Friction vs Interlocking Kelly Bar: What Used Rotary Rig Buyers Should Check

Read published depth figures correctly

Manufacturer documents often show two maximum depths: one for friction and one for interlocking Kelly. For example, archived SANY SR360R documentation lists multiple bar combinations with different section counts and depths. Those figures depend on the specified bar and do not automatically apply to every used SR360R or to the bar included in a listing.

Usable drilling depth is affected by tool length, bar engagement, mast geometry, working platform and the need to keep safe overlap between sections. Ask the supplier to calculate the working depth for the exact bar and tool, then record the dimensions in the contract.

Inspect a used Kelly from top to bottom

Clean paint can hide the areas that matter, so request close-ups before cosmetic preparation where possible. Extend and retract the bar safely, rotate it through the available inspection position and photograph identifying marks. A specialist should measure critical wear where the purchase value justifies it.

• Straightness of every visible section and evidence of bending or heat correction
• Dents, local buckling, corrosion, cracks and non-original weld repairs
• Guide strips, drive keys, locking pockets and contact surfaces
• Smooth extension, retraction, lock engagement and release
• Top connection, damping components, pins, stops and lower tool connection
• Actual outer diameter, section count, section length, weight and compatible rotary drive

Put the Kelly identity in the commercial documents

The quotation and sales contract should state friction or interlocking type, manufacturer if known, diameter, sections, length, included adapters and current condition. Use photographs and a unique package reference. If a different bar is substituted before loading, require written approval and repeat the compatibility check.

If the bar will be shipped separately, add its piece weight, length, support method and lifting points to the packing plan. Confirm how it will be protected from bending during inland transport and sea freight. The destination team also needs the correct procedure and lifting equipment for installation.

A faster way to request the right rig-and-Kelly package

Send GLOBMACH the bore log, diameter, depth, tool type, casing plan, rig preference and destination. State whether depth or hard-layer penetration is the limiting requirement. We can filter current rotary rigs by the installed or available Kelly configuration and mark any dimension that still needs measurement.

The result should be a complete package comparison: machine condition, Kelly identity, tools, transport and missing evidence. That prevents a common purchasing error—selecting the right machine class and then discovering that the included Kelly cannot perform the intended work.