Understanding the difference between routine and Rotary Shouldered Connection

With the growth of oil companies and the growing need to drill deeper and faster, the need for effective connections to withstand a highly demanding environment’s expectations has grown. Engineers around the world are starting to develop new and advanced versions of the shouldered connections.

The standard version of the API threads and connections have single torque shoulders, and the modern Rotary Shouldered Connection, on the other hand, has two shoulders, i.e., a primary and secondary.

As a result of the same, you attain the following benefits -

· Enhanced load distribution across the threaded area

· Increased torsional capacity compared to standard API 7–2 and Rotary connections.

• Extra power for aggressive drilling

The additional torsional capacity gives the drillers extra torque strength that is beneficial for drilling to new depths or even more demanding areas.

Double shoulder tool joints can support larger IDs than single shoulder ones. The capacity to drill mud through the pipe improves hydraulic efficiency. Such connection can improve tolerance against wear and tear as compared to a single shouldered one.

• Performance calculation

The calculation for performance for single and double shouldered connections is done differently, and as a result, the MUT value is more than 60 percent of the torsion capacity. Some pipe suppliers accept that the must be increased to a higher value, but it must be lower than 70 percent of the torsional capacity.

Torque shoulders also work as seal shoulders, and even though the API RSC value is not pressure rated. Some of these connections are comparable and can be joined with single-shouldered ones.

Care and maintenance of Shouldered Connections

Even if the connections are heavily coated using phosphate solutions, the threads’ damage cannot be avoided. Use a generous coating of high-quality thread dope, i.e., 40–60 percent by weight metallic zinc, ideally for drill collar. It will help you to minimize galling.

New connections need to be walked in using chain tongs. For this, it is recommended to use makeup torque for handling the thread design. Care must be exercised to maintain the calibrated torque measures and indicate the gauges for long-term benefits. Once such a case happens, it is best to clean, inspect, etc., the connection, threads, faces, etc., to identify minor damage. Relubricate and use torque for such a connection.

Maintenance and repairs for the connections

It is recommended to break out a third time before going into the hole. Similarly, it is recommended to monitor torque value, and ideally, the same should be the same or less than the makeup torque. High breakout torque indicates problems, and as a result, all the connections must be monitored closely for damage.

You can also use thread protectors on both the connections when handling the drill products. Once done, clean and inspect the individual connections. Using the aid of qualified personnel means that you can ensure timely maintenance and repairs. The drill stem products that are left idle or put into storage must be cleaned, inspected, and repaired before installing the thread protectors. Similarly, proper running and handling of the drill pipe are essential to save time and money.