L4 in ASME B31.3 Branch Calculation

[onrush]

Dear member,

When we calculate the branch reinforcement as per ASME B31.3 para.304.3.3, L4 is defined as height of reinforcement zone outside of run pipe. And Fig 304.3 indicates that L4 is the height of limits of reinforcement zone.

My question is,

when we calculate the reinforcement area generated by fillet welds to be included in area A4, the fillet weld leg dimension to be used for area calculation should be within L4 height?

For example, fillet leg is 6.2 mm as per para.328.5.4 and L4 is 3.2 mm as per para.304.3.3. Then the fillet leg for calculation should be reduced considering L4?

I am so confused because some excel calculation sheets do not consider this, but others do.....

If we do not need to consider this, what is the background?

I guess that we should reduce the fillet leg for calculation when it is larger than L4 based on example H4 of appendix H (sample calculations for branch reinforcement) of ASME B31.3.

Please help me....

Thanks in advance...!

 

[nickelkid]

H304 Example 4 provides a clear case of "total reinforcement area" that is "greater than the required area" and states that "minimum size fillet welds would provide adequate reinforcement". The example does not reduce the total available reinforcement area to the required area. Why wouild you do it anyway?

Additionally, the throat dimension of the fillet weld is a minimum of 6 mm per 328.5.4

 

[onrush]

Dear RCHandy,

Very thanks for the reply.

However I am still confused.

Of course the minimum throat dimension of fillet weld shall be 6 mm as per 328.5.4.

The point is whether the fillet leg dimension to be used for branch calculation shall be reduced considering L4 or not when fillet leg dimension is larger than L4. Of course the actual welding size shall be same as per 328.5.4, not changed.

I am saying the numbers only for calculation....

Howe do you think about it?

 

[nickelkid]

Your calculations should refect what your are going to fabricate. From what I understand you will have more reinforcement that the code requires and that is ok.

Besides having a calculation that shows you have only the reinforcement required, and not excess, what are you gaining?