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Submerged Arc Welding (SAW) trials for Cleveland Bridge UK

Introduction

Funding from the European Regional Development Fund enabled TWI Middlesbrough to conduct a technology transfer project on behalf of Cleveland Bridge UK Ltd (CBUK). Assistance was offered to businesses in the North East of England, which allowed CBUK to identify a specific area where external support would be beneficial to them.

CBUK construct structural steel assemblies for a wide range of applications including major bridge building, bridge strengthening and refurbishment, as well as commercial, civil and industrial buildings and structures. It was hoped that TWI could assist in the development of procedures to exploit and expand the productivity capabilities of submerged arc welding (SAW) using existing equipment.

Problems and Objectives

The objective of the project was to develop SAW welding parameters for a single run 12mm leg length fillet weld, which could then be taken into production. While CBUK had the capability to run tandem wires through their SAW equipment, a lack of tandem wire welding parameter information and existing production commitments meant that they were unable to conduct the relevant trials without disruption to production work. Because of this, TWI was able to assist by conducting the tandem wire SAW trials at TWI Middlesbrough, with CBUK providing the materials.

General set-up
General set-up

Method

CBUK provided TWI Middlesbrough with 15mm thickness lengths of BSEN 10025 grade S355 plates and SAW welding consumables including 4mm diameter ESAB Autrod 12.22 wire and ESAB 10.71 flux for the trials, these being the consumables normally used by CBUK. 

Both wires were set up at a nominal configuration on Lincoln Powerwave AC/DC 1000 power sources, with the results from a series of tests being recorded and then adjusted to create the final weld parameters. These adjustments included altering the angle of the weld, the amps, the voltage, the offset and the spacing for the welds.

Results and Conclusions

The various tests produced an acceptable fillet with no undercut at lengths just below 12mm. The results showed that a single run 10mm leg length fillet is achievable using tandem wire SAW and that some extra work and trials could probably achieve a 12mm leg length fillet weld. The test parameters also produced excellent penetration and offered a throat thickness greater than that of a 15mm leg length fillet.  

The tests have led to tandem wire SAW welding being trialled on their Sri Lanka project by CBUK, with an associated increase in welding speed of over 100%, from 450mm per minute to 1000mm per minute, with an overall 12% increase in productivity across the whole process. 

The results of the project are planned to be put to work in an ongoing contract in Sri Lanka, leading to significantly improved efficiencies. The work has also been extended by Cleveland Bridge’s welding engineer Dean Baker, resulting in the introduction of square wave technology, which has enabled improvements in quality and a reduction in the risk of centre line cracking.  Cleveland Bridge is now planning to develop the square wave approach for other products, including the use of weathering steel. 

Cleveland Bridge UK Ltd reported that the experience of working with TWI and the principal project leader, Glenn Allen, was extremely positive. This included a visit to TWI Middlesbrough to witness the welding trials and the valuable upfront procedure work completed by Glenn, which provided the initial parameters on which subsequent work was based. 

For more information, please email contactus@twi.co.uk.

Cleveland Bridge Project
Cleveland Bridge Project