CIS Case History NACE Eastern Area Conference Jeffrey L. Didas Colonial Pipeline Company 2607 Willard Road Richmond, VA 23294-3639 804-672-2718

INTRODUCTION Close - Interval Potential Surveys (CIS or CIPS) are performed for many reasons. The primary purpose of a CIS is to ensure that a pipeline is cathodically protected in its entirety. CIS is also used as a method to verify pipeline integrity, evaluate coating condition and follow up on areas after pipeline rehabilitation.

CIS GENERAL DISCUSSION Close - Interval Potential Surveys have been utilized for decades. In the early years it involved hand reels or multiple hand reels of wire stretched out between test points and bulky analog meters which remained stationary at the test points, with a moving reference electrode(s) traveling along and over the pipeline.

CIS GENERAL DISCUSSION Today’s data loggers and wire dispensers provide a light – weight, accurate and fairly simple method of recording, analyzing and displaying CIS data.

CIS GENERAL DISCUSSION Motorized or power reels with several miles of survey wire supplemented the hand reels and improved the process, which still used a stationary analog meter and moving the electrodes. During the 1970’s digital meters, data logging hardware, small diameter survey wire and wire dispensers evolved into an over the line surveyor having all the survey equipment with the surveyor.

CIS GENERAL DISCUSSION Today’s data loggers and wire dispensers provide a light – weight, accurate and fairly simple method of recording, analyzing and displaying CIS data. With today’s computer technology and what is known about the technology, the survey interval has become fairly standard at 1 m (2.5 feet).

CIS ISSUES GENERAL DISCUSSION CIS specification – one is required whether for internal or external use. CIS contractor or in house personnel – proper training, experience and OQ’s are required. CIS data quality and availability – data must be per the specification, be usable and repeatable and available in a timely manner upon completion of the CIS.

CIS ISSUES - GENERAL DISCUSSION Pipeline operators have implemented Integrity Management Plans – (IMP’s) which gives them a long term plan to use for evaluating the pipelines integrity and implementing a rehabilitation plan These evaluations use a combination of internal inspections using ILI, external inspections using CIS and DCVG, then wrapping all these programs together using External Corrosion Direct Assessment (ECDA), Internal Corrosion Direct Assessment (ICDA) and Stress Corrosion Direct Assessment (SCCDA).

CIS ISSUES and ANSWERS - GENERAL DISCUSSION When ILI is not practical for the IMP, CIS becomes extremely valuable as the primary component for performing the evaluations. The CIS will determine the areas not meeting a cathodic protection (CP) criterion. The areas not meeting these criteria will be further evaluated using an above ground coating evaluation survey and normally a depolarized potential survey.

CIS – GPS Survey In Progress Typical Cross Country Pipeline ROW

CIS – GPS Survey In Progress Where’s the pipe? They appear to be lost in the field.

CIS Technical Issues Locating Pipeline Interrupter Accuracy and Quality Interruption Cycle Reference Electrode Calibration Crew Quality ROW Conditions Level of CP and Coating Quality

Typical CIS Data Plot

Data Issues Repeatability of Data Ability to locate Deficiencies – GPS Accuracy Data integration into database

CIS DATA ANALYSIS The results of the coating evaluation testing will drive the rehabilitation program and allow selection of the rehabilitation method Which method or combination of methods is determined by the corrosion engineer analyzing all the data, performing current require testing, performing coating conductance and / or quality surveys, running design calculations for CP systems and determining the most cost effective methods.

CIS Case History 32” Products Pipeline Installed 1961 Asphalt Enamel Coating Recently had a CP Upgrade Performed ILI has had Multiple Runs – no corrosion issues ON/OFF survey with GPS and depth of cover survey was run Areas not meeting -850 ON were addressed

Results 30 anomaly locations were selected for recoat 45 anomaly locations were selected for new CP or upgrading existing CP 100% compliance was achieved after rehabilitation was completed and follow up survey run

Location Selected for Recoating

Area Being Excavated

Problem Area Identified and Coating Being Removed

Entire Area That was Examined

Area Kept Growing

Some Coating was Actually Sticking to the Pipe

Found a Problem at the Area of Investigation

Problem Remediated

Abrasive Blasting in Progress

Recoating in Progress

Coating Inspection

Coating Inspection

Recoating Complete

Follow Up Survey in Progress

Summary and Conclusions Close Interval Potential Survey is a proven tool to use to evaluate pipelines to ensure it is cathodically protected or to locate areas that are not protected. Using CIS to determine areas of your pipeline that require coating rehabilitation does work and works very well.

Summary and Conclusions CIS data alone should not be used in locating areas that require coating rehabilitation, but a combination of CIS data, ILI data (when available), above ground coating surveys and competent corrosion engineering analysis of the entire rehabilitation project is required.