Center portion of elliptical and torrispherical heads 1

[TankTheFrank]

What is the code case that allows the center 80% of an elliptical and torrispherical head to be calculated as a hemispherical head?
API 510 allows it in para 7.4.6, ASME infers it in the nozzle calc in UG37, and API 579 has it in their head calcs in para 2C.3.5 and 2c.3.6... but I cannot find anything that allows it for NBIC... I am assuming that having an ASME Code Case would be ok.

 

[david339933]

NBIC should refer you back to the original construction code.

 

[TankTheFrank]

I can't seem to find it in ASME Section VIII Div 1 so I thought it was in a code case. I remember the center 2/3rd or 80% of the head can be considered hemispherical... do you know where that is referenced?

 

[chicopee]

Mathematically it makes sense because you can approximate the surface area of an ellipsoidal sector with a spherical sector as long as the axis of the ellipsoidal sector is large and I am thinking at least 8 feet.

 

[SnTMan]

"considered hemispherical..." for what purpose?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[david339933]

Yes, you get a bonus when calculating tr when then nozzle + reinforcement is within 80% of head diameter. UG-37 under definition of tr.

 

[jte]

TankTheFrank- Are you perhaps thinking of VIII-1 Appendix 32? Specifically 32-6(h)?

 

[TankTheFrank]

jte - yup... that's it... I knew I've seen it somewhere... thanks!

 

[chicopee]

"... but I cannot find anything that allows it for NBIC..." You should not find the information in this document as it deals with inspections after installations, repairs, alterations, safety appliances, and rerating. Read the purpose and the scope of the NBIC.