The provisions of §§ 53-1-5 through 53-1-120 do not apply to manufacturing establishments or to research and development operations of any person, including the support services necessary for these operations, or to the employees of these operations when these establishments in the nature of their business involve manufacturing processes requiring continuous and uninterrupted operation or which for economical operation must engage in a continuous process nor do the provisions apply to maintenance, repair, and other service personnel of any manufacturing establishment.