Shell Nozzles Flange Types API 650

[hamidun]

Dear All,

As per you guys notice, in API STD 650, Figure 5.8, for Regular-type flanged nozzle, there are three types of nozzle flange:

1. Single Flange
2. Double Flange
3. Special Flange

Can someone help me to understand the differences between those flange types? When to use Single Flange, Double Flange or Special Flange? In what purpose we use Single Flange, Double Flange or Special Flange.

Thanks for the help!!

 

[JStephen]

Single is the standard.
Use double when there is piping inside the tank- diffusers, sump piping, floating roof drains, etc.
"Special" only when needed for some specialized application. I think I've only seen Victaulic couplings used in the fire-protection industry, for example.
It is also possible to have a butt-welded connection inside, see Fig. 5.21, for example.

 

[hamidun]

Why we cannot use single flange for sump piping? Is it about installation or maintenance?