Suitable for steel material , Hardness grade S Stainless Steel/Metal Grinding Discs Depressed Centre PFERD Performance line SG pipeline Grinding wheel is designed for grinding and cutting of pipeline root pass, weld and flame cut grinding, and all facets of steel and nonferrous metal production and fabrication. Norton Bluefire 66252843211 24 Coarse Grit Zirconia Alumina Type 27 Pipeline Weld Grinding CGW® 35624 Flat Depressed Center Wheel, 4-1/2 In Wheel Diameter, 1/4 In Zirconia Alumina Grinding Disc For weld grinding, chamfering, deburring, root pass grinding application PFERD 63251 1/8" Type 27 Zirconia Alumina Grinding Wheel | 7/8" Arbor Hole | 4-1/2" Diameter (Box of 10) Designed for use on high-powered angle grinders on steel pipelines RPM: 13300; Bore Size: 7/8; Abrasive: Zirconia Alumina Z. Premium zirconia grain, high edge stability and tight dimensional tolerance for professional root pass grinding operations.