End of Life CNG Containers and Tanks – A Review of the 3D’s

As the extraction and distribution of natural gas grows globally, so does the use of Compressed Natural Gas (CNG) in the transportation industry. Because of this, more and more CNG containers are in circulation in North America. However, when these units reach the end of their life, it is critical that they are disposed of properly.

CNG containers are pressurized, which means users must take special precautions when it comes to proper maintenance, replacement, and disposal. Any person who handles a CNG container must have knowledge of its useful life and strictly follow the expiration date of the container. It can be safely used until its expiration date, which is clearly marked on the label, provided there is no damage, corrosion, or other issues with the container. Keeping them in use after the expiration date or operating damaged containers can have serious safety consequences.

CNG containers and liquefied natural gas (LNG) tanks typically have a 15-20 year lifespan. Since natural gas vehicles (NGVs) have been deployed for decades, these containers and tanks are reaching their end of useful life. Fleet owners and operators have an interest, need, and a responsibility to understand how to safely defuel and dispose of these containers and tanks once they have expired and need to be removed from service.

Tow operators will not transport a vehicle with CNG containers or LNG tanks to a scrap yard since most yards will not accept them. Owners are then forced to remove them – often on their own – and keep them in their possession as a storage solution. To address this critical safety issue, CSA Group and key industry stakeholders developed an industry-wide guideline to serve as guidance for incident prevention and to alert technicians, owners, and recyclers to the potential hazards and safe practices when defueling, decommissioning, and disposing of containers and tanks. These “3Ds” are paramount to industry, and the safety and well-being of natural gas transportation operators and the general public.

The Basics of the 3Ds

Defueling – While the term “defueling” might sound simple, it can be one of the most dangerous operations related to CNG containers. NGV technicians who perform this task must be adequately trained on this procedure, as it requires several complex steps. Some basic rules when defueling a CNG tank include ensuring the tank is empty, notifying the appropriate personnel prior to defueling, and always wearing personal protective equipment (PPE) to name just a few.

Decommissioning – Decommissioning is the process whereby something is dismantled to the point that it no longer requires safety monitoring and inspection for hazard mitigation purposes. It is time sensitive and more than just a technical task – it is also highly administrative.   It includes clean-up of any hazardous materials, and inspection for safety before it can be released from regulatory control.

Disposal –CNG container disposal also entails a step-by-step process, beginning with verifying the completed decommissioning of the container. Proper disposal must comply with regulations set by the AHJ, and must be documented.

How Can CSA Group Help?

 In 2014, CSA Group and industry experts set out to create a best practices document focusing on the 3Ds which was published in 2016.  This first edition is not an accredited publication but rather a guidance document intended for use by industry, container owners, and authorities having jurisdiction (AHJs) to safely and effectively remove containers from service. It focuses on natural gas containers since that was the immediate need of industry.

At the backbone of CSA SPE 2.1 is an emphasis on consistently adhering to compliance requirements and following manufacturer recommendations and proven methods. Critical guidance that users can expect to find in this document includes:

  • Defueling, decommissioning, and disposing of CNG containers should only be done by a qualified person or agency;
  • CNG containers that have been damaged or have reached their end of life should be permanently removed from service; and
  • CNG containers should be destroyed or irrevocably rendered inoperable prior to being disposed, using proven methods applicable to the container’s type of construction.

In addition, CSA Group is offering a limited-time offer of a free online training course, with support from Natural Resources Canada (NRCan), to offer more detailed guidance. Further building on this critical topic, CSA Group published best practices for LNG vehicle fuel tanks early in 2018.

For more information on the global growth of natural gas vehicles, and the role of standards, testing & certification, download our free white paper on Life after Widespread Adoption of Natural Gas Vehicles.