چكيده لاتين :
The applicability of medium density polyethylene (MOPE) gas pipes in hot climate
areas of southern Iran (such as Khuzestan) has been one of the main concerns
of local gas company officials and their engineers. This is due to the facts that
buried pipes can experience sever stresses due to internal pressures, traffic load, soil
height, daily and/or seasonal temperature variations if not properly designed and
installed underground. This research investigates the sole effect of each parameter and
their combination on maximum stress produced in MOPE gas pipes and their sockets
which are made from PE100. The analysis was performed through a comprehensive
finite element process and the results were compared to those of empirical equations,
where possible. The maximum local stresses in pipes and sockets were determined
and compared to their critical values for an operating pressure of 4 bars at various
depths and temperatures. The design curves and the range of applicability of MOPE
are then deduced based on a life time of 50 years. According to the results, assuming
a target temperature of 30°C for the pipe and its socket, then MOPE pipe and its HOPE
socket (PE100) can well sustain the imposed load of a temperature rise of 15°C at a
depth of 120 em, in presence of all other loads mentioned above. For higher temperature
rises, some stress relief mechanisms must be employed. Hence, by applying the
right procedure, these pipes can be used for gas transportation even in hot climate
areas of Iran, where the ground surface temperature may reach a high value of 67°C
in summer time.
