Okla. Admin. Code § 252:100-39-2
The following words and terms, when used in this Subchapter, shall have the following meaning, unless the context clearly indicates otherwise.
"Petroleum refinery" means any facility engaged in producing gasoline, aromatics, kerosene, distillate fuel oils, residual fuel oils, lubricants, asphalt, or other products through distillation of crude oil or other hydrocarbons or through redistillation, cracking, rearrangement or reforming or unfinished petroleum derivatives.
"Refinery unit" means a set of components which are a part of a basic process operation, such as distillation, hydrotreating, cracking or reforming of hydrocarbons.
"Submerged fill pipe" means any fill pipe or discharge nozzle that meets any one of the following conditions.
(A) The bottom of the discharge pipe or nozzle is below the surface of the liquid in the receiving vessel for at least 95 percent of the volume filled.
(B) The bottom of the discharge pipe or nozzle is less than 6 inches from the bottom of the receiving vessel.
(C) The bottom of the discharge pipe or nozzle is less than 2 pipe or nozzle diameters from the bottom of the receiving vessel.
Okla. Admin. Code § 252:100-39-2