Collector with multiple openings

[ElCidCampeador]

Code: ASME VIII Div.1

I have this collector for a water bath heater. It's a pipe, 8" diameter, with multiple openings aligned and evenly spaced. Above these opening are welded with set-on type a series of pipes, diameter 3", which enter inside the vessel for the coil purpose.
Question: what do I check for reinforcement of these multiple openings?
For UG-40 I check the area of the openings and it doesn't overlap the others. Do I have to check anything else? Because in this case the single openings are exempted according to UG-36(c)(3)(a)(-1), but what about point UG-36(c)(3)(c) and (d)? thanks

 

[Jano6924]

ElCid:

Do you have a sketch you can share, showing arrangement, spacing and thicknesses of pipes?

Design pressure, temperature & corrosión, and materials as well.

Regards.

 

[ElCidCampeador]

ElCid:

Do you have a sketch you can share, showing arrangement, spacing and thicknesses of pipes?

Design pressure, temperature & corrosión, and materials as well.

Regards.

Sorry, I can't.

The only image I can show you is this:

 

[XL83NL]

What about materials, design pressure & temperature, corrosion allowance?
And with reference to the drawing; dimensions and spacing of the openings? Kinda hard based on little info.

 

[ElCidCampeador]

I can't say anything else, I'm sorry. I only want to know what rules of ASME apply to check (if required) reinforcement. Material: carbon steel.

 

[Jano6924]

ElCid:

No design data, no details. Hard to provide specific recommendations. Also you mention that you calculate the areas and there is no overlap. The overlap shall be checked using "d" or "Rn+tn+t" use the larger value.

It is my opinion that you shall do the following:

1) Thickness of header (or collector) shall be calculated per UG-27(c)(1) or App. 1-1(a)(1) using ligaments. Thickness of 3" pipes shall be calculated per same paragraphs but no ligaments.

2) Check limitations listed in UG-36(c)(3)(c) and (d).

3) Check fillet welds per UW-16

4) Check 3" pipes thickness per UG-45, see interpretation VIII-1-15-10

5) Calculate reinforcement as needed. If there is overlap then you shall follow UG-42 rules.

6) Check if App. 1-7(a) applies.

Hope this helps.

 

[ElCidCampeador]

1) Ok, passed
2) Every single hole in the collector is exempted acc. to point (-a)(-1), because the hole is about D.65mm (I take the inside diameter, which is the "real" hole in the collector) with a required min. thk of the collector wall of 9mm. Next step is checking point (-c). The sum of the diameters of 2 openings (130mm) is less than the distance between the centers, so it's ok.
Then point (-d). In this case, the holes are all aligned, so cos (angle)=1, so distance between center must be more than 2,5*(sum of diameter). In my case it's less, so I need a reinforcement. Is it correct?
3)Ok, passed
4)Ok, passed
5) No overlap. Now how could I check the reinforcement? Is stil necessary even if the openings have "walls" (the pipes to coil)?
6)Not applicable

thank you

 

[Jano6924]

Yes, since distance between holes is less than 2.5*(sum of diameters) then you need to reinforce at least one opening. Since there is no overlapp between reinforcing limits, and all openings are equal (same "d" same materials and thicknesses) if you reinforce one opening you will have all openings reinforced.

Use current geometry as you have, "d", thicknesses for 3" pipe, collector diameter and thickness, materials, etc. and check if opening is properly reinforced. If it is properly reinforced then you are done, if not then you will need to increase thickness of 3" pipe or collector.

Regards.

 

[ElCidCampeador]

So what I have to do is: check if the extra-area (over the min. thk) in the walls (both pipe and collector) is more than the area which is lacking because of the hole. If yes, it's not necessary to add reinforcement. Correct?

 

[Jano6924]

Follow the procedure shown on Fig. UG-37.1 for "Without Reinforcing Element". Calculate "A" first, then calculate A1, A2 and A43. For your case A3 does not exist.

A1+A2+A43 must be >= A, otherwise higher thicknesses are required.

Regards.

 

[ElCidCampeador]

Follow the procedure shown on Fig. UG-37.1 for "Without Reinforcing Element". Calculate "A" first, then calculate A1, A2 and A43. For your case A3 does not exist.

A1+A2+A43 must be >= A, otherwise higher thicknesses are required.

Regards.

yes, thank you!