Shell and roof manhole

[Syahar1975]

As per API 650 the roof and shell manhole flange are fabricated from the plate.

I understand sometimes the client has their own specs which is different from API.

Have you ever seen the flange of 24" shell and 24" roof manhole made from 24" Flange RFSO 150# and cover made by 24" 150# Blind Flange RF?

From the weight off course this would be heavier. Maybe from the cost also more expensive.

 

[IFRs]

It exceeds the requirements, ergo it is OK.
Yes it is heavier and more costly.
Yes I have seen them...

 

[Duwe6]

I have indeed. They look, and are, ignorantly heavy and require a davit arm to open & close. API is sufficiently conservative in their design criteria; adding massive items in *not* an improvement.

 

[11echo]

it's semi-rare to have manways that large on tank roofs, at those sizes they are normally for side mounted for actual entry into the tan), the so-called "roof manways" are at 10" to 18" and they are really just inspection ports, to check interior trim like target board indicator float & guyed wires ...etc, NOT to enter the tank through the roof. IF you did, it would be necessary to now have a platform to deal with entry and any davit to lift a ASME B16.5 blind off any roof flanges. Tell your client that they'd followed API-650 for tank construction, follow the part about "thickness of shell manholes cover plates" (Table 3-3 pg. 3-12) ...Good Luck!

 

[Syahar1975]

Good morning Gents,

Thanks for your comments.

This is really new for me. Even 6 M dia meter tank they are using RFSO flange and RF blind flange for shell manway. Yes we have davit arm.

With 130 mmBar design pressure for the bigger tank I don't see the advantage of using this ASME B16.5 flange. Yes we do not need to buy, fabricate the 20 mm plate.


But I am still believe the overall cost of the plate + bolts and nuts still cheaper than ASME B16.5 flange for this case. Manway from plate only require 5/8 x 85 mm bolt while ASME flange will require 1 1/4" x 175 mm. Maybe not to much for 1 tank but we have 18 tanks.

 

[Duwe6]

You should be able to buy prefabricated API 24" shell M/W's and 20" roof M/W's. They are used so much, they are available as a 'commodity' item. Cheaper than making them yourself.

 

[valleytank]

What Duwe6 said. Why in the world would you even consider the alternative originally posted?

Anyone else getting tired of people doing everything and anything possible to cover their butts no matter what the cost and effort vs doing a little research, crunching some numbers if needed, and making an economical and code acceptable decision?

 

[Syahar1975]

Duwe6 / Valley Tank,

I have never heard there is ready stock 24" roof and shell manhole in the market.

If there is (especially in GCC region) please advise me the website.

Sure this would be much much cheaper.