Bolted Flat Cover design with an opening in it.

[DK44]

Dears,

Kindly advise me on following:
1.Design problem: Heat Exchanger Designed to ASME Sec VIII Div 1 + TEMA-R, having Flat Bolted Channel Cover with an opening in it

2.Applicable rules are found to be UG 34 together with UG 39.

3. It is observed that thickness required per UG-34 fails when UG-39 is applied with a value using double under the root in the formula at UG 34.

4. When we consider UG-16(a)which allows to use Div 2 rules, together with the provisions of APP 46, Design By Analysis (ex FEA) can be considered since Div 2 does not cover Reinforcement of opening in the Bolted cover.
4.1 Is it permitted to take this route and Pass with UG-34 basic thickness formula (without doubling the value under root)even with an opening in it meeting other requirements of UG-39, and will it be agreeable to AI, provided it passes FEA accordingly.

 

[SnTMan]

3. It is observed that thickness required per UG-34 fails when UG-39 is applied with a value using double under the root in the formula at UG 34.

I am having trouble making sense of this statement. Does doubling the subject quantity not increase the thickness as required by UG-34? How can this result fail UG-34?

Regards,

Mike

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

 

[DK44]

Thank you SnTMAN
I try to elaborate the subject as below:

1. Bolted Flat circular covers are designed per UG-34(c)(2)eq(2). This does not consider reinforcement of opening in it.

2. UG-39 (d)(2) rules for reinforcement of opening in Flat Head, gives an alternate approach to double the value under root of formula at UG-34 (c)(2)eq(2). It is found by calculation thickness of cover by this, increases considerably over above UG-34 equation .

3. With a view to optimise the thickness to above UG-34 formula, code alternate approach is considered as allowed per UG-16(a) to use Appendix-46 provisions which in turn allows to use Div 2 method with certain limitations.
3.1 However, as there are no rules in Div 2 for reinforcement of opening in Bolted Flat Covers, it allows at App 46-4 to use Design by Analysis, which is understood as FEA method.
3.2 Finally, if we follow the FEA, Channel cover Thickness is generally found to pass UG-34 Value thus achieving the optimisation.

4. The question is whether what is outlined at (3) above permitted by code and acceptable to AI?

 

[SnTMan]

DK44, 2. Yeah, understood, that is the point of it.

4. No idea

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

 

[r6155]

Avoid openings that connects with piping, only use opening for instruments.

Regards

 

[IdanPV]

Per U-2(g), Where complete details of construction are not given, the Manufacturer, subject to the acceptance of the AI, shall provide the appropriate details to be used.
And where design rules do not exist in ASME VIII-1 you may use FEA per ASME VIII-2 & Appendix 46.

As far as I understand it, you do have design rules and formulas in ASME VIII-1.

It pretty much depends on your AI so you may ask him and try to convince him.

 

[DK44]

Thank you IdanPV (Mechanical)

According to the provisions of the code rules, do you mean to say that the Bolted Flat Channel cover Thickness of a Shell & Tube Heat Exchanger Designed to ASME Sec VII Div 1 shall be greater of following:
a) Thickness as per UG-34 alone.
b) Thickness as per UG-34 together with the provisions of UG-39
Please confirm.

 

[IdanPV]

If you have a single (or multiple) opening in the cover, you can use the alternative way to deal with it [(d)(2) instead of (b)(1)].
As far as I understand it, you just found the "design rules" to calculate the required thickness. Therefore, FEA in accordance with MA 46 & ASME VIII-2, Part 5 is prohibited.