Controlling surge in liquid pipeline
- Grove Valve and Regulator Co., Houston, TX (United States)
What is Surge? Surges or hydraulic transients, commonly known as water hammer are sudden increases or decrease of the total pressures in a piping system due to changes in velocity of the fluid in a pipeline. Change in velocity, such as would result from the sudden closure of a valve in a flowing pipeline, causes the fluid to suddenly come to rest, resulting in a pressure increase in the system above the operating pressure. The energy associated with the moving fluid is converted into energy of pressure when it is suddenly stopped. In steady state pipeline flow, there is no change in the flow conditions at a point with passing time. The hydraulic grade line (HGL) elevation varies with two independent variables; namely, the distance from the upstream end of the conduit & the flow rate. On the other hand, transient flow introduces time as a second independent variable such that both the flow velocity and the HGL elevation vary with both distance and the time elapsed from the start of a disturbance. When a pump begins to fail or to start, or when a valve starts to open or to close, steady state conditions are disturbed throughout the entire pipeline system. This disturbance (or surge) propagates both upstream and downstream with a definite speed (the pipeline acoustic wavespeed) which is determined by the fluid characteristics. It takes the form of a pressure wave traveling upstream and a rarefaction wave traveling downstream, or vice versa, depending on the nature of the disturbance. The amplitude of the surge waves superimpose algebraically on the existing HGL elevation and may have blunt or gradual wave fronts depending on the rate with which the disturbance took place. Moreover, the attenuation of the surge pressure wave as it arrives initially at a given location of the pipeline is followed for a long time by pressure increases due to {open_quotes}packing{close_quotes} which is associated with long pipelines.
- OSTI ID:
- 146376
- Report Number(s):
- CONF-950553-; TRN: 95:007831-0138
- Resource Relation:
- Conference: International school of hydrocarbon measurement, Oklahoma City, OK (United States), 16-18 May 1995; Other Information: PBD: 1995; Related Information: Is Part Of Proceedings of the seventieth International School of Hydrocarbon Measurement; PB: 811 p.
- Country of Publication:
- United States
- Language:
- English
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