When Choosing A Second-hand Rotary Drilling Rig for Bridge Construction, What Should Be Noted about The Drill Pipe And Drill Bit?

Bridge construction has strict requirements for the accuracy, depth and stability of drilling. The drill pipe and drill bit of second-hand rotary drilling RIGS, as core working components, directly affect the quality of hole formation and construction safety. The following six key perspectives are provided to popularize the inspection and compatibility points of drill pipes and drill bits when purchasing second-hand equipment.

1. Inspection of drill pipe material and wall thickness: Prioritize the use of high-strength alloy drill pipes. Measure the wall thickness with a caliper. If there is local wear exceeding 15% of the original wall thickness, replace them to prevent breakage caused by insufficient drill pipe strength during bridge pile foundation construction.

2. Inspection of drill pipe connection parts: Focus on checking the thread wear and sealing condition of the drill pipe joint. If the thread is stripped or the sealing gasket is aged, it is easy to cause mud leakage during construction, affecting the verticality of the hole formation.

3. The number of drill pipe sections should be adapted to the requirements of the bridge: The number of drill pipe sections should be selected based on the design depth of the bridge pile foundation. For example, for a 30-meter deep pile foundation, 5 to 6 drill pipe sections should be matched to avoid frequent splicing due to insufficient sections, which would reduce construction efficiency.

4. Drill bit type matching geological conditions: If rock strata are encountered during bridge construction, cone drill bits should be selected to enhance rock-breaking capacity. If it is a soft soil layer, a cylindrical drill bit can be selected to reduce the risk of hole wall collapse and ensure the quality of pile foundation formation.

5. Inspection of the drill bit cutting edge and tooth seat: Observe whether the cutting edge of the drill bit is cracked and whether the tooth seat is loose. If the cutting edge is severely worn or the tooth seat falls off, it needs to be replaced before use to prevent the drilling speed from slowing down or the problem of "off-hole".

6. Drill bit diameter matching with pile foundation: The drill bit diameter must be consistent with the designed diameter of the bridge pile foundation, with a deviation controlled within ±5mm to prevent excessive concrete usage or insufficient structural strength of the pile foundation due to diameter mismatch.

In conclusion, when choosing a second-hand rotary drilling rig for bridge construction, attention should be paid to the material, connection and pitch compatibility of the drill pipe, and the type, cutting edge condition and diameter accuracy of the drill bit. Only by strictly controlling the quality and compatibility of these two major components can the efficiency, accuracy and safety of bridge pile foundation construction be guaranteed, laying a solid foundation for subsequent bridge construction.