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SSPC: The Society for Protective Coatings

Paint Application Guide No. 11

Protecting Corners, Edges, Crevices, and Irregular Steel Geometries by Stripe Coating

1. Scope

1.1 This guide discusses the technique called “stripe coating” or “striping” as a way of providing extra corrosion protection measures on edges, outside corners, crevices, bolt heads, welds, and other irregular steel geometries, including optional techniques that can be used to improve coating performance. It is not intended to provide all-encom-passing guidance but rather offer options when preparing a project specification. The engineer should evaluate and address details on a project-specific basis.

1.2 Appendix A contains recommendations and sample language to assist the specification writer in addressing corrosion protection of edges, crevices, and irregular steel geometries, and Appendix B contains representative photographs of configurations or geometries that may benefit from stripe coating.

1.3 Units of Measure: This guide makes use of both the ASTM(1) SI 10, “American National Standard for Metric Practice” International System Units (SI) units and U.S. Customary units. The measurements are not exact equiva-lents; therefore each system must be used independently of the other, without combining in any way. This guide uses SI units with the U.S. Customary conversions shown in parentheses.

2. Definitions

Bolted Connection: Two or more steel plates connected by a mechanical fastening system consisting of a threaded metal rod or pin (bolt) joined to a metal nut (with or without a washer).

Corner: The intersection of two surfaces.

Crevice: A narrow opening; fissure.

Edge: An exposed, through-thickness surface of a plate or rolled shape created either during the rolling process (for example the as-rolled side face of a beam flange, channel flange or angle leg), or by thermal cutting, sawing, or shearing. Edges may be planar or rounded, and either perpendicular or skewed to adjacent faces.(1) ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.

Standards available online from <http://www.astm.org>

3. Background

3.1 Sharp edges, outside corners, crevices, and welds are often sites where coating failures and corrosion begin due to reduced coating barrier protection (see Figure 1). Reduced coating thickness on these surfaces can be a result of application of inadequate amounts of coating, but the surface tension of the wet coating or coating shrinkage during the drying/curing process can also pull the film away from edges. Sharp edges resulting from cutting, burning, and shearing are especially difficult to coat adequately. Bolt threads and fastener systems combine the adverse effects of sharp edges and crevices. Crevices, depending on their inherent width, are also difficult to protect using coatings. Wet coating may flow over rather than into tight crevices, creating a temporary bridge over the crevice that opens as the coating cures and shrinks, thus leaving the crevice interior unprotected. In this case caulking is oftentimes a better alternative. All of these irregular geometries are susceptible to premature corrosion.

3.2 A “stripe coat” is a layer of coating applied to specific areas such as edges, welds, outside corners, bolt heads and threads, nuts, and crevices, to provide additional barrier protection. The stripe coat may be applied either before or after a layer of coating (often called a “full coat”) is applied over the entire surface being coated. The practice of applying a stripe coat is frequently referred to as “striping.” The coating manufacturer should be consulted on whether application of a stripe coat is recommended, as well as the thickness of the stripe coat. The project specification should provide detailed instructions on the surfaces to be stripe coated.

This guide was first issued in 2008 and was revised in 2020 by SSPC C.3.16.

Figure 1. Schematic showing how coating thickness is reduced at a sharp corner.

Poor

Coating

Ideal

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3.3 There are several factors and options to consider when specifying protection of edges, crevices and irregular geometries; the option of choice may be determined by the best cost/benefit ratio. Factors that enter into a cost/benefit analysis include the severity of the service environment (e.g., atmospheric versus immersion or below grade), interference with production during maintenance, difficulty in accessing the structure to perform maintenance painting, width of crevices, and aesthetics (e.g., architectural applications). These factors are often unique to each project. In some cases, both preparation and stripe coating may be specified for a given configuration or environment.

4. Preparing Outside Corners and Sharp Edges

4.1 Sharp corners may be avoided at the fabrication stage. They can also be remedied by grinding after construction, but at a much higher cost. When filing (grinding) corners, care should be taken to assure that additional sharp corners are not created while modifying the original corner. It is generally much less expensive and easier to grind corners in the shop than in the field since the work is more accessible. In addition to corners, rough surfaces such as weld caps should also be ground smooth. NACE Standard SP01781 provides guidance on finish requirements for welds for immersion environments.

4.2 Common options for preparation of outside corners, if corner preparation is determined to be necessary, include one grinding pass, three grinding passes (shown in Figure 2), or 2 mm [1/16 in] radius (sometimes known as “2R”). The increased performance resulting from corner or edge grinding depends on the service environment, the generic type of coating or coating system and the degree of grinding specified (see Appendix A1). For example, the International Maritime Organization (IMO) Performance Standard for Protective Coatings (PSPC)2 requires either a 3-pass or 2R preparation of all corners inside ballast tanks since seawater is frequently used for ballast. It should be noted however that the cost differential between one pass and three pass (or radiused) corner preparation is substantial and the specification writer should carefully consider the degree of corner grinding required and even conduct a cost-benefit analysis prior to invoking such requirements in a specification.

4.3 The use of coatings with edge-retention properties (see Section 5.1.3) may minimize or eliminate the need for corner grinding. It is important to note that corners in the as-rolled condition are not normally in need of any treatment and that some corner “softening” (flattening) occurs during blast cleaning; however, blast cleaning alone will not sufficiently break a sharp corner.3

4.4 Flame-cut edges can be ground over the entire edge surface to remove the hardened surface layer resulting from flame cutting and permit creation of a profile (see

Appendix A2). Grinding on flame cut edges can be used to remove martensite, a hardened form of steel that may result from rapid re-solidification following flame cutting. This layer is typically very thin, about 0.25 to 0.50 mm (0.01 to 0.02 in) thick and is dependent upon the chemistry and thickness of the steel. Light grinding is generally sufficient to remove this material and is only necessary if the hardness interferes with achieving the desired profile during blast cleaning. The very rapid heating and cooling from plasma or laser cutting are unlikely to cause the formation of martensite.

5. Stripe Coat Application

5.1 The project specification normally specifies the areas to be stripe coated, allowable methods of stripe coat application (brush or spray), whether to apply the stripe coat before or after the full coat, the coats that are to be “stripe” applied, whether tinting of the stripe coat or use of another color of coating is required, and information on the drying/curing requirements between application of the stripe and full coat (may defer to the coating manufacturer). “Wet” striping is typically regarded as the application of a stripe coat that is permitted a short dry time (i.e., <5-10 minutes), before a full-coat application of the same product. “Dry” striping is typically regarded as the application of a stripe coat that is permitted the manufacturer’s minimum recoat time (e.g., 4-8 hours) before the application of a full coat. Dry striping is generally performed after the full coat of primer has been applied to prevent rust-back of prepared steel surfaces.

5.1.1 Welds and crevices are best protected when striped with a coating with good wetting properties such as 100%-solids penetrating sealers, while high-build coatings are best for striping edges. However, it is impractical to specify two different stripe coatings on a structure with edges, crevices, and welds; therefore, the stripe coating selected should be capable of functioning on all areas where striping is required.

5.1.2 The coating manufacturer should be consulted to determine the appropriate coating to use as a stripe coat. If the stripe coat contains a zinc loading and is to be applied over a surface already primed with inorganic zinc, an organic zinc primer should be used for the stripe coat,

Figure 2. Options for Preparation of Outside Corners.

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as inorganic zinc coatings do not bond well to themselves. High-solids coatings may have relatively short dry times and may not possess good wetting properties, which are important for proper performance of stripe coats. In such cases, a compatible stripe coat with a slower drying time and improved wetting capability should be used with the high-solids coating. The coating selected for stripe application should be appropriate for the service environment.

5.1.3 Coatings with Edge-Retention Properties: Coatings with edge-retention properties can provide improved film build (retention) at corners and improve protection in these critical areas. The edge-retention properties of a coating should be established prior to its use. A method for measuring the edge-retention properties of a coating is published in MIL-PRF-23236.4 This test method compares the film thickness of three specimens cut from a sample of coating applied to a non-chamfered 90-degree angle. The ratio of the film thickness at the apex vs. the film thickness on the flat area is calculated and expressed as the percentage of edge retention of the coating, as shown in Figure 4. According to MIL-PRF-23236, any specimen having less than 50 percent edge retention fails the test. An average value of 70 percent edge retention for three test specimens measured using an optical microscope is required to qualify a coating as having edge-retention properties.

Note that very sharp corners, or “knife edges,” are very difficult to protect, even with coatings having edge-retention properties. In order to improve corrosion protection, “knife edges” should be modified as described in Section 4 before the coating is applied.

5.2 WHAT COATS TO STRIPE: Usually, a stripe application of the primer coating is specified to increase primer thickness. Occasionally, multiple stripe coats may be required over rough hand welds. In critical areas, the specifier may require that striping be done for two or more coats in a multi-coat system.

5.3 AREAS TO STRIPE

5.3.1 The facility owner/specification writer normally determines whether stripe coating is warranted for some or all areas of the particular project. Sometimes only specified areas of outside corners, edges, welds, and crevices are required to be stripe coated. Stripe coating is most effective on corners that are either rounded or chamfered by grinding (see Section 4) but may not be required if edge-retentive coatings are used.

5.3.1.1 Situations where stripe coating is usually warranted include:

• Immersion service (e.g., interiors of fuel or water storage tanks; ship hulls)

• Areas with high corrosion rates (e.g. cooling towers and splash zones)

• Areas where access is difficult (e.g., towers, some bridges).

• Built up members (e.g., lattice bars and boxes)

5.3.1.2 Situations where stripe coating may not be cost-effective include:

• Non-critical components (e.g., interior wall in living space on a ship)

• Mild exposure (e.g., SSPC environmental exposure zones 1A and 1B)5

• Inside corners (can be adequately covered using proper spray technique)

5.3.1.3 Areas that are usually stripe coated include:• Crevices• Plate and sharp edges• Plate seams• Back-to-back angle seams (built up members)• Pitted steel• Bolt heads and nuts• Rivet heads• Welds• Other sharp discontinuities• Outside corners

Figure 3. Example of Stripe Coat.

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Notches in the probe tip aid in alignment of the gauge and thin flexible shims can be used to verify the accuracy of the gauge when measuring on an edge.

4.7 Coatings to use for Striping

4.7.1 Welds and crevices are best protected when striped with a coating with good wetting properties. High build coat-ings are best for striping edges. However, it is impractical to specify two different stripe coatings on a job with edges, crevices and welds. The paint should be of a consistency to function on both surfaces.

4.7.2 The manufacturer should be consulted to determine the appropriate coating to use for the striping. If the stripe coat contains a zinc loading and is to be applied over a surface already primed with inorganic zinc, an organic zinc primer is used for the stripe coat, as inorganic zinc coatings do not bond well over themselves or over organic zinc. High solids coatings may have a relatively short dry time and may not possess good wetting properties, which is paramount to the success of the stripe coat. In this case, a compatible stripe coat with a slower drying time and improved wetting may be used with the high-solids coating. The coating selected for striping should be designed for the service environment.

4.7.3 Coatings with edge Retention Properties: An alternative method for the protection of edges that may avoid the need for grinding and chamfering is the use of a coating that has edge retention properties. Typically these types of coatings are high-solids products that provide improved film thickness retention at the apexofanedge to improve protection in these critical areas.A methodfor measuring the edgeretention properties of a coating is published in MIL-PRF-23236C.7 This test method compares the film thickness of three specimens cut from a sample of coating applied to a non-chamfered 90 degree angle. The ratio of the film thickness at the apex vs. the film thickness on the flat area is calculated and expressed as the percentage of edge retention of the coating, as shown in Figure3.According toMIL-PRF-23236C, any specimenhaving less than 50 percent edge retention fails the test. An average value of 70 percent edge retention for three test specimens measured using an optical microscope is required to qualify a coating as having edge-retention properties.

Note that very sharp edges, or “knife” edges, are very difficult to protect even with coatings with edge-retention properties. It is recommended that “knife” edges have their surface modified as described in Section 3 prior to coating to provide suitable corrosion protection.

5. disclaimer

5.1 This guide is designed to describe, review, or analyze new or improved technology and does not meet the definition of a standard as defined by SSPC. A guide differs from a stan-dard in that it is not suitable for referencing in a specification or

procurement document. SSPC guides are intended to provide consensus recommendations for best industry practice. They are not written as requirements that may be cited in a contract. However, specifiers may incorporate information fromanSSPC guide into job-specific contract requirements.

5.2 While every precaution is taken to ensure that all information furnished inSSPCguides isasaccurate, complete, and useful as possible, SSPC cannot assume responsibility nor incur any obligation resulting from the use of any materials, coatings, or methods described herein, or of the guide itself.

5.3 This guide does not attempt to address problems concerning safety associated with its use. The user of this specification, as well as the user of all products or practices described herein, is responsible for instituting appropriate health and safety practices and for ensuring compliance with all governmental regulations.

References

1. Corbett, W. D. “The Same Old Grind...An Investigation of Zinc-Rich Primer Performance Over Steel Corners.” Modern Steel Construction, Vol. 40, No. 6: p. 43-49.

2. Graco Publications, Airless Spray Techniques. Minne-apolis, MN: Graco Inc., 1993. This document is available as a downloadable .pdf file from http://www.graco.com.

3. Graco Publications, Air Spray Techniques. Minneapolis, MN: Graco Inc., 1995. This document is available as a down-loadable .pdf file from http://www.graco.com.

4. NACE Standard SP0178 (latest edition); Standard Recommended Practice: Fabrication Details, Surface Finish Requirements, and Proper Design Considerations for Tanks and Vessels to Be Lined for Immersion Service.” Houston, TX: NACE International (http://www.nace.org).

Measure paint thickness here (dft )

Measure paint thickness here (dft )

PAINT

PAINT

SUBSTRATE

�at

Measure paint thickness here (dft )�at

edge

Figure 4. diagram of edge retention test (courtesy of Mil-PRF-23236C)

The edge retention percentage is calculated as: % Retention = dft (edge)/dft (flat) x 100

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5.4 HOW TO STRIPE

5.4.1 Brushing is the preferred method of applying stripe coats. Brush application provides the highest quality stripe coat on most surfaces because it works the paint into the pores and crevices and allows the greatest control over the boundaries of the painted area. The coating should be allowed to “dry to recoat” according to the product data sheet before the full prime coat is applied unless “wet” striping is permitted. Coating manufacturers will usually provide guidance on the amount of dry time required before application of subsequent coatings. Table 1 compares application of stripe coats by brush or spray.

5.4.2 When applying a stripe coat, the brush strokes should run parallel to, not across, edges and crevices. Variations in pressure of the brush during application can result in thin film on sharp corners and accumulation of coating on adjoining perpendicular surfaces. To assure adequate film build on sharp corners, multiple brush applications may be necessary. Bolt heads and nuts should be striped in a circular brush motion. Striping should extend at least 3 cm (1 inch) from corners and other irregular surfaces. Round or oval brushes are generally considered most suitable for rivets, bolts, irregular surfaces, and rough or pitted steel.

5.4.3 SSPC-PA 1 does not permit rollers to be used to apply coatings on irregular surfaces, such as rivets, bolt heads, crevices, welds, outside corners or edges unless otherwise specified. If the project specification permits the use of rollers for stripe coat application in these areas, SSPC-PA 1 requires that the coating be brushed out to form a continuous and unbroken film over these surfaces.6

5.4.4 Stripe coats should be applied by spray only when specifically permitted by project specifications. Spraying the

stripe coat can reduce the amount of time spent in brush application, but the applicator has less control over the precise boundaries of the area being coated. Spray may be the best method for applying stripe coats using coatings with edge-retention properties or zinc-rich coatings, or for applying a stripe coat to edges that have already been painted. To minimize excess film builds on flat surfaces, outside corners should be coated by spraying directly at the corner. When feasible, the spray pressure should be minimized and the fan width should be made narrow to minimize overspray.

5.4.5 Another method that reduces the amount of time brushing the stripe coat is by spraying the material onto the area and back brushing to work the paint into the pores and crevices. In this case, spraying is only used to deliver the material to the surface more efficiently.

5.4.6 When striping with coatings that are prone to pigment settling, such as zinc-rich primers, the coating in the pot should be constantly agitated unless otherwise recommended by the coating manufacturer.

5.4.7 When striping with a multi-component thermosetting coating, the curing reaction will eventually progress to the point where the coating fails to wet the surface and level adequately. Since high temperatures often accelerate curing rates, this effect is most pronounced in hot weather. Heat of reaction (exotherm) may also be generated when multiple components of thermosetting coatings are mixed, so it may be more cost effective to use smaller kits (e.g., 1-liter or 1-gallon units) rather than 5-liter or 5-gallon units. (Note that most coating manufacturers prohibit mixing of partial kits.) Other alternatives to mixing large quantities include the use of cartridge guns that mix tubes (similar to “caulking tubes”) of the components using a static mixer. Thinning should not be used to restore the flow properties of

TABLE 1COMPARISON OF METHODS USED TO APPLY STRIPE COAT

Application

MethodAdvantages Limitations

Brush • Best method to work paint into pores and crevices.

• Most complete coverage of rivet heads, bolt heads, nuts, and threads

• Best control of extent of area coated

• The most labor-intensive method• May pull incompletely cured paint from the edge

Spray • Fastest method of application• Least labor-intensive method

• May bridge (rather than penetrate into) pores and crevices. Back-brushing is often necessary to work wet coating into pits, crevices, and angles

• More likely to skip areas in tight spaces, resulting in holidays

• Builds coating thickness on larger area (control of ex-tent of area coated is difficult)

• More risk of overspray and dry spray

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a multi-component coating that has increased viscosity from partial curing.

5.4.8 It is good practice for the color of the stripe coat to differ from the color of adjoining full coats or the bare steel surface. The color difference enables applicators and inspectors to visually verify there are no misses, skips, or thin spots in the stripe coat. In addition, the application can be verified after the fact (as necessary) for thickness and proper coverage using a nondestructive electronic coating thickness gage equipped with a microprobe, a destructive thickness gage (i.e., Tooke Gage), a holiday detector, or (on some specialty coatings) ultraviolet light.

5.5 WHEN TO STRIPE - BEFORE OR AFTER FULL COAT

5.5.1 Many coatings professionals feel that the stripe coat of the primer should be applied first to maximize corrosion protection. For example, it is easier to work stripe coats into crevices that have not been bridged by a spray-applied full coat. However, there are several reasons why the stripe coat could be applied after the first full coat.

• If the stripe coat is applied before application of a full coat of primer, there is opportunity for the surrounding clean, unprotected steel to deteriorate while the stripe coat is drying/curing.

• Application of the stripe coating over a spray-applied full coat (particularly an intermediate coat) will fill in pinholes and other holidays that may have formed in the spray-applied coat.

5.5.2 If striping is specified for each coat in a multi-coat system, application of the stripe coat before the final finish coat will result in a more uniform finish.

5.5.3 When painting a tank floor or other surface subject to foot or vehicle traffic, it may be wise to delay application of the final stripe coat over the welds to minimize erosion of

the coating by foot traffic or air hoses being dragged across the raised welds prior to the coating being put into service.

5.5.4 The advantages and limitations of striping before and after the full coat are summarized in Table 2. Final determination of the best sequence of stripe coats and full coats will depend on the coating systems being used and the specific requirements of each project.

5.5.5 If the stripe coat is applied first, it is usually allowed to dry to touch (per ASTM D1640)7 before the full coat is applied. However, there can be exceptions to this practice. The recoating instructions in the coating manufacturer’s product data sheet should be followed unless otherwise specified.

5.6 CONTROLLING THICKNESS

5.6.1 The thickness of the stripe coat is difficult to control; however, for practical purposes it should be the same thickness as a full coat. The total (cumulative) DFT of the stripe coat and full coat may be specified; however, it is unnecessary to specify the thickness of the stripe coat alone. Certain coatings may be sensitive to over-thickness and may microcrack if applied over the recommended DFT. The coating manufacturer should be consulted regarding the recommended thickness of any stripe coat. Thickness is often controlled by the skill of the applicator and use of a wet film thickness (WFT) gage. However, notch gages cannot provide reliable WFT readings on irregular surfaces and should not be used on edges. Some contractors will measure thickness to assure the minimum and maximum specified thickness limits have been satisfied, while others will make only a visual check for excessive build.

5.6.2 Leeway on maximum thickness of the stripe coat plus full coat may be allowed within 5 cm (2 inches) of an edge or 3 cm (1 inch) of a weld. Coatings may be tolerant of thickness beyond the specified upper limit.

TABLE 2 ADVANTAGES AND LIMITATIONS OF STRIPING BEFORE AND AFTER THE FULL COAT

Timing Advantages LimitationsBEFORE • Better application and protection of

irregularities• Better appearance• Holidays, light spots are more obvious• Assists painter in monitoring progress

• Rust-back of cleaned area surrounding the striped area may occur before full coat can be applied.

AFTER • Surrounding blast cleaned surface will not rust while stripe coat dries

• Can sometimes apply by spray (brush-back usually required

• Better coverage of pinholes and holidays• Can visually ensure that stripe coat has

been applied properly.

• Damage to previously coated surfaces may occur during application of stripe coat

• Higher chance of incomplete coverage of irregularities

• Aesthetics (stripe coat may be more visible)

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5.6.3 Conflicts can be avoided if thickness requirements at or near the stripe coat and any allowed deviation from specified minimum and maximum DFT thickness requirements are clearly stated in the project specification and/or discussed during the preconstruction conference.

5.6.4 Although thickness of the stripe coat can often be measured in the immediate vicinity of an edge, it is difficult to measure thickness of a coating on the edge itself. Some electronic gages include very small tips (probes) to improve the reliability of dry film thickness readings taken on an edge.8 Notches in the probe tip aid in alignment of the gauge and thin flexible shims can be used to verify the accuracy of the gauge when measuring on a corner or an edge.

6. Disclaimer

6.1 This guide is designed to describe, review, or analyze new or improved technology and does not meet the definition of a standard as defined by SSPC. A guide differs from a standard in that it is not suitable for referencing in a specification or procurement document. SSPC guides are intended to provide consensus recommendations for best industry practice. They are not written as requirements that may be cited in a contract. However, specifiers may incorporate information from an SSPC guide into job-specific contract requirements.

6.2 While every precaution is taken to ensure that all information furnished in SSPC guides is as accurate, complete, and useful as possible, SSPC cannot assume responsibility nor incur any obligation resulting from the use of any materials, coatings, or methods described herein, or of the guide itself.

6.3 This guide does not attempt to address problems concerning safety associated with its use. The user of this specification, as well as the user of all products or practices described herein, is responsible for instituting appropriate health and safety practices and for ensuring compliance with all governmental regulations.

References

1. NACE Standard SP0178 (latest edition); Standard Recommended Practice: Fabrication Details, Surface Finish Requirements, and Proper Design Considerations for Tanks and Vessels to Be Lined for Immersion Service.” Houston, TX: NACE International (http://www.nace.org).

2. Performance Standard for Protective Coatings (latest edition), Lambeth, U.K.: International Maritime Organization (http://www.imo.org)

3. NSBA S.8.1-2014/SSPC-PA Guide 13 (latest revision) Guide Specification for Application of Coating Systems With Zinc-Rich Primers to Steel Bridges. Chicago, IL: AASHTO/NSBA.

4. MIL-PRF-23236 (latest edition); Coating System for Ship Structures. Washington Navy Yard, DC: Naval Sea Systems Command. This standard is available online at http://assist.daps.dla.mil/quicksearch

5. SSPC, Using SSPC Coating Standards (latest revision). Pittsburgh, PA: SSPC.

6. SSPC-PA 1 (latest edition), Shop, Field, and Maintenance Painting of Steel. Pittsburgh, PA: SSPC

7. ASTM D1640 (latest edition), Standard Test Methods for Drying, Curing, or Film Formation of Organic Coatings. West Conshohocken, PA: ASTM International

8. SSPC-PA 2 (latest edition) Procedure for Determining Conformance to Dry Coating Thickness Requirements, Appendix 6 – Method for Measuring the Dry Film Thickness of Coatings on Edges. Pittsburgh, PA: SSPC.

Appendix A: Recommendations and sample language to assist the specification writer in addressing corrosion protection of edges, crevices, and irregular steel geometries

A1 For immersion service and other environments where increased corrosion protection is required, very rough welds (when present) should be ground because many coatings cannot adequately protect them from the electrolyte. NACE Standard SP0178 provides guidance on finish requirements for welds in immersion service and references a plastic replica that may be used as a guide to evaluating finish requirements for both lap and butt welds.

A2 Sample Specification Language (non-structure specific):

A2.1 “All outside corners and edges shall be rounded to a 2 mm (1/16 inch) radius followed by the application of a stripe coat.”

A2.2 “All outside corners and edges shall be ground using a one-pass procedure followed by the application of a stripe coat.”

A2.3 “All outside corners and edges shall be ground using a three-pass or 2R (2mm radius) procedure followed by the application of a stripe coat.”

A3 Sample Specification Language (bridges or other structures with bolted/riveted connections):

A.3.1 “All plate and sharp edges, plate seams, back-to-back angle seams, pitted steel, and other sharp discontinuities shall be hand-striped with a brush in the longitudinal direction with the primer. Bolted connections shall also have all bolt heads and nuts hand-striped using a circular brush motion with the primer material. Stripe coats may be applied before or after the full prime coat application. The prime coat material used for hand-striping shall be tinted to distinguish it from material used for full prime coat application.”

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A.3.2 “Apply stripe coats to achieve additional thickness on, or sealing of, welds, outside corners, edges, crevices, seams, bolts, nuts, rivets and rough or pitted surfaces. Stripe coating is not required for the inside surface area of steel box girders. Stripe coat with the appropriately tinted primer before the steel receives its first spray-applied full prime coat of paint. Striping shall extend a minimum of 25 mm (1 inch) beyond the edge, seam, rivets, etc. Apply stripe coat by brush. Use brush or dauber to spread stripe coat and work into crevices and uncovered areas.”

A.3.3 “When a stripe coat is required, apply a 50-mm (2-inch) stripe by brush to all exposed edges of the steel before applying the finish coat. Locate the edge in the approximate center of the paint stripe.”

A.3.4 “The stripe coat may be applied before or after the first full coat of primer is applied. Such striping shall extend a minimum of 25 mm (1 inch) from the edge. To prevent removal of the stripe coat by the following coat of paint, the stripe coat shall be allowed to dry to touch before the next paint coat is applied. However, on bare metal surfaces the stripe coat shall not be permitted to dry for a period long enough to allow rust-back of the unprimed steel.”

Copyright ©SSPC standards, guides, and technical reports are copyrighted world-wide by SSPC: The Society for Protective Coatings. Any photocopying, re-selling, or redistribution of these standards, guides, and technical reports by printed, electronic, or any other means is strictly prohibited without the express written consent of SSPC: The Society of Protective Coatings and a formal licensing agreement.

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APPENDIX B: REPRESENTATIVE CONFIGURATIONS/GEOMETRIES THAT MAY BENEFIT FROM STRIPE COATING

Riveted Connections & Crevices

Built-up Member with Crevices, Fasteners, Pitting, Corners, & Edges

Pitted Steel, Fasteners, Crevices, Corners & Edges

Edges, Corners and Crevices Welds and Outside Corners

Bolted Connections

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Crevices Corners and Edges of Weep Holes

Corners and Edges of Cut-outs