2" Low type nozzels

[EcuaDerek]

Colleagues:

If I want to install a 2" nozzle lower than the minimum distance from tank bottom to center of nozzle (Hn), as indicated in table 5.6a DIMENSIONS FOR SHELL NOZZLES, in theory I could use a low type nozzle, meaning using a special reinforcment plate.

However reinforcing plates are not normally used for nozzles less than NPS 2. In fact, the same table 5.6a doesn’t give minimum heights for low type nozzles NPS 2 and smaller. It only refers to note h, which in turn refers to figure 5.6 which gives minimum weld requirements for openings. For low type openings, it sends you right back to table 5.6a, which makes me believe that you cannot have a NPS 2 low type nozzle or smaller.

What is the common industry practice for NPS 2 low type nozzles?

What would be the minimum suggested distance from tank bottom to center of the nozzle in this case?

Cheers,

 

[IFRs]

The low height will be determined by weld spacing. 5.7.3 I think.

 

[EcuaDerek]

This means I must put a re-pad, even though the nozzle is less than NPS 3? (normally nozzles less than NPS 3 do not need reinforcement) In order for the nozzel to qualify as low type, it must have reinforcemnet (the "low type" refers to the re-pad, not the nozzle itself)

 

[IFRs]

See dimension "C" in figure 5.6. No repad is needed - you have a "S/N" type nozzle.