Pre-processing phase
Residual liquid recovery→ nitrogen displacement→ surface cleaning (degreasing or steam purging).
Core testing items
Visual inspection→ air tightness test→ static evaporation rate test→ helium leak detection→ vacuum retest (when unqualified).
Compliance Standards
Follow GB/T34347 "Periodic Inspection and Evaluation of Low-temperature Insulation Gas Cylinders", focusing on controlling evaporation rate, tightness and vacuum maintenance performance
