using cold water for hydrotest of boiler
using cold water for hydrotest of boiler
(OP)
Dear All
My question may be very very simple and very silly but still I want to ask it. I want to know that why cold water is used for hydrotest and not hot water?
Regards
Pradeep
My question may be very very simple and very silly but still I want to ask it. I want to know that why cold water is used for hydrotest and not hot water?
Regards
Pradeep





RE: using cold water for hydrotest of boiler
RE: using cold water for hydrotest of boiler
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: using cold water for hydrotest of boiler
What's wrong with room temperature water? :)
RE: using cold water for hydrotest of boiler
RE: using cold water for hydrotest of boiler
So, if you fill it with hot water, then close it all up and step back, it will start to equalize to the surrounding temperature. As it cools it will decrease in volume and the internal pressure will also decrease. Depending on how hot you're talking about, you could fairly quickly drop below your mandatory hydrotest pressure when inspections for leaks are done.
RE: using cold water for hydrotest of boiler
How hot is hot? Depending on what code you are using the ratio of the allowable stress at the test temperature to the design temperature is a factor in calculating the hydraulic test pressure, i.e. part 8.2 in ASME VIII-2 and section 5.8 in PD5500. This ratio is to increase the test pressure due to the material weakening due to the design temperature.
How cold is cold? The minimum temperature is to avoid brittle fracture during the test.
RE: using cold water for hydrotest of boiler
Cold water means I mean to say water at room teperature or ambient temperature.
Regards
RE: using cold water for hydrotest of boiler
RE: using cold water for hydrotest of boiler
NO operator and NO testing mechanic is going to want to "inspect" around a hot boiler pipe when the water and steam inside the pipe could burn him to death by blowing out of a bad joint or a bad valve stem or a bad gasket!
RE: using cold water for hydrotest of boiler
regards
Pradeep
RE: using cold water for hydrotest of boiler
1. Hot, pressurized water for a hydrostatic test medium is dangerous. It does you no good, and is not needed. The unisulated pipes you need to handle and look at during the hydrostatic test are ALSO dangerous to climb around and look at and handle.
If there is a leak, the leaking/spraying/jetting hot water IS VERY dangerous!
2. You CANNOT heat the water to fill the boiler and feed piping and steam piping and isolation valves to start the test without some external (VERY expensive) temporary boiler. Once you have paid for that expensive hot water, the water cools off VERY quickly as the boiler pipes and walls and pipe and supports and valves heat up. So you don't have hot water anyway.
Why would you, your boss, your client, your plant want to pay for that?