FOCUS ON WELDING
Producing the component
The various wall thicknesses in the transition to the branch were implemented via different oscillation amplitudes . A constant heat balance was required to ensure the necessary optimal weld toe from bead to bead , and the uniform weld seam flow . Layer-specific welding jobs with specific parameters were used for this .
A water supply and return were provided for the component during the welding process . The water level this produced had to be far enough away from the welding point to maintain the interpass temperature in the qualified area . This allowed continuous welding without cooling breaks . Cooling of the component minimised component distortion and increased the deposition rate .
“ To observe the build-up of the layers , we used a camera that was triggered in synchronisation with the process . This allowed us to analyse the process deviations accurately afterwards ,” added Reiter of Fronius R & D .
WeldCube welding data management software monitored the parameter limits stated in the AMPS ( additive manufacturing procedure specification ) and issued a warning as soon as the preset limits were exceeded . The sum of all the parameters yielded the “ fingerprint ” of the additive build-up and facilitated analyses in the event of possible discontinuities .
Final component testing and looking ahead
The final testing , including confirmation of CE conformity , was performed by notified body 0036 of TÜV SÜD Industrie Service GmbH . In the present case , a starting material with mechanical data in a future , harmonised European standard (“ harmonised ” design ) and a component of design class DC1 , the result was a component inspection scope in accordance with the table below .
Pressure vessel with additively manufactured pipe branch and CE label .
We can definitely say that decades of experience with arc-based welding processes offer compelling reasons to increase the use of metal 3D printing in plant and container construction
“ In parallel with these tests , we developed metallographic analyses covering especially those areas where imperfections had been detected . Also affected were the transition areas between the classic material and the additive welding deposition , the hybrid area . The main purpose of the metallographic analyses was to verify the data collected from parameter monitoring and from mechanical , technical and non-destructive testing . In this case , samples were taken to gain a clear idea of the extent to which the material and the applied manufacturing process were flawless ,” explained Boche .
The conformity assessment procedure has now been completed ( according to Module G of the European Pressure Equipment Directive 2014 / 68 / EU ) in the form of a “ model qualification ” of an additively manufactured pressure vessel , with subsequent CE label to confirm compliance with the requirements of this EU directive . The pressure vessel joint working group of the German Institute for Standardisation ( DIN ), represented by Linde Engineering , TÜV-SÜD Industrie Service GmbH , MIGAL . CO and Fronius , is therefore looking to increase the acceptance of additive manufacturing in general , and in plant and container construction in particular .
“ In conclusion , we can definitely say that decades of experience with arc-based welding processes — combined with stable and innovative processes such as Fronius CMT
Type of test Testing processes Scope of testing
Non-destructive testing
Destructive testing
Final testing
■ Volume testing ( RT or UT )
■ Surface testing ( VT and PT )
■ Chemical analysis
■ Tensile test to determine strength and elongation
■ Bending test
Water pressure test Bursting test ( optional )
Per component , 100 % of the relevant areas of the design ( or 20 % if using a suitable grid to fully cover the area )
1x in the additively manufactured area
2x in the unfavourable direction , and also in the hybrid area
2x in the unfavourable direction , and also in the hybrid area
68 | ismr . net | ISMR December 2024 / January 2025