Partially drilled holes in Flat Cover ASME VIII-1

[jakov11000]

Hello,

I am reviewing a design of heat exchanger - cilindrical shell (heat transfer plates inside) with flat heads designed to ASME VIII div 1.

Each flat head have 8 partially drilled holes (d=25mm). Holes are 40 mm deep and are drilled in 50 mm thick flat cover (Cover material SA516Gr60 - required thickness is 34mm). The purpose of the holes is to attach supports to flat heads. Diameter of flat heads is 792 mm (OD). Design pressure 15 barg, design temp 370 degC.

My question is:
Is there a requirement in section VIII-1 (or somewhere else) regarding partially drilled holes in flat heads?
Appendix 30 of VIII-1 talk only of "Partially drilled radial holes in cylindrical and spherical shells" not in flat covers.

Thanks

 

[SnTMan]

jakov11000, not really AFAIK, but see UG-43(d) for margin below a tapped hole.

Regards,

Mike

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

 

[TGS4]

Section VIII, Division 2, 4.3.9 had rules applicable to this situation.

 

[Fizza453]

4.3.9 is applicable only for spherical and cylinderical surfaces, see 4.3.9.2.



Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi

 

[XL83NL]

My first pick would be UG-43(d) as well, as Mike already mentioned.

For VIII-2 in the 2015 edt, 4.3.9.2 is still for spherical and cylinderical surfaces.

 

[TGS4]

Fizza453 and XL83NL are correct. However, in VIII-2, 4.5.3.1(b) may apply. "Partially tapped holes for studded connections shall not penetrate within one-fourth of the wall thickness from the inside surface of the vessel after deducting corrosion allowance"

 

[XL83NL]

On a side-note; would the partially tapped bolt holes of the below example of a 'flanged' nozzle (which is an integral part of the shell - not attached by welding but machined from the same piece of bar as the shell) also be considered to fall under the UG-43(d), when it comes to minimum required wall thickness between the shell's ID and the end of the bolt hole?

 

[SnTMan]

XL83NL, looks to me like this is specifically addressed by UG-43(d).

Regards,

Mike

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

 

[GenB]

Small holes will do nothing to the head. CA lculate for full openings and reinforce accordingly. Use the extra HD t. And you'll be okay. Don't forget to check for ligament reinforcing in case the openings overlap. Genblr.