Pipelines continue to be the safest method of delivering gas and petroleum products across great distances and over all manner of terrain. The hundreds of thousands of major transmission pipelines throughout the world operating virtually around-the-clock, unseen to the general public, attest to this fact.

However, pipelines as an engineered facility do fail from time to time. The consequences of a catastrophic failure most certainly costs the operator additional money through repair and possibly loss of product throughput. Damage to the surrounding environment, especially in sensitive areas, can be very expensive. Most important, public safety must be maintained.

A safe, longlasting, and profitable pipeline is every operator's goal. Consequently, maintenance measures that are both cost-effective and prevent failures or high repair costs must be considered. In Canada alone there is an excess of 250,000 km of natural gas, crude oil, and petroleum product pipelines. In the world and up to 1999 there exists 1,700,000 km of such transmission pipeline Mohitpour (2000). In all of North America, over half of the large-diameter pipeline system is more than 25 years old. With limited maintenance resources, it is essential that the available funds be spent where they are most effective in reducing the risks posed by pipeline failures to life, the environment, and financial assets.