today we test new pumps in our new plants. we used Nitrogen to test the plant system and when it comes to pumps, we started to pressurize the pump till we reached 450 psig.(note pump is off) then during pressurizing the pumps we observed the Pressure Indicator on the inboard and outboard for the mechanical seal leak off started to read good amount of leak. the more pressure is admitted to the pump, the more reading Pressure indicator leak off would read.


When Pressure Indicator reaches 35PSI we opened drain line valve to atmosphere and found PI went down to read almost zero PSI.

is that normal leak amount and how we can test if the mechanical seal is in good condition before we start to run the pump for the first time ever.

Interesting enough, is there any leakage limit for the mech seal? What type of mech seal is it?

for the limit, we can run up to 5 psig of leakage with drain line to atmosphare wild open.

its single mechanical seal.

Hello, Jawal,

I ever had worked at chemical plant for 8 years, Met many mechanical seal issues . But I know that after rebuilding mechanical seal commonly we use water booster pump to pressure mechanical to check seal under static status for any leakage. I remember if doing seal test with gas a little of mechanical seal can be kept from leakage.

Thanks
Lux

Mechanical seals , when stationary will normally not hold gas. It will leak, depending upon what type of seal you have, what is the preloading, it is dry or gas seal? Check for seal face flatness under monochromatic light source . For gas, it should not be more than 2 light bands.
Regards
Irwshad