水垢可以导致蒸汽发生器金属过热
The scale can cause the steam generator to overheat
蒸汽发生器受热面运用的钢材，一般均为碳素钢，在运用进程中，答应金属壁温在450℃以下。锅炉在正常运转时，金属壁温一般在280℃以下。
Boiler heating surface of steel used, generally all is carbon steel, in the process of using, promised to metal wall temperature below 450 ℃. The boilers in normal operation, the metal wall temperature under 280 ℃ in general.
当蒸汽发生器受热面无垢时，金属受热后能很快将热量传递给水，此刻两者的温差约为30℃。可是，假如受热面结生水垢，情况就不大一样了。
When the boiler heating surface without scale, the metal is heated to transfer heat water soon after, the temperature difference is about 30 ℃ at the moment. However, if the heating surface is the scale, the situation is not the same.
也就是说此刻金属壁温在钢材答应温度以内。但当水垢是3毫米时，金属壁温则上升到580℃，远远超越了钢材的答应温度。
In other words, the metal wall temperature is within the promised temperature of the steel. But when the scale is 3 mm, metal wall temperature increased to 580 ℃, far beyond the promised temperature of steel.
因而，这时钢材的抗拉强度就会由本来的3．92Mpa降低到0．98Mpa，
蒸汽发生器受压元件就会在内压作用下发作过热鼓疱、变形、走漏。
Therefore, the tensile strength of the steel will be reduced from 3.92 Mpa to 0.98 Mpa, and the pressure component of the boiler will heat up the blister, deformation and leakage under pressure.
