TWI Industrial Member Report Summary 853/2006
By C Punshon
Electron beam welding offers many advantages for thick section fabrication, particularly when applied to large structures where significant savings in both costs and time are anticipated. To date, however, the full potential of the process has not been realised commercially because of restrictions associated with working at high-vacuum with the entire structure to be welded enclosed in a vacuum envelope.
TWI has demonstrated that operating the EB process in the pressure range 0.1-1mbar (so called 'Reduced Pressure') in preference to high-vacuum (~10-3mbar) offers the possibility of eliminating the need for a vacuum chamber by permitting the practical use of local sealing and pumping.
To date, however, Reduced Pressure EB (RPEB) welding has only been applied industrially in a few specific cases. It is envisaged that many more industrial applications of the process could be promoted, and the true viability demonstrated by the further development of practical local sealing devices.
This report covers work carried out in the first year of a three year programme.
The specific objectives of the part of the programme reported here were to:
- Examine and critically review the range of methods for reliable generation of local vacuum or Reduced Pressure conditions in which EB welding can be carried out.
- Design and construct an experimental local sealing and pumping test facility to permit evaluation of various seal/pumping concepts.