API Plan 53A vs 53B

[Abualnassr]

Hi guys,

We have an agitator with these parameters :
T = 210 C
P = 18 Barg

The seal installed is EagleBurgmann HSL double seal.

The plan used is Plan 53A, are the process parameters OK with the 53A ? Or it's recommended to upgrade the flushing system to 53B ?

And, what is the max. temp. & pressure for Plan 53B ?


Regards,

 

[flexibox]

There are a lot more questions to ask, what is the barrier fluid? Is the Plan 53A vessel getting hot hence the reason for the question or are you having failures when topping up?
It is common to see Plan 53A system is these applications and the most common problem is operator error when topping up. It would be nice to better understand the reason for your question.
Plan 53A is suited for this application but you may need better circulaion or cooling coils in the vessel to disappate the heat. Plan 53B is a better system because it uses a bladder accumulator which makes topping up easier and less prone to reverse pressure failure.
Plan 53B can handle high Temp and pressure, for example I have used them at 160Bar and on other high temp applications of 350C.
If you advise what you are experiencing we may be able to point you in the right direction.

trust this helps.

 

[Abualnassr]

Thanks flexibox for your reply.

The barrier fluid is oil SAE 30 with N2 gas.

The problem is that we are having leakage of the barrier fluid from the top of the seal.

By the way, what do you mean by topping up ?


Regards,

 

[flexibox]

If the top seal is leaking then the first question I would ask is How do you vent the seal? Ensure that there is no air trapped in the top part of the seal. Also this seal will see full pressure Is the seal suitable for 18bar pressure? Is it a balanced or unbalanced seal? What is Seal size? Do you have shaft deflection causing the seal to leak and not necessarly the seal !
Topping up means when you refill the Plan 53B accumulator or Plan 53A vessel.
Also API682 recommends that the N2 pressure on a Plan 53A not exceed 10bar. please refer to API682 for this information.

 

[HoustonMechEngr]

The main reason why one implements a plan53B in lieu of a plan 53A is the issue of nitrogen entrainment within the barrier fluid. The plan 53B provides a bladder accumulator that prevents a barrier between the fluid and the pressure source. Circulating barrier fluid with nitrogen entraqinment can cause major issues at the seal interface. API 682 advises moving towards a plan 53B in excess of 150 psig.