Engineering and applications
Kelly Bar Sizing Guide
A clear engineering checklist for specifying length, stages, torque and interface details.
Use this guide to connect the bar configuration with the drilling method, equipment limits and service routine that will shape performance on site.
Start with the machine envelope
Record the rig model, rotary drive interface, available torque, crowd force, mast height and transport limits. The bar must be compatible with the drive while leaving enough clearance for the mast and casing arrangement. Treating these as fixed boundaries early prevents later redesign and protects the expected working stroke.
Set the working depth
Target depth, tool height and required overlap determine the useful bar length. A theoretical maximum is less important than the depth the crew can reach without losing stability or spending excessive time on section changes. Include the tool connection and any temporary casing in the working calculation.
Select the number of sections
More sections can improve transport and give flexibility, but each interface adds handling and inspection points. Fewer longer sections may simplify drilling, yet they can increase lifting requirements. The right balance depends on project logistics, rig capacity and how often the tool will work at different depths.
Confirm the load path
Torque is transferred through the drive, bar sections and tool connection. Check key or friction behavior, section wall thickness, guide clearances and weld transitions. A drawing should show the critical dimensions and tolerances in one place so procurement, production and the drilling crew are working from the same information.
For a project-specific discussion, compare this guide with the product range, the sizing checklist and the quotation form. Keeping those three references together helps the team move from an idea to a verified configuration.
Project reference notes
Kelly Bar Sizing Guide | Kelly Bar Systems is intended to be used as a working reference alongside the rig documentation and the approved project drawing. The useful decision is always specific to the machine, tool and ground: check the rotary interface, available torque, crowd behavior, target depth, section overlap and handling space before a final configuration is released. These details also help the field team understand why a particular bar arrangement was selected.
Keep the page available during quotation, commissioning and service review. During installation, confirm the section order and connection fit at low speed. During production, record ground changes, tool changes and any new sound or movement. During demobilization, clean the contact areas, protect the connections and carry the inspection record with the section marks. That small information loop makes the next decision faster and keeps the equipment history useful across projects.
For procurement and site planning, identify the bar by its complete model and section arrangement rather than by a shortened label alone. Confirm how it will be packed, lifted, stored and connected to the selected tool. If the project involves more than one rig, compare the interfaces before standardizing the order. Clear information at this stage reduces field modifications, protects the schedule and gives the service team a reliable starting point when the equipment returns from the job.