Using Manway as Nozzle

[starrproe]

We have a 24" manway with standard flanges per ANSI B16.5 in a 8840mm dia. process column.Our Process engineers want to do some modification, for which they need to use this manway as an inlet nozzle by cutting a 16" opening in the blind flange and connecting it with a 16" line.

However, this doesn't seem to be feasible from strength considerations, as ASME code doesn't seem to allow it(Per UG-39, Only openings in size upto half the head dia. are allowed, for bigger openings, App. 14 is referred to.)

On taking a quick glance at App.14, I noted that this probably doesn't address bolted connecions, it is applicable only to integral connections.

1. Am I correct in my understanding of App. 14?
2. If yes, Can somebody please suggest other methods for evaluating reinforcement of such opening?

Regards,
Starrproe

 

[prex]

You can design the flange as a ring flange per App.2 with an unusual proportion of A to B. Of course you'll get an also unusual thickness, but that's what the code would allow...
More usually you would use a flanged conical reducer.

prex

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[vesselfab]

First thing, you have to make sure the Manway has been designed as a nozzle and not a manway. Basically std wt plus corrosion allowance wall thickness.

As for cutting a hole in the blind, well, it would be much easier to use a 24 X 16 reducing flange and not worry about code calculations.

When it becomes a nozzle instead of manway, the connection flange becomes piping instead of vessel part.

 

[vpl]

You might look at these two previous threads (found through the site Google-assisted search function):

thread794-262240
thread292-257098

Patricia Lougheed

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