134412126 NACE NO7 SSPC VIS 4 Visual Reference Photographs for Steel Cleaned by Water Jetting PDF

SSPC-Guide to VIS 4(1) July 1, 1998

Editorial Changes September 1, 2000

SSPC: The Society for Protective Coatings

INTERIM GUIDE TO SSPC-VIS 4(1)/NACE NO. 7 Visual Reference Photographs for Steel Cleaned by Water Jetting

Disc la i mer Foreword

SSPC and NACE International issue this Guide to reference photographs in conformance with the best cur- rent technology regarding the specific subject. This Guide represents a consensus of those individual members who have reviewed this document, its scope, and provisions. This Guide is intended to aid the manufacturer, the con- sumer, and the general public. Its acceptance does not in any respect preclude anyone, whether he has adopted the Guide or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this Guide. Nothing contained in this Guide 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 protecting anyone against liability for infringement of Letters Patent. This Guide represents minimum requirements and should in no way be interpreted as a restriction on the use of better products or materials. Neither is this Guide intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this Guide in specific in- stances. Neither NACE nor SSPC assumes responsibility for the interpretation or use of this Guide by other parties.

Users of this Guide are responsible for reviewing appropriate health, safety, and regulatory documents and for determining their applicability in relation to this Guide prior to its use. This Guide may not necessarily address all safety problems and hazards associated with the use of materials, operations and/or equipment detailed or referred to within this document. Users of this Guide are also responsible 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 Guide.

CAUTIONARY NOTICE: This Guide is subject to peri- odic review and may be revised or withdrawn at any time without prior notice. This Interim Guide must be reaffirmed, revised, or reviewed no later than two years from the date of initial publication. The user is cautioned to obtain the latest edition. For information on this and other joint SSPCI NACE publications, contact either organization. The SSPC Publications Dept. may be reached at 40 24th Street, Pittsburgh, PA 15222-4656 (telephone +1 41 2-281 -2331). The NACE International Membership Services Dept. may be reached at P.O. Box 218340, Houston, Texas 77218- 8340 (telephone +1 281 228-6200).

This guide describes the use of the visual reference photographs depicting the appearance of mill scale-free, unpainted, rusted carbon steel prior to and after cleaning by water jetting (WJ). The steel surfaces had previously been blast cleaned to remove the mill scale and were then allowed to rust. Although prepared from unpainted steel, the photographs are also suitable for depicting the appearance of painted steel after water jetting.

NOTE: SSPC and NACE International Visual Refer- ence Photographs are intended to supplement SSPC-SP 12/NACE No. 5. Due to the time required for consensus review, and the industry demand for immediate assistance in evaluating surfaces cleaned by water jetting, SSPC and NACE have issued this document as an interim status guide, using preexisting photographs which could not be adjusted or replaced. Therefore, these photographs and their descriptions do not exactly match the descriptions in SSPC-SP 12/NACE No. 5. The pictures and descriptions of flash rusting are included for information only and have not been established as standards. A new series of photographs is currently undergoing consensus review, which will result in the development of a set of photographs and text which will replace this interim guide. As the written standards are the primary means to determine conformance with cleaning requirements, the photographs should not be used as a substitute for these standards.

The guide is applicable to surfaces produced by a range of water jetting pressures. This guide can be used to clarify the acceptable level of flash rusting allowed prior to the application of protective coatings.

1. General

1.1 DESCRIPTION: The Visual Reference Photo- graphs consist of a series of color photographs which represent various conditions of unpainted steel surfaces prior to and after surface preparation by high pressure or ultrahigh pressure water jetting as defined in SSPC-SP 121 NACE No. 5 (see Section 2.3).

1.2 DEFINITIONS

1.2.1 High Pressure Water Jetting (HP WJ): cleaning performed at pressures from 70 to 170 MPa (10,000 to 25,000 psi).

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SSPC-Guide to VIS 4(1) July 1, 1998 Editorial Changes September 1, 2000

1.2.2 Ultrahigh Pressure Water Jetting (UHP WJ): Cleaning performed at pressures above 170 MPa (25,000 psi).

1.2.3 Low and High Pressure Water Cleaning: In addition to high pressure and ultrahigh pressure water jetting, SSPC-SP 12/NACE No. 5 defines two additional cleaning methods using water at lower pressure.

Low Pressure Water Cleaning (LP WC) is cleaning performed at pressures less than 34 MPa (5,000 psi)

High Pressure Water Cleaning (HP WC) is cleaning performed at pressures from 34 to 70 MPa (5,000 to 10,000 psi).

1.2.4 Generic Terms: The terms hydroblasting, hydrojetting, and water jetting describe the process in which pressurized water is directed through a nozzle to impact a surface. For purposes of this guide, hydroblasting, hydrojetting, and water jetting essentially mean the same thing. However, it is noted that the term hydroblasting is used generically to describe cleaning methods that range from low pressure water cleaning to ultrahigh pressure water jetting.

1.3 Use of Guide: This guide describes a procedure for determining the degree of surface cleanliness by water jetting. The guide further describes a procedure for determining the degree of flash rusting.

1.3.1 The user of this guide must designate the degree of cleaning as WJ-3 (“Thorough Cleaning”) or WJ-2 (“Very Thorough Cleaning”). (See Section 3.2.)

1.3.2 The user of this guide must designate the maximum degree of flash rusting permissible as None (original condition), Light (L), Moderate (M), or Heavy (H) rusting. (See Section 3.3.)

2. Reference Standards

2.1 The standards referenced in this guide are listed in Section 2.3 through 2.6 and form a part of this guide.

2.2 The latest issue, revision, or amendment of the reference standards in effect on the date of invitation to bid shall govern unless otherwise specified.

2.3 SSPC/NACE INTERNATIONAL JOINT STAN- DARD:

SSPC-SP 12/ NACE NO. 5

Surface Preparation and Clean- ing of Steel and Other Hard Materials by High- and Ultrahigh

Pressure Water Jetting Prior to Recoating

2.4 SSPC VISUAL STANDARD:

VIS 1-89 Visual Standard for Abrasive Blast Cleaned Steel

2.5 INTERNATIONAL STANDARDS ORGANIZA- TION (SO) STANDARD:

8501 -1 :1988 (E) Color photographic standard for visual assessment of steel substrates

2.6 ASTM STANDARD:

D 5367 Standard Practice for Evaluating Coatings Applied Over Surfaces Treated With Inhibitors Used to Prevent Flash Rusting of Steel When Water or Water/Abrasive Blasted

3. Procedures For Using Visual Reference Photographs

3.1 Determine Initial Condition (Rust Grade C or Rust Grade D): Select the photograph of rust grade that most closely resembles the condition of the steel to be cleaned. Previously painted steel can be classified as either C or D grade, depending on the degree of pitting.

3.2 Select the photograph that most closely resembles the degree of cleaning that has been specified. For example, if the initial rust grade is D and thorough water jet cleaning is specified (WJ-3, Vis WJ-3), use photograph D Vis WJ 3. (Refer to Section 4.)

3.3 Immediately after water jetting but before the surface has flash rusted, compare the prepared surface with the photograph selected to evaluate the degree of cleaning (see Appendix A.3).

3.4 Prior to painting, compare the flash rusted surface with the flash rusting photographs. For example, use D Vis WJ-2 L, D Vis WJ-2 M, or D Vis WJ-2 H to evaluate the degree of flash rusting that has occurred.

IS0 standards are available from the American National Standards Institute, 11 West 42nd Street, New York, NY

ASTM, 100 Bar Harbor Drive, West Conshohocken, PA 10036, (212) 642-4900.

19428-2959, (61 O) 832-9500.



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SSPC-Guide to VIS 4(1) July 1, 1998

Editorial Changes September 1, 2000

3.5 Degree of Flash Rusting: The degree of flash rusting specified shall be in accordance with Section 4.3. If no flash rusting is acceptable, the surface must conform to Section 4.2 immediately prior to topcoating. Note: The coating manufacturer may be contacted to verify that the coating material selected is suitable for application over the degree of flash rusting that has occurred. (See Appendix A.3, A.4, A.5 and A.7.)

4. Conditions Depicted

4.1 Initial Condition: The reference photographs illustrate two initial conditions (rust grades) of mill scale- free, previously unpainted, rusted carbon steel before surface preparation. Each of the photographs showing the initial conditions was selected to show the variations which can be found within the rust grade C and D definitions. The initial condition surfaces are not necessarily the same areas which are depicted in the cleaned condition photographs.

4.1.1 Rust Grade C: Steel surface completely covered with rust, little or no pitting visible (definition taken from SSPC-VIS 1-89).

4.1.2 Rust Grade D: Steel surface completely covered with rust, pitting visible (definition taken from SSPC- VIS 1-89).

4.2 Condition Immediately After Water Jet Clean- ing: The row of visual reference photographs (C WJ-2, C WJ-3, D WJ-2 and D WJ-3) depicts the appearance immediately after water jetting. Steel surfaces show variation in texture, shade, color, tone, pitting, flaking, etc., which should be considered when making comparison with the reference photographs. A brown-black discoloration of ferric oxide may remain as a tightly adherent thin film on corroded and pitted steel and is not considered as part of the percentage staining as described in Sections 4.2.1 and 4.2.2.

4.2.1 Very Thorough Cleaning (Vis WJ-2): Avis WJ- 2 surface, when viewed without magnification, shall be cleaned by water jetting to a matte (dull, speckled) finish which is free of all visible oil, grease, paint and rust except for randomly dispersed stains of rust, paint, and other foreign matter. The staining is limited to a maximum of 5% of the surface.

Note: The Vis WJ-2 reference photographs are comparable in degree of staining permitted to C Sa 2-112 and D Sa 2-112 of IS0 8501 :1, and C-SP 1 O and D-SP 1 O of SSPC- VIS 1-89.

4.2.2 Thorough Cleaning (Vis WJ-3): A Vis WJ-3 surface, whenviewed without magnification, shall be cleaned by water jetting to a matte (dull, speckled) finish which is

free of all visible oil, grease, paint, and rust except for randomly dispersed stains of very thin residues of rust, paint or foreign matter. These stains and residues are limited to a maximum of 33% of the surface and shall be firmly adherent.

Note: The Vis WJ-3 photographs depict a surface cleanliness which has less staining than the allowed maximum of 33% staining. The Vis WJ-3 reference photographs are comparable to C Sa 2 and D Sa 2 of IS0 8501 :1 and C- SP 10 and D-SP 10 of SSPC-VIS 1-89.

4.3 Flash Rusting: The visual reference photographs also illustrate three degrees of flash rusting. “Flash rusting” or “rust bloom” is a light oxidation of the steel, which occurs as water jet cleaned steel dries off and will quickly change the initial appearance. (See Appendix A.4.)

4.3.1 Light Flash Rusting (L): When viewed without magnification, small quantities of light tan-brown rust will partially discolor the original metallic surface. This layer may be evenly distributed or in patches, but it will be tightly adherent and will not be heavy enough to easily mark objects brushed against it.

4.3.2 Moderate Flash Rusting (M): When viewed without magnification, a layer of dark tan-brown rust will obscure the original metallic surface. This layer may be evenly distributed, or in patches, but it will be heavy enough to mark objects brushed against it.

4.3.3 Heavy Flash Rusting (H): When viewed without magnification, a heavy layer of dark tan-brown rust will completely obscure the original metallic surface. This layer of rust will be loosely adherent and will easily mark objects brushed against it. (See Appendix A.5.)

4.4 Appearance: The photographs are illustrative of some variations in color, texture, and general appearance that can result from water jet cleaning. In water jet cleaning, a brown-black discoloration of ferric oxide may remain as a tightly adherent thin film on corroded and pitted steel (see Appendix A.2). The steel surfaces produced by water jetting do NOT look the same as those produced by dry abrasive blasting, or air/water/abrasive (slurry) blasting. This is because water on its own cannot cut or deform steel like abrasives.

4.4.1 Water jetting will not produce an etch or profile of the magnitude currently recognized by the surface preparation industry; rather, it exposesthe original abrasive-blasted surface profile.

4.4.2 Surfaces cleaned by water jetting tend to look dull, even before they “flash out,” or flash rust. In addition, Grade D steel, with active corrosion pitting, showsa mottled appearance after water jetting. Mottling occurs when the



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SSPC-Guide to VIS 4(1) July 1, 1998 Editorial Changes September 1, 2000

corrosion products are washed out of the pits leaving a bright patch, and the surrounding areas are left a dull gray, brown to black color. This pattern is the reverse of that left by abrasive blasting, where anodic pits are often dark, due to corrosion products not being entirely removed, and the surrounding areas are bright.

Appendix A. Notes*

A.l Removal of Oil and Grease: The water jetting process can emulsify and remove oil and grease from a surface as it is cleaned. However, this does not preclude the need for proper degreasing procedures as specified in SSPC-SP 1, “Solvent Cleaning,” prior to water jetting.

A.2 Discoloration of Corroded and Pitted Steel: The gray, brown to black discoloration seen on corroded and pitted steel after water jetting cannot be removed by further water jetting. Analysis shows that this thin film consists mainly of ferric oxide, which is an inert material. As it is tightly adherent, it does not present a serious contami- nation problem.

A.3 Inspecting Water Jet Cleaned Surfaces Prior to Flash Rusting: When large areas are water jetted, flash rusting obscuring the level of visual cleanliness may occur before an inspection can be carried out. Establishing the required visual cleanliness by cleaning (hydroblasting) a small test area prior to production may help, providing the rest of the job is cleaned to the same degree. Methods for ensuring the rest of the job is cleaned to the same degree will vary from project to project.

A.4 The temperature of steel substrates can rise during the water jetting process. Compression of the water to reach jetting pressure will create a temperature rise in the water itself, and the velocity of the water striking the steel will impart energy to it as heat. This temperature rise can be substantial, and may help water jetted surfaces dry off more quickly, with a corresponding reduction in the severity of flash rusting. (See Appendix A.3.) Drying with hot air blowers is also a method to reduce the severity of flash rusting.

A.5 Removal of Flash Rusting: When flash rusting is too heavy for coating application, some coating manufac- turers permit its reduction or removal by clean, hand-held

wire brushes or by pressure washing with fresh water. Pressure washing at pressures above 7 MPa (1,000 psi), using either the rotational nozzles, or fan jet lances of the water jetting equipment itself, is a preferred method. It will cause the area to re-rust, but it is possible to reduce the degree of flash rusting from heavy to light using this method. Hand wire or bristle brushing to remove heavy flash rusting may be acceptable for small areas. For large surfaces, mechanical cleaning with power tools can produce acceptable results when the cleaning head does not produce a peened surface or remove the anchor profile needed for coating adhesion.

A.6 Inspecting Areas of Difficult Access: Special attention must be given to areas which are difficult to access, such as the backs of stiffening bars. Water cannot be ricocheted into these areas in the same manner as abrasives. Instead, specially designed angled nozzles should be used. These areas should be inspected care- fully.

A.7 Chemical Corrosion Inhibitors: Flash rusting can be prevented by the use of water soluble chemical corrosion inhibitors. These inhibitors may leave a crystal- line layer on the steel surface as the water evaporates, which can then lead to a loss of adhesion and osmotic blistering, if coatings are applied over this type of surface. If inhibitors are used, they should be thoroughly washed off with fresh water. The coating manufacturer should be contacted for compatibility.

See Section 4.3 and Appendix D.1.5 of SSPC-SP 121 NACE No. 5. ASTM D 5367-94 “Standard Practice for Evaluating Coatings Applied Over Surfaces Treated with Inhibitors Used to Prevent Flash Rusting of Steel When Water or Water/Abrasive Blasted” provides a means for evaluation.

A.8 Soluble Contaminants Removal: This visual reference photograph series makes no attempt to define levels of soluble contaminants (salts) remaining on surfaces cleaned by water jetting, or to relate degrees of flash rusting to remaining soluble contaminants. However, the ability to remove chemical contaminants (salts), particu- larly from badly pitted and corroded steel, is a major advantage of the water jetting process.

*Notes are not requirements of this guide.



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134412126 NACE NO7 SSPC VIS 4 Visual Reference Photographs for Steel Cleaned by Water Jetting PDF