1 reply to this topic

[seth]

Dear Professional,

I just want to know the following.

1. I just want to ask some clarification regarding introducing an annular plate to the bottom plate of a Tank. In API 650 Standard except BSEN 14015, i never found any reccommendation regarding introducing an annular plate and to what minimum tank diameter. our Client insist to design according to API 650 wherein in sec. 5.5.2 they mentioned only the minimum annular plate width but the application of annular plate to what diameter limitation is not available.

2. Tank Roof Walkway, for walkway application also, when can we say that at a certain diameter it is reccommended to introduce a walkway.

3. For Spiral staircase, when can we say that spiral staircase should be introduced and to what minimum tank diameter.

4. In introducing an emergency vent, It is important to introduce an emergency vent on non frangible roof type, roof vent has been provided already. anyway type of fluid to be stored inside is lube oil.

Thanks,

Seth A. Duazo

[Hyper]

hi
1- According to 5.5.1 of API 650,When the bottom shell course is designed using the allowable stress for materials in Group IV, IVA, V, or VI, butt-welded
annular bottom plates shall be used.
But When the bottom shell course is of a material in Group IV, IVA, V, or VI and the
maximum product stress for the first shell course is less than or equal to 160 MPa (23,200 lbf/in.2) or the maximum hydrostatic test stress (see 5.6.2.2) for the first shell course is less than or equal to 172 MPa (24,900 lbf/in.2), lap-welded bottom plates may be used in lieu of butt-welded annular bottom plates.

2&3-walkway & staircase nessesity have been specified in the client basic design.
but ussually tanks need to walkway & stairway for access to roof .(i think its necessary).
also you can consider wind girder or stiffening ring as walkway.
A stiffening ring or any portion of it that is specified as a walkway shall have a width not less than 710 mm (28 in.) clear of projections
including the angle on the top of the tank shell. The clearance around local projections shall not be less than 610 mm (24 in.). Unless the tank is covered with a fixed roof, the stiffening ring (used as a walkway) shall be located 1100 mm (42 in.) below the top of the curb angle and shall be provided with a standard railing on the unprotected side and at the ends of the section used as a walkway.