Toolform Case study:
Laser and Sheet Processes Group

Pressure vessels, tanks, containers and pipelines require robust and reliable welding (Photos courtesy of Portobello Fabrications Ltd)

Laser Welding for Pressure Vessel and Pipework Fabrication

The Toolform programme, joint funded by the DTI, Yorkshire Forward and Objective 1, has assessed the feasibility using of laser welding to add to the existing arc welding expertise already in use by a Sheffield pressure vessels fabricator to produce high quality welded components.

Portobello Fabrications, located in Sheffield, is a leading fabricator of heat exchangers, chemical tanks and pressure vessels used in the oil, gas and chemicals industry as well as water, food, pharmaceuticals, power generation, and nuclear industries.

The materials used in these products must always be welded reliably to meet stringent welding standard requirements. Portobello Fabrications specialise in producing components that see extremes of corrosive environment, elevated temperature or pressure from 2-20 bar, so it is vital to obtain reliable welds. By implementing laser welding, considerable savings in set-up times and efficiency can be attained over conventional arc welding.

Tubes of 304L stainless steel and IMI 130 Grade 2 titanium, with bore size varying from 40mm to 200mm and 1.5mm, 2mm and 4mm wall thickness, were joined using an HL4006D lamp pumped Nd:YAG laser manufactured by Trumpf, with a Kawasaki JS30 robot used to manipulate the beam during welding operations. The flexibility of fibre optic beam delivery and use of robotic manipulation, were ideal for this application, particularly for angled butt joints and various configurations of fillet welds, as well as for straightforward circumferential butt welds.

Circumferential laser girth weld of titanium pipe

Amongst the advantages of choosing laser welding over arc welding, is the ability to repeatedly weld standard sizes according to programmed routines, reducing welding time and ensuring that manpower can be more effectively distributed. Welds on non-standard configurations can also be achieved with similar results to the manual arc welding procedures currently employed by Portobello. Provided that acceptable fit-up can be achieved prior to joining, laser welding can produce single pass welds in the wall thicknesses evaluated with full penetration at welding travel speeds up to 5m/min.

This support, provided to Portobello Fabrications Ltd, was made possible through the Toolform Strand of the Advanced Metals Technology Initiative (AMTI) funded by the DTI, Yorkshire Forward and the European Union through the South Yorkshire Objective 1 programme. The AMTI project is managed by NAMTEC, the National Metals Technology Centre.

For more information on the Toolform programme, please contact: Eliana Fu (email eliana.fu@twi.co.uk.