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ASTM F1428

ASTM Protective Coatings

ASTM 153/A153M (HDG)
ASTM B766M (Cd+)
ASTM B695 (Mech Zn)
ASTM B840 (ZnCo+)
ASTM B841 (ZnNi+)
ASTM B994 (CoNi+)
ASTM F1136/F1136M (ZnAi+)
ASTM F1137 (Phosphate)
ASTM F1428 (AL+)
ASTM F1941/F1941M
ASTM F2329/F2329M
ASTM F2833
ASTM F3019/3019M

ISO PROTECTIVE COATINGS

ISO 4042
ISO 10683
ISO 15726
ISO 17668

ASTM F1428 Organic Aluminium Particle Filled Basecoat with Organic/inorganic TopCoat Coating for Fasteners

Stud Bolts, Nuts, Screws, Threaded Rod & Washers

ASTM F1428 specification covers the basic requirements for a corrosion-resistant coating consisting of an inorganic aluminum particle-filled basecoat and an organic or inorganic topcoat, depending on the specific requirements.
The coating may be specified with basecoat only, or with the top coated with compatible organic polymer or inorganic topcoats, depending on the specific requirements. The basecoat is a water-dilutable slurry containing aluminum particles dispersed in a liquid binder of chromate/phosphate compounds. The organic topcoats consist of polymer resins and dispersed pigments and are for service where temperatures do not exceed 230°C (450°F). The inorganic topcoats consist of ceramic oxide pigments dispersed in a liquid binder of chromate/phosphate compounds and are for service where temperatures do not exceed 645°C (1200°F). These coatings are applied by conventional dip/spin, dip/drain, or spray methods. The coating process does not normally induce hydrogen embrittlement, provided that the parts to be coated have not been subjected to an acid cleaner or pretreatment

Grade No.Coats of BasecoatCoats of TopcoatsAverage Thickness, μmSalt Spray Life Hours
ASTM F1428 Grade 1AA1110-15168
ASTM F1428 Grade 2A2115-25240
ASTM F1428 Grade 3A2220-30720
ASTM F1428 Grade 4A2220-301000
ASTM F1428 Grade 1BB1110-15168
ASTM F1428 Grade 2B2115-25240
ASTM F1428 Grade 3B2220-30500
ASTM F1428 Grade 4B2220-301000
ASTM F1428 Grade 1CC20 010-20168
ASTM F1428 Grade 2C2010-20400
  • ASTM F1428 Grades with Suffix A are organic topcoated for a maximum service temperature of 230°C (450°F).
  • ASTM F1428 Grades with Suffix B are inorganic topcoated for a maximum service temperature of 645°C (1200°F).
  • ASTM F1428 Grades with Suffix C are basecoated only for a maximum service temperature of 645°C (1200°F).
  • Regardless of the processes or materials used, the inorganic and organic coatings shall conform to all of the applicable requirements of ASTM F1428 specification.
  • 1) ASTM F1428 Grades 4A, 4B, and 2C require basecoat burnishing.
  • 2) The torque tension relationship of coated fasteners may be different from those of uncoated fasteners. A wax lubricant may be specified to improve the torque-tension characteristics of coated fasteners.
  • 3) When spray application methods are employed, the thickness requirements of the two individual coats may be achieved in one single spray application.

ASTM F1428 Requirements

Appearance
The coatings shall have a smooth, uniform appearance and shall be free of lacerations and other discontinuities that may affect the appearance or performance of the coatings. All topcoat colors shall be agreed upon by both the purchaser and the supplier.
Adhesion
The coating shall show no evidence of blistering or other appearance changes after exposure to humidity testing for 96 h, it shall show no more than 3.0-mm peel-back from the intersection of scribed lines that are tape-tested immediately after a 10-min recovery period from the humidity test, and there shall be no other peeling under the tape.
Corrosion
These coatings shall be capable of withstanding neutral salt spray testing for the minimum time specified in Table above. Unless otherwise defined, acceptable corrosion resistance shall be considered to be met where there is no base metal corrosion on signifiant surfaces.
Significant surfaces on threaded fasteners are defined as the surfaces exposed when the fasteners are installed in a normal manner (bolt head, nut drive, face, and so forth). On other surfaces on which coating control cannot be obtained under normal processing, such as holes, recesses, threads, and so forth, the above requirements do not apply.
Thread-Fit
The coating shall not have an adverse effect on normal installation and removal practices, as determined by the proper “GO” thread gage or the fit and function inspection method .
Sizing
The thickness of the coating is limited by the basic thread size. Where greater thickness is necessary, threads may be produced undersize or oversize (before coating) to accommodate the coating thickness, providing that the finished fastener (after coating) meets all specified mechanical properties, as agreed upon by the supplier and the purchaser.
Weathering
The coatings shall show no blistering, peeling, cracking, loss of adhesion, discoloration, or red rust on significant surfaces after exposure to the weathering test for at least as many hours as specified for salt spray resistance for the various codes.

ASTM F1428 Application

  • Any conventional cleaning procedure that does not induce hydrogen embrittlement or intergranular attack of the basis metal can be used, followed by grit blasting or micro-zinc phosphating . If not properly controlled, zinc phosphate coatings and certain acid descaling processes may produce hydrogen embrittlement or severe etching of the basis metal.
  • The coatings are applied by conventional dip/spin, dip/drain, or spray methods.
  • The coatings shall be applied under suitable control conditions and in the stages necessary to meet the requirements of the specification. Unless otherwise specified, these coatings shall be applied after all machining, forming, and heat treatments have been completed, but prior to final inspection.
  • The contractor (applicator) shall maintain control over factors that affect the quality of the treatment, including, but not limited to, dip/spin parameters, coating viscosities, and temperature. Chemical analyses, coating replenishment, visual inspection, and other process control devices shall be conducted with the frequency required to maintain good quality of the treatment and to meet the requirements of ASTM F1428 specification. Visual inspection is intended to include appearance factors such as (1) streaking, (2) dulling, (3) uncoated areas, and (4) loss of color where color is specified.

ASTM F1428 Test Methods

Corrosion
Corrosion resistance shall be tested in accordance with Practice B117.
Coating Thickness
Coating thickness shall be tested in accordance with Test Methods D1186, magnetic-permeability; Practice E376, eddy-current; or Test Method B568, X-ray spectrometry. For referee purposes, micro-examination in accordance with Test Method B487 shall be used.
Humidity Test
The humidity test shall be conducted in accordance with Practice D2247.
Adhesion
After exposure to the humidity test, adhesion shall be tested in accordance with Test Methods D3359.