IMO’s PSPC regulation adopted recently for ship’s water ballast tank specified the allowable NaCl limit to be 50 mg/m2 or less for primary and secondary surface preparation which shall be obtained by conductivity measurement in accordance with ISO 8502-6 & ISO 8502-9. However, the specified method provides the level of Total Soluble Salt (TSS) which is quite different from the amount of NaCl or chloride ion. Still, it has been specified to measure amount of NaCl on steel surface in IMO’s PSPC, which might be a source of dispute in world wide implementation of the PSPC for new shipbuilding.