This fourth edition volume offers updates and new technical content throughout. The chapter on physics has been extensively revised and includes new equations. Chapters on safety, pressure, and vacuum and bubble testing have been significantly updated. New sections on blower doors and designing for leak testing have been added. Chapters covering helium, mass spectrometry, thermography, halogens, acoustics, and hermetic seals have been expanded and updated. Citations to applicable standards have been updated throughout. There are more than 100 new color photographs, including some from ASNT members overseas.