Instruction for steam boilers preservation during shut down period

Very important

These instructions are valid only when the plants have been treated with FINEAMIN during minimum 3 to 6 months before shut down. In all the cases of preservation of boilers in wet conditions it is highly recommended to recirculate the boiler water with the pump ensuring a minimal flow in all the parts of the boiler (particularly in all the tubes). The circulation pump must be in service for 2 - 3 hours per day

1. Shut down period from 3 to 6 days

In this case, the boiler can be stopped without particular measures

2. Conservation for boilers in wet conditions and under pressure

In this case the boilers have to be kept at a temperature of more than 100°C and under pressure. The polyamine excess has not to be increased compared to the normal conditions when the boilers are running. Every 2 weeks the pH and polyamine excess have to be measured and if necessary corrected. The minimal pH is 9.5 and the polyamine excess has to be kept higher than 5ppm. When the plant is restarted, an efficient and frequent blow down of the boilers must be done.

2.2 Conservation of boilers in cold conditions and with the water level at the top of the boiler drum

2 days before shut down, increase the dosage rate in order to reach 20 ppm polyamine excess and minimum pH of 9.5 to 10.5 in the boiler water of water tubes boilers and minimum pH of 10.5 to 12 in the boiler water of fire tubes boilers. After shut down, fill completely the boiler drum and add 0.5 liter per m3 of water contain of oxygen scavenger (FINEAMIN 18 or FINEAMIN SCAV). Every 2 weeks the pH and polyamine excess have to be measured and if necessary corrected. The minimal pH is 9.5 and the polyamine excess has to be kept higher than 5ppm. When the plant is restarted, the water level in the drum must be decreased to the normal level and an efficient and frequent blow down of the boilers must be done.

2.3 Conservation of boilers in cold conditions and with the water level at the normal level (ready to go)

2 days before shut down, increase the dosage rate in order to reach 20 ppm polyamine excess and minimum pH of 9.5 to 10.5 in the boiler water of water tubes boilers and minimum pH of 10.5 to 12 in the boiler water of fire tubes boilers. After shut down, add 0.5 liter per m3 of water contain of oxygen scavenger (FINEAMIN 18 or FINEAMIN SCAV). We highly recommend using nitrogen protection to fill the steam part of the boilers. Every 2 weeks the pH and polyamine excess have to be measured and if necessary corrected. The minimal pH is 9.5 and the polyamine excess has to be kept higher than 5ppm. When the plant is restarted, an efficient and frequent blow down of the boilers must be done.

3. For shut down period of more than 6 months

In this case we highly recommend keeping the boilers empty. That means to empty the boiler when still cold (just after shut down) and to permit an air circulation in the boiler.