供水灰口铸铁管内壁初始腐蚀影响因素研究

Influence Factors of Initial Internal Corrosion of Grey Cast Iron Pipes in Water Distribution System

以灰口铸铁挂片为研究对象,以《生活饮用水卫生标准》(GB 5749—2006)中规定值为参考值,分析p H值、溶解氧、余氯、温度、氯化钠浓度等因素对管壁初始腐蚀的影响,同时研究初始腐蚀过程中腐蚀量、腐蚀速率以及各个影响因素的变化规律。结果表明:随着溶解氧浓度、余氯浓度、氯化钠浓度以及温度的升高,挂片腐蚀量以及腐蚀速率变大;在p H值较小时,挂片腐蚀速率较快。在腐蚀过程中,溶液p H值基本呈现先上升后下降最后保持恒定的趋势;而且腐蚀速率的衰减与余氯、溶解氧浓度衰减呈正相关。运用灰色关联度分析方法就各因素对腐蚀的影响力大小进行排序,即溶解氧>温度> p H值>氯化钠>余氯,说明在试验条件下,溶解氧对于腐蚀的影响较大,温度次之,余氯的影响力最弱。

Refer to the values specified in the Standards for Drinking Water Quality （ GB 5749 - 2006 ）, the influence of pH, DO, residual chlorine, temperature and NaC1 concentration on the initial internal corrosion of the grey cast iron pipes were studied. The analyses on the corrosion mass, the corro- sion rates and the sensitivity of the influence factors were carried out. The results showed that the corrosion mass and the corrosion rate increased with the increase of DO, residual chlorine, NaC1 and tempera- ture. A higher corrosion rate was observed in the acidic environment. During the corrosion process, pH demonstrated a pattern that firstly increased, then decreased, and finally remained constant. The decay of the corrosion rate was positively correlated to the decay of the residual chlorine and DO. The grey correlation analysis method was utilized to analyze the significance of various factors on the corrosion process, which in descending orders were DO 〉 temperature 〉 pH 〉 NaC1 〉 residual chlorine. The effect of dissolved oxygen on corrosion was greatest, followed by the temperature, and the influence of residual chlorine was the least.