5 foot manway on storage tank 2

[crosby84]

As the title says, we have a client who wants a 5' manway on the shell...

Now per 650, this wouldn't be a "manway" but would just be a 60" nozzle. Based on some catalog lookups, a flange/blind combo would be a minimum of ~3000 lb (for 75# flange and blind), at a minimum required offset distance from the shell of 16 inches, per 650. I know 650 gives reinforcement requirements based on area, but it doesn't explicitly address the weight on nozzles due to flanges (to my knowledge- please advise if otherwise). Do flanges and blind covers need to be analyzed under Annex P? Or are these considerations built into the 650 reinforcement requirements from 5.7?

 

[JStephen]

I think, neither. I think it would normally be assumed that the weight of a flange, blind flange, nozzle neck, and product in the nozzle neck, are negligible loads compared to the strength of the nozzle.
I would doubt that Annex P could be used on a 60" nozzle, for that matter, but haven't checked to see.

 

[IFRs]

API 650 does not have a 60" manway but it does show a 60" nozzle. I'd use the neck and reinforcing for the nozzle and make a manway plate flange using section 5.7.5.6. The tank shell will be properly reinforced and the manway should be good at the flange.

 

[LittleInch]

Why don't you go for a flush type clean out to 5.7.7 instead?
They go up to 1219 x 1219 opening. maybe not 60", but pretty close and a lot easier to actually get inside the tank

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[crosby84]

LittleInch, we suggested that, however the customer insists that they need 5' to provide access for repairs with large internal components.

I appreciate everyone's responses.

 

[MJCronin]

Has this client actually thought out how the massive manway cover will be handled in the field ?

Has the maintenance department made comment yet.... Or have you only taken instruction from the MBA on the job ?

Will they ask next week for a giant davit and jacking device to get the damn thing off and on ?

Please share with us pictures/drawings of the final design

MJCronin
Sr. Process Engineer

 

[JStephen]

I actually did check the wording in API-650 to see if it restricted you to the manway sizes in there. I think so. It says manways shall comply with table so-and-so, OR may use forged pipe-type flanges and blind flanges.

There's always the exception, but normally little tanks have little nozzles and bigger nozzles are on bigger tanks. So there's probably a presumption that if you're using a 60" shell nozzle, you have some monster tank that it's attached to, and that 3,000 lb weight is not too significant. Now, if you're putting a 60" nozzle into a 40' tank with 3/16" shell, you may have a more questionable situation.

 

[mk3223]

Instead of the many style, is it okay to have a 5'x5' cut out on shell for the maintenance access?
What's the engineering function to spend $ fro a 5' manway for the tank?

 

[MJCronin]

Yes, please tell us the device or machines that requires this 60" manway.

How many of these huge expensive manways does the client want on the shell ? Most clients that I have specified 650 tanks for want two shell manways

(Telling us that "that is what the client wants" is unacceptable

I have never seen a piece of tank equipment that requires a shell nmanway bigger than 40"

Furthermore, if there is something large that must go into and out ofthe tank, a large square access hatch on the roof will be much easier to use.

http://www.eng-tips.com/viewthread.cfm?qid=160574

MJCronin
Sr. Process Engineer

 

[crosby84]

Thank you for the additional suggestions everybody.

They plan on going in these tanks every year and replacing/repairing the internal components, one of which they say is 4'-9" wide. We suggested they cut a slit or doorsheet, but they do not want to cut/weld every year, and want a more permanent situation.

I think at this point we are going to refer them to a tank fabricator who could probably do this project turnkey, which is probably safer and more cost effective than us engineers designing our own davit, and having this project blow up in cost and be dragged out.

Thank you everyone for the input.

 

[JStephen]

Suggestion: Horizontal beam and rolling trolley with hoist instead of a davit.

 

[IFRs]

A hatch in the cone roof may be the hot setup.