Low Nozzles Violating API-653 Weld Spacing 1

[TankDude]

Does anyone have any advice regarding steps to take when evaluating new shell nozzles that have been installed in a tank and that do not meet current API-653 weld spacing criteria?

 

[KiwiTanks]

I would say unless you can find another code that it complies with, then the only thing is to remove, patch and reinstall the nozzles at the API653 code compliant spacing.

Would be interested in others comments too...

 

[JoeTank]

Don't go cutting and slashing just yet!!!! API-653 doesn't specify the spacing for installation of new nozzles. It refers you back to API-650. Or are you referring to existing nozzles added to the tank sometimes after its initial construction? That said, how can we offer any advice when you've not helped us know more about the problem? How about shell thickness, materials, nozzle size, actual spacing? Any tidbits would help us help you.

Joe Tank

 

[TankDude]

In short the nozzles were installed using tombstone-style insert plates but the nozzle centerlines are below the minimum centerline specified by Table 5-6. As a result the minimum weld spacing dimension 'D' per Figure 5-6 has not been met.
The tank has already been hydrotested and sits on a concrete ringwall. The tank is 42'-6" Dia. x 45' High, 3/8" tub ring thickness. The material is unknown.
The insert nozzles range from 4" to 12" diameter.

 

[IFRs]

Check API 653 section 9.10.2.7 - does this fit your situation?

 

[JoeTank]

Tankdude,
If the tombstomes are thickened inserts, you can consider the "C" dimension (only 3"), not the "D" dimension. Check out the footnote on the S-N detail.

Notwithstanding that option, there is an old API-653 inquiry that addresses the sad case of finding a problem with weld spacing after the hydro was completed. I believe that API answered it as possibly being okay without repair. Check that out and see how it works.

IFRs,
I don't beleive that 9.10.2.7 applies directly, but I like the tangential thinking on your part. That's the kind of open-mindedness that your clients respect. A star to you.

Joe Tank

 

[BoyTNDT99]

Tankdude,
If the tombstomes are thickened inserts, you can consider the "C" dimension (only 3"), not the "D" dimension. Check out the footnote on the S-N detail.

 

[JoeTank]

Good advise BoyTNDT99. Looks like you cut and pasted directly from my post. What's up with that?

Joe Tank