Q
QA Quality Assurance
QAM  Quadrature Amplitude Modulation 
QAP Quality Assurance Plan
QC Quality Control
QFs Qualifying Facilities
QI Qualified Individual
QPSK Quadrature Phase-Shift Keying
QRA Quality/Quantitative Risk Assessment/Analysis
QT  Quenched and Tempered (steel)
QTF  Quadratic Transfer Function
QUADs  Permanently mounted gas cylinders