ISO 19840-2012 pdf download.Paints and varnishes – Corrosion protection of steel structures by protective paint systems一Measurement of, and acceptance criteria for, the thickness of dry films on rough surfaces.
ISO 19840 specifies a procedure for the verification of dry-film thickness against nominal dry- film thickness on rough surfaces, including the adjustment of the instruments used, the definition of inspection areas, sampling plans. measurement methods and acceptance/rejection criteria.
For the purposes of this standard, any specified thickness is taken to be nominal as defined in ISO 12944-5, and the dry-film thickness is the typical thickness above the peaks of the surface profile.
The procedure described in this International Standard is based on the use of instruments of the permanent magnet, electromagnet and eddy current type. Instrument accuracy is verified both at zero and at a known thickness on a smooth surface and adjusted if necessary.
Measurements taken on a coating on a roughened steel substrate will therefore be higher than the actual value above the peaks of the profile. The thickness of the dry film above the peaks of the profile is defined as the instrument reading minus an appropriate correction value.
The dry-film thickness is obtained by using the appropriate correction value applied to readings based on adjustment on a smooth, flat steel surface.
Where individual readings, based on adjustment on a smooth, flat steel surface without the use of correction values, are specified or agreed, it is important to recognize that this method does not conform with this International Standard.
This standard is applicable if the nominal dry-film thickness is 40 pm or greater.
NOTE If the nominal thickness Is less than the surface roughness of the substrate, the uncertainty of the measurement
will increase.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2808, Paints arid varnishes — Determination of film thickness
ISO 8503-1. Preparation of steel substrates before application of paints and related products — Surface roughness characteristics of blast-cleaned steel substrates — Part 1: Specifications and definitions for ISO surface profile comparators for the assessment of abrasive blast-cleaned surfaces
ISO 12944-1, Paints and varnishes — Corrosion protection 01 steel structures by protective paint systems — Part 1: General introduction
ISO 12944-2, Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 2: Classification of environments
ISO 12944-3, Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 3: Design considerations
ISO 12944-4, Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 4: Types of surface and surface preparation.ISO 19840 pdf download.