ASME Sec. 8, Div. II, Cl. 6.1.6.3 (c), Weld peaking Height (dp) calculation.

[prasad26]

Dear All,
I am new to code hence please bear if my understanding is not clear.

As per ASME Sec. 8, Div. II,
Cl. 6.1.6.3 (c) If the vessel is operating at a temperature where the allowable stress is governed by time dependent properties, or
if a fatigue analysis is required, the allowable value of dp shall be determined using paragraph 4.14 and shall be shown in
the Manufacturer's Design Report.

For my vessel fatigue analysis is required. So according to the clause above allowable weld peaking height needs to be mentioned in design report.
But ASME code does not specified how to arrive at weld peaking height (dp).
Also referring to API-579 Fig. 8.11, values of a1/ a2 or b1/b2 is not specified.

Kindly guide how should I prepare template for checking weld peaking height.

Thanks in advance.

 

[prasad26]

Kindly help

 

[TGS4]

The weld peak height is the difference between an idealized cylinder and the actual weld peak - as shown Figure 6.1. What, specifically, is your question/concern?

 

[prasad26]

My main concern is with this point only.
If it is the one which we can find after welding, how we can show its allowable value in manufacturer design report before actual manufacturing.

 

[TGS4]

You can determine the maximum-acceptable value based on the fatigue analysis - and then you can steward your fabrication and inspection programme to that. Excessive peaking would result in an NCR.

 

[prasad26]

Thanks for your valuable reply.
We are moving ahead with FEA analysis for allowable limit.
Meanwhile can you please let us know any book/code reference from where we can calculate this height manually.
Also while drawing template, I came across some confusions.
This peaking height shall be check for Cat. A welds. Its fine for my shell & Hemi head.
But at shell to hemi-head joint, shell is extended (negative SF) to match hemi-head profile.
Can I exclude this joint as profile is straight line + curve, peak height will not be applicable.

 

[TGS4]

This is a question more appropriately to be asked of your analyst. If the design is sensitive to weld-peaking, then you will need to figure out a way to measure it. Otherwise, no.

 

[Duwe6]

Peaking typically refers to Out-of-Round condition, caused by longitudinal seam welding
Weld-induced changes on a circumferential seam are usually 'Hoop Shrinkage' related, and not nearly as detrimental as 'Peaking of a long. seam

And yes, the weld-induced deflection - 'Hoop Shrinkage' - of the head-to-shell weld for a hemi head is still a Category A weld, as are all the long. seams of the hemi-head. [think 'orange peel']. Check the illustration in VIII Div-1, Figure UW-3.