High Pressure Boilers 1069 * QUESTIONS WITH COMPLETE SOLUTIONS

Boiler water is treated in order to prevent a) sludge, mud, pitting, corrosion b) foaming, corrosion, carryover, sludge c) sludge, corrosion, scale, carryover d) scale, sludge, mud, pitting e) foaming, carryover, pitting, corrosion c Dissolved solids in raw water a) cause pitting of boiler surfaces b) cause grooving of piping surfaces c) are organic matter d) cannot be removed with filters e) cause corrosion of boiler surfaces d Boiler surfaces may have what appears to be blisters which are composed of a) iron oxide b) sodium sulphite c) caustic soda d) ferric sulphate e) chelates a Boiler water with an alkalinity that is too high will likely a) have a lot of scale b) show signs of pitting c) have a low pH d) foam e) have grooving on its surfaces d Corrosion products in feedwater can cause a) slag deposits in superheaters b) decreased steam pressure c) increased steam pressure d) increase in boiler efficiency e) tube failure e Boiler water with a pH of 6 is considered a) alkaline b) basic c) acidic d) neutral e) acceptable for boiler water c Which of the following is an example of suspended matter? a) sodium b) sand c) salt d) calcium e) magnesium b Which of the following is an example of dissolved solids? a) magnesium sulphate b) oxygen c) clay d) sand e) carbon dioxide a Temporary hardness in feedwater is caused by a) calcium sulphate b) sodium nitrate c) magnesium bicarbonate d) calcium carbonate e) magnesium sulphate c Feedwater for a high pressure boiler should be a) treated with phosphate b) treated with phenolphthalein c) treated city water d) treated with salt e) softened water e A method of treatment which is often used in conjunction with settling tanks is a) deaeration b) zeolite softening c) demineralizing