Hello all, I'm new to this forum.

[Shine19]

Hello all,
I'm new to this forum. I need to know about reinforcement calculations for roof nozzles of tanks [API-650].
I intend to provide a dia. 14" roof nozzle for venting or equivalent rectangular opening. As per Table 5-14a only nozzle sizes up to 12" are mentioned. Does code allow roof nozzle sizes above this? what will be the procedure to calculate reinforcement pad? if it does not allow nozzles above this size, then can we provide 02 nozzles of smaller [dia. 10"] size or rectangular opening of similar area? how will the reinforcement of rectangular opening be calculated.
Please advise.
Thanks
Shine

 

[Dhurjati Sen]

Dear Shine19,

Check for roof manholes in API 650.

Regards.

DHURJATI SEN
Kolkata, India

 

[Shine19]

Thanks Dhurjati Sen
But this opening shall act as roof nozzle, not manhole. also manhole size are 20" & 24" which are not desired.

 

[Dhurjati Sen]

Dear Shine19,

I have come across quite a few roof appurtenances where the size is 14", 16" or 18". Use RF pads as per Table 5-14 A.

However, if it is not in the code then it is non-standard and you ought to avoid such sizes.

Regards.

DHURJATI SEN
Kolkata, India

 

[Shine19]

Yes
We got the size 14”

 

[IFRs]

The ODs of the repads listed is consistently a little less than the ODs for shell nozzles. It would be good engineering judgement to either continue that for larger nozzles or use the shell nozzle repad size.

 

[JStephen]

It is not uncommon to have larger roof nozzles when required. This is generally considered a less-critical area.
While the standard only gives certain sizes for round nozzles and round manways, it includes rectangular manways up to 3'x6' with a statement that anything larger shall be designed by an engineer (5.8.6.3), so it does not seem to be the intent to limit the size of nozzles or manways.
For some of the tanks falling under Annex F, the roof nozzles are required to be detailed like shell nozzles, which would allow a wider range of sizes.

 

[Shine19]

Thanks all for the help