TWI Frequently asked questions
by Vic Wright
Before making any critical weld repair, the defective area should be checked with magnetic particle/liquid penetrant to locate the extent of all surface defects associated with the repair.
Major repairs and complete joint penetration welds in cast iron where minimum specified base metal strength is required should be tested by all three techniques above.
Joints and repairs in non-critical areas require only visual examination and penetrant testing.
All acceptance criteria for visual, penetrant and radiographic testing should be in accordance with an appropriate standard eg: Appendix D in ANSI/AWS D11.2
Specification of non-destructive testing techniques and acceptance criteria for welding cast iron requires care. If in doubt, contact an experienced practitioner.
Further information on welding of cast iron is available in:
Welding of cast irons - a guide to best practice
C.L.M.Cottrell, 'Welding cast irons', published by TWI, Abington, Cambridge, UK, 1986 and available from Woodhead Publishing, Abington, Cambridge, UK. e-mail: sales@woodhead-publishing.com
ISBN 0 85300 176 6
Guide for Welding Iron Castings - ANSI/AWS D11.2-89, American Welding Society, Miami, Florida, USA. e-mail: info@aws.org
ISBN 0 87171 295 4
