For example , in boilers , concentration of non-volatile impurities may occur in crevices near heat - transfer surfaces because of the continuous water vaporization .
Crevices can develop a local chemistry which is very different from that of the bulk fluid .
In boilers , concentration of non-volatile impurities may occur in crevices near heat - transfer surfaces because of the continuous water vaporization .
Crevices can develop a local chemistry which is very different from that of the bulk fluid .