The newly launched Southern African Institute of Welding (SAIW) labor-atory will test and evaluate the quality of welds, while the technology centre will assist in improving the quality of welding in South Africa.

The R12-million metallurgical testing laboratory, officially launched in July at the SAIW’s head office in City West, Johannesburg, will undertake testing, evaluation and failure analysis of welds that were previously outsourced to third-party laboratories.

“The laboratory will be used for the in-house testing of welds, where the SAIW will under-take the testing and qualification of weld procedures and welders. “The SAIW will also offer the service to other qualification organisations [such as the universities of theWitwatersrand and Pretoria] and manufac-turers,” said SAIW technical services manager Sean Blake at the launch.

The laboratory will also be used to demonstrate the testing of materials in cases where it is part of the teaching curriculum for welding professionals, including inspectors, technologists and engineers.

Blake stated that the “world-class” labor-atory equipment was supplied by capital equipment suppliers IMP Innovative Solutions and Toolquip & Allied.

Further, he noted that the tensile testing machine, with a capacity of 300 kN, per-formed a fundamental materials science test in which a sample is subjected to a tensile force until failure.

“The test is commonly used to determine the strength of the material and specifically, in our case, the strength of welded joints. The results of tests are used for quality con-trol purposes and also to select materials and welding consumables for particular applications,” Blake explained.

Additionally, he said properties directly measured using a tensile test included tensile strength and ductility (elongation and reduc-tion in area).

Other laboratory equipment includes a 450 J Charpy impact machine, which tests the impact strength of materials, a spectrometer for chemical analysis, an XRF analyser for material sorting and chemical analysis, as well as a microhardness tester for hardness testing and hardness traverses.

There is also a hydrogen analyser for testing diffusible hydrogen in weld metal and a Nikon MA-200 optical microscope, with various sample preparation and machine equipment for the preparation of test speci-mens, which includes specialist Blacks impact specimen preparation equipment.

The laboratory will undertake bend testing using its SANS/MTS Criterion machine to determine the ductility of a weld and reveal any defects in the weld; typically lack of fusion defects are revealed in this test. The SANS/MTS Criterion machine contains a range of formers, from 12 mm to 40 mm, for testing purposes.

The laboratory can also perform hardness testing using the EmcoTest Durascan 70 Vickers-unit machine.

“Hardness testing measures the ability of the materials to resist plastic deformation,” Blake explained.

He highlighted that the EmcoTest Durascan 70 Vickers-unit was an automated machine, with a load capacity of between 10 g and 10 kg, which could be programmed to undertake hardness testing.

The laboratory will be managed by Blake and SAIW materials testing technician, Confidence Lekoane, who are both qualified metallurgists.

Challenges
The construction of a metallurgical testing laboratory started at the beginning of 2011, when the SAIW council realised the welding industry required such a service.

“During the installation of the equipment, a civil problem became evident and resulted in the floor of the laboratory having to be reconstructed,” said SAIW executive director Jim Guild, who also spoke at the launch.

He added that although the launch of the laboratory was delayed by a year, the equip-ment for the facility was installed in early 2013 and the laboratory is already in use.

The SAIW team, including Blake, will undergo training next month to ensure all the members are trained in the efficient operation of the equipment.

Guild pointed out that, while the laboratory does not yet have ISO 17025 accreditation from the South African National Accredita-tion System, which details the general requirements for the competence of testing and calibration laboratories, the SAIW team is working on this as a priority and plans to be ISO 17025 accredited by the end of the year.