PHMSA is proposing to amend the Hazardous Materials Regulations applicable to the design, construction, certification, recertification and maintenance of cargo tank motor vehicles, cryogenic portable tanks and multi-unit tank car tanks (ton tanks) in response to petitions for rulemaking from the American Society of Mechanical Engineers (ASME), the National Board of Boiler and Pressure Vessel Inspectors (National Board), and the Pressure Vessel Manufacturers Association (PVMA).