scope:

With origins dating back to approximately 1,000 B.C. (with the Phoenicians first using a form of pipeline to transport water), pipelines have become one of the most reliable, cost-effective, and safest modes of transporting vital commodities. Today, an elaborate network of pipelines can be found in nearly every developed country around the world, with more than 1.35 million miles (2.17 million km) of oil and gas pipelines worldwide. This vast network helps deliver more than 50% of the world's energy supply.¹ Ensuring the integrity of this infrastructure is paramount to delivering this critical energy source to its various users and the communities that depend on them.

Pipelines are recognized as being by far the safest mode of transporting natural gas and hazardous liquids, with fatalities resulting from accidents on pipelines occurring much less often than accidents caused by transportation of goods by truck or barge. Fires or explosions are 35 times more likely per barrel of oil transported by vehicle than when oil is transported by pipeline.2 However, despite being one of the safest modes of transportation, pipelines are subject to a variety of threats and accidents that can result in property damage, injury, loss of life, or environmental damage. Corrosion remains a constant threat to the integrity of pipelines, accounting for over 20% of all significant transmission incidents in the U.S.³

Corrosion attacks the steel walls of a pipeline, reducing its capacity to retain pressure. If corrosion is left unchecked, the resulting failure of the pipe wall can rapidly release oil or gas into the environment, causing fire and environmental damage. Figure 1 shows a pipeline failure caused by corrosion.

This guide presents a defined process for the management of corrosion specific to pipelines carrying natural gas and hazardous liquids. To help define

this corrosion management process and provide context for the process, this guide provides a basic overview of the following topics:

(1) A high-level overview of the corrosion threats to onshore gas and hazardous liquid transmission pipelines;

(2) Methodology and process workflow along with economic considerations to assist in the corrosion management decision-making process;

(3) Approaches to evaluate the risks posed by corrosion threats; and

(4) Key mitigation, assessment, and remediation strategies to preserve pipeline integrity and reduce the risk from corrosion threats.