Drilling Method

Choose based on drilling technique:
▪ DTH (Down-the-Hole)
▪ Top Hammer
▪ Rotary Drilling
▪ Casing-Advancing / Hollow Auger / CFA etc.

Ground Formation

▪ Soft soils: lightweight thin-wall rods
▪ Medium to hard rock: alloy steel with heat treatment
▪ Gravel/boulders: rods with high torsional and bending resistance

Hole Depth & Diameter

▪ Deeper holes require heavy-weight drill pipes
▪ Larger boreholes demand high-rigidity and thicker wall drill rods

Rig Compatibility

▪ Match clamping diameter, torque capacity, and percussion frequency
▪ Ensure thread connection compatibility (API REG, BECO, R32, T45, etc.)

Flushing System

▪ Air flushing → requires through-hole design
▪ Mud flushing → corrosion-resistant and smooth inner wall
▪ Water circulation → high sealing performance at joints

Project Budget & Frequency

▪ High-frequency drilling → choose forged or heat-treated premium rods
▪ Short-term use → mid-range or budget-friendly options acceptable

Mining & Blast Holes

Hollow steel body + alloy construction + heat treatment + DTH threads (API REG, BECO)

Slope Anchoring / Support Drilling

Lightweight drill rods + high-torque threads (R32 / R38) + fast-connect joints

Water Well Drilling

Extended-length rods (3–6 meters) + anti-corrosion coating + large flushing channel

Core Sampling & Geotech Investigations

Thin-wall high-straightness rods (e.g., NW, HW) + precision threads

Rotary / Casing Drilling

Heavy-wall rods with high fatigue resistance and premium thread connections

Using small rods for large holes

Causes bending, breakage; always match bore diameter with rod size

Thread mismatch with hammer or coupling

Leads to thread damage, connection failure—verify thread specs carefully

Ignoring complex geology

Hard or mixed formations require stronger, impact-resistant rods

Choosing low-cost, poor-quality rods

Lower upfront cost, but higher failure risk and downtime overall