UFC 3-240-13FN
25 May 2005
CHAPTER 9
CHEMICAL CLEANING OF WATER SYSTEMS
9-1
GENERAL GUIDANCE. Chemical cleaning of water systems can be
divided into two classifications: pre-operational and remedial. Pre-operational cleaning
is performed to prepare the water-contacted metal surfaces to receive chemical
treatment, which provides protection from scale, corrosion, and microbiological growth.
Remedial cleaning is performed to restore water systems that have been fouled with
scale, corrosion products, and microbiological growth due to inadequate or ineffective
water treatment. Cleaning, particularly remedial cleaning, is often performed by outside
contractors familiar with cleaning procedures, techniques, and safety. It should be noted
that if the water system is significantly scaled, the chemical treatment program was
obviously inadequate and was not properly designed, set-up, controlled, or applied.
After cleaning has been completed, the chemical treatment program and QC program
must be improved so the same problem does not recur. Use of a well-designed QA
program would have produced identification and notification of potential and developing
problems before they became serious. Pre-operational cleaning is often performed by
contractors responsible for the fabrication of the water system before turning it over to
the military installation. Water system operations personnel must assess the
effectiveness of any cleaning process that has been performed.
9-1.1
Pre-Operational Cleaning. Pre-operational cleaning can be performed on
all new systems or pieces of equipment installed in any existing system, including new
boiler tubes or new chiller copper tube bundles. New piping and coils will usually be
contaminated with materials such as mill scale, rust, oil, and grease resulting from the
fabrication, storage, and installation of the equipment. Pre-operational cleaning is
performed to remove these materials and prepare metal surfaces to receive corrosion
protection from chemical treatment. Pre-operational cleaning agents that are used
include detergents, wetting agents, rust removers, and dispersants. These cleaning
agents have a pH in the range of 9 to 11. Water systems containing piping or
components constructed of galvanized steel and aluminum should not be subjected to
procedures that require high pH (greater than 8.5) because this would contribute to
initiating corrosion of these surfaces.
The requirement for performing a pre-operational cleaning process is usually
written into the specification for new construction of a water system that must be
performed by a mechanical contractor. The mechanical contractor is required to perform
the work as directed in the specifications; however, if the specifications are not
appropriate for the specific system, including consideration of all system metallurgy, the
cleaning process may contribute to corrosion to mild steel, galvanized steel, copper, or
aluminum, or it may result in incomplete cleaning of dirty and corroded metal surfaces.
The specifications should be reviewed by a qualified base inspector or qualified
independent consultant to ensure that cleaning agents and procedures have been
specified appropriately. A contracting officer or other individual responsible for QA
should inspect the equipment after cleaning and document the effectiveness of the
cleaning process.
184
Previous Page
