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Fundamentals of Corrosion
and common contributor to underground and natural water corrosion problems in underground systems.
For production-gathering pipelines, internal blistering and cracks have
occurred where the gas has a high hydrogen sulfide (H 2 S) content.
In only a few cases has stress corrosion cracking or hydrogen stress cracking
been a problem. Stress corrosion cracking occurred on the external surface of
underground gas pipelines where there had been a mixture of nitrates, carbonates, and bicarbonates in the soil. Hydrogen stress cracking has occurred
in localized areas of extreme hardness (hard spots) induced during manufacturing of the pipe by accidental localized quenching by water spills.
11.3.5.2 Methods of Control
The main methods of corrosion control on underground pipelines include:
Complete coating of the underground piping
•
Cathodic protection
•
Insulated fittings at stragic points
•
Mitigation of stray currents via insulation of control bonds to the
•
source of the stray current
The National Association of Corrosion engineers (NACE) issued a pamphlet
entitled Recommended Practice RP-01-69, “Control of External Corrosion of
Underground or Submerged Metallic Piping Systems,” presenting the procedures and practices that are presently in use in the gas industry. Contact can
be made at 1440 South Creek, Houston, Texas 77084.
The Department of Transportation Office of Pipeline Safety has issued
minimum safety standards that contain minimum corrosion requirements
for pipeline facilities carrying natural gas. This is labeled as Subpart 1 of Part
192, Title 49, Code of Federal Regulations.
11.3.6 Pipeline industry
The more common means of corrosion control for the pipeline industry are
discussed in the following paragraphs.
11.3.6.1 Coatings
The first approach to corrosion control used in the pipeline industry
involves the use of coatings. It was recognized early on that the corrosion
process was of electrochemical origin, and it was logically reasoned that
if the pipeline metal could be electrically isolated from its environment,
there could no longer be a flow of current between separate points on the
Fundamentals of Corrosion
and common contributor to underground and natural water corrosion problems in underground systems.
For production-gathering pipelines, internal blistering and cracks have
occurred where the gas has a high hydrogen sulfide (H 2 S) content.
In only a few cases has stress corrosion cracking or hydrogen stress cracking
been a problem. Stress corrosion cracking occurred on the external surface of
underground gas pipelines where there had been a mixture of nitrates, carbonates, and bicarbonates in the soil. Hydrogen stress cracking has occurred
in localized areas of extreme hardness (hard spots) induced during manufacturing of the pipe by accidental localized quenching by water spills.
11.3.5.2 Methods of Control
The main methods of corrosion control on underground pipelines include:
Complete coating of the underground piping
•
Cathodic protection
•
Insulated fittings at stragic points
•
Mitigation of stray currents via insulation of control bonds to the
•
source of the stray current
The National Association of Corrosion engineers (NACE) issued a pamphlet
entitled Recommended Practice RP-01-69, “Control of External Corrosion of
Underground or Submerged Metallic Piping Systems,” presenting the procedures and practices that are presently in use in the gas industry. Contact can
be made at 1440 South Creek, Houston, Texas 77084.
The Department of Transportation Office of Pipeline Safety has issued
minimum safety standards that contain minimum corrosion requirements
for pipeline facilities carrying natural gas. This is labeled as Subpart 1 of Part
192, Title 49, Code of Federal Regulations.
11.3.6 Pipeline industry
The more common means of corrosion control for the pipeline industry are
discussed in the following paragraphs.
11.3.6.1 Coatings
The first approach to corrosion control used in the pipeline industry
involves the use of coatings. It was recognized early on that the corrosion
process was of electrochemical origin, and it was logically reasoned that
if the pipeline metal could be electrically isolated from its environment,
there could no longer be a flow of current between separate points on the