Flush type Openings in a Tank 5

[SyedAdnanHussain2411]

As I go through API-650, I read about Flush Type Clean Out Fittings and Flush Type Shell COnnection, As I donot have design back ground, please help me to understand these terms and how they differ from the common fittings we now in a tank?

 

[fegenbush]

Flush type fittings, whether they are for clean out or process connection, have their lower edge flush with the floor of the tank.

 

[aamir2003]

How do we check the nozzle loads on these Flush type nozzles? Do we apply appendix P as well?

 

[fegenbush]

P.2 of Annex P (formerly Appendix P) is intended for nozzles which are located at or above the low type nozzle height. Figure P.1 shows this arrangement. If you were to use this approach, X_B would be a negative value equal to the thickness of the wall of the nozzle. I think this would cause you some problems in calculating the allowable moment.

I would suggest using Finite Element Analysis (FEA) and a competent engineer in such analyses to determine the allowable loading on the nozzle. It is intended in future editions or addenda to incorporate this approach into P.3 which is presently absent.

 

[11echo]

We deal with flush type clean-out on tanks (API-650 & API 12B & 12D) all the time. They are a door way (normally 24”x 36”) with the bottom elevation equal to the bottom of the tank (…ie “Flush Connection”). This is used in conjunction with a “Mud Apron”, that attaches to the front of this door way and acts like a dam to pool the remaining liquid in the tank (during clean out operations) in this exterior location it can be easily vacuumed up. Otherwise it would require somebody to crawl inside the tank to do this vacuuming, and now they would have to deal with the whole tank floor.
To carry this farther, this is why the manways on tanks are positioned approximately 180 Degrees from this flush clean-outs, the clean-up crew would enter the tank through the manways with squeegees and brooms to push the gunk remaining in the tank to the flush bottom clean-out door, where the vacuum truck can easily deal with it, and why the flush bottom clean-outs are positioned where it can easily be reached by a vacuum truck.