ISO 17752-2012 pdf free download

ISO 17752-2012 pdf free download.Corrosion of metals and alloys — Procedures to determine and estimate runoff rates of metals from materials as a result of atmospheric corrosion
Corrosion des métaux et alliages Modes opératoires pour determiner et évaluer le faux dentraInement par les eaux de ruissellemerit des métaux presents dans des maté riaux soumis a Ia corrosion atmosphérique.
The runoff water in the collection vessel shall be collected continuously. The vessels shall be changed before being completely filled to ensure no loss of released metals and enable determinations of actual amounts of precipitation impinging on the specimens, amounts influenced by prevailing exposure conditions and wind directions, If the collection vessel is overfilled, an estimate of the impinging rainfall volume shall be made. This can be based on meteorological measurements of rainfall units during the specific sampling period, or estimated based on similar previous sampling periods. The time period for changing collection vessels depends on the amount of precipitation, prevailing precipitation conditions and the volume of the vessels used. Depending on rain characteristics, a volume of (2 to 5) L is recommended. If evaporation of collected runoff water takes place, runoff water collection should be performed more frequently to minimize this effect (e.g. by coverage of the collection container with aluminium foil). Metal runoff measurements from specimens releasing low (pgIL) concentrations of metals, typically coated specimens, shall be conducted using acid-cleaned collection vessels to avoid any metal contamination through soaking in pure 10 % HNO3 for at least 24 h, followed by rinsing at least four times with ultra-pure water, and then dried in ambient laboratory air before use.
Runoff water shall be collected from an inert identical specimen holder exposed in parallel at identical exposure conditions and collection-time periods to determine background metal concentrations. Measured concentrations should be subtracted from the runoff data generated from the specimens,
After collection, the collected runoff solutions shall be transported to the laboratory for determination of the total runoff water volume and pH (at ambient laboratory temperature) and analysis of the total metal content. Before analysis. the runoff solution shall be acidified to a pH less than 3 by using, for example, HNO3 or HCI. Acidification is performed to dissolve possible metal complexes formed on the walls of the collection container and conserve the runoff water. After acidification, the runoff solutions can be stored for up to one month (or longer) before analysis (preferably in dark conditions),
7.3 Evaluation of results
Depending on the metal(s) to be anaiysed, determination of metal concentrations exceeding 1 mgiL is normally performed by means of flame atomic absorption spectroscopy (FAAS). Analysis of metal concentrations in the range of pg/L and upwards, can be accomplished by means of graphite furnace atomic absorption spectroscopy or inductively coupled plasma/atomic emission spectroscopy.
By adding the measured released metal content from each sampling period (metal concentration multiplied by the collected runoff water volume) after subtracting the background content measured for each sampling period, the total amount of released metal can be calculated and expressed In g/(m2a). An alternative unit for expressing runoff rate is im/a. The former is more appropriate when presenting actual metal runoff rate data. the latter possibly when comparing data with corrosion rates.
The runoff rate is based on the total volume of precipitation impinging the surfaces, expressed either as Urn2 (based on the exposed area of the specimen inclined 45’ from the horizontal, largely influenced by the prevailing wind direction) or as mm precipitation (U of rain per m2 of horizontal area), impinging on the surface during the total exposure period. The meteorological unit ‘mm precipitation is mainly used for metal runoff predictions and comparison between runoff data for different sites and surface inclinations and orientations.ISO 17752-2012 pdf free download.