Pipeline Crack Propagation
05.13
When natural gas
pipelines exhibit weaknesses, the pipes may be more prone to corrosion,
according to the American Gas Association. Companies may want to be on the
lookout for rapid crack propagation (RCP), or when a brittle crack in a
material grows and results in fractures, as one of the red flags for pipeline
failure, Pipeline and Gas Journal said. Since the risk of RCP is high for metal
pipes, pipeline and utility companies are increasingly choosing durable
polyethylene (PE) pipes for upstream and midstream systems.
According to
Alliance for PE Pipe, PE pipe is not only durable, but it's also flexible. The
properties of PE pipe allow this material to withstand corrosion and chemicals
while underground. Since plastic pipes can endure corrosion better than metal,
PE is often used for natural gas pipelines because the process used to make PE
pipe makes it less prone to leaks. Utilities could choose PE piping systems
when overhauling underground infrastructure, which may protect them from
corroded pipes and joints that could lead to leaks.
Some factors
could raise risk of RCP. One risk is the size of the pipe; the pipe's diameter
may influence cracking. The publication notes that as the diameter of the pipe
grows, the risk for RCP also increases. Another factor is the operating
temperature of the pipe. Pipeline operators may want to make sure pipes are
protected from lower temperatures because frigid conditions could cause RCP.
Pressure is also a significant factor because a pipeline pressure pulse may
contribute to RCP. Companies may want to be aware that there is a higher chance
of RCP when the stress in the pipe wall rises. In the event RCP occurs, the
consequent pressure waves may result in fragmentation, causing pieces to travel
at a high velocity and distance.
When replacing
their existing pipeline and underground infrastructure, pipeline operators may
want to look out for warning signs that indicate RCP cracks. Although PE
pipelines are more durable against such cracks, they also can appear in this
type of material. According to Pipeline and Gas Journal, an RCP crack is
usually presented by a sinusoidal crack within the pipe. Other signs of an RCP
crack include the crack going into two directions and butt fusion joints, or
when cracks are arrested by electrofusion couplers. As companies determine what
is the best pipeline material for their transmission and distribution
operations, they should look into PE pipes for their strength and ability to
withstand several factors that could lead to RCP. Although PE is still
vulnerable to RCP, there are a variety of ways pipeline operators can prevent
these cracks in PE pipes. If operators choose PE pipeline, they should test the
pipe for the amount of pressure it can endure to make sure they limit the
chance of RCP.
Sumber:
http://solutions.borderstates.com/rapid-crack-propagation-rcp-what-does-it-mean-for-pe-gas-pipeline
0 komentar