Section 28(4)(v) in The Static and Mobile Pressure Vessels (Unfired) Rules, 2016
(v)before a vehicle is moved, the electrical and the liquid and vapour connections shall be disconnected, care being exercised to avoid spillage. Where wheel chock blocks have been used they shall be removed. The vehicle shall be checked to ensure that it is in safe working order and the surrounding areas checked to ensure that any liquefied flammable gas that may have leaked or has to be vented has safely dispersed.