The Pipeline and Hazardous Materials Safety Administration has upheld an emergency restriction order placed on National Distribution Inc.'s cargo tanks by the FMCSA.

The California-based hazardous material carrier had appealed the restriction after the FMCSA prohibited the company from transporting hazardous materials in its entire fleet of cargo tanks. In May, a National Distribution cargo tank exploded during while being repaired.

An investigation by the FMCSA revealed that the cargo tank had not been cleaned and purged prior to the repairs. Further probing found that multiple instances of unauthorized repairs were performed on National Distribution’s cargo tanks without adhering to federal safety requirements.

After a restriction order was placed, National Distribution was allowed to use some cargo tanks after providing documentation that the tanks had successfully passed required tests and inspections to show that the tanks did not have any post-manufacture welds.

The company was also allowed to haul cargo not transported in USDOT specification cargo tanks.