How Cold Root Rolling Improves Strength and Efficiency

The Simple Process for Saving Cash in Oil Drilling

Drill string assemblies are complex, sophisticated, and utterly essential systems in the oil and gas industry, down to the smallest parts.

The importance of the connections that keep these systems running is not only key for environmental and work efficiency, it’s also crucial to saving costs – according to reports, a failed connection in offshore drilling comes with an average price tag of $250,000 a day.

Step 2 Burnishing

Cold root rolling, an independent mechanical process that strengthens the connections in question, may offer the most innovative solution the industry has seen yet.

The Basics

Cold root rolling involves a specialized set of tools that burnish the root radius of a cut thread in a rotary shouldered connection. The tools are versatile, affordable and compatible with the existing equipment at most companies.

Cold Root Rolling

Burnishing changes the structure of steel material on a fundamental, atomic level. The work-hardening effect on the surface results in a shift from typical, crystalline steel structure to a dislocated, interlocked steel. The resulting material is less susceptible to shallow cracking and wider structural flaws and damage.

The Perks

  • Improved Strength: The complexity of drill string assembly – offshore, extended-reach drilling, multi-lateral wells, and horizontal well applications – requires stronger parts as performance demands increase. Burnished, strengthened steel is better able to carry these stresses.

  • Increased Resistance to Thread Root Stress: One of the by-products of cold root rolling is residual compressive stress, which offsets the tensile stress of service in the crucial regions of a root thread. It decreases the chances for failure while increasing the chances for successful repair.

  • Reduced Corrosion: Cold root rolling smooths away scratches and imperfections in steel surfaces, reducing access for chemicals.

  • More In-House Work: With simple, intuitive tools, the process is highly accessible to all kinds of operations.

With this increased strength, studies have shown an increase of three to five times in the joint life of cold root rolled connections. In an unsteady oil and gas industry, less maintenance and downtime promise major advantages for equipment manufacturers. For more information about the benefits of cold root rolling, visit

This article was submitted by CJWinter.


Our Privacy Pledge