HAZOPs are not fun!  Maybe that’s not a problem, but they also don’t achieve what they could and that is a problem. Why don’t we learn what we should from HAZOPs?

  • Tunnel vision.  The focus on small nodes obscures the big picture.    
  • Guideword excess – Flow, pressure, temperature, and level are usually discussed in the HAZOP.  But flow deviations cause most pressure, temperature and level deviations. 
  • HAZOPs are supposed to identify operability issues, but they really don’t.
  • Risk assessment in HAZOPs is typically difficult, ambiguous and not repeatable.
  • HAZOP reports are difficult to read and are of limited use.
  • Most people don’t enjoy HAZOPs and that impacts participation.

GATE Systems Engineering Manager Howard Duhon has been developing this process for the past 20 years.  The GATE Stream-based HAZOP process avoids these pitfalls via some novel modifications to the process.

Stream-Based Nodes

The main difference between the GATE Stream-Based HAZOP and a typical HAZOP is that we define nodes based on ‘streams’ for the FLOW deviation discussions.  For this purpose a stream is a continuous flow of fluid across piping and equipment items.  For example: oil production from the reservoir all the way to the dry oil tank can be considered one stream-based node.  A change in flow anywhere in the node affects the flow everywhere, or at least downstream.  This allows us to ask much more interesting questions that are hard to tackle in a typical HAZOP with small nodes.  Issues like startup, shutdown, commissioning, sampling, chemical injection, spec breaks, recycle are much more meaningful at the stream-based level. 

Equipment-Based Nodes

We do, however, have to resort to the typical equipment-based nodes for the temperature, pressure and level deviation discussions.  But we do all the stream-based node discussion first and that populates almost all the causes of pressure, temperature and level deviation.  So the pressure, temperature and level discussion are crisper and more efficient.