CSC Production Square and Hexagonal Kelly

Kelly is a critical component located at the top of the drill string, available in both square and hexagonal designs. During rotary drilling operations, the kelly connects with the square bushing and the rotary bushing, transferring the surface rotary torque to the drill pipe and driving the drill bit. It also supports the weight of the entire drill string. In applications involving turbine or mud motor drilling, the kelly helps bear both the weight of the drill string and the counter-torque generated.

Introduction

Continental Steel Co., Ltd. (CSC) offers high-quality square and hexagonal kellys manufactured strictly according to API Spec 7-1 standards. The materials used are AISI 4145H modified alloy steel, fully heat-treated to achieve a Brinell hardness range of 285–341 and a minimum Charpy impact value of 40 ft-lbs. Each kelly bar undergoes ultrasonic inspection along its full length and cross-section to ensure quality and reliability.

Parameter Table

Size (in) Top Connection (LH) Bottom Connection I.D. (in) Drive Section (in)
Standard O.D. (in) Optional O.D. (in) Square O.D. (in) Hex. O.D. (in) Square Hex. A B
2-1/2 6-5/8 REG 7-3/4 4-1/2 REG 5-3/4 NC26 / 1-1/4 / 3-2/7 /
3 6-5/8 REG 7-3/4 4-1/2 REG 5-3/4 NC31 4-1/8 NC26 3-3/8 1-3/4 1-1/4 4 3-3/8
3-1/2 6-5/8 REG 7-3/4 4-1/2 REG 5-3/4 NC38 4-3/4 NC31 4-1/8 2-1/4 1-3/4 4-1/2 4
4-1/4 6-5/8 REG 7-3/4 4-1/2 REG 5-3/4 NC46 6-1/4 NC38 4-3/4 2-4/5 2-1/4 5-4/7 4-4/5
6-5/8 REG 7-3/4 4-1/2 REG 5-3/4 NC50 6-3/8 NC38 4-3/4 2-4/5 2-1/4 5-4/7 4-4/5
5-1/4 6-5/8 REG 7-3/4 / 5-1/2 FH 7 NC46 6-1/4 3-1/4 3 7 6
6-5/8 REG 7-3/4 / NC56 7 NC50 6-3/8 3-1/4 3-1/4 7 6
6 6-5/8 REG 7-3/4 / / 5-1/2 FH 7 / 3-1/2 / 6-4/5
6-5/8 REG 7-3/4 / / NC56 7 / 3-1/2 / 6-4/5

CSC's kelly products are designed for durability, performance, and compliance with industry standards. Whether you're working on conventional rotary drilling or more advanced drilling systems, our kellys are engineered to meet the demands of modern oil and gas exploration. With a wide range of sizes and connection types, we ensure that there is a solution for every application. Our commitment to quality ensures that each product is reliable, safe, and built to last under the most challenging conditions.

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September 26, 2025