Skip to main content
Clean Hydrogen Partnership

Premature opening of a pressure relief valve

Event

Event ID
1135
Quality
Description

A CGH2 tube trailer was transferring hydrogen to a customer cylinder skid. The pressure relief on the customer system opened, the escaping hydrogen ignited and burned for approximately 10-15 seconds, causing a 30 ft (10 m) flame.
This occurred at the end of the filling process, the gauge pressure was approaching 2400 psi (166 bar) and the driver was proceeding to terminate the process. The safety relief valve vented before the driver could complete the process. The driver received burns while trying to close valves. Safety relief valve was designed to activate at 2400 psig (166 bar).

Event Initiating system
Classification of the physical effects
Hydrogen Release and Ignition
Nature of the consequences
fire
Macro-region
North America
Country
United States
Date
Component involved
TPRD
Failure mode
rupture & ignition
Initiating cause
unknown
Root CAUSE analysis

The INITIATING CAUSE was the premature activation of a pressure relief valve.
ROOT CAUSE could be attributed to a (i) defective component (the valve), or (ii) to a erroneous choice of the pressure value for the activation (erroneous design), or (ii) to the transfer procedure which was not allowing for uncertainty in the final pressure of the process (erroneous procedure). A human error cannot be excluded either.
The source does not provide elements for a choice.

Root causes
Unknown
Date entry in HIAD
25/10/2024

Facility

Application
Hydrogen transport and distribution
Sub-application
CGH2 tube trailer
Hydrogen supply chain stage
All components affected

Pressure Relief Valve or Device - Non-Reclosing

Process temperature range [C]
ambient temperature (-50°C to +50°C)
Process pressure range [MPa]
medium to high pressure (10 to 50 MPa)
Location type
Open
Location
industrial area
Operational condition

Emergency & Consequences

Number of fatalities
0
Number of injured persons
0
Currency
US$
Property loss (onsite)
0

Lesson Learnt

Lesson Learnt

This incident could be attributed to:
(i) A defective component (the valve) which activated before its set pressure,
(ii) An erroneous choice of the pressure value for the activation (erroneous design),
(iii) The transfer procedure which was not taking into account the possible variation/ uncertainty in the final pressure of the process (erroneous procedure).
(iv) An error of the operator (the driver) who allowed the pressure to achieve the valve activation value.

The report does provide the data and the information necessary to clarify these options: for example, the exact value of the filling pressure in the system when the valve activated and the actual pressure in the trailer tank. The design of the customer tank and the position of the pressure relief system is unknown. This played an important role in the consequence, because the driver was near the activating valve when the release occurred. Could a better knowledge of the customer system and a better design reduce the hazards?
Moreover, it appears that the transfer process consisted in a series of manual steps. Could more automatic steps perhaps help reducing some of the hazards?

In-depth data

Release type
gas
Involved substances (% vol)
H2 100%
Release temperature [°C]
25
Release pressure [MPa]
16.5
Probable IGNITION SOURCE

References

Sources categories
PHMSA
Reference & weblink

Incident I-2005060281 of the US Pipeline and Hazardous Materials Safety Administration PHMSA:
https://portal.phmsa.dot.gov/analytics/saw.dll?Portalpages&PortalPath=%…
(accessed September 2024)