September - October 1999
By joining Group Sponsored R&D Projects TWI Industrial Members gain access to substantial programmes at low cost, with the opportunity to steer work undertaken into areas of specific interest. The following GSPs have been, or are about to be, launched.
For a full list of proposed, active and closed projects see here
Advanced repair of hot section gas turbine components
Launch September 99, duration 2 years
Cost per sponsor £20 000 pa
Project leader: Geoff Melton
Gas turbine blades, damaged in service by high temperature erosion, corrosion or cracking, are mostly replaced with new rather than repaired parts. Although the use of repaired parts could save £60,000 per aero-engine blade set or £0.5 million for a power generation turbine blade set, operators are currently unable to maximise the savings potential, because repairs are restricted to low stress locations, where the risk or implications of failure are minimal. The objective of this project is to develop procedures for producing repaired blades with improved high temperature mechanical properties, with a view to extending the range of approved turbine blade repairs.
Reliability of lead free solder joints for high reliability, high density applications
Joint TWI/Cambridge University Project
Launch September 99, duration 2 years
Cost per sponsor £20 000 pa
Project leader: N R Stockham
Legislative and commercial pressures could result in the phasing out of lead in solders over the next 5-10 years. This will have a major impact on all electronic and electrical manufacturing companies. Lead free soldering is technically possible but its introduction is restricted by the lack of long term reliability data. This project is designed to provide the data that will allow manufacturers confidently to introduce lead-free solders by undertaking an extensive long term testing and modelling programme. The work of the project will be jointly undertaken by TWI and the Material Science and Metallurgy Department of Cambridge University.
New interconnection techniques for lead frame harness and insulated wire applications
Launch November 99, duration 1 year
Cost per sponsor £12 000
Project leader: N R Stockham
The electrical and electronic industries make extensive use of soldering technologies for attaching/connecting lead frames, wiring harnesses and wires. However, the drive to reduced component size/weight, lower production costs, environmental restriction on lead solders and the use of high temperature insulation has placed significant pressures on current assembly techniques. The aim of this programme is to improve existing and to develop new welding/adhesive/joining solutions to overcome these problems and to give higher yield/lower cost production systems.
Fatigue of welds in areas of complex stress distribution
Launch September 99, duration 2 years
Cost per sponsor £15 000 pa
Project leader: S J Maddox
Current fatigue design rules for welded structures are based on data obtained from small-scale specimens, with relatively uniform stress distribution near the weld. There is a need for guidance on the practical application of such rules for the more complex stress distributions which arise in real structures. Large-scale specimens incorporating features to induce stress concentrations and sharp stress gradients will be fatigue tested and the stress distributions investigated using both finite element analysis and strain gauging, in order to formulate the necessary guidelines.
Cathodic protection of duplex and super duplex stainless steel
Started August 98, duration 2 years
Cost per sponsor £5 000 or £20 000 pa
Project leader:P Woollin
Sponsors: Arco, BP, DERA, HSE, Marathon, Shell, Weir
A hydrogen analysis procedure has been derived for duplex consumables, to generate data on hydrogen levels of commercial products based on vacuum hot extraction (VHE). However, the results, which have not been related directly to those from other techniques, suggest that published data relating cracking sensitivity to hydrogen content might be subject to some error. Further attention, therefore needs to be paid to the hydrogen analysis procedure and to generating cracking data for welds in which the consumable hydrogen level has been defined using the VHE method. The proposed project will address the second objective by examining the effect of weld metal hydrogen content and ferrite level on cracking behaviour of duplex stainless steel deposits.
Optimising the properties of weldments in weldable martensitic and super martensitic stainless steel
Started February 99, duration 2 years
Cost per sponsor £15 000 pa
(£10 000 buy back fee)
Project leader: P Woollin
Sponsors: Arco, Chevron, ESAB, Lincoln Electric, NKK, Shell, Sumitomo, Total
Low carbon weldable martensitic and supermartensitic stainless steels offer lower cost alternatives to duplex stainless grades. However, the limits of applicability of these martensitic materials when welded are not yet defined. The project will examine resistance to corrosion and cracking in a range of recently developed martensitic steels, in both the as-welded and postweld heat treated conditions. Sweet (CO2-containing) and sour (H2-containing) environments will be studied, as will the susceptibility to cracking under cathodic protection.
Fracture control for installation methods introducing cyclic plastic strains
Joint TWI/DNV Project
Started April 99, duration 2 years
Cost per sponsor £20 000 pa
Project leader: H G Pisarski
Sponsors: Coflexip Stena, DNV, ETPM, HSE, Marathon Oil, Shell Expro, Stolt Comex
This project sets out to define realistic flaw acceptance criteria and material property requirements to ensure that steel pipe and girth welds can be reeled and operated with minimum risk of failure. Experimental studies will be conducted on representative pipe materials to measure changes in material properties and assess flaw stability as a result of cyclic plastic strains caused by reeling. This will be complimented by the development of specific analysis procedures for reeled pipe, which will help define acceptance criteria. The project will be carried out in collaboration with DNV.
Preferential corrosion of ferritic steels in CO2 containing production environments.
Launch September 99, duration 2 years
Cost per sponsor £20 000 pa
Project leader: D C Buxton
Localised corrosion of carbon and carbon-manganese steel weld regions of flowlines and topside pipework has been reported in recent years, occurring in the UK North Sea and onshore gas reception facilities. Identical forms of corrosion have been observed in the US Gulf of Mexico during 1999. It is not possible to predict the location or rate of attack that may occur in these CO2-containing, wet gas production environments. Replacement with a corrosion resistant alloy is not economic for existing facilities, and specification of such alloys (eg duplex stainless steels) may adversely impact upon the cost of development of new facilities.
