Abbreviations
PWHT Post weld heat treatment, Heat treatment after welding
HAZ Heat affected zone, the area that was changed but not through melting.
GMAW Gas Metal arc welding  
MMAW Manual Metal arc welding (stick electrodes)
FCAW Flux cored arc welding
SAW Submerged Arc welding
GTAW Gas Tungsten arc welding
ITP Inspection & Test Plan, a plan listing the events, during fabrication, some of which will be 'Hold points' points when fabrication stops while inspections are made to ensure it complies.
QA Quality Assurance (the plan)
QC Quality Control (quality measured)
PQR Procedure Qualification Record, (actual values used in the test weld)  
WPS Weld Procedure Specification (range of values based on PQR)
WQ Welder Qualification (a form which describes the limitations of the welder based on the weld test he made)