Guy Wires Connected to API 650 Storage Tank Roof

[withak36301]

The question has come up as to whether reinforcement pads are required when guy wires are connected to a API 650 storage tank roof via a lug. The lug is a vertical plate welded to the roof that has a hole in it for the guy wire.

I've looked at API 650 and it does not appear to address attachments like this on the roof. Does API 650 address this? IF so, where? Also, if I was to evaluate for the need of reinforcement, what would be the best approach? Please advise.

 

[MJCronin]

I guess my question is "Why do you want to attach the guy wires ?"....

Was there some kind of mistake in the original design of the tank ? Are the wires for wind loading ?

I suggest you consider using a standard pad-reinforced design for a pressure vessel lug

MJCronin
Sr. Process Engineer

 

[JStephen]

I don't think there's anything in the standard relating to that.

I'm not aware of a good approach. You can treat a cone roof as a cylinder with radius equal to the normal radius of the roof, which will be very large for a low-slope roof. You can use the approximation that Bednar gives for line loads on a cylinder. The result will be very low allowable loading. If the roof is steeper or thicker, it will help. If you can run the guy lines to the top angle, you have more to work with. If you use struts instead of guy lines, you could run bracing between rafters to transfer loads to structure below (assuming there is structure below).

 

[withak36301]

MJCronin, The guy wires are attached to a nearby scrubber stack, separate from the tank. Don't know if that helps, but that's what I'm looking at.

JStephen, thanks for your reply.

 

[MJCronin]

I agree with JStephen.... attachment to the angle at the top of the shell is far superior to a pad attached to the roof

Consider gusset reinforcements of the angle for this connection.

MJCronin
Sr. Process Engineer

 

[IFRs]

Can't talk about this without knowing the loads imposed.