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causes of pressure & temp variation while hydrotest

causes of pressure & temp variation while hydrotest

causes of pressure & temp variation while hydrotest

(OP)
guys plz help me out in this  

RE: causes of pressure & temp variation while hydrotest

environmental difference between the fluid temp inside versus the air temp on the outside & the effect of pressure inside.

RE: causes of pressure & temp variation while hydrotest

Just a relatively small amount of exposed pipeline can have a significant effect.  The variations can be extreme if there is a relatively small amount of trapped air inside as well.  The variation is caused by pipe expanding when heated by its surroundings and it expands faster than the water inside, which tends to remain cooler than the pipe for longer periods during the day, and warmer for longer periods at night.  Steel and other metallic piping heats up and cools off much faster than the water inside too.  The amount of expansion and pressure loss, or contraction and pressure increase can be calculated to see if the cause is a temperature change, or it was from an actual leak in the system.

We will design everything from now on using only S.I. units ... except for the pipe diameter.  Unk. British engineer

RE: causes of pressure & temp variation while hydrotest

is it hydrotesting rigid pipe only? also dont valves have allowable rates they are allowed to leak? some more some less depending on class...  not sure if that would have enough effect to make the pressure drop...

is the temp and pressure increasing or decreasing? are you reading the temperature inside the pipe or what

RE: causes of pressure & temp variation while hydrotest

Shouldn't normally be testing against closed valves.

We will design everything from now on using only S.I. units ... except for the pipe diameter.  Unk. British engineer

RE: causes of pressure & temp variation while hydrotest

Ensure that a vent valve located at the highest of the piping system is included. As you see the water flowing from it, you could be sure that no trap air is within your system.Minimum hydrotesting time is 30 minutes and beyond that is better however pressure and temperature variation will be experienced depending on your place.  

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