There are two common present day approaches to pipeline rehabilitation.

1. Identification and repair of Metal Loss areas. This approach maintains the ability of the pipe to do the job for which it was constructed but does not identify the basic cause (coating failure and poor CP in corrosive soil) which has resulted in the metal loss.

2. Improve the effectiveness of Cathodic Protection through the repair of the Protective Coating and upgrade of the Cathodic Protection system. This does not detect but can prevent future metal loss.

The major reason for coating rehabilitation is not today's metal loss but the desire to improve the application of CP. It is known that if a coating is kept in good condition, it is easy to apply effective CP and tomorrow�s potential for metal loss is therefore less. This knowledge drives current practice into excessive coating repair which is not cost effective. It is a fact based on the analysis of data from many pipelines, that 99% of all coating faults have no metal loss, whilst 80 to 85% of all metal loss tool indications occur at coating faults. As rehabilitation is cost driven WHY excavate and repair when, according to experience , there is no real need. The secret is to identify critical defects.

A NEW APPROACH TO PIPELINE REHABILITATION.

PIM's new approach builds on the above present day approach by directing effort only to where it will be most cost effective, the critical defects. Repair activities are concentrated at those areas that have a direct impact upon structural integrity and distribution of CP Current, utilising the analysis of numerous quality data inputs in a computer program called ECDA (External Corrosion Direct Assessment). ECDA is capable of comparing both above and below ground survey data

Part of the analysis identifies coating faults that consume large amounts of CP current which are prioritised for repair. More CP current therefore becomes available to minimise corrosion at coating faults left un-repaired particularly those at more remote locations from the CP source. Coating fault current consumption is only one of a number of selection parameters whose individual contribution to the corrosion processes can be varied and used by ECDA to identify a final list of critical defects for repair.

TOTAL PLAN OF ACTION TO MAINTAIN STRUCTURAL INTEGRITY OF A PIPELINE SYSTEM.
� Prioritise Pipelines on basis of Integrity and Commercial Importance.
� Status of current knowledge, historical records and methods through Technical Audit.
� Plan of Action to:
1) Gather and Analyse further Survey Data.
2) Produce Scope Of Work and Projected Costs.
3) Materials/Repair Method Selection.
4) Quality Control Methods and Interpretation.
5) Contractual Documents, Bid Preparation.
6) Contractor Auditing and Selection.
7) Bid Evaluation.
8) Project Initiation.
9) Project Technical and Cost Control. � 5,10,20 Year Plans for Monitoring and Maintenance.