what will happen if many boiler tubes are blind?
Edited In a high pressure water tube power boiler, if just a single boiler tube becomes even partially internally encrusted with a deposit, long before it becomes plugged or blind the metal at the location can become overheated and weakened to the point of failure. This is because the tube internal fouling (scaling) will act as an insulation to retard the heat of the fire from being transferred into the water. The water and steam actually cool the tube. These types of vertical, water (inside the) tube boilers are not constructed so that individual tubes can be intentionally plugged for operation. A deffective tube will be replaced during the boiler inspection and maintanence when it is out of service. Boiler feed water is treated to remove dissolved minerals so that there is nothing in it to deposit. Scaling is more of a concern with higher pressure power boilers. Scaling was and is not as much of a concern with the other style of horizontal fire tube power boilers and water heaters. Here the water surrounds the tubes. These were the older lower temperature boilers used with the saw mills, steam ships and railroads and are still common. Those tubes could be intentionally plugged if a leak was found. Of course the plugging of leaking tubes would reduce the boiler capacity.
