Page 410 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

388 CONSEQUENCES OF CORROSION

and leisure centers. The collapse of the ceiling above a swimming pool showed how a
simple structural concept could be sensitive to the loss, through corrosion, of support
from one of many hangers.
The Federal Materials Testing Institute, based in Duebendorf, Switzerland, and
the Federal Materials Research and Testing Institute of Berlin concluded that the
collapse of the swimming pool roof was the result of chloride-induced SCC. The steel
rods had been pitted, causing the roof to cave in. The roof collapsed in a zipper-like
fashion, starting with the corroded rods. The collapse continued as the remaining
rods were unable to bear the increased load. The chloride was either already present
in the concrete or came from the pool through water vapor. Chloride can overcome the
passivity of the natural oxide film on the steel surface. The inspection of safety-critical
stainless steel components for SCC and loss of the section by pitting should be viewed
as a priority. The following inspection procedure has been recommended to avoid
future accidents: compile an inventory of all stainless steel components in the pool
building identifying their grade, location, and function. SCC may be difficult to detect
in the early stages. Pitting and brown staining, varying from a pale, dry discoloration
to wet pustules may indicate SCC.
Yearly inspection or twice in a year inspection of stainless steel components espe-
cially load bearing components is desirable. Where staining or corrosion is found, cor-
rosion products may be removed and the loss of cross section and integrity assessed.
Load bearing or other safely components should be tested for SCC. When necessary,
components should be more corrosion-resistant stainless steel parts.

5.3.7.4.27 Pipeline Failures The history of pipeline safety has been reviewed (41).
Compared to other forms of transportation, pipelines are inherently safer; however,
pipeline failures can have serious consequences. For example, in June 1999, a pipeline
rupture in Bellingham, WA, USA, spilled 946,000l (250,000 gal.) of gasoline into a
creek. When the gasoline ignited, three people were killed, eight more were injured,
several buildings were damaged, and the banks of the creek were destroyed along
a 2.4-km section. In July 2000, a natural gas pipeline ruptured in Carlsbad, New
Mexico, and when the gas ignited, 12 people were killed.
Table 5.10 summarizes the pipeline accidents and injuries between 1989 and
1998 (41).
Table 5.11 summarizes the major accidents reported to the US Department of
Transportation by the operators for the 6-year period between 1994 and 1999. The
data show that for transmission pipeline systems, inclusive of hazardous liquid and
natural gas, approximately 25% of all reported accidents were because of corrosion
(see Table 5.10). Of the hazardous liquid pipeline accidents caused by corrosion, 65%
were because of external corrosion and 34% were because of internal corrosion.
In the case of natural gas transmission pipelines, 36% of the accidents were
caused by external corrosion and 63% were caused by internal corrosion. In the case
of natural gas distribution pipeline accidents, only 4% of the total accidents were
caused by corrosion, and the majority of these were caused by external corrosion.
The corrosion-related accidents in pipelines carrying natural gas and hazardous
liquids are summarized in Table 5.11.