Metals Conference 2017 The cost of quality Dr Michail Karpenko General Manager NZWC, HERA Alan McClintock Senior Welding Engineer, HERA
The New Zealand submarine Platypus The Platypus was designed by Monsieur Villaine for digging and sluicing underwater around 1871. It was an iron cylinder constructed of 9.5 mm plates. Platypus was lunched in Dunedin harbour on 14 December 1873.. http://divenewzealand.co.nz/article-627/
BHP's Olympic Dam mine in South Australia Photo: Supplied pic.
0.1 What is the cost of quality?
Visible and hidden costs of quality Reference: AS/NZS 2661 All too often the costs due to the lack of quality in a product or process can be viewed as an iceberg with only the tip of the iceberg being seen
Visible and hidden costs of quality Reference: AS/NZS 2561
Understanding quality costs
Re-work cost moment end plate welding Fitting and welding: 4 hours x 75 $/h = $300 NDT: $150 Handling/gouging: 3 hours x 75 $/h = $225 Re-welding: 3 hours x 75 $/h = $225 Loss of production: 6 hours x 75 $/h = $450 NDT after repair: $150 Total cost (production + re-work): $1500 Re-work cost: ~ 3.3 x fabrication cost $450 Production weld cost $1050 Re-work cost
What is the rate of defects in welding fabrication?
The rate of defects reports summary Product and sector Reference Repair rates [%] Cross country gas pipeline with references to large M.J. Wagner and B.M. 17% (10,000 welds and above) project size Patchett (1991) Cross country gas pipeline with references to medium 11% - 25% (5,000-9,999 welds) project size Cross country gas pipeline with references to low (less 31% - 37% then 5,000 welds and above) project size Cross country gas pipelines (summer - winter) 17% - 27% Repair rates expectations pipe welding 5%-10% Onshore gas transmission pipeline Cousin and Baguely (1992) 12.9% - 25.9% Offshore gas transmission pipeline Rae (1984) 10% - 70% Pressure vessel Salter and Gethin (1973) 43% Boiler tube and pipe of fossil fuel power plant APS (1979) 1.16% Piping in Nuclear Power Plant Duke Power (1978) 0.60% Plates in Nuclear Power Plant 0.70% Aluminium tanks Howard (1976) 1% Offshore jacket steel structure Thurlbeck (1996) RT: 0% to 5.5% UT: 12.8% and 13.7% Shipbuilding L.W. Sander (1980) VT: 2% - 25% RT: 5% - 20% UT: 1% - 14% MT: 1% Aluminium military bridge deck panels VALDEMAR MALIN (1995) 3.4% (83% of that due to operator/welders errors) Offshore structures and pipelines TWI 2012 2% Piping systems and onshore pipelines 3% Pressure vessels 2% U.S. Navy Shipbuilding structural components A CULLISON (AWS 3%-4% U.S. Navy Shipbuilding pipe welds 1991) 2%
The cost of quality to the Fabricator 1. Assumed rate of defects: 3 % 2. Re-work cost: 3.3 x fabrication cost 3. Total loss: ~ 10% of the fabrication cost 4. Annual tonnage: 10,000t 5. Man-hours per tonne: 20 hours/tonne 6. Annual loss: 20,000 man-hours; or an equivalent of 6 people with overtime Change this to presentation title
The cost of quality to the industry 1. 170,000t of heavy steel fabricated annually 2. Man-hours per tonne : 20 hours/tonne 3. Total annual loss: 340,000 man-hours 4. Assumed man-hour rate: $60 $/hour 5. Total loss: > $20m Total potential saving is more than $20m! Change this to presentation title
The cost of quality
0.2 What are the quality management strategies?
Targeting the key impact factors Reference: TWI Distribution of factors affecting repair rates in welds
Non-compliance rate [%] Performance of individual welders over to the number of welds 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% BD AD AE DL BF BU AJ AC AK CW DP DF FJ EW AR BA 0 100 200 300 400 500 600 700 Number of welds Non-compliance rate for individual welders with more than 100 tested welds. The data is based on NDT reports from 36 structural steel projects. Source: NZWC NDT project Change this to presentation title
The labour factor
Some factors influencing quality of welding fabrication Site welding Decisions of design engineer Welding inspection and NDT Storage of welding consumables Section design and welding position Welding Supervision Welder Qualification Welding procedures
Quality Management in Welding Fabrication - Basics Welding is a special process as quality of welding cannot be fully verified by final inspection. The quality cannot be inspected into the product it has to be built into it. It requires Control over all relevant inputs e.g. design, qualifications, welding procedures as defined in AS/NZS ISO 3834
RHS welding correct and incorrect procedures
Weld prep control
Storage of welding consumables
Weld metal properties not all welding wires are created equal
Approved welding procedure
SC-DSCF0015 SC-DSCF0013
Quality means doing it right when no one is looking. Henry Ford
0.3 How quality systems certification can help?
About Steel Fabrication Certification Scheme Launched 2014 27 certified fabrication companies (32% SCNZ fabricator members) Represents +80% of local industry output Aims Introduces a mark of quality to structural steel sector Benefits Reduced risk of non-compliance Simplify role of engineer/builder - Lower level of construction monitoring (likely) - Independent expert assessment of fabricator capability assessment (ie prequalified capability to meet standard) Based on international best practice
SFC and traceability Steel NDT and third party Welding consumables Internal inspection Welding procedures Welders
AS/NZS 5131:2016 - Introduction Represent best practice Based on European approach Based on ASI/SCNZ/HERA funded Code of Practice Includes welding QA, ISO 3834 Aim to improve quality outcomes in context of global procurement
SFC in time perspective SFC Rules developed IIW Accreditation for ISO 3834 First 8 fabricators certified AS/NZS 5131 published 27 fabricators certified; 80% of fabricated steel 2013 2014 2015 2016 2017 Development of the concept The work on DR AS/NZS 5131 started 16 Fabricators certified SFC Rules aligned with AS/NZS 5131 SFC made mandatory for SCNZ members
www.steelfabcert.co.nz
0.4 What are the recent developments in the field of technology?
Some of the process monitoring options available for arc welding Arc-on time control Equipment usage Weld process data WPS library Limited access to WPSs Factory quality system integration
Internet of things based fabrication quality system
0.6 Q&A