WELDING
All welds are made using the Tungsten Inert Gas method with high purity
argon/hydrogen shielding to exclude atmospheric gasses and prevent the
formation of oxides and nitrides in the weld, thereby allowing the molten
metals to run together without employing any flux. After welding all welds
are carefully checked for pits, cracks and virtual leaks. Filler materials
are not normally employed in any of our welds. All parts exposed to vacuum
are polished or electro-polished to produce optimum surface cleanliness,
degreased and passivated to eliminate outgassing.
LEAK DETECTION
Helium detection mass spectrometers are used for leak detection. These
are sensitive and accurate instruments capable of indicating extremely
small leak rates (better than 1x10-9 mbar litre sec-1).
Helium detection is a non-destructive test which is capable of quickly
determining the integrity of a seal.