Vessels Manways 2

[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.

 

[KevinNZ]

Company, local or national regulations should have requirements for access and confined space work. Our national standards cover wide a range of requirements including required training and rescue provisions.

Regarding manways, DN750 is often the minimum plant owners now require.

 

[David3399]

12" x 16" elliptical manway or 16" diameter is minimum per Sec. VIII.
Provincial regulations will usually coincide with these minimum sizes. Site specs may be way different.

 

[Krausen]

Anyone who's ever had to actually enter a vessel manway would never design one to 18". 24" should be the minimum size. This is written in many of the major company design standards

 

[LittleInch]

The length of the manhole is also important in terms of ease of entry.

But is this existing and you don't want to go in (anything less than 24" is difficult) or in design?

Smallest I can recall is 24" unless its a really small vessel and you only need to reach in with your hands or just stick your head inside.

 

[dgeesaman]

Anyone who's ever had to actually enter a vessel manway would never design one to 18". 24" should be the minimum size. This is written in many of the major company design standards

Whenever I see manways like that I think of the Amazing Yu character in Ocean's Eleven.
"We've got a grease man!"

 

[r6155]

Manhole diameter is defined by:
1) during fabrication inspections, test and NDE.
2) dismantling internals for repair, replacement, etc.
3) weld repair during service.
4) special elements for cleaning, painting, etc.

 

[Krausen]

Manhole diameter is defined by:
1) during fabrication inspections, test and NDE.
2) dismantling internals for repair, replacement, etc.
3) weld repair during service.
4) special elements for cleaning, painting, etc.

Per the American Society of Common Sense (ASCS) - Manhole diameter is defined by:
1) An internal diameter everyone can fit thru