Preliminary Hazard Analysis (PreHA)

Preliminary Hazard Analysis (PreHA) is a method for the identification of hazards at an early stage in the design process, and it is a term normally used to describe a qualitative technique for identifying hazards relatively early in the design process. PHA is a requirement of the MILSTD-882D Standard Practice for System Safety. The CCPS Guidelines state that PHA is intended for use only in the preliminary stage of plant development, in cases where past experience provides little insight into the potential hazards, as with a new process. The information required for the study is the design criteria, the material and equipment specification, and so on.
Reference: Lees’ Loss Prevention in the Process Industries
A quick identification of any threatening event in a plant.
Preliminary Hazard Analysis (PHA) is an inductive method of analysis whose objective is to identify the hazards, hazardous situations and events that can cause harm for a given activity, facility or system. It is most commonly carried out early in the development of a project when there is little information on design details or operating procedures and can often be a precursor to further studies. It can also be useful when analyzing existing systems or prioritizing hazards where circumstances prevent a more extensive technique from being used.
A PHA formulates a list of hazards and generic hazardous situations by considering characteristics such as:
   a) Materials used or produced and their reactivity;
   b) Equipment employed;
   c) Operating environment;
   d) Layout;
   e) Interfaces among system components, etc.
The method is completed with the identification of the possibilities that the accident happens, the quantitative evaluation of the extent of possible or damage to health that could result and the identification of possible injury or damage to health that could result and the identification of possible remedial measures. PHA should be updated during the phases of design, construction and testing to detect any new hazards and make corrections, if necessary. The results obtained may be presented in different ways such as tables and trees.
Reference: IEC 60300-3-9
Technical Tools/Hazards Identification/Non-Scenario-Based Hazard Evaluation Procedures