The pipes are 4 inches of steel wrapped in 6 inches of concrete. It's hard to see that being something that would rupture easily by accident. Especially 4 at a time.
The weight ist 13 tonnes steel + 13 tonnes concrete per segment, IIRC, diameter is 1.1m and segment length is 13m. Steel is ~7kg/dm³ => You can now calculate the wall thickness.
OK, OK, let's not talk: 130 dm * ((11/2dm + X)² - (11/2 dm)²) * \pi * 7kg/dm³ = 13000kg => X = 0.39dm
EDIT: Corrected the sign...