Page 405 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

CORROSION DAMAGE, DEFECTS, AND FAILURES 383

seepage of 500 l of water into the methylisocyanate storage tank. The consequences
of this reaction were exacerbated by the failure of containment and safety measures
and by a complete absence of community information and emergency measures.
The long-term effects were aggravated by the absence of systems to care for and
compensate the victims. Further, the safety standards and maintenance procedures at
the plant were deteriorating and ignored for a long time.

5.3.7.4.19 Carlsbad Pipeline Explosion On August 19, 2000, a 75-cm diameter
natural gas transmission pipeline operated by El Paso Natural Gas Company ruptured
adjacent to the Pecos River near Carlsbad, New Mexico. The released gas ignited
and burned for nearly an hour. Twelve people camping under a concrete-decked steel
bridge that supported the pipeline across the river were killed and their three vehi-
cles destroyed. Two nearby steel suspension bridges for gas pipelines crossing the
river were damaged extensively amounting to a million dollars in property and other
damages or losses (37).
The force of the rupture and the violent ignition of the escaping gas resulted in a
16 m wide and 34 m rupture along the pipe. A 15-m section of the pipe was ejected
from the crater in three pieces measuring nearly 1, 6, and 8 m in length. The 8-m-long
piece was found nearly 90 m northwest of the crater in the direction of the suspension
bridge. Visual examination of the pipeline that remained in the crater as well as the
three ejected pieces was done. All three pieces showed evidence of internal corrosion
damage with one of the pieces showing significantly more corrosion damage than the
other two pieces. Pits were observed inside the piece with the greatest extent of cor-
rosion, and the pipe wall showed significant thinning. At one location, through-wall
perforation was visible. No significant corrosion damage was visible on the outside
portion of all three pieces or on the two ends of the pipeline lying in the crater. Sam-
ples were cut from the ruptured pipeline segments for further analysis by the Safety
Board’s Materials Laboratory in Washington, DC.
The drip between the closest block valve and the rupture site was removed from
the pipeline and visual examination showed the drip to contain a blackish oil powdery
grainy material. At the area of the large amount of the deposit, ∼4m from the drip
opening, the deposit filled ∼70% of the cross-sectional area of the drip. There was
no significant amount of the material underneath and several centimeters away from
the siphon drain at the closed end of the drip. There was no significant corrosion in
the drip.
Interconnecting pits were observed inside the pipe in the ruptured area. The pits
showed striations and undercutting features that are associated with microbial cor-
rosion. A pit profile showed the chloride in the pits increased steadily from top to
bottom. Sulfate-reducing, acid producing, general aerobic, and anaerobic bacteria
were present in the deposits taken from two pit areas in the piece of line where internal
corrosion was noted after the accident ∼630 m downstream of the rupture site.

5.3.7.4.20 Guadalajara Sewer Explosion This corrosion failure is because of a
combination of human error and shared responsibilities. The explosion killed 215
people and caused a series of blasts that damaged 1600 nearby buildings and injured