The influence of distance between compressor stationon the gas pipeline's vulnerability to different types of SCC

Mikhail V. Chuchkalov OJSC «Gazprom transgas Ufa» Ufa, Russian Federation mchuchkalov@ufa-tr.gazprom.ru
Alexey G. Gareev OJSC «Gazprom transgas Ufa» Ufa, Russian Federation  
This article provides an analysis of accident statistics the linear part of main gas pipelines (MGP). It is shown that the main cause of its destruction is stress corrosion cracking (SCC). Discovered essential features of different types of SCC as you move away from compressor station (CS).
Materials and methods
Applied mathematical statistics methods, including methods of exploratory analysis.
Results
The overall frequency of accidents and accidents due to longitudinal SCC depends on the distance from the CS and is described by an exponential distribution. The design features of this distribution have almost identical statistical significance. This is probably due to the fact that cracks have developed in most cases SCC longitudinally (perpendicular to the maximum tensile stress ring). Binding to the CS is probably reactive with the influence of temperature, pressure and vibration on kinetics of SCC (values of these characteristics are reduced as MGP from the CS). The frequency of accidents because of SCC, an equal or exceeding the bending strains of ring does not depend on the distance from the CS and is described by a normal distribution. Using this distribution describes the processes under the influence of several independent factors. To them, along with the distance from the CS is a deviation from the design decisions in the construction of karst phenomena, erosion ditches, etc.
Сonclusions
Marked features of longitudinal SCC enables planning for its monitoring. Upon detection of transverse SCC requires finding and fixing additional factors that caused the destruction.
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compressor station gas pipeline stress corrosion cracking