TY JOUR TI Technology of Accumulating Sampling at Mass Spectrometric Method of Tightness Inspection KW leaktightness KW mass-spectrometry KW helium KW inspection sensibility JO NDT World AU Voronov, A.V. AU Kozlov, I.N. AU Lukashevsky, M.K. PY 2021 IS 23 PB LLC SVEN