Basically pressure guage is an instrument mounted on the pipelines, reactors, pumps, vessels, tanks etc to measure the pressure inside the system or
pressure of the motive fluid.
The working principle of pressure gauges is based on Hooke’s law.
Pressure guages are mainly three types
a) Bourdon type Pressure Guage:
It comes in three variant C type, Spiral type amd helical type.
They are generally used in the gaseous and liquid media which are not highly viscous in nature, do not crystallise and fluid do not attack copper alloys.
b) Diaphragam Pressure Guage:
It is suitable for all type of gaseous and liquid media may be corrosive, as well as whre fluid is viscous or containing suspended solids.
c) Differential Pressure Guage:They are widely used to monitor filtration, liquid levels, and liquid flow.
Important Points:
Wherever IBR requirement comes following shall be complied to:
a) All pressure gauges under IBR service shall be tested and test certificates in Form III C shall be furnished duly
undersigned by IBR authority or its approved representative.
b) For pressure gauges which shall be used under IBR service, Carbon contents in steel shall not exceed to 0.25% for flanges, body parts etc. or
any part that may require welding, also the sulphur and phosphorous shall also be limited to 0.05% each.
For pressure gauges under NACE service, the following shall be complied to:
a) Maximum hardness in weld joints & cast body/ bonnet shall not exceed to 200BHN.
b) The hardness of any material shall be limited to RC22 (BHN200).
c) The valves shall comply to NACE MR 0175 standard requirements.
d) All weld joints shall be 100% radiographed and all types of weld shall be wet flourescent MP tested.
