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Re: [MW:30875] Welding of DissimilThickness

Dear George,

It's called tapered weld or tapered joint.
I'll copy/paste some web page content for your reference.




Weld End Preparation at Unequal Wall Thicknesses

Acceptable Design in Piping components

In most piping systems there are components such as valves, castings, heavier header sections, and equipment nozzles which are welded to the pipe.

In such instances, the heavier sections are machined to match the lighter pipe wall and the excess thickness tapered both internally and externally to form a transition zone.

Limits imposed by the various codes for this transition zone are fairly uniform.

The external surface of the heavier component is tapered at an angle of 30° maximum for a minimum length equal to 1½ times the pipe minimum wall thickness and then at 45° for a minimum of 1½ times the pipe minimum wall.

Internally, either a straight bore followed by a 30° slope or a taper bore at a maximum slope of 1 to 4 for a minimum distance of 2 times the pipe minimum wall are required.

The surface of the weld can also be tapered to accommodate differing thickness. This taper should not exceed 30°. It may be necessary to deposit weld metal to assure that these limits are not violated.

Below some tables with the acceptable design for unequal wall thicknesses ASME B31.8

Internal Offset
A

Weld End Preparation at Unequal Wall Thicknesses

Internal Offset
B

Weld End Preparation at Unequal Wall Thicknesses

Internal Offset
C

Weld End Preparation at Unequal Wall Thicknesses

Internal Offset
D

Weld End Preparation at Unequal Wall Thicknesses

External Offset
E

Weld End Preparation at Unequal Wall Thicknesses

External Offset
F

Weld End Preparation at Unequal Wall Thicknesses

Combination Offset
G

Weld End Preparation at Unequal Wall Thicknesses

Note:
(1) No minimum when materials joined have equal specified minimum yield strengths.



Regards
Ramin  Kondori
Sr. QA/QC & Welding Engineer
-----------------------------------------------------------
PG-Dip. in Welding Engineering (IWE  AT  0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
                        
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On Thu, May 14, 2020 at 4:13 PM george keribo <berepele@gmail.com> wrote:
Team i want to know how it can be possible to weld materials with dissimilar wall thickness of 5mm. DSS pipes to flanges. Flanges are higher than the pipes in thickness with 5mm.

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