"Local Thin Areas," section VIII div 1 2

[Nubcakes]

Shells and hemi heads have mandatory appendix 32 in section VIII div 1 as guidance for calculating a "local thin area." Is there an acceptable method of calculating a local thin area (such as a bolt hole) for flat heads and/or tubesheets?

 

[TGS4]

Bolt holes are not LTAs. Nevertheless, there are no existing rules for LTAs in flat plats or tubesheets - see U-2(g).

 

[SnTMan]

Nubcakes, assuming you are talking of blind holes, only rule that might be considered applicable is UG-43(d). See the third sentence.

Regards,

Mike

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

On Edit: In reality, the presence of a few-ish, small-ish holes such as tie rod holes in tubesheets or for studs attaching a blind flange to a flat head with inspection opening is routinely ignored.

 

[Nubcakes]

In this case specifically, the holes are being used to attach a non-Code water box to the tubesheet of a single-pass evaporator. On a lot of other units from this manufacturer, those holes are located outside of the pressure boundary making it act as a sort of flange, but with these units the holes are inside the pressure boundary.

Is anybody aware of something that can be used outside of the Code that they can utilize via U-2(g) for such a case as this?

Thank you for your helpful replies, by the way.

 

[SnTMan]

Nubcakes, at a previous employer we often used that type of construction. Long-standing practice, moderate temperatures and pressures, air and water. Nobody bothered much about it

Regards,

Mike

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

 

[TGS4]

If you are referring to partially-drilled holes for studded connections, you could also apply the rules in Division 2 - 4.3.9.

 

[SnTMan]

TGS4, not at all familiar w/ Div.2. It'd be nice to have some rules to "borrow", assuming it comes out favorably

I'll see if there's a copy around here somewhere...

Thx

Mike

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