As used in this act: (a) The term “person” includes one or more individuals, partnerships, associations, corporations, legal representatives, trustees and receivers in bankruptcy and reorganization of any group whether or not it is incorporated.

(b) The term “oil-field equipment” means oil-field supplies, oil-field machinery, materials, heavy machinery, buildings, tubing, tanks, boilers, engines, casing, wire lines, sucker rods, oil pipelines, gas pipelines and all other material used in digging, drilling, torpedoing, operating, completing, maintaining or repairing any such oil or gas wells or oil pipelines or gas pipelines, or in the construction or dismantling of refineries, casing-head gasoline plant and carbon black plants.