Our drawing not showing any rat 1

[Satyenrp]

Our drawing not showing any rate hole for the Wind girder.

Please advise us is it really require?????
Because Our Engineering team told us It is not necessary since It will impact on Wind girder strength. However as per API 650 5.9.3.4 we have to make notch to avoid cross weld with vertical weld seam.

 

[LittleInch]

Yes it is required as you note in API 650.

If nothing else it will stop the wind girder filling up with water....

That's a pretty tall tank alright.

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

 

[HTURKAK]

API 650 '5.9.3.3 Rings that may trap liquid shall be provided with adequate drain holes. Uninsulated tanks having rings shall have small water-shedding slopes and/or drain holes or slots unless the Purchaser approves an alternate means of drainage...'

I think the requirement is clear ...

 

[JStephen]

Drain holes are required, but are not required to be rat-holes at shell verts. And in fact, it may be undesirable to send all rain running down the shell due to rust streaks, etc. From a strength standpoint, preferred location would be near the center.

There was another recent thread on the rat-holes, and the way I read that statement, the rat-holes are allowed, not required.

 

[IFRs]

API 650

5.9.3.3 Welds joining stiffening rings to the tank shell may cross vertical tank seam welds. Any splice weld in the ring shall be located a minimum of 150 mm (6 in.) from any vertical shell weld. Stiffening rings may also cross vertical tank seam welds with the use of coping (rat hole) of the stiffening ring at the vertical tank seam. Where the coping method is used, the required section modulus of the stiffening ring and weld spacing must be maintained.

The way I read this section is that the first statement says you may cross shell verts, without prejudice or anything special. Then it says that you may use a rat hole if you maintain the stiffener strength.

If they intended rat holes to be required, the first sentence would not be there.