Mobile electron beam welding - a new 'on-site' process

Connect, no.107, July-August 2000, p.7

Compact Reduced Pressure EB gun column capable of welding up to 200mm steel sections

High power, deep section electron beam welding can now be carried out at work piece chamber pressures in the range 0.1 to 10mbar. This coarse vacuum level can be readily achieved with local sealing on components too large to fit chambers, uses simple pumps and makes possible more rapid pump down of a chamber for production welding.

Before Reduced Pressure EB Welding, one of the major technology developments at TWI over the past few years, EB welding machines would generally be located in workshops where components were presented to them. The job had to be put in the chamber, which limited the size, and be pumped to a low pressure of 10-3 mbar or less (which takes time, and is impractical with local seals).

The welding performance of the TWI equipment matches if not exceeds the quality achieved at the lower pressure levels normally used for EBW.

Reduced Pressure EB Welding enables

Welding of large components in a locally-sealing vacuum chamber
Thick section, single pass welding (up to 200mm in steels)
On-site welding
EB welding of components too large to fit into a vacuum chamber
EB welding of components that cannot be pumped to low pressures
High production welding due to greatly increased chamber pumping speed

Immunity to gun flash-overs is one of the integral advantages of the system.

Both SKB (Swedish Nuclear Fuels and Waste Management Company) and Saipem (the Italian pipe laying company) have become users of Reduced Pressure EB Welding during the last few years. Equipment is also operated at TWI and can be used for proving trials for Industrial Members. Contact Allan Sanderson or Colin Ribton to find more about how to apply this process in your production. E-mail: allan.sanderson@twi.co.uk or colin.ribton@twi.co.uk