BakerRisk HTHA Update for the Ammonia Industry

Recent discussions at the Ammonia Safety Symposium have focused on the failure mechanism known as high temperature hydrogen attack (HTHA).  HTHA affects equipment and piping in ammonia production, and it involves the possibility of catastrophic failure at medium/high pressures at raised temperatures.

Due to HTHA incidents and recent technical findings relevant to ammonia producers, changes in the industry standard (API Recommended Practice (RP) 941 – Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants) have been finalized and issued in the 8th Edition of API RP 941 (2016).

BakerRisk has issued an update to provide summary information to ammonia plant users about some of these recent developments, which can serve as an aid in making knowledgeable decisions for ammonia plant design and operations.


Notice on Upcoming API Inspection Summit:  The API will be hosting a panel discussion at the
7th Biennial Inspection Summit in Galveston, Texas from January 30 to February 2, 2017, Input from the ammonia industry will be included. The topics for the panel will include:

  • “How are sites reacting to the Tesoro event and the new edition of API RP 941”.  Who’s doing what?
  • Who’s surveying all their hydroprocess equipment for susceptibility?
  • Who’s replacing some equipment?  Who’s going to rely on inspection?  Who’s in between those options?
  • What’s new since the last summit on Inspection Technology?

Information on the summit can be found on the API website at:

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