Enbridge failure - photos 2

[davefitz]

They may want to also review the SCADA data for valve position events- a sudden closure of a valve on the UG gasoline pipeline in Bellingham Washington 10 years ago led to the waterhammer pressure surge on that 100 mile long pipeline, pipe failure , multiple fatalities. That valve closure was due to the not-so-bumpless transfer that occurred when the backup DCS was switched on, causing valves to fail closed.

Of more interest is the planned 2500 mile long crude oil line planned from the tar sands to the vancouver island terminal- I can only guess at the overpressure that would occur if a valve slammed shut on that beast.

 

[davefitz]

correction:

The Enbridge Gateway project is only 1150 km ( plus 1150 km return for recycled distillate) .

 

[Duwe6]

In the photo, the left end of the split looks to be a brittle-type crack. It 'wanders' a little too much to be only a pressure-related birdmouth. Perhaps a toe-crack from the seam HAZ, possibly started from enviromental Stress Corrosion Cracking on the ID. I also agree that there probably were pressure transients that might have been up to Waterhammer force, and not properly evaluated while they were occurring. Half the mass [weight] of a cylinder of heavy crude 30" in diameter, several miles long times the flow velocity squared is an incredible ammount of energy. Very easy for it to overstress 1/4" 1960-vintage steel.