UW-21 minimum requirement for External weld for SO Flange

Amr Shams · Jan 9, 2023

In compress,
Using slip on flange in 2" pipe sch.160 will lead to a deficiency in external fillet weld.
" UW-21: External fillet leg minimum (9.02 mm) is greater than the flange hub thickness (7.87 mm) " this message is shown during code calculation. but in UW-21 external fillet " X min = the lesser of 1.4t n or the thickness of the hub ". I think there is a problem with the software in determining the minimum requirement of External fillet leg. What do y'all think about that ?

Cobra17 · Jan 10, 2023

9.02mm is greater than the hub thickness of 7.87mm, so you can only put a 7.87mm weld on the hub.

tn = 8.7mm (2" SCH 160)
Hub = 7.87mm

Xmin1 = 1.4 * tn
= 1.4 * 8.7
= 12.18

Xmin2 = Hub
= 7.87

Xmin = MIN(7.87,12.18)
= 7.87

Amr Shams · Jan 11, 2023

When we ask the software company about the 9.02mm min.thickness. They told us that they add corrosion allowance after taking the lesser of (1.4x tn & hub thickness)!.this issue happens only when adding slip on flange to any pipe size with sch.160. If we use sch.80 or 40 it will has no deficiency

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UW-21 minimum requirement for External weld for SO Flange

Amr Shams

Mechanical

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