This technique involves the comparative analysis of all occurrences of a single design element on all P&IDs. These elements are easily located even on complex P&IDs by the design engineers or an individual familiar with the type of facility. Parallel element review is fast, thorough, and very revealing of errors and omissions. It works well with groups and for individual review.
Optimally, only one element at a time is selected for analysis, because several aspects of each element may need examination simultaneously, such as use, need, aptness, and engineering rationale. One might take several passes through the P&IDs to review the following equipment connections: vessel drain size for each vessel, flanged versus stub weld connections, all flanged thermocouple locations, piping classification changes for lines tying into vessels in corrosive service, etc.