Javed Nasir wrote:
As per ASME Section I, addenda 2009.
When the drain piping shall be considered as blow-off piping?
what is the surface blowoff piping ?
I am very confused between bllowdown, drain, continous blow down, surface blowoff, blowoff piping while reading out PG-58, PG-59.
Best Regards,
Nasir
Iaved, me either don't remember the meaning of blow-down vs blow-off but I know the functions.
The boiler receives distilled water where a very small amount of salts remains. And steam with no salts contained. With the time the water which remains in the boiler becomes richer in salts. That's why a surface blow-off piping removes water to renew it and keep salt concentration low. This system called also de-concentration of salt from the water (literally translated from Italian), is continuous.
A blow down pipe is required at the bottom of the boiler to remove, when the boiler is in pressure, the deposited mud. Mud is formed because the additives remove the salts and aggregate them in mud. It is intermittent.
A drain is required in the lowes part of the boiler to discharge all water when the boiler is emptied to be out of service or repaired.
The drain can be operated also as a blow-down, in which case it shall have double valve
Mauro
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