Most audits try to look at a representative selection of the plant pro
cedures and equipment. An alternative is a survey, a look in depth at
selected procedures (such as those for testing alarms and trips, issui
ng permits-to-work, controlling modifications, taking samples or testi
ng relief devices) or selected equipment (such as level glasses or equ
ipment for handling LPG). If the procedure or equipment is well-chosen
, surveys may make a bigger contribution to safety; per person-hour, t
han a conventional audit.