ABSTRACT

The pressure drop of gas in a long pipeline after its rupture can be described by similar equations as the temperature changes in a cooled wire. The heat models are suitable for the location of a rupture. Depending on the state of valves and the position of measuring devices, four different methods have been applied for rupture location. The models have been verified by numerical simulations based on complete, not simplified equations, and by the analysis of three real accidents. Prerequisites for the utilization of these methods are also given.

INTRODUCTION

Usually, it is easy to localize a pipeline rupture in a densely populated area. However, it is a problem in hardly accessible, uninhabited sites (there are no witnesses). Fast and precise location of a rupture is important as it can prevent human casualties and environmental disasters after an accident. Prompt closing of shut-off valves minimizes the inevitable gas losses by decreasing the volume of damaged pipeline section and by stopping the delivery of gas to the rupture from the adjoined pipeline network.

There are precise leak detection and location methods based on temperature changes caused by leaking gas and measured by Raman or Brillouin scattering of light in an fiber optic cable installed along the length of the monitored pipeline [1], [2]. The rupture site can be located by light reflecting from the end of a torn optic cable. However these methods are expensive and therefore are applied mostly to high-risk areas.

Location systems based on pressure sensors commonly installed along the transit pipelines or flow-meters in delivering points, need no additional expenses. A leak divides the monitored pipeline into the upstream and downstream parts. Assuming a steady pressure profile along both parts, a leak (not rupture) location can be calculated, e.g., from two upstream and two downstream measured pressures.

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