The primary objective of positive isolation  is to provide a safe environment for performing maintenance, repair or replacement operations on process facilities. Positive isolation while performing maintenance or repair activities on process facilities means that, all the hazardous energy sources must be identified 

• All hazardous energies must be isolated at the source
• Residual energies must be eliminated.

Positive isolation can be provided to equipments or piping items for maintenance purpose using various arrangements depending on following factors,

• # rating of the piping
• Process fluid type - hydrocarbon, utility, toxic service, non-hazardous etc.
• Operational status of the system - shutdown and depressurized or still in service