Shell to Bottom Fillet Weld Sizes - Leg Length or Throat Thickness??

[sajk14]

Hello All,

I would like to get clarification on a couple of things regarding shell to bottom welds..........

1) Clause 5.1.5.7 - Are the fillet weld sizes shown in the table referring to 'Leg length' or 'Throat thickness'?
My original understanding was that the table specifies the minimum Leg length required for the fillet weld.... However Clause 5.1.2.2 states that fillet weld sizes should be based on the cross section or 'throat' of the weld (provided i have deciphered the over complicated text of this clause correctly!)

2) Figure 5-3C shows detail of a Double Fillet Groove Weld for Annular plates greater than 13mm.
If you have an Annular plate say 10mm thick can you just have a fillet weld either side of the shell without having to chamfer the bottom edge of shell plate? I.e looking at figure 5-3c there is no requirement to have a weld for dimension 'B' you only need to have a weld for dimesion 'A'?

What is everyone elses thoughts or interpretations on the above points?

 

[JStephen]

Section 5.1.2.2 doesn't mention "throat" that I see, are you looking at an older edition?

Section 5.1.5.7 should give leg lengths.

Figure 5-3C is for annular plate over 10mm, otherwise, you just have the fillets per 5.1.5.7(a) and Fig. 5-3(a).

 

[IFRs]

Fillet welds are always measured by leg length. Their strength is calculated with the throat area.
5.1.5.7 is giving leg lengths
Figure 5-3C does not apply to annular plates under 1/2".

 

[sajk14]

Hi J Stephen,

My API 650 code is the ELEVENTH EDITION, JUNE 2007 - Addendum 3, June 2011 (Effective Date September 1, 2011)

Clause 5.1.2.2 in this edition states the following............

"The size of an equal-leg fillet weld shall be based on the leg length of the largest isosceles right triangle that can be inscribed within the cross-section of the fillet weld. The size of an un-equal leg fillet weld shall be based on the leg lengths of the largest right triangle that can be inscribed within the cross-section of the fillet weld."

I feel this particular clause in the code is poorly worded or difficult to interpret. When i read this paragraph it sounds like they are talking about the throat of a weld? However as i say it is not clear what the code actually means! what do you think it is saying?


IFRs...yes i agree with your comments also, thanks for the second opinion.

what is your interpretation of the above clause 5.1.2.2 statement taken from the code?

 

[IFRs]

I think 5.1.2.2 is pretty clear and unambiguous. There is no mention of throat or area or strength. It is simply geometry.

 

[JStephen]

That's what I was reading, it nowhere mentions "throat", and says "based on the leg length".

 

[sajk14]

ok guys,

So we can all agree that this statement has no relevance on the actual sizing of a shell to bottom fillet weld but is just merely defining the geometry of a fillet weld.

Thanks for you thoughts and comments on the matter.