January - February 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
Friction stir welding of steels
Launched June 98, duration 3 years.
Cost per sponsor £16 000 pa.
Project leader: P L Threadgill.
Friction stir welding has been successfully developed for many non-ferrous alloys, and its feasibility for steels has been demonstrated. The process is fully mechanised, needs no traditional welder skills, no consumables, and produces solid state welds with minimal distortion, and excellent mechanical properties. It is also very useful for joining dissimilar materials. A programme of work is proposed in which aspects such as optimum tool material, tool design, and process parameters will be developed for a number of typical ferritic and stainless steels, in thicknesses up to 10mm thick, including some grades which are challenging to weld by conventional fusion processes. The project may also address issues such as process economics, joint design, parameters tolerance, reproducibility, mechanical properties, microstructure, etc. The results will allow fabricators and end users to develop further the process for specific applications. Developments for high productivity welding installation & service of Ti alloy risers.
Joint TWI/SINTEF Project.
Launched November 98, duration 2 years.
Cost per sponsor £40 000 pa.
Project leader: T Dickerson.
Titanium alloys are attractive candidates for offshore applications because of their good corrosion resistance, high specific strength and good flexibility (low modulus of elasticity). This project is aimed at the potential use of titanium for riser applications. The key research areas are joining process, fatigue and fracture toughness properties, stress corrosion cracking, the in-service inspection as well as some of the design aspects.
A new approach to monitoring the quality of titanium alloy welds
Joint TWI/EWI Project.
Launched June 98, duration 2 years.
Cost per sponsor £12 000 pa.
Project leader: M F Gittos.
Current acceptance criteria for titanium TIG welds are based on surface colour which results in over elaborate gas-shielding arrangements. Development of inspection procedures which are more directly related to weld performance would decrease the difficulty and expense of titanium welding. Weldments will be manufactured in commercially pure Ti and a 6Al-4V-Ti alloy material with varying levels of contamination and the mechanical properties and chemical analyses correlated with electrical resistivity measurements.
Optimisation of single sided welding techniques for vehicle body assembly
Launch December 98, duration 2 years.
Cost per sponsor £10 000 pa.
Project leader: S T Riches.
The use of steel hydroformed tubes and aluminium extrusions have been proposed as a prime means of reducing vehicle weight and enhancing cost savings for high volume vehicles. One of the main issues concerning the assembly of vehicles containing hydroformed tubes/extrusions is the need to demonstrate robust industrially accepted joining processes which can operate with single sided access. This project is designed to address the challenge of single sided welding for hydroformed tubes/extrusions by carrying out objective work on four material combinations, to assess for each the process optimisation and robustness on up to three joining processes. Recommendations will be made regarding the implementation of the most promising technique for each material combination in a production environment.
Basic adhesives classification in engineering (BACE)
Launch December 98, duration 3 years.
Cost per sponsor £20 000pa.
Project leader: A Bush.
Although adhesive bonding is the most widely used joining technique, no performance standards or classification exist. Therefore, design engineers are reluctant to specify adhesive bonding as safety issues affect the fitness for purpose and performance predictions. TWI has developed Guidelines for Adhesive Bonding which form the basis of joint design, adhesive selection and assembly in marine structures. However, non-destructive testing and performance predictions remain a significant limitation to further use of adhesive bonding in industry. This project has three main aims: to define performance based classification for adhesive joints, to develop a reliability based approach to adhesive bonding, (incorporating joint classification), and to provide a design model leading to a reduction in structural redundancy.
Mechanical and corrosion properties of friction stir welds in Al alloys
Joint TWI/EWI Project.
Launched October 98, duration 2 years.
Cost per sponsor £15 000 pa.
Project leader: T Dickerson.
Friction stir welding (FSW) is now a viable joining process for aluminium structures. However, design data and an understanding of in-service behaviour are needed for its efficient application. The project will generate fracture, fatigue and corrosion design data and a better understanding of failure mechanisms. It will be concerned mainly with butt welds in 6-10mm alloy plate typical of the 2000, 5000, 6000 and/or 7000 series.
Knowledge management in the Oil and Gas Sector (JoinITOG)
Launch March 99, duration 3 years.
Cost per sponsor £30 000 pa.
Project leader: N Elbourn.
In addition to its acknowledged expertise in joining technologies and long experience in the Oil and Gas sector, TWI has developed a unique set of skills in knowledge management. This three-year project aims to develop an internet-based knowledge management and trading system with special relevance to companies in the sector. JoinITOG will form part of TWI's overall JoinIT knowledge trading umbrella, with the project team generating content to augment the wealth of material originating from TWI. The site will be secure to participating companies providing low cost and fast access to sector specific knowledge.
Assessment of electrofusion welding of PE pipes
Launch December 98, duration 2 years.
Cost per sponsor £15 000 pa.
Project leader: M Troughton.
Although the electrofusion (EF) technique has been used in the gas and water industries for many years, there is still concern regarding joint failures due to poor site practice, especially as the technique is being used for joining larger pipe sizes. At present, one of the main methods for assessing the quality of EF joints is a destructive peel test. However, whether the results from this test give any indication of the long-term integrity of the joint is questionable. Also, there is, as yet, no reliable non-destructive testing (NDT) technique for EF joints. This project has three main aims; firstly to determine the effect of poor joint preparation on the long-term integrity of EF joints, and how this is affected with increasing coupler size. Secondly, to determine which short-term specimen tests provide the best correlation with long-term whole pipe tensile tests; and, finally, to develop reliable NDT procedures for EF joints. Corrosion fatigue crack growth in sour media
Launch November 98, duration 2 years.
Cost per sponsor £17 000 pa.
Project leader: T G Gooch.
The oil and gas sector has undertaken extensive study of stress cracking mechanisms such as that due to sour (H2S) media, but not their potential for acceleration of fatigue crack growth. Fatigue may arise from external loading, eg maritime conditions, or service eg vibration or pressure fluctuations. It is therefore surprising, especially with increasing developments in deepwater or tidal locations, that there are so few data available applicable to practical service for oil & gas process facilities, risers or pipelines. This study therefore aims to generate data for parent metal and welded joints covering a range of materials in sour (H2S) environments. Resultant improved knowledge and design will benefit industry reducing failure risk, leading to greater safety and significant cost reduction due to avoidance of unforeseen failure.
Evaluation of the flux cored arc process for underwater wet welding
Joint TWI/Cranfield University project.
Launched June 98, duration 2 years.
Cost per sponsor £15 000.
Project leader: W Lucas.
Underwater welding is normally carried out using dry (hyperbaric) or wet welding techniques. Compared with hyperbaric welding, wet welding has the advantages of low equipment costs, and as welding is only limited to access by the welder, it is extremely flexible in its capacity to handle both small and large scale applications. A completely new wet welding technique has recently become available from the Paton Institute (PWI) based on the self-shielded flux cored arc (FCA) wire process. When used for wet welding, the process offers the following potential additional benefits compared with MMA welding: high productivity, easier to use, and suitability for adaptation for automatic or robotic welding. The proposed project will evaluate the PWI technique for underwater wet welding by: optimising the system for underwater semi-automatic welding, evaluating commercially available consumables, conducting welding procedure approval tests, developing welding procedures for specific applications, and conducting mechanised robotic welding trials.
