Mechanical Seal, Support sytem API 53B

[Samir Mammadov]

I am working as a mechanical engineer in the chemical industry. We mainly use the double seal in pumps. But a week ago we replace the mechanical seal with a new one. It works with API 53B support system. Although we pressurized the seal until maximum barrier pressure before starting the motor, the motor can't rotate the pump. Does it have some special procedure to pressurize to make a barrier between the seals?

Pump: API 610 type (OH2)
Suction pressure: 25atm
Discharge pressure: 29 atm
Chamfer pressure: 27.1 atm
min. Barrier pressure: 29.8 atm
max. Barrier pressure: 35.1 atm
Nitrogen pressure in accumulator: 26.8 atm

How do we make a barrier fluid between the seals' faces so that the seal work with API 53B support system?

 

[Manish Waykole]

Please try de-energizing the motor and then rotate the pump with pipe wrench in a coupled condition. At this time it is preferable to maintain the barrier pressure of the seal, while de-pressurizing the pump casing. If the pump rotates then try to normally start the pump again. If the pump does not rotate then there is possibly some other issue. Some other issue can generllay pertain to bearing of the pump or motor. In denergized motor condition decouple the motor and pump and try rotating individually.

Regards,
Manish Waykole

 

[georgeverghese]

When you say the motor cannot rotate the pump, do you mean there is some process control interlock that inhibits motor start ? If so, which interlock is preventing motor start?

 

[geesaman.d]

Get the startup and dynamic torque consumption of the new seal from the seal vendor. Double seals can have fairly high drag and consume significant motor HP.

Also, are you sure all air is bled from the system? And you may need to hand rotate it to get the seal faces wetted.