Wearing resistance of drill rod joint is an important study in drill machine manufacture for years.

The three fail form of scoring,fillister and corrosion for 127 mm(5″) S135 drill rod joint,corrosion rate and corrosion production have been researched by means of analysis of chemical composition and microstructure,testing of mechanical property.

Reasons of wear-reistant zone dropout in spray-welding coating on drill pipe joint and its preventive measures;

There are geometric defects at the shoulder of drill pipe joint.

Based on the theory of contact non-linear finite element, the non-linear finite element analysis model of drill pipe joint screw was established, and the effect regular of external diameter of drill pipe joint on the its strength was researched by means of large general-purpose finite element analysis software .

Study of the torsion strength and material toughness criteria of drill pipe tool joint;

Due to the increasing number of deep wells and directional wells being drilled,longitudinal fracture occurred on the box-ended drill pipe tool joint is often reported.

This paper discusses how to establish the methods and parameters of heat treatment of petroleum tool joint based on selecting material and elementary analysis,and how to improve the technology by analyzing the results of practice.

Analyses of longitudinal cracks of tool joints were performed based on field background search, macro and micro crack morphology analysis and material testing of both cracked and not cracked tool joints.

Based on the planar beam theory, the models for calculating the maximum bending stress of drilling rod under axial tensile load, compressive load, and zero load are given, in consideration of the effects of tool joint, axial force, drilling rod weight, and attachment of drilling rod with the wall of wellbore on bending stress of drilling rod.