Investigation of welding quality in the Kenyan informal sector (“Juakali-sector”)

Abstract

Welding is a joining method extensively used in fabrications and repairs of most metallic items. In Kenya most of the repairs are done in the unregulated “Juakali” industry by the manual shielded-metal-arc-welding technique. There is however a growing concern over the safety of the “Juakali” works. Failures of many products such vehicle parts is blamed on poor quality of weld joints and such failures may lead to fatal accidents and losses. In general these kinds of failures have created a negative image of “Juakali” products/services and hindered the growth of this vibrant informal industry. In this study, welding work by various “Juakali” enterprises was sampled and analyzed. A total of 92 samples comprising of repaired components and test coupons were collected from eight different locations across Kenya namely Ngong, Dagoretti, Mlolongo, City-stadium, Kitale, Kisumu, Mombasa and Meru. The welded joints were subjected to visual inspection, radiographic tests and tensile tests to identify the kind of flaws present and their mode of failure. It was found that the defects most prevalent in the 92 “Juakali” welds analyzed by visual and radiographic tests were: Incomplete Penetration (41 % of the samples); Lack of Fusion (29 % of the samples); Undercuts (12 % of the samples); Porosity (8 % of the samples) and Cracks (2 % of the samples). From 124 samples subjected to tensile tests, 60 % of them fractured in the welds. Additionally a total of 110 samples comprising of plate and pipe test coupons from the more established SMEs were also subjected to visual and radiographic tests for purpose of comparison. Defects found in SME samples were: Porosity (13 % of the samples); Incomplete Penetration (9 % of the samples), Lack of Fusion (6 % of the samples), and Undercuts (5 % of the samples). From this study it was concluded that the quality of welding is very poor in Kenya especially in the “Juakali” Sector. This was observed to be a result of incompetency and weak skills of artisans and technicians in the sector. Retraining was therefore recommended to improve the knowledge and hands-on skills of the artisans and technicians. Additional studies also need to be taken to determine other variables that may have an impact on the quality of welding such as type of equipment, materials used experience of artisans and level of education.