Gas pipeline brittle fracture propagation / Alaska gas pipeline feasibility

Decompression velocity in gas < fracture velocity → crack tip always sees full pressure → 30-mile cracks. Two responses: A710 crack-arrestor rings; raise base-plate toughness to 80 ft-lb.

In a gas pipeline, it turns out the decompression velocity of the gas is slower than the speed of brittle fracture. So the brittle fracture is always pressurized — it's running faster than the decompression velocity, so the tip of the crack is always seeing full pressure. They've had cracks in smaller pipelines, like a six-inch pipeline, run for 30 miles. You don't even store enough pipe for a 30-mile fracture, and how long would it take to replace 30 miles of pipeline?