John Yesberg

HAZID and HAZOP (also known as Hazard Studies 2 and 3 in the ICI series) are a central part of risk management in some process engineering sectors. 

Sources of information include:

• The original author: Trevor Kletz's HAZOP and HAZAN. https://www.amazon.com/Hazop-Hazan-Trevor-Kletz/dp/0852955065
• An Australian Standards publication: Australian Standard AS IEC 61882:2017 Hazard and operability studies (HAZOP studies)-Application guide
• ISO 17765:2016 Petroleum and natural gas industries — Offshore production installations — Major accident hazard management during the design of new installations
• An Australian (NSW) government publication: Hazardous Industry Planning Advisory Paper No 8 HAZOP Guidelines
• Wikipedia pages on HAZID and HAZOP.