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.

Read More about the GATE HAZOP Process in the August 2010 GATEKEEPER: A More Effective HAZOP Process