Water hammer event on aboveground section of oil piping
during hydro test
The reason for the destruction of the air piping was a waterhammer due to a guillotine rupture of the underground section of the oil pipeline (500 m to the transition) during the hydraulic tests.
A dynamic model was developed and the hydraulic impact modeling from the sudden break of the oil pipeline during the hydraulic test was conducted, which led to the discharge of the pipeline from the supports on the aerial section .
The simulation results recreated the process of the emergency situation and predicted the discharge of the pipeline from the corresponding supports.
According to the applicable standards, before testing the new pipelines to demonstrate their integrity and performance, tests should be carried out with increased hydrostatic pressure. In carrying out such planned hydraulic tests after the construction of the Zhulin-Nadvirna oil pipeline there were several pipeline gusts at various sites. As a result of the last impulse at a distance of 540 m from the beginning of the air transition across the Lemnitsea River at a test pressure of 94 kg / sm^2, a considerable displacement and as a result of the fall of the transition from the supports became a consequence.
Structurally, the air transition contains two Z-shaped compensators (at the entrance and exit from the ground) and one L-shaped compensator located almost in the middle of the transition. When the underground section of the pipeline burst, a waterhammer occurred, which led to a dynamic process and deformation of the air transition. In this transition was carried out oscillatory motion, where the compensators acted as springs, and the straight sections of the transition between the compensators were lumped masses.
To understand the causes of the accident and ensure the reliable operation of the oil pipeline, a research work was carried out, the essence of which was to analyze the adopted constructive decisions regarding the transition through the Limnytsia River during the design; calculation of possible variants of failures and damages that arise when the gusts of the pipe; developing measures to strengthen the design of the transition to prevent possible similar accidents in the future.
To achieve this goal in the framework of this work, the following activities were carried out:
1. Analysis of the stress-strain state of the pipeline in the air transition section through the Limnitsa River according to the design documentation under normal operating conditions.
2. Analysis of the mathematical model of the reproduction of the events of destruction of the air transition at the pipeline bursting at a distance of 540 m from the transition.
3. Modeling of the air transition behavior in case of hypothetically possible accidents.
