Embed Size (px)
Citation preview
Welding Quality in Kenya: Application of Radiography
Michael M. GATARI1, John K. BIRIR1, David M. MAINA1, Stephen M. MUTULI2, Wilson M. KAIRU1.
1 Institute of Nuclear Science and Technology, College of Architecture and Engineering, University of Nairobi, P. O. Box 30197, Nairobi, Kenya, Phone: +254 20 318262, Fax: +254 (020) 2245566
Email: [email protected], [email protected], [email protected], [email protected]
2Department of Mechanical and Manufacturing Engineering, College of Architecture and Engineering, University of Nairobi, Kenya.
E-mail: [email protected]
Introduction Methodology
Conclusion
Discussion
Results
References
• In this study radiography was used to assess the
quality of industrial welds and evaluation of
skills and competency of welders.
• Applications of welding include areas such as;
the construction industry, fabrication of
domestic products, repairs of machinery and in
transport industry.
The following samples were analyzed;
• 64 plate samples (3 mm thick) from the
informal sector across the country
• 92 plates (10 mm thick) and 18 pipes (8 mm
thick) from the formal sector.
• For all the acquired samples the field
investigators witnessed the welding processes
on site and performed visual inspection
before, during and after the welding process.
• The sizes of imperfections permitted by ASME
codes [2,3] were compared with the
dimensions of indications revealed by
radiographs.
• The type of discontinuities obtained were as
shown in the table and chart below;
• The percentage of samples with defects was
unacceptably high in both sectors investigated.
• Welders in the formal sector produced better
quality of welds as compared to informal sector
welders.
• This difference was attributed to the fact that
welders in the formal sector are subjected to
annual assessment, re-trainings, and make use of
welding procedures.
• Radiography was successfully used in
inspecting the quality of welding services in
Kenya.
• It revealed the wide deficiencies in the
quality of welds services given by the both
formal and informal sectors.
• Re-training of welders and annual assessment
through testing and licensing was found to be
an important aspect in the two sectors.
• The study also affirmed the importance of
radiography as an important tool in industrial
services/products inspection.
Acknowledgement• International Science Programme (ISP), University
of Uppsala, Sweden
• International Atomic Energy Agency (IAEA)
• University of Nairobi, Kenya
1. GOK Government of Kenya, “Economic survey,
2012”, Government press, 2012.
2. ASME Boiler and Pressure Vessel Code, “Section
VIII: Rules for Construction of Pressure Vessels”,
ASME press, USA, 2010.
3. ASME Boiler and Pressure Vessel Code, “Section
IX: Qualification standard for welding and
Brazing Procedures, Welders, Brazers, and
Welding and Brazing Operators”, ASME press,
USA, 2010.
• In Kenya, welding services are extensively
employed in both the formal and informal
sectors.
• Welding needs continue to increase with
increasing population, infrastructure and
vehicle fleet, and economic development.
• The Informal sector is an important sector as it
employs over 80 % of the working population
[1].
• The samples were subjected to further
examination by radiography.
0
20
40
60
80
100
Informal
Sector Plate
Welds
Formal Sector
Plate Welds
Formal Sector
Pipe Welds
Welds Type of Discontinuity Total
DiscontinuitiesUndercut Porosity Cracks (C) Lack of Fusion
(LOF)
Incomplete
Penetration (IP)
Informal
Sector Plate
Welds
16 % 6 % 3 % 34 % 33 % 92 %
Formal
Sector Plate
Welds
5 % 15 % 0 % 8 % 10 % 38 %
Formal
Sector Pipe
Welds
0 % 0 % 0 % 0 % 6 % 6 %
Note: The % indicated represents the percentage of total samples tested
having the given defect.
11th European Conference on Non-Destructive Testing (ECNDT 2014), October 6-10, 2014, Prague, Czech Republic
