Vessels Manways

[Inchtain]

According to the relevant standards and codes, is there a minimum recommended diameter for a manway e.g. 24 inches." , so that the entry into the vessel can be refused due to safety reasons.

Is that also valid for entering pressure vessels for inspection during total shutdown of the Plant?

Regards,

 

[r6155]

Please be clear: what kind of safety reasons?

 

[jt1234]

UG-46 is very clear what minimum size of manway or inspection hole must have. As long as you meet that criteria, your entering of the manhole is at your own risk, no one can stop you. Any concern, you'd better hire a hole watch to recue you in time. However, making sure well ventilation and no residual gas, liquid that can harm you.
The minimum size I have done is 18" ID because owner wanted to save cost, and as big as more than 100" ID for special internals to get in and out.
Nowadays, since American are getting bigger, 30" could be the trend.

 

[r6155]

One person must remain outside while you are inside. Both people must maintain eye contact at all times.