Full Description

The scope of this standard practice is that of pH depression detection, correction, and restoration to safe operating conditions that ensure future avoidance of excessive corrosion and fouling rates as well as process throughput capacity derating. A discussion of the importance of preplanning, the elements that comprise it, in the form of a check list and populated tables containing the types of chemicals, their federate and inventory required that are site specific for the cooling system volume and maximum blowdown rates are provided. Auditing and identifying high-risk unit processes that could be a source of low pH ingressors to be completed. Sampling and monitoring the outlets of the high-risk areas with the appropriate on-line sensors or grab sample test apparatus with sufficient reagent inventories are also noted. Knowledge of the site environmental discharge limits and the management of the cooling system discharge during the recovery are addressed. The contingency processes to restore the pH, recover from excursion and completion of repassivation are based upon four degrees of severity associated with excursions. The individual contingencies are defined in the text and illustrated in Figure 1.