API 650 Tank - Intermediate Wind Girder design - For Tank with Firefighting system 1

[citrix12]

Dear All,

We are designing a Tank with Deluge System (Fire water ring) provided near Top of Tank Shell. The Tank also has an intermediate wind girder (I.W.G) with "T" cross-section located below the firewater ring.Can anyone share your thoughts on the design requirements to be considered on the I.W.G?

In particular, i would like to know, if there is any standard requiring holes to be provided on I.W.G to allow the deluge water to run down smoothly over the Tank shell and to avoid corrosion of I.W.G due to water stagnation.

Comments/thoughts would be appreciated.

Thanks

Arun

 

[JStephen]

See API-650 Section 5.9.3.3.
I assume you don't plan to regularly ignite the tank, so the fire water system is not an issue. The drain holes are so rain and condensation don't accumulate there.

 

[r6155]

The fire water system shall be tested frequently
Intermediate wind girder obstruct the water to get wet the shell under the girder.

Regards
r6155

 

[citrix12]

Thank you JStephen & r6155. For your additional info, I also noted another reference in Shell DEP 80.47.10.31, cl. 4.2.6, which reads "Where reinforcing rings, supports, stairs, platforms, nozzles, manholes etc. interfere with the spray patterns or the rundown water layer, additional spray nozzles shall be provided to guarantee complete coverage (including appurtenances)."

Also, in one of a Client specification for Tanks, the requirement given is as follows "Additional water spray ring of tank shall be provided at the nearest level below the tank wind girder.".