Profile: Holly Pipe Corp. is a machine shop. We serve water well drilling, mining, oilfield and utility industries. We provide oilfield drill pipe or drill collars, drill pipe, water well tubulars and mining tubulars. We also offer inspection and repair services. We offer 3 1/8" to 11" steel or non-magnetic drill collars with spiral, slick, slip recess, elevator groove, hard banding, bore-back on box or special threading. Heavy weight drill pipe (HWDP) is usually run in between the drill collars and the drill pipe, in order to prevent fatigue of the drill pipe in the vertical drilling industry. Heavy weight drill pipe is also utilized in the horizontal directional drilling industry for added strength in high stress situations.