchasers may receive current information on all standards and other publications by contacting the organizations at the addresses below:SSPC: The Society for Protective Coatings40 24th Street, Sixth FloorPittsburgh, PA 15222(telephone +1 877/281-7772)NAC
11、E International 1440 South Creek Houston, TX 77084-4906 (telephone +1 281/228-6200) forewordThis joint standard covers the use of blast cleaning abrasives to achieve a defined degree of cleaning of steel surfaces prior to the application of a protective coating or lining system. This standard is int
12、ended for use by coating or lining specifiers, applicators, inspectors, or others who may be responsible for defining a standard degree of surface cleanliness.The focus of this standard is brush-off blast cleaning. White metal blast cleaning, near-white metal blast cleaning, commercial blast cleanin
13、g, and industrial blast cleaning are addressed in separate standards.Brush-off blast cleaning provides a lesser degree of cleaning than industrial blast cleaning (SSPC-SP 14/NACE No. 81). The difference between an industrial blast cleaning and a brush-off blast cleaning is that the objective of a br
14、ush-off blast cleaning is to allow as much of an existing adherent coating to remain as possible and to roughen the surface prior to coating application, whereas the purpose of the industrial blast cleaning is to remove most of the coating, mill scale, and rust, while the extra effort required to re
15、move every trace of these is determined to be unwarranted. This joint standard was originally prepared in 1994 and revised in 2000 by the SSPC/NACE Task Group A on Surface Preparation by Abrasive Blast Cleaning. This joint task group includes members of both the SSPC Surface Preparation Committee an
16、d the NACE Unit Committee T-6G on Surface Preparation. It was reaffirmed in 2006 by the SSPC Surface Preparation Committee, and NACE Specific Technology Group (STG) 04, Protective Coatings and Linings: Surface Preparation.SSPC-SP 7/NACE No. 4January 1, 200723.2 If there is a conflict between the req
17、uirements of any of the documents listed in paragraph 3.3 and this standard, the requirements of this standard shall prevail.3.3 Documents cited in the mandatory sections of this standard include:document TitleSSPC-AB 13Mineral and Slag AbrasivesSSPC-AB 24Cleanliness of Recycled Ferrous Metallic Abr
18、asivesSSPC-AB 35Ferrous Metallic AbrasivesSSPC-SP 16Solvent CleaningSSPC-VIS 1 Guide and Reference Photographs for Steel Surfaces Prepared by Dry Abrasive Blast CleaningSection 4: Procedures Before Cleaning4.1 Before blast cleaning, visible deposits of oil, grease, or other contaminants shall be rem
19、oved in accordance with SSPC-SP 1 or other agreed-upon methods.4.2 Before blast cleaning, surface imperfections such as sharp fins, sharp edges, weld spatter, or burning slag should be removed from the surface to the extent required by the procurement documents (project specification). Additional in
20、formation on surface imperfections is in Paragraph A4 of Appendix A. 4.3 If reference photographs or comparators are specified to supplement the written standard, the condition of the steel prior to blast cleaning should be determined before the blasting commences. Additional information on referenc
21、e photographs and comparators is in Paragraph A3 of Appendix A.Section 5: Blast Cleaning Methods and operation5.1 Clean, dry compressed air shall be used for nozzle blasting. Moisture separators, oil separators, traps, or other equipment may be necessary to achieve this requirement.5.2 Any of the fo
22、llowing methods of surface preparation may be used to achieve a brush-off blast cleaned surface:5.2.1 Dry abrasive blasting using compressed air, blast nozzles, and abrasive.5.2.2 Dry abrasive blasting using a closed-cycle, recir-culating abrasive system with compressed air, blast nozzle, and abrasi
23、ve, with or without vacuum for dust and abrasive recovery.In SSPC/NACE standards, shall and must are used to state mandatory requirements. Should is used to state that which is considered good and is recommended but is not absolutely mandatory. May is used to state that which is considered optional.
24、Section 1: General1.1 This joint standard covers the requirements for brush-off blast cleaning of uncoated or coated steel surfaces by the use of abrasives. These requirements include the end condi-tion of the surface and materials and procedures necessary to achieve and verify the end condition.1.2
25、 The mandatory requirements are described in Sections 1 to 9. Section 10, “Comments,” and Appendix A, “Explanatory Notes,” are not mandatory requirements of this standard.1.3 Information about the function of brush-off blast cleaning is in Paragraph A1 of Appendix A. 1.4 Information about use of thi
26、s standard in maintenance coating work is in Paragraph A2 of Appendix A.Section 2: Definitions2.1 Brush-off Blast Cleaned Surface: A brush-off blast cleaned surface, when viewed without magnification, shall be free of all visible oil, grease, dirt, dust, loose mill scale, loose rust, and loose coati
27、ng. Tightly adherent mill scale, rust, and coating may remain on the surface. Mill scale, rust, and coating are considered tightly adherent if they cannot be removed by lifting with a dull putty knife after abrasive blast cleaning has been performed. 2.1.1 The entire surface shall be subjected to th
28、e abrasive blast. The remaining mill scale, rust, or coating shall be tight. Flecks of the underlying steel need not be exposed whenever the original substrate consists of intact coating. 2.1.2 SSPC-VIS 12may be specified to supplement the written definition. In any dispute, the written definition s
29、et forth in this standard shall take precedence over reference photographs and comparators. Additional information on reference photographs and comparators is in Paragraph A3 of Appendix A. Section 3: associated documents3.1 The latest issue, revision, or amendment of the docu-ments listed in paragr
30、aph 3.3 in effect on the date of invitation to bid shall govern unless otherwise specified.SSPC-SP 7/NACE No. 4January 1, 200735.2.3 Dry abrasive blasting using a closed-cycle, recircu-lating abrasive system with centrifugal wheels and abrasive.5.3 Other methods of surface preparation (such as wet a
31、brasive blast cleaning) may be used to achieve a brush-off blast cleaned surface by mutual agreement between those responsible for establishing the requirements and those responsible for performing the work. Information on the use of inhibitors to prevent the formation of rust immediately after wet
32、abrasive blast cleaning is in Paragraph A5 of Appendix A.Section 6: Blast Cleaning abrasives6.1 The selection of abrasive size and type shall be based on the type, grade, and surface condition of the steel to be cleaned, the type of blast cleaning system used, the finished surface to be produced (cl
33、eanliness and surface profile rough-ness), and whether the abrasive will be recycled.6.2 The cleanliness and size of recycled abrasives shall be maintained to ensure compliance with this standard.6.3 The blast cleaning abrasive shall be dry and free of oil, grease, and other contaminants as determin
34、ed by the test methods found in SSPC-AB 1, SSPC-AB 2, and SSPC-AB 3. 6.4 Any limitations on the use of specific abrasives, the quantity of contaminants, or the degree of allowable embed-ment shall be included in the procurement documents (project specification) covering the work, because abrasive em
35、bedment and abrasives containing contaminants may not be accept-able for some service requirements. Additional information on abrasive selection is in Paragraph A6 of Appendix A.6.5 When a coating is specified, the cleaned surface shall be roughened to a degree suitable for the specified coating sys
36、tem. Additional information on surface profile and the film thickness of coating applied over the surface profile is in Paragraphs A7 and A8 of Appendix A. Section 7: Procedures following Blast Cleaning and immediately Prior to Coating7.1 Visible deposits of oil, grease, or other contaminants shall
37、be removed according to SSPC-SP 1 or another method agreed upon by those parties responsible for establishing the requirements and those responsible for performing the work.7.2 Dust and loose residues shall be removed from prepared surfaces by brushing; blowing off with clean, dry air; vacuum cleani
38、ng; or other methods agreed upon by those responsible for establishing the requirements and those responsible for performing the work.7.2.1 The presence of toxic metals in the abrasives or coating being removed may place restrictions on the methods of cleaning permitted. The chosen method shall comp
39、ly with all applicable regulations.7.2.2 Moisture separators, oil separators, traps, or other equipment may be necessary to achieve clean, dry air.7.3 After blast cleaning, any remaining surface imperfec-tions (e.g., sharp fins, sharp edges, weld spatter, burning slag, scabs, slivers) shall be remov
40、ed to the extent required by the procurement documents (project specification). Any damage to the surface profile resulting from the removal of surface imperfections shall be corrected to meet the requirements of Paragraph 6.5. Additional information on surface imperfections is in Paragraph A4 of Ap
41、pendix A.7.4 Immediately prior to coating application, the entire surface shall comply with the degree of cleaning specified in this standard. Information on chemical contamination, rust-back (rerusting), and the effect of dew point (surface condensation) is in Paragraphs A9, A10, and A11 of Appendi
42、x A. Section 8: inspection8.1 Work performed and materials supplied under this standard are subject to inspection by a representative of those responsible for establishing the requirements. Materials and work areas shall be accessible to the inspector. The proce-dures and times of inspection shall b
43、e as agreed upon by those responsible for establishing the requirements and those responsible for performing the work.8.2 Conditions not complying with this standard shall be corrected. In the case of a dispute, an arbitration or settlement procedure established in the procurement documents (project
44、 specification) shall be followed. If no arbitration or settlement procedure is established, a procedure mutually agreeable to purchaser and supplier shall be used.8.3 The procurement documents (project specification) should establish the responsibility for inspection and for any required affidavit
45、certifying compliance with the specification.Section 9: Safety and environmental requirements9.1 Because abrasive blast cleaning is a hazardous opera-tion, all work shall be conducted in compliance with applicable occupational and environmental health and safety rules and regulations. SSPC-SP 7/NACE
46、 No. 4January 1, 2007410. NACE Standard RP0287 (latest revision), “Field Measure-ment of Surface Profile of Abrasive Blast-Cleaned Steel Surfaces Using a Replica Tape” (Houston, TX: NACE).11. ASTM(1) D 4417 (latest revision), “Standard Test Methods for Field Measurement of Surface Profile of Blast C
47、leaned Steel” (West Conshohocken, PA: ASTM).12. SSPC-PA 2 (latest revision), “Measurement of Dry Coating Thickness with Magnetic Gages” (Pittsburgh, PA: SSPC).13. SSPC-SP 12/NACE No. 5 (latest revision), “Surface Prepa-ration and Cleaning of Metals by Waterjetting Prior to Recoating” (Pittsburgh, PA
48、: SSPC, and Houston, TX: NACE).14. SSPC-Guide 15 (latest revision), “Field Methods for Retrieval and Analysis of Soluble Salts on Steel and Other Nonporous Substrates” (Pittsburgh, PA: SSPC).appendix a: explanatory notes (nonmandatory)a1 funCTion: Brush-off blast cleaning (SSPC-SP 7/NACE No. 4) prov
49、ides a lesser degree of cleaning than industrial blast cleaning (SSPC-SP 14/NACE No. 8). It should be used when the service environment is mild enough to permit tight mill scale, coating, rust, and other foreign matter to remain on the surface. The primary functions of blast cleaning before coating are (a) to remove material from the surface that can cause early failure of the coating and (b) to obtain a suitable surface profile (roughness) to enhance the adhesion of the new coating system. The hierarchy of blasting standards is as follows: white metal blast cleaning, near-white metal blas
