Abstract
The results of field and theoretical studies to determine the degree of hydrophobicity of the inner pipe walls in static and dynamic conditions are reported. The water drops spreading nature in contact with the horizontal and concave surface of different materials with the definition of contact angles is determined. The flow pattern formed when the critical mass of liquid miniflow is reached on an inclined surface in the form of an open trough was studied. The geometric parameters of the frontal and coaxial miniflow projections were determined, its dimensions and hydraulic characteristics were studied. The trial stand design for the protective coatings hydrophobic properties study was presented and described and method of evaluation of the pipeline work surfaces hydrophobic properties by applying the relative hydrophobicity ratio. Calculation formulas of the relative hydrophobicity ratio for work surfaces were presented. The relationships of hydrophobicity of various coatings used in the trenchless technologies to relative roughness coefficients were established.
Highlights
Nowadays trenchless technologies are widely used for rapid recovery of old water supply and water disposal pipelines [1]
No deterioration of hydraulic parameters compared to the initial for corresponding piping material shall be observed in the recovered pipelines [3]
Based on the obtained data it was suggested to evaluate the degree of hydrophobicity in dynamic both by the contact angle and by relative hydrophobicity ratio determination Krel.: Krel =Sup./(Swet.·i), where Sup – upper lens area (АВСОA), mm2; Swet. – trough surface wetting area (ААCC) by compact miniflow part L, mm2; i – trough slope
Summary
Nowadays trenchless technologies are widely used for rapid recovery of old water supply and water disposal pipelines [1]. Recovered pipelines must have the appropriate strength parameters determined by static calculations, and ensure a long efficient lifetime [2]. No deterioration of hydraulic parameters compared to the initial for corresponding piping material shall be observed in the recovered pipelines [3]. Are subject to accounting [4]. Mechanical parameters – the degree of abrasion of inner pipes surfaces and their coatings, fatigue wear, etc. Such parameters as hydrophobicity and hydrophilicity stand apart in the drinking and waste water transportation, and more precisely in the physical and chemical properties study of the inner pipe walls or their protective coatings
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