Cathodic protection vs pipe line casings

Journal Article · Fri Jul 01 04:00:00 EDT 1977 · Pipe Line Ind.; (United States)

OSTI ID:7303299

Orton, M D

Pipeline tests were conducted using wrapped pipes and both bare and coated casing to determine the effectiveness of cathodic protection. It was found that pipelines inside of casings when the annulus is completely filled with water can be adequately cathodically protected if the casing is effectively insulated from the pipe line. One problem is that casing end seals often leak to let water enter the casing annulus; they can also leak to let water out and complete protection cannot be assured. Pipe lines cannot be cathodically protected inside of casings from an external current source if the casing is shorted to the line even when the casing annulus is full of water. Galvanic anode material installed in the annulus would have limited life due to the large bare area of the internal surface of the casing. Galvanic anode material installed inside of the casing or an external protective current source would be completely ineffective for protecting the pipe line if the casing annulus was empty. Condensation and even bacterial growth could create an atmospheric corrosion problem that may require a better quality coating on the pipe line inside the casing. From a safety/corrosion control standpoint, pipe lines should be installed without casing wherever possible. Where casings are utilized, they can ultimately become shorted to the line due to settling or traffic vibration and effective, positive corrosion control cannot be assured. (JRD)

• Research Organization: Pacific Gas and Electric Co., San Francisco
• OSTI ID: 7303299
• Journal Information: Pipe Line Ind.; (United States), Journal Name: Pipe Line Ind.; (United States) Vol. 47:1; ISSN PLINA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
022000 -- Petroleum-- Transport
Handling
& Storage
03 NATURAL GAS
032000* -- Natural Gas-- Transport
Handling
& Storage
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
CATHODIC PROTECTION
CHEMICAL REACTIONS
CORROSION
CORROSION PROTECTION
COVERINGS
ELECTROCHEMICAL CORROSION
NATURAL GAS DISTRIBUTION SYSTEMS
PIPELINES
TESTING