短钻铤用途：短钻铤主要用来调整底部钻井工具位置和改善底部钻具功能的工具。特点：其机械性能和钻铤相同，但其长度较短，可根据要求确定Drill Collar SpecificationФ89 Ф105 Ф121 Ф146 Ф159 Ф165 Ф178 Ф203It's made from rolled or forged AISI4145H chrome-molybdenum steel. The content of chemical composition and microelement is controlled effectively throughout the whole process. According to its different figures and materials, it can be divides into three types: Type A (columnar): made from ordinary alloy steel, both inside and outside of the cross section of the pipe are cycloidal.Type B (spiral): made from ordinary alloy steel, with a spiral chute on the outer surface of the pipe Type C (non-magnetic): made from stainless alloy-steel of low magnetic permeability, both inside and outside of the cross section of the pipe are rounded.