Steam blow is a step before start up steam boiler to ensure there is not debris, scale, dirty, scrub resulting from welding activity in superheater and reheater. Prior to perform steam blow procedure, the operator should do steam blow start up procedure. The following below is step by step procedure of steam blow:
1.Configure temporary and permanent piping for target blows of the main steam through the exit points at the turbine main stop valve. All other branch flow paths will be isolated.
2. Proceed trough Steam Blow Start-Up Procedure steps for the main steam line.
3. Continue the steam blow at specified flow rates, pressure and temperature. The blowing out duration is 1 – 2 minutes blast per blast. Note that with long blowing gate valve run times (greater than 30 seconds), the blowing out duration must be extended by the run time of the blowing gate valve.
4. With the first two or three blast, no steel mirrors are installed to the check cleanliness due to the high levels of contamination that can be expected.
5. The blowing out will be carried out continuously until achieve satisfactory levels of cleanliness in the steam piping.