Page 296 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

274 CORROSION CONTROL AND PREVENTION

TABLE 4.34 Corrosion Control Program Implementation Flowchart for Internal
Corrosion
Step 1 Document extent and magnitude of (a) Water quality impact
corrosion (b) Piping deterioration
(c) Environmental issues
Step 2 Determine possible causes of corrosion (a) Water quality characteristics
(b) Susceptible piping
(c) Workmanship and materials
Step 3 Develop and assess corrosion control (a) pH and alkalinity
alternatives (b) CaCO saturation
3
(c) Inhibitors
(d) Material replacement
Step 4 Evaluate alternatives and select (a) Performance
corrosion control strategy (b) Cost
(c) Side effects
Step 5 Document findings in a report (a) Formal documentation
(b) Regulatory requirements
Step 6 Implement corrosion control and (a) Design, construction
monitoring effectiveness (b) Treatment monitoring
(c) Distribution system monitoring

TABLE 4.35 Repair Methods for Water Systems with Corrosion Damage

Water System Damage Repair Method
Any system Small corrosion Evaluate structural integrity. If fit for service, then
area or general apply coating to protect metal and inspect
corrosion over according to schedule
large area
Localized corrosion Identify root cause of corrosion. Remove
materials causing corrosion. Replace damaged
material
Wall of dam or Wall thinning Evaluate structural integrity. If necessary,
storage tank reinforce wall with extra steel
Metal pipe Small leak Clap or sleeve around pipe or replace small pipe
section
Multiple leaks Replace pipe section
Large leak/rupture Replace pipe section
Internal corrosion Apply cement lining. Insert PVC tubing in pipe
External corrosion Evaluate structural integrity. If fit for service, then
apply coating to protect metal and/or apply
cathodic protection to reduce corrosion rate
Cement-based Reinforcement If localized, remove loose concrete. Reapply
pipe corrosion concrete