Full Encirclement Sleeve Fillet Weld Calcs

[Krausen]

I’m installing a permanent Type B full encirclement sleeve around a large line that has a local thin spot on it (but not actively leaking). New Type B sleeve will have pressure-containing circ seam fillet welds. I have run some calcs on the new sleeve circ seam fillet welds to check the total bending stress on them. I’m getting very high total combined bending stresses on these fillet welds due to the eccentricity of the load path. Much higher than B31.3 code allowables. Looking to see if anyone may have a helpful calc procedure or spreadsheet for this to help me confirm these high fillet weld stresses I’m getting? Trying to see if my calcs are realistic or not. My thought is they are over conservative, as I think about similar circ seam fillet welds on slip-on flanges for example, where you have the same eccentric load path taking place at the fillet weld btw slip-on flange & straight pipe. If my current calcs are valid, I don’t believe the code would ever allow the fillet welds btw a slip-on flange & straight pipe, which I know is not the case. Thank you in advance

 

[akpipelineengr]

I've never tried to calculate the bending stresses in a sleeve fillet weld. Most folks just follow the limits in API 579. I'm not sure how you could develop huge bending loads with the sleeve tightly fitted to the parent pipe. There is certainly some stress concentration, but the loads should be significantly less than with slip on flanges or socket welds. Perhaps you can share some of your calculations and assumptions?

 

[MJCronin]

Some piping codes only permit fillet/socket weld joints up to a certain diameter.

Because a slip-on flange/sleeve exists in a certain diameter, it does not mean that the joint is permitted by your code of record.

Oh, and BTW .... what is your code of record ?

Is your sleeve being installed in order to retain liquid pressure ?

Please give us more information aboit piping magterials, design/operating temperatures and pressures etc..

How many of these sleeves do you want to install on you system

Can you provide a sketch with dimensions ??

MJCronin
Sr. Process Engineer