New projects

November - December 2001

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.

Validation of Keronite ^® - a novel hard coating for light metal alloys

Keronite ^® is a new surface treatment for aluminium, magnesium, titanium and other light metal alloys that transforms the metal surface to form a well bonded layer of hard dense ceramic. The process offers an environmentally friendly process for enhancing the wear, tribology and corrosion properties of a component surface, including restricted access surfaces, whilst retaining initial component dimensions. This project will demonstrate the application of novel Keronite ^® coatings to components selected from industry, including aerospace, automotive and hydraulics, and validate improved surface performance compared to conventional surface treatments such as hard anodising, hard chrome plating and thermal sprayed coatings.

Hybrid laser-arc processing for improved productivity and quality

Hybrid laser arc welding combines the advantages of both processes resulting in high joint completion rates with increased tolerances to fit up and without compromising joint quality and distortion control. This work aims to develop robust welding procedures which demonstrate the advantages of a range of hybrid laser arc processes. The benefits to industry will include increased productivity, simplified set-up procedures and reduced post weld reworking costs.

Linear friction welding of blisks for gas turbine components

Linear friction welding (LFW) offers an alternative method of joining blades to disks in gas and steam turbine engines, creating a welded blisk at an attractive cost compared to a machined structure. It also allows the advantages of dissimilar blade and disk materials to be exploited. The process can also be used for blings, blums, etc. Although this approach is being adopted in aeroengine manufacture, it offers similar benefits of reduced weight and cost for ground based turbines. This project will further develop the process for power generation turbines, and provide information on welding procedures, joint properties and input data for lifing studies. An option to build a linear friction welded blisk is also available.

Multimedia training software for welders in the aerospace industry - Phase 1

PC-based multimedia training can provide an efficient alternative to conventional training methods. It offers a highly effective learning environment in terms of knowledge retention, without the overhead costs associated with attending a classroom-based training course. This project will develop a multimedia training course on the GTA (TIG) welding process specifically for the aerospace industry. A second phase of the project could be used to cover a wider range of welding and joining processes, or to develop company specific modules.

RIPIPE, design and integrity of pipe-in-pipe riser system application

Insulated pipe-in-pipe (PIP) flow lines are increasingly used to transport production fluids from a subsea satellite well head back to the processing platform. These flow lines are designed to maintain the fluid temperature above certain process critical values and the welding design of these PIP joints can have a significant effect upon the thermal, mechanical (static and fatigue) performance, onshore prefabrication, and offshore installation efficiency. This project will provide a series of guidance notes which will ensure the critical welding design aspects for PIP joints are fully included at the most appropriate stage in the design, manufacturing and installation programmes.

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 of the project 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.

Risk of preferential weldment corrosion of ferritic steels in CO ₂-containing environments

Localised corrosion of carbon and carbon-manganese steel weld regions of flow lines 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 attach that may occur in these CO ₂-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.

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 of £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.

The use of ERW/HFI welded linepipe for sour service applications - Phase II

A recent TWI review of the fabrication, application and performance of ERW/HFI welded pipeline in oil and gas service gave clear directions on how to ensure good performance, at least in sweet service. This proposed project will comprise experimental work to provide more data on properties required to ensure good performance in sour environments. It will increase confidence in the application of ERW/HFI pipe in sour service by determining safety margins on best quality pipe and will provide recommendations for improving the specification of ERW/HFI pipe for such service. Resulting cost savings will be significant and could be up to several x106 US$ for material costs alone, with further cost benefits due to the effects of good dimensional tolerances on pipe laying.