New projects

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. If you are interested please contact the project leader at TWI.

Procurement of welding fume exposure data - phase 2

There is a need for welding fume exposure data for use in applications such as health studies, risk assessment, definition of exposure limits, etc. Phase 1 was initiated with the objective of gathering exposure data, to satisfy these needs, by surveying literature, TWI member companies and personal contacts. Phase 2 will:

• Procure welding fume exposure data from sources identified in Phase 1.
• Critically review the data to determine its suitability for inclusion in an exposure database.
• Create a database for the reviewed data, allowing searches to be conducted using a range of search parameters.

Improving the reliability and cost performance of thermally sprayed aluminium coatings

Thermally sprayed aluminium (TSA) coatings are widely specified for protection of steel structures and components against saline corrosion, but there is increasing industrial requirement to extend its application to very severe environments including deep water, and to reduce the cost for existing applications. The objective is to develop improved TSA coatings through evaluation and validation of recently developed thermal spray equipment and sealant compositions. Benefits will include improved coatings, reduced application and maintenance costs, and a reduction in the operator exposure to respirable fume and the risk of fire or explosion from residual fine metal dust.

Corrosion reliability inspection scheduling (CRIS)

This project aims to complete the work started in RACH, a previous EC Thermie project, which investigated inspection reliability for corrosion in pipework and other pressure containing equipment for hazardous materials. CRIS will provide corrosion modelling data, probability of detection (POD) and sizing data for corrosion inspection equipment, and a validated methodology for reliability-based inspection scheduling. All information, results and a full report will be provided in a CRIS database.

Acceptance criteria for pipe girth welds inspected using automated ultrasonic testing

Automated ultrasonic testing (AUT) is becoming the method of first choice for inspection of pipeline girth welds, due to its speed, sizing ability and health and safety advantages compared with radiography, and its ability to size the through-thickness dimension of flaws. It is readily integrated into an engineering critical assessment (ECA) approach. The project will address:

• Reliability and accuracy of AUT
• Cost effective qualification of inspection by AUT
• Flaw acceptance criteria for pipe girth welds inspected using AUT

Advanced repair of hot section gas turbine components

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 aeroengine blade set, operators are 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 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 HVOF coating subject to environmental exposure

There is increasing evidence that HVOF coatings not only display excellent wear but also good corrosion resistance, eg HVOF coatings are already being applied as economic alternatives to the environmentally hazardous hard chrome plating process. However, there is an urgent need to understand the impact of a corrosive environment on mechanical properties such as wear, adhesion and fatigue, so that longer-term coating reliability can be developed. TWI is launching a GSP to evaluate the long-term reliability of HVOF coating properties subject to corrosion and to evaluate coating material options for specific combined wear and corrosion applications.

Development of an NDT technique for the detection of non-standard butt welds in plastics pipes

Current non-destructive tests for butt fusion welds in plastics pipes, although capable of detecting planar flaws and particulate contamination, cannot detect cold welds ( ie welds which appear visually to be of good quality but which fail in a brittle manner when tested in flexure or tension). A new technique, which involves applying a pre-determined amount of local heat energy to the surface of the weld after removing the bead, has been shown in initial trials to achieve a detection rate of cold welds of over 90%. The objectives are to optimise this NDT technique for different types and grades of plastic pipes and to develop prototype equipment for use in the field.

Joining of thin sheet aluminium, stainless and coated steels by the AC pulsed MIG welding and brazing processes

AC MIG welding is claimed to offer significant advantages in welding sheet materials. The AC wave form can be precisely controlled to reduce the depth of weld penetration during welding. This enables the AC MIG process to weld thinner materials and bridge wider gaps than can be achieved with the traditional DC and pulsed MIG welding and brazing processes for a range of applications as chosen by the sponsors. The project has been budgeted for 12 applications in total, enabling two applications to be evaluated per sponsor. This will involve up to three sheet material types including aluminium, steel and coated steel.