Session: 07-04-01 Integrity Threats

Paper Number: 133920

133920 - Risk Assessment of the Transmission Pipeline Appurtenance Threat 

Abstract: 

The Enbridge liquids pipeline system contains more than 28,000 KM of transmission pipe. Systemwide assessments are conducted to evaluate the risks associated with integrity threats, whereby historically the focus has been on crack, corrosion, dents, and geohazards.  However, there are other threats, such as appurtenances, which also exhibit environmental risk.  

Prior assessments used average historical failure rates which enabled high-level risk quantification; however, this approach was overly simplistic and did not differentiate between different locations of the same asset class. In 2021-2022, four appurtenance models (valves, sleeves, flanges, and offtakes) were developed to enable comprehensive systemwide risk management.  During model development, there was an objective to limit the model inputs to only those that are readily available from drawings and in-line inspection data.  Correspondingly the model inputs included only: asset information (i.e. vintage, construction), site specific attributes (i.e. proximity to other appurtenances), and operational considerations (i.e. proximity to pump stations, pressure cycling, product types).

The steps conducted to enable risk assessment of the appurtenance threat included:

·       Literature review of historical failures and failure modes based on operator specific databases and publicly available literature to identify key factors that lead to failures.

·       Application of model factors based on appurtenance characteristics and subject matter expert input.

·       Calibration of models based on comparisons between systemwide predicted failure rate values to historical failure rates.

·       Application of failure rate adjustment factors based on volumes exceedance.

·       Application of location specific asset failure rates and consequence to quantify appurtenance risk and enable suitable risk mitigations.

It was demonstrated that the models captured the key characteristics that impact possible failure modes for pipeline appurtenances. 

This paper describes how the risk associated with the pipeline appurtenance threat may be assessed and includes a description of each of the four appurtenance (flanges, valves, sleeves, and branched connections) reliability models that were developed by Enbridge. 

Presenting Author: Samir Fazli Enbridge

Presenting Author Biography: To be updated at a later point.

Authors:

Samir Fazli Enbridge
Millan Sen Enbridge
Saheed Akonko Enbridge