標準號：BS EN 60609-1-2005
中文標準名稱：水輪機,蓄能泵和水泵水輪機.氣蝕損壞的評定.反擊式水輪機,蓄能泵和水泵水輪機的評定
英文標準名稱：Hydraulic turbines, storage pumps and pump-turbines - Caviatation pitting evaltuation - Evalution in reaction turbines, storage pumps and pumps-turbines
標準類型：J71
發布日期：2005/2/10 12:00:00
實施日期：2005/2/10 12:00:00
中國標準分類號：J71
國際標準分類號：23.080;27.140
適用范圍：This part of IEC 60609 serves as a basis for the formulation of guarantees applied to cavitation pitting for reaction hydraulic turbines, storage pumps and pump-turbines. It addresses the measurement and evaluation of the amount of cavitation pitting on certain specified machine components for given conditions, which are defined in the contract by output, specific hydraulic energy (E), speed, material, operation, etc. The cavitation-pitting evaluation is based on the loss of material during a given time and under accurately defined operating conditions. All wetted surfaces are considered. The contract documents shall state whether cavitation pitting on the hydraulic machine should or should not be anticipated in all or in some operating ranges. Guarantees that restrict the extent of cavitation pitting are necessary in the contract whether cavitation pitting is anticipated or not. 1 Excluded topics and limitations This standard does not cover other effects which cavitation may possibly have on the machine such as: - output, efficiency, vibration, mechanical integrity, and noise; and - material defects revealed during operation. Material defects revealed by wear on the machine surfaces during operation are not included in a guarantee against cavitation pitting. 2 Considerations concerning chemical composition of water It is assumed in this standard that the water is not chemically aggressive. In cases where the water is considered to be chemically aggressive, the cavitation-pitting guarantee shall be given on the basis of an agreed water analysis. Since chemical aggressiveness is dependent upon so many possible chemical compositions, and the materials of the machine, it is beyond the scope of this standard to set particular limits. If it becomes apparent in the course of later analysis that the water is in fact more aggressive than the agreed analysis indicated, this must be taken into consideration when evaluating whether the cavitation-pitting guarantees have been met. If cavitation pitting occurs in zones where damage can be separately attributable to chemical or electrochemical corrosion, such damage shall be excluded from the evaluation of cavitation pitting. If cavitation pitting occurs in zones where damage can be proven to have been increased by chemical or electrochemical effects additional to those normal to cavitation in water of the agreed analysis, then such zones shall be excluded from the evaluation of cavitation pitting. 3 Considerations concerning water containing solids Abrasion due to water contaminated with solids (for example, sand) cannot be considered as cavitation-pitting damage. When a machine operates in water containing a significant amount of solids, the weight loss of material will be intensified due to the joint action of both cavitation pitting (if it exists) and abrasion. The degree of intensifying destruction depends on various aspects, such as sediment concentration, mineral composition, size gradation and impact parameters (i.e. relative velocity and incidence angle) as well as the material characteristics and hydraulic machine operation conditions. When a surface is altered by abrasion erosion, cavitation-pitting damage can be initiated and accelerated because of the hydraulic shape change. With respect to measurement of damage, it is important to realize that, for cavitation erosion damage and abrasion erosion damage, the appearance, position and mechanism of destruction is not similar. If cavitation pitting occurs in zones where damage can be separately attributed to abrasion, such damage shall be excluded from the evaluation of cavitation pitting. While the examples of amounts of cavitation pitting and measurement methods given in this standard cover cavitation-pitting damage only, it must be recognized that some hydro sites operate in water that contains significant amounts of solids for at least some portion of the year. Since erosion due to abrasion is so dependent o