(71as) High Integrity Pressure Protection Systems: Design, Analysis, Justification and Implementation

HIPPS (High Integrity Pressure Protection Systems) are installed to provide protection to critical equipment ranging from high/low pressure interfaces to equipment overpressure scenarios in upstream and downstream processes.  Any of these conditions could result in damage to the plant, the environment, loss of life and financial consequences.

To avert such an event, HIPPS generally shut down, reduce or divert the pressure sources feeding the system that is experiencing the overpressure.  In those cases where overpressure in a system causes a huge liquid or vapor relief load being sent to a flare system, the right HIPPS system can help reduce excessive load on an existing flare system and eliminate the high costs associated with purchasing new relief devices, resizing existing flare headers, re-rating flare knock out drums, redesigning the flare stack, etc., in addition to the opportunity costs due to loss of operations.

Currently, the approach is to design HIPPS for flare load reduction as a Safety Integrity Level (SIL) 3 Safety Instrumented Function (SIF) or a SIL 2 SIF (depending on the code or company standard being followed). This work discusses how instead of taking the customary “one size performance fits all approaches”, the design could be based on a IEC 61511 Safety Lifecycle view point to determine the required risk reduction and thereby choosing the actual required SIL.  This presentation will discuss current practices; review benefits and drawbacks of SIL selection in these scenarios, and describe the impact on total cost of ownership.