Experts say dilbit could have created pressure swings, hydrogen cracks in Pegasus rupture

[BlueToTheBone]

http://www.arktimes.com/arkansas/experts-say-dilbit-could-have-created-pressure-swings-hydrogen-cracks-in-pegasus-rupture/Content?oid=3037915
In the five months since ExxonMobil's Pegasus oil pipeline burst in Arkansas, two things have become clear. Flawed, 1940s-era welding techniques used when the Pegasus was built set the stage for the rupture, and an internal pipeline inspection failed to spot the problem just weeks before the spill.

The most critical question of all, however, has yet to be answered — What caused the pipe's long-dormant flaws — assumed to be J-shaped "hook cracks," in this case — to awaken and grow undetected until catastrophe struck?
snip
But there could be other factors, too, including problems associated with the type of product the Pegasus was carrying — an oil-like substance called bitumen that is mined in Canada and diluted to form diluted bitumen, or dilbit.

One theory is that dilbit made pressure swings inside the pipe larger and more frequent — and thus more harmful over time — because it's heavier and harder to push through pipe, and because its ingredients can vary more widely than conventional crude oils.

Another theory holds that an excessive amount of hydrogen accelerated or triggered the crack growth. In that scenario, the destructive hydrogen could have come from an overcharged corrosion protection system or from the sulfur-heavy dilbit being carried by the Pegasus.

Long article with good information about how the Keystone pipeline is a disaster.

[Benton D Struckcheon]

1. Very informative.

Good stuff. Makes it clear Keystone XL would be insult on top of injury.

[BlueToTheBone]

2. And the "spill" going on in Alberta

where the fracking opened up a crack and now there is no stopping the tar sand oil from contaminating the earth until it stops and it is a VERY LARGE pool of nasty oil. Yeah, the 1% hates life and everyone is going to suffer.

[petronius]

3. Of all the subject lines I've read, in all my years on DU (including a lot of time

in the Lounge), this one was the most cryptic! Didn't know if it was astronomy, veterinary science, or something in between...

Interesting and important article though - thanks for posting.

[BlueToTheBone]

4. You have to really know the story line!

I didn't know that's what they call the nasty shit from tar sands....dilbit. Makes it sound like a cartoon.