using cold water for hydrotest of boiler

[pradeep4u]

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

 

[david339933]

I don't know what you mean by cold, or what Code you are talking about but Section I PG-99 mandates a minimum water temp of 20 Deg.C.

 

[SnTMan]

Cold water is more readily available.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[1gibson]

You need to define "cold" and "hot" if you want to ask a meaningful question.

What's wrong with room temperature water?

 

[metengr]

Depending on how hot the water is, 120 deg F or higher, this could present a safety risk for the Inspector while checking for leaks.

 

[marty007]

Water has a coefficient of thermal expansion.

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.

 

[BenStewart]

In addition to the above...

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.

 

[pradeep4u]

dear All
Cold water means I mean to say water at room teperature or ambient temperature.

Regards

 

[Duwe6]

pradeep4u not really in the USA. Room temp is 70°F / 20°C - in central & northern US, due to ground temperature, water from the faucet can be as low as 50 or even 45°F. Major Code violation for hydroing boilers under ASME Sect I.

 

[racookpe1978]

How will you heat the water to fill the (untested) boiler and feed and condensate piping?

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!

 

[pradeep4u]

If want to use hot water of about 60-70deg celcius for hydrotest then how can boler parts will be hot. I just want to know that if there is any technical aspect is there for it. I am asking like expansion in boiler parts subjected to water of about 70 degrees compared to wateer at about 30 degrees. If parts are expanded then how leakage will be found. It is my assumption.Please guide.

regards
Pradeep

 

[racookpe1978]

No, you are missing both of my points. 70 degree c ~ 160 deg F.
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?