| The research on online leak sealing with injecting sealant is of great significance to lengthen the safe service life of the equipment and the pipeline. The existing standards and literatures of online leak sealing with sealant injection don’t have clear definition about injection hole arrangement for big size clamp,the influence of temperature on injection process,the cavity pressure and so on.In this paper the flow law of sealant in the process of online leak sealing was studied through experimental method.The optimized hole arrangement schedule was put forward.The relationship between injection pressure and volume of sealant injecting under the match of different temperature of sealant gun and pipeline,the influence of sealant injecting sequence on the performance of sealing and the determination about the pressure distribution within the sealing cavity of clamp were also discussed. Finally taking the straight pipeline axial crack for example, whether the pipeline with crack could be cured with sealant injectionon method was evaluated.The main word and conclusion are as follows:(1)The parameters measuring device of sealant injecting with alterable temperature of injection gun and pipeline was established, the flow shape of sealant was observed through visual means. It turns out that toroidal flow is ahead of the axial flow, the difference between them becomes larger with the increasing of volume of sealant injecting.(2) It is found that the axial stagger style of hole arrangement can improve the property of sealant distribution in the cavity.The hole arrangement optimization scheme of cassette clamp was put forward, the calculation formula of circumferencial and axial hole arrangement was gived.(3) It is found that when the temperature of injection gun is80℃, the pipe temperature changes from60℃to90℃, the temperature change of pipe has a less impact on the injection pressure.When the temperature of the pipeline is80℃, the temperature of injection gun changes from60℃to100℃, the injection pressure falls obviously with increasing the temperature of injection gun. But when the temperature of the injection gun is higher than80℃, the performance of injection gun goes bad, so the temperature of injection gun should be selected as80℃.(4) For two subdivision clamp with single-column uniform injection hole, the cross injection sequence with top of clamp as the starting point is better than others, it can ensure the force of bolts of clamp grows equably. (5) At lower pipeline temperature, the cavity pressure distribution is unequable.With the temperature of pipeline rising, cavity pressure reduces at the moment of the clamp seal cavity fully filled, and the cavity pressure distribution tends to be uniform when the temperature of pipeline reaches up to75℃.(6) The sealing method with injection sealant can not be used when crack expands because of the pressure.The critical half length of axial crack under different diameter of pipeline was obtained by the method of numerical analysis based on fracture toughness index, which can provides reference for safety assessment of actual service pipeline. |
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