Check-valves are utilized in all sorts of applications, including safety applications - most notably in process safety and hazardous materials safety.  In some state fire codes, these valves may even be required in certain lines and in some process safety RAGEGEPs they are required.  Although this incident occurred in an off-shore rig, the sight-glass involved can be found in just about any "processing facility" in the world.  Our first line of protection for these sight-glasses MUST be to protect them from external damage (e.g. mobile equipment striking them); our second layer of protection are these check-valves should the sight-glass fail/begin to leak.  These valves can work and work well when they are designed into the process properly, installed properly and maintained properly.  Although the Bureau of Safety and Environmental Enforcement (BSEE) bulletin does not indicate how these valves came to be missing their primary component, we can still learn from this incident and use it to drive awareness around this layer of protection.  Both OSHA and EPA have stated that "check-valves" can aid in the reduction of a release, they should NEVER be relied upon solely to stop a release (pdf download from SAFTENG).  

Also, Chemical Safety Alert: Shaft Blow-Out Hazard of Check and Butterfly Valves

NOTE: SAFTENG Members can read my 2/2016 article Does your PSM/RMP utilize “check valves” as a safe guard to PRVENT “reverse flow”? (NRC and API 570)


On January 5, 2017, a failed vessel apparatus (broken sight glass) located outside of the Heater Treater discharged oil because the ball checks were not present in the gauge cock valves. As oil discharged from the sight glass, it saturated the protective insulation on the Heater Treater and blew into the Pipeline Pump #1 exhaust system, causing an ignition. As a result of the fire, damages to the Heater Treater and associated equipment were estimated at $2.7 million dollars. Fortunately, there were no injuries to personnel.

The investigation revealed that the gauge cock valves, located on the top and bottom of the sight glass assembly, were not fully functional because there were no ball checks present in either valve. If the ball checks were in place, they could have prevented the flow and/or mitigated the amount of oil discharged out of the system due to sight glass breakage. Since the ball checks were not in place, a constant discharge of oil from the system occurred until the level of oil dropped below the bottom gauge cock valve.

BSEE check valves alert

Therefore, BSEE makes the following recommendations to Operators:

  1. Gauge cock valves should be equipped with an automatic ball check shutoff, in accordance with API 14J 3.3.2, to help prevent/mitigate rapid loss of fluid due to accidental glass breakage.
  2. Ensure that personnel are familiar with the manufacturer’s installation, operation and maintenance requirements related to gauge cock valve assemblies.
  3. Ensure that personnel are familiar with and trained on the status/position of gauge cock valve assemblies.
  4. Ensure that personnel are familiar with and trained on operating procedures and maintenance related to sight glass assemblies.
  5. Periodically inspect the gauge cock valves to make sure that the balls are still in place and that they are functioning properly.

CLICK HERE for the official bulletin

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Training Course: 

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Process Safety Managers 

September 18-22, 2017

Dayton, OH

CLICK HERE for more


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