Is a square Kelly stronger than a hexagonal Kelly?

‌In terms of strength and durability, there is no conclusive answer as to whether a Square Kelly is stronger than a Hexagonal Kelly. The choice between a Square Kelly and a Hexagonal Kelly often depends on the specific drilling application and requirements.

Square Kellys are typically less expensive than Hexagonal Kellys, as they are simpler in design and do not require the additional complexity of hexagonal shaping. However, Hexagonal Kellys are often stronger and more durable, as they have a greater surface area for torque transmission and can better withstand the axial forces applied during drilling.

In deep drilling applications, where high torque and axial forces are required, Hexagonal Kellys are often preferred due to their superior strength and durability. However, in shallower drilling applications or where cost is a primary concern, Square Kellys may be a more suitable option.

Ultimately, the choice between Square Kellys and Hexagonal Kellys should be based on the specific drilling requirements, taking into account factors such as torque transmission, axial force resistance, durability, and cost.