The due dates for Piping and
Instrumentation Diagram, P&ID and Safe Chart always is a conflict
personally for me and generally for a project. This is because due date for
P&ID is more critical deliverables compared to Safe Chart. However, Safe
Chart is a checklist practice to be done on P&ID to evaluate requirement on
safety devices/devices. This is developed conjunction with of API RP 14C where
clear guidelines are provided where to provide all the safety devices/devices.
With this Safe Chart, we able to
identify which equipment need relevant safety devices, Low alarm, Low Low trip,
High alarm, High High trip, check valve, etc. This is very crucial because it
gives minimum requirement and acts as basis when developing P&IDs. The
P&IDs being developed will be based on minimum requirement and at least
will have some idea on minimum safety devices to be installed on related
equipment before it is used for design review and later for Hazard and
Operability (HAZOP).
Development of safe chart should
be earlier than P&ID so that most of the safety devices requirement can be
captured but producing P&ID earlier than safe chart becomes common practice
nowadays. The issue with this practice is that if the design is done for
detailed design or EPCC and instrument items are bought during development of
safe chart. As highlighted earlier, priority of issuing documents is more
weighed to P&ID and sometimes issuance of safe chart could be during
IFC/AFD of the P&ID. With this scenario, safe chart might be developed
based on existing P&ID and not really based on API RP 14C guideline which
sometimes some crucial safety devices might be missing in both P&ID and
safe chart.
