Seal flush plan

[maintennance]

For the coker unit feed pump, as per licensor document the seal flush plan is 11,52. The service fluid temperature is 200 deg C ( normal) and (max) 260 deg C. One seal vendor offer the same seal flush plan as indicated where as the other seal vendor offers 23,52. It is obvious that since the temperature is high the second vendor is offering for 23 seal flush plan. What could be different in design between these seal vendors How come the pioneers of the seal manufacturers differ in their recommendation? I would also like to know what would be probable reasons to go in for 11 seal flush plan eventhough the temperature is high as indicated above. Thanks to clarify

 

[flexibox]

One probable reason Plan 11 is specified is that the product will not Vapourize and therefore plan 23 not required. The Vendor with Plan 11 may have offered offered a Metal Bellows seal and the Vendor with Plan 23 offered a pusher seal (with Orings). Can you confirm?

Plan 11 is normally cheaper than plan 23 as it does not require a Heat Exchanger. To determine whether you need plan 23 have a look at the Vapour margin. Is the VP close to the chamber pressure? If your product will not vapourize then Plan 23 not required.

If VP is low then it looks like Plan 11+52 is sufficient with a Tandem Metal Bellows Seals. If you accept Pusher seals then you should use Perfluoroelastomers.

 

[REVenezuela]

Just curious, what is the stuffing box pressure?. I had really bad experiences with 11/52 plan applications on this service (Tandem Metal Bellows Seal).

Have you considered Plan 32 or 54?, I know it's way more expensive but at the end pay off.