Valves at Water Crossings for Outflow Control - Questions and Answers

Safety Forum 2015

Has C-FER done a sensitivity analysis on whether additional valves or investment in reducing time to detection provides the greater risk reduction?

Mark Stephens: As mentioned in my presentation, additional valves have the greatest potential to reduce release volumes from ruptures whereas reduced detection times generally have the greatest potential to reduce release volumes from small leaks. Managing the risk associated with both types of failures is important. However, no comparative assessment has yet been done to determine which of the two provides the greater reduction in overall risk. When we have a better handle on achievable leak detection times, this exercise would be worthwhile.

Kori Patrick: Enbridge has done some sensitivity analysis on this. On our largest line the volume out over a ten minute interval is approximately 7700 barrels. Pipelines vary by different diameters and pump rates. Typically the pump rate is not the dominant component of the total worst case volume, when considering a short detection time (10 mins).

How often do ground patrols walk sections of the line themselves? It seems preferable to have staff discover a lead before a landowner (for public awareness as well as risk management).

Kori Patrick: There is no formal guidance on foot patrolling the line. Foot patrols happen during regular maintenance, which may include all types of work on the right of way. Aerial patrols are conducted every two weeks at a minimum. Yes it is preferable for operators to find any issues before a landowner.

Does the leak detection system work on shut-in pipelines? If it doesn't, what internal based method is used to detect leak in a shut-in pipeline?

Mark Stephens: Some of the new external leak detection technologies being evaluated, specifically those that respond to direct contact with oil or contact with the vapour off-gasing from spilled oil, will work for shut in lines.

Kori Patrick: Generally no, our leak detection system is based on mass balance systems which require inputs on volumes, pressures and temperature changes. These measurements are all static during a shut-in. If a shut in is related to a potential event, then field staff are dispatched to investigate the area of interest.

It is important to understand that while the emerging external leak detection technologies have been through multiple rounds of testing, the technology has not been operationalized.

Mark Stephens: It is fair to say that the long term operational capabilities of many of the new external leak detection technologies have not been demonstrated.

Kori Patrick: There are unconfirmed reports that fiber optic cable was installed on the new line that just ruptured in Northern Alberta. Some technologies are being used, but their long term benefits have not yet been proven in an operational environment.

How significant an effort is it to restart an oil line after a shutdown? Is there R&D in this area to minimize the deterrent to shutdown when in any doubt?

Kori Patrick: There are specific procedures to startup and shutdown a liquid pipeline. Column separation, pressure cycling, changes in instrumentation readings all occur during shutdowns or even changes in batches between heavies and light products. It is definitely the preference of operators to limit the amount of pipeline cycling.

Does TCPL employ the same controller rules for its mainline gas transmission system? i.e. Controllers have full authority to shut down the mainline?

Rob Sillner: Yes they do.

Is there a minimum/maximum setback that valve locations must have from watercourses?

Kori Patrick: No minimum or maximum setback exists. Consideration for flood zones and meeting requirements for access, power and communications are reviewed by engineering teams.

Is C-FER developing a similar approach to determining product loss and valve spacing for gas transmission lines, given the different parameters associated with pressurized gas systems?

Mark Stephens: Valve spacing and valve closure times for high pressure gas transmission pipelines have public safety implications and studies have been carried out in the past by others that have looked at this issue. Following the gas pipeline rupture and fire in San Bruno, California in 2010, this issue has garnered renewed interest and attention. However, C-FER is not currently involved in a formal review.

Does the NEB Board acknowledge and use the Guidance for Pipeline Flow Reversals, Product Changes, and Conversion to Service, put forward by the US DOT PHMSA?

NEB: The NEB is aware of and has examined the Guidance published by PHMSA almost a year ago. The NEB’s Onshore Pipeline Regulations and the CSA standard CSA Z662 Oil and Gas Pipeline Systems form the framework for the regulation of NEB-regulated pipeline facilities. These regulations make mandatory most of the elements provided in the PHMSA guidelines.

Is hydrostatic testing a requirement by the NEB as included in the Guidance for Pipeline Flow Reversals, Product Changes, and Conversion to Service per US DOT PHMSA?

NEB: Many factors influence whether a pipeline should be hydro tested prior to a flow reversal, product change or conversion to service, including the prior integrity history of the pipeline. The NEB considers each such application on its own merits. It is worth noting that the majority of large pipelines in Canada have been inspected internally by sophisticated inline inspection tools, which provides a significant amount of information regarding the operational integrity of the pipeline.

TCPL's Rob Sillner indicated that a communication to TCPL of a petroleum product leak in proximity to a TCPL line is analyzed, identified, verified or at 10 minutes from the communication the line is shutdown. What is the NEB requirement in the event of a liquid petroleum product leak at water course crossings at energy pipeline corridors?

NEB: The NEB requires immediate notification of an incident involving any volume of a liquid petroleum release to a water course. The “10 minute shutdown rule” has become an industry standard. There are no regulations regarding how quickly a pipeline must be shut down in the event of an operational anomaly. However, the NEB requires companies to have an emergency management program that anticipates, prevents, manages and mitigates conditions during an emergency to minimize the potential for adverse effects on property, the environment or the safety of the public.

 

Date modified: