Applies to oil field specialist contractors engaged in well maintenance operations at oil lease sites which are not otherwise classified. Separately rate pipeline construction, tank building, rig or derrick erecting or dismantling, installation or recovery of casing, drilling, cementing, cleaning and swabbing of wells or well shooting. Refer to code 1320 for employees of an oil or gas lease owner/operator, code 6213 for contractors engaged in specialty tool operations at oil or gas wells and code 7515 for pipeline construction and pipeline maintenance.