Manhole size per Asme VIII 3

[MhFitri]

Hi guys,

I`m designing a atmospheric/low pressure horizontal tank with opening for manhole of 600mm and i use 24" Flange for the manhole flange and blind cover. The thing is, client and fabrication team asking to reduce the thickness and number of bolts of the flange. The reason is because the thickness cause the blind flange be too heavy for the system and operating people. Any opinion is most welcome. Thanks in advanced

 

[Tothesky]

SEE ASME SEC. VIII APP.2 AND UG-34.

OR CLIENT ACCEPTS OTHER CODE OR STANDARD, YOU CAN USE 'JIS CODE' ( <--- JAPANESE CODE.)
IN ASME, MIN. FLANGE RATING IS 150 PSIG ( 10.5 KG/CM2G).
BUT, JIS CODE PROVIDES FLANGE RATING BY 5 KG/CM2G.

REGARDS,
MOON.

 

[r6155]

See AWWA C207.
Use davit

Regards
r6155

 

[r6155]

Also try with API 650 for manhole flange and blind flange

Regards
r6155

 

[SnTMan]

MhFitri, if you could reveal your Code of construction (if any) you might get some truly applicable advice.

Note also that hinges / davits / etc are often used on manway covers to avoid having to physically handle them.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[DSB123]

Manhole flanges and covers are generally designed rather than using a standard rating flange from B16.5. Also the cover is normally provided with a davit to aid removal. If you do not know that I think you definitely need to get your tank calculations reviewed by a competent vessels engineer.

 

[MhFitri]

The manhole blind cover is connected with the davit arm. Previously they were agreed to follow B16.5 flange. However during fabrication the team wishes to change the flange and did not follow B16.5 since it was too heavy and the number of bolts was too many

 

[JStephen]

Typically, API atmospheric tanks use specialized flanges and blind flanges (cut from plate) that are substantially lighter than 150# flanges. They have more bolts but of smaller size.
Similar flanges would be used on AWWA, NFPA, and UL atmospheric tanks.
AWWA C207 plate flanges and blind flanges are available, that are lighter than 150# flanges, but heavier than the manway flanges in the tank standards. They generally have the same bolt patterns as the heavier flanges. For vessel use, they would be designed by the vessel code, and may not meet the code when designed that way.
Elliptical in-swing manways are also available.
Various quick-opening manways are commercially available, but won't necessarily meet the tank standards above.