Major Quality Failure Globalisation ‘The missing link’
The Failure –April 2008 cracking found in a Valve Body. –Testing programme undertaken to assess chemical composition of all Work In Progress (1460 valves fitted on each submarine).
Grain Size Problem
CONTAINMENT –Cause of cracking was the Manganese was below specification and in conjunction with excessive grain size was responsible for the failure. –Containment action initiated immediately to identify out of specification material and scale the size of the problem. –Three tier material assessment process established to check and confirm the acceptance of material. Sort, using X-Ray fluorescence analysis (XRF) Confirm material composition by analysing a scraping from below specification valve body determined by the XRF tool. Detailed material analysis using sample sections from valve bodies.
T1 Supplier UK Submarine UK Supply Chain Investigation Make Bar Italy Make Bar France Manufacture UK Source Mill India Forge Bodies Italy Stockist Germany
Source Mill Investigation –The method of mixing the alloy in its molten state was not effective in ensuring the homogeneity throughout the ingot. –The extrusion procedure was inadequate and did not meet the NES requirements e.g. soak time and the reduction ratio were inadequate. –No control over calibration standards. –Wet Sample records and spectrometer results did not match. –Identification throughout the plant varied from permanent stamping to chalk which was considered inadequate and could result in loss of traceability. –C of C stated that material was annealed yet the company did not anneal that particular size
Investigation Recommendations –Improve visibility of the entire supply chain. –Insist on original documentation accompanying transposed certificates. –Ensure appropriate balance of product verification and documentary evidence. (BS EN 10204:2004 Para 3.2 certification introduced) –Drive the development and modernisation of industry Quality Standards including MOD’s SSCP25 and ISO 9001 alternatives –Increase the use of commercial specifications e.g. define grain size –Continue with Positive Metal Indication (PMI) testing of in-coming material. Ensuring a safe quality product ………