(Hydrotest Temperature As Per UG-99(h

I have case wherein my Equipment MDMT is 16 deg.C

I have water in winter condition in the range of 20 to 25 deg C.

The relevant provisions in UG-99 recommended that the metal temperature during hydrostatic test be maintained at least 30°F (17°C) above the minimum

design metal temperature. It means that the lowest wall temperature of your equiment during testing is  16+17=33 ℃

and the temperature of the water for testing should be maintained above 33 ℃

If the actual MDMT is -10℃，you can use water at 20℃. But you should be monitored the Metal temperature during tesing and ensure the temperature higher than 7 ℃