ASME B31.4 - Branch connection - special spool (body filter)

[Fario]

Hi guys,

I must to make a design about ASME B31.4 for a special spool. This special spool is the basket filter body, with 36 inch header pipe and 24 inch to input and output.
Pd = 285 psig, 12,7 mm WT in header, corrosion allow. = 0,0, Hoop Stress = 71 [MPa], ASTM A53B with Sy = 240 [MPa], then hoop strees / Sy = 30% and D branch / D header = 24/36 = 67%.
In Table 404.3.4-1 Design Criteria for Welded Branch Connections...... says See para. 404.3.4(a).

Now my question,

In para. 404.3.4(a) says... "Smoothly contoured wrought tees or crosses of proven design or integrally reinforced extruded headers are preferred"..... says are preferred, this means that it is not mandatory and I can make the body filter with fishmouth?.
I have calculated whether or not reinforcement is necessary.... and NO... not necessary (pad o saddle).

Anyone can say me if i am inside or outside of ASME B31.4 specifically in this detail?


Cheers
Derek Marshall

 

[mk3223]

Should the basket filter be outside the B31.4 scope? Instead, it may be made per ASME Pressure Vessel Code.

 

[Fario]

Hi mk3223

the answer to your question is NO.
The basket filter must be covered under ASME B31.4, that is the final client requirement.
In summary, the basket filter will be a spool (piping) designed per ASME B31.4

 

[LittleInch]

It seems rather odd that you don't just go an buy a filter, but yes, you can make a fabricated tee / joint if you follow the re-inforcing rules.

Seems rather odd that you don't need any reinforcement or pads, but if that's what you come out with then yes, you can make it.

But it is very odd. Have considered stress concentration and other forces acting on the filter?

Put it into an FEA / stress model?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Fario]

LittleInch

1. ok, thanks. Then I understand that I can to made the basket filter body with "fishmouth" for the branchs.

2. If I to define the thickness of the header in 9,53 mm ..... need reinforcement, but if wall thickness is 12,7 mm is not necessary because the minimun thickness to Pd = 285 psi is 5,7 [mm] for 36 inch according to ASME B31.4, then the thickness excess are 7 [mm] (is a huge area...4.963 mm2 > 3.071 mm2), also for example ASME B31.4 is pretty more relaxed than ASME VIII D1, in my case ASME B31.4 has S adm = FxExS = 0,72 x 1,0 x 240 [MPa] = 172,8 [MPa] (ASTM A53 B) and ASME VIII D1 has S adm = 118 [MPa] @ 40 C. If I to calculate the same filter per ASME VIII D1, needs reinforcement still with 12.7 wall thickness for the header.

3. NO. I am just following the para. 404.3.5 (b) ASME B31.4 standard "rule that the metal area available for reinforcement shall be equal to or greater than the required cross-sectional area".

4. I try not to use this tool in easy problems, my doubt was only if ASME B31.4 is mandatory or not when says .... "are preferred" in the para. 404.3.4(a) or if anyone have passed for the same doubt.

thanks LittleInch