1 Steel tube
●Seamless alloy tube
same ashydro-cylinder
●Much higher nominal
loadingtorque of Kelly bars
●Shot Blasting before
welding
2 Extermal strips
●Alloy material
heat-treated
●High hardness and highabrasion-resistance
●Single length no less than 9m
3 Locking plate
●Alloy material
heat-treated
●High hardness and
highabrasion-resistance
●Robot cutting
●Tail structure reduce
crackingtendency
4 Upper guide ring
●Three moving rings
●Wear-resistance
●Impact resistance
5 Drive shell
●Robot cutting and welding
●Intergral arc plate
●High wear resistance
6 Terminal joint
●Robot cutting and
welding
●Overlapping of intermal
andexternal plates
●Small tendency for
cracking
7 Anti-friction plate
●Full-rotating
●Reduce wear on pipe
endsand stopper plate
8 Tool joint
●Integral forging with leghth no less than1.2meters
●Significantly reduce weld load