Quick Facts:
- Corrosion is the natural process that occurs when materials made from metal return to their original state through a chemical reaction known as oxidation.
- Corrosion of all types is one of the leading causes of pipeline leaks and ruptures.
- Improved technologies have led to better prevention, monitoring, detection, and mitigation of internal pipeline corrosion – even for old pipelines.
- New pipeline Integrity Management regulations will promote early identification of potentially corroded sections and their repair.
- Refer to other Fact Sheets for specific discussion of issues related to corrosion in general, external corrosion, selective seam corrosion, and stress corrosion cracking.
What is corrosion and why does it occur?
Corrosion is the deterioration of metal that results from a reaction with the environment which changes the iron contained in pipe to iron oxide (rust). For example, if your car develops a rust spot, that is corrosion of metal. The same process can occur in various forms on pipelines . As is the case with your car, there are effective methods for preventing and arresting corrosion damage to pipelines.
Internal corrosion occurs due to chemical attack on the interior surface of the steel pipe from the commodities being transported within the pipeline. In some cases, the corrosive liquids may be contaminants such as water or other chemicals entrained or suspended within the commodity being transported. Typically, either the commodity’s quality is controlled, internal coatings are applied, or corrosion inhibitors utilized to prevent internal corrosion. When one or more of these protective measures break down, internal corrosion can occur.
What are the risks from internal corrosion?
Internal corrosion can result in the gradual reduction of the wall thickness of the pipe and a resulting loss of pipe strength. It can occur relatively evenly over an area of the pipe surface (sometimes referred to as “General Corrosion”) or in isolated spots on the pipe. This loss of pipe strength could result in leakage or rupture of the pipeline due to internal pressure stresses unless the corrosion is repaired, the affected pipeline section is replaced, or the operating pressure of the pipeline is reduced.
Internal pipeline corrosion creates weaknesses at points in the pipe, which in turn makes the pipe more susceptible to third party damage, overpressure events, etc. (i.e., corrosion doesn't necessarily need to cause the leak or rupture itself to increase risk).
Pipeline failurer rates from Corrosion
While data specific to internal corrosion alone is not available, corrosion in all its various forms is one of the most prevalent causes of pipeline spills or failures. For the period 2002 through 2003, incidents attributable to corrosion have represented 25% of the incidents reported to OPS for both Natural Gas Transmission Pipelines and Hazardous Liquid Transmission Pipelines.
Over this same period, approximately 1 percent of the incidents reported to OPS for Gas Distribution Pipelines were due to corrosion.
What is being done to prevent/mitigate internal corrosion?
- Modern manufacturing processes for steel pipe and coatings are subject to rigorous fabrication and installation standards and quality control to reduce the occurrence of defects that can lead to corrosion-induced failures.
- Operators attempt to control the moisture and chemical content of the products transported through their pipelines, where possible, to reduce the occurrence of internal corrosion.
- Operators routinely run devices called “cleaning pigs” through their lines to remove accumulations of materials that can lead to internal corrosion.
- Operators introduce corrosion inhibitors into the pipeline to control internal corrosion.
- The Office of Pipeline Safety has implemented new Pipeline Integrity Management (“IM”) regulations that require all pipeline operators to inspect and assess all of their pipelines that could affect areas of high consequence such as populated areas or environmentally sensitive areas. The operators are required to inspect and assess their pipelines for integrity issues, such as corrosion, and repair or replace affected pipe.
- By implementing the requirements of the regulations and through responsible maintenance programs, pipeline operators continuously inspect their pipelines for internal corrosion damage.
Internal Corrosion: What more can be done?
- Public : Be aware of pipelines located near you. Be observant for signs of pipeline damage, leakage, or security concerns. Report any concerns you have regarding pipeline safety to the pipeline operator immediately. Always respect the pipeline right-of-way. Do not dig or build on a pipeline right-of-way without first contacting the pipeline operator or your state one-call center.
- Industry : Pipeline operators and industry stakeholders can continue to develop and implement improved corrosion detection and prevention technologies. Operators must continue to implement corrosion protection effectively and strengthen pipeline integrity management programs. Operators must mitigate the effects of corrosion when it is detected.
- Regulators : OPS and state regulators must continue to inspect pipeline operators to ensure they effectively implement required integrity management and corrosion control programs to ensure that risks to pipelines are identified and mitigated at the earliest possible time. Better coordination is needed between local permitting agencies and pipeline operators to facilitate expeditious granting of permits when public safety is potentially threatened.
Internal Corrosion: Where can I learn more?
- Public : Be aware of pipelines located near you. Be observant for signs of pipeline damage, leakage, or security concerns. Report any concerns you have regarding pipeline safety to the pipeline operator immediately. Always respect the pipeline right-of-way. Do not dig or build on a pipeline right-of-way without first contacting the pipeline operator or your state one-call center.
- Industry : Pipeline operators and industry stakeholders can continue to develop and implement improved corrosion detection and prevention technologies. Operators must continue to implement corrosion protection effectively and strengthen pipeline integrity management programs. Operators must mitigate the effects of corrosion when it is detected.
- Regulators : OPS and state regulators must continue to inspect pipeline operators to ensure they effectively implement required integrity management and corrosion control programs to ensure that risks to pipelines are identified and mitigated at the earliest possible time. Better coordination is needed between local permitting agencies and pipeline operators to facilitate expeditious granting of permits when public safety is potentially threatened.
Internal Corrosion: Where can I learn more?
Date of Revision: 041306