BS EN 13507:2010 pdf free download Thermal spraying — Pre-treatment of surfaces of metallic parts and components for thermal spraying
This European Standard specifies the processing of surface preparation for thermal spraying. Importantprinciples indicated in this European Standard should be taken into consideration when surfaces of metallicparts are to be prepared for thermal spraying.This European Standard applies for production of new parts aswell as for the repair of worn parts.
This European Standard does not apply for thermal spraying in the case of protection against atmosphericcorrosion by coatings of zinc and/or aluminium and their alloys, for which EN ISO 2063 applies.
2Normative references
The following referenced documents are indispensable for the application of this document. For datedreferences,only the edition cited applies. For undated references,the latest edition of the referenceddocument (including any amendments) applies.
EN ISO 8501-1,Preparation of steel substrates before application of paints and related products — Visualassessment of surface cleanliness— Part 1: Rust grades and preparation grades of uncoated steelsubstrates and of steel substrates after overall removal of previous coatings (ISo 8501-1:2007)
EN ISO 11124-1,Preparation of steel substrates before application of paints and related products —Specifications for metallic blast-cleaning abrasives — Part 1: General introduction and classification(iso 11124-1:1993)
EN ISO11124-2,Preparation of steel substrates before application of paints and related products —Specifications for metallic blast-cleaning abrasives — Part 2: Chilled-iron grit (ISO 11124-2:1993)
EN ISO11126-1,Preparation of steel substrates before application of paints and related products —Specifications for non-metallic blast-cleaning abrasives — Part 1: General introduction and classification(iso 11126-1:1993, including Technical Corrigenda 1:1997 and 2:1997)
Principles
The surface preparation of a work piece has a substantial effect on the quality of the sprayed coatingespecially with regard to its adhesion to the substrate.
To achieve a sufficient adhesive strength the metallic surface shall be processed until a technically cleaninterface is generated.
The surface to be prepared shall be accessible for grit blasting.EN 15520 gives information regarding suitablecomponent design.
Welding splashes and residues of welding slag shall be removed, and weld seams and brazed or solderedjoints shall be prepared with particular accuracy.Oxides,oil, grease and other contamination shall beremoved.
The roughness of the surface shall enable a good interlocking of the sprayed coating to the substrate.Gritblasting is a suitable method for obtaining appropriate roughened metallic surfaces, thereby also enlarging theeffective area.
The surface to be sprayed shall be kept dry during the preparation and spraying process.For outdoorspraying this requirement shall be met by taking suitable precautions.The prepared surface shall be coatedsubsequently after carrying out the grit blasting without any undue loss of time 1)’.
4Methods of surface preparation
4.1General
Depending upon the function of the sprayed coating and the initial condition of the surface,differentpreparation procedures are used. In any case scale,rust, dust and other contaminants shall be removed bymechanical cleaning.
4.2Degreasing
Oil and grease contaminants shall be removed thoroughly prior to processing the surface. In particularattention shall be given to bores, slots and channels. Design of components shall be such that fluids can drainout.
Degreasing can be done by heating, dipping and spraying processes with or without additional mechanicalsupport by ultrasonic cleaning, brushing or steam jet blower. Aqueous wash solutions or organic solvents aresuitable. For the application of wash solutions a mild alkaline cleaner with a high content of surfactants maybe preferred.Whenever possible cleaner free of phosphate should be used.The application of chlorinated orfluorinated hydrocarbons should be avoided due to their detrimental effect on health and the environment.Subsequent rinsing and drying is necessary.
For health, safety and environment aspects see 4.7.
4.3Grit blasting
4.3.1Cleanliness
For thermal spraying the surface shall be sufficiently cleaned and roughened by applying a suitable grit.Thegrit blasting process shall be continued until the area to be coated shows a metallic surface with a uniformstructure according to EN ISO 8501-1 Sa 3.
Unwanted loss of material, which can occur by excessive blasting, shall be considered.
Generally, the preparation grade Sa 3 is necessary but often not sufficient for the purpose. If necessary, therequired condition of cleanliness and roughness shall be agreed between the contracting parties.
The preparation by grit blasting will vary depending on the type and size of the abrasive, blasting parameters,e.g. blasting time,distance,angle,particle velocity and machine type. Furthermore,the wear rate of theabrasives substantially effects the properties of a grit blasted surface.Therefore, the operating parameters forgrit blasting shall be adequate to meet the required roughness criteria and, if necessary, have to be optimisedby grit blasting of test pieces of similar material.
For health, safety and environment aspects see 4.7.