AISI 4145h Oil Drilling Drill Collar 165.1mm-Nc46 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Water Well Drilling Drill Collar 158.8mm-Nc46 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Oil/Gas/Water Drilling Drill Collar 158.8mm-Nc46 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Oil Drilling Drill Collar 158.8mm-Nc46 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Water Well Drilling Drill Collar 127mm-Nc38 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Oil/Gas/Water Drilling Drill Collar 127mm-Nc38 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Oil Drilling Drill Collar 127mm-Nc38 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Water Well Drilling Drill Collar 120.7mm-Nc35 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Oil/Gas/Water Drilling Drill Collar 120.7mm-Nc35 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. AISI 4145h Oil Drilling Drill Collar 120.7mm-Nc35 with API Spec 7-1/7-2 Hebei Shitan Machinery Manufacturing Co., Ltd. <<<2122232425>>>