ISO 8504-3:2018 pdf download – Preparation of steel substrates beforeapplication of paints and related products -Surface preparation methods— Part 3: Hand- and power-tool cleaning.
4.4.3 Use power-wire brushing, power abrading. power impact or power-assisted rotary tools to remove loose mill scale, loose or non-adherent rust and loose paint to the specified or agreed preparation grade.
4.4.4 Use rotary impact tools to provide a surface profile.
4.5 Final preparation before painting
Remove any burrs, sharp ridges or sharp cuts that have been produced during the cleaning operation (see ISO 850 1-3).
Immediately before painting, unless otherwise specified, ensure that any remaining sound paint has no residual gloss. Ensure that the edges of any remaining intact paint have been feathered (bevelled) using one of the methods given in 4,3 or 4,4.
Dry the surface, if necessary, and remove any residual loose matter resulting from the cleaning methods by brushing, vacuum cleaning or a blast of clean. dry compressed air.
S Reference standards
Unless otherwise agreed, visual reference standards shall be used to supplement the cleaning criteria given in Clause 4. These reference standards shall be either samples or photographs provided by one of the parties or published reference standards as given in ISO 8501-1 or ISO 8501-2 (see also Introduction, last paragraph).
6 Assessment
Work performed under this standard is subiect to assessment by a representative of those responsible for establishing the requirements. Work areas shall be accessible to the assessor. The procedures and times of assessment shall be as agreed upon by those responsible for establishing the requirements and those responsible for performing the work.
Assess all cleaned surfaces in accordance with ISO 8501-I and ISO 8501-2 for conformity. In the event of non-conformity repeat the procedure (see Clause 4).
Representative photographic examples of steel substrates after hand- or power-tool cleaning are provided In ISO 8501-1.
The materials and hand tools which can be used include the following:
a)knives, scrapers, chisels and chipping hammers for removing slag, laminated rust scale, chipping
old paint, loose rust,etc.;
b) hand wire brushes, abrasive coated paper and plastic fleece with embedded abrasive for final hand
preparation including feathering edges of any firmly adhering coating system.
The use of “non-spark” tools can be necessary in areas subject to fire or explosion hazards. However,tools made from metals whose residues can lead to galvanic corrosion, for example those madefrom bronze, are not suitable in such cases.Tools having bristles consisting of plastic materials withembedded abrasive can be a suitable alternative.
B.1 Acceptable power tools are those driven by either compressed air or electricity.The tools might beattached to remote controlled or robotic equipment.
The types of tools which can be used include the following:
a) chipping hammers, rotary impact tool and rotary descalers for removal of rough scale, including
heavy laminated scale;
b]needle guns for welds,recessed work and fasteners;
c)sanding machines, sanding discs, rotary wire brushes, rotary impact tools, rotary abrasive-coated
paper wheels (flap wheels), rotary finishing brushes having filaments impregnated with abrasivegrit, and plastic fleece with embedded abrasive for removing rust, rust scale and paint;
d]power grinders to smooth welds, edges, etc., prior to general finishing;
e)rotary impact tools to provide a surface profile.
B.2 Power-tool cleaning requires care to prevent excessive roughening of the steel surface. Ridgesand burrs contribute to paint failures as sharp edges are often not covered by the specified thicknessof paint. Similarly, excessive power wire brushing or disking can also be detrimental to paint adhesion.For instance, residual mill scale can easily be burnished (polished]) to a smooth surface to which paintwill adhere poorly.The use of needle guns should be limited to welds, corners, uneven edges, etc, as theimpact of the needles can cause an unacceptable profile on flat surfaces. Grinding tools can cause “burnmarks” in the substrate that can result in surface cracks, metallurgical alteration, and causes prematurecomponent failure.”Non-spark” tools can be necessary in areas subject to fire or explosion hazards (seeAnnex A, last paragraph).