Guidelines for preplanning for, recovering from, and repassivation after a low pH excursion in open recirculating water systems, no matter what the cause. Historical Document 1995
This standard recommended practice presents guidelines for preplanning for, recovering from, and repassivation after a low pH excursion in open recirculating water systems, no matter what the cause. The procedures presented in this standard in ro way preclude the use of other procedures but are presented as a consensus of experience gained over the years in a variety of plants. The provisions of this standard should be applied under the direction of qualified water-treatment personnel from water-treatment suppliers and/or consultants and plant personnel.
This standard was originally prepared in 1992 and subsequently revised in 1995 by Task Group T-7A-15, a component of Unit Committee T-7A on Cooling Water. The task group is composed of representatives from the refining, petrochemical, chemical, and water-treatment industries. This standard is published by NACE International under the auspices of Group Committee T-7 on Corrosion by Waters.
1.1 The discussions and procedures in this standard are applicable to low-carbon steel metallurgy. They need to be modified for systems that contain copper-based alloys, stainless steels, other metals, and other materials of construction. Low pH excursions are perhaps the most devastating of all cooling water system upsets. The inadvertent reduction in pH because of acid overfeed, process leaks, or airborne acid gases can result in a number of serious problems. Examples of these problems follow:…