Metal fusion bonding – Process – With shaping
Patent
1987-07-20
1989-01-10
Godici, Nicholas P.
Metal fusion bonding
Process
With shaping
228176, 228112, 403271, B23K 2012, B23K 3102
Patent
active
047967994
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to sucker rods, namely, to methods for making sucker rods.
PRIOR ART
Sucker rods applied for oil production serve to impart drive to the well pump located at the hole bottom. A sucker rod is in fact a lengthy central stem or body provided at its both ends with end heads having a thread for the rods to join into a string which is then to run down the well. Each of the end heads of the sucker rod has two cylindrical collars, one of which, i.e., the more removed from the central stem or rod body serves for the threaded coupling interconnecting the sucker rods, to thrust against. The transition from the other collar located closer to the central stem or rod body, is in effect a long-sweep curve to reduce the concentration of stresses and provide a good fit onto the elevator, i.e., a tool with the aid of which the rod string round-trip operation is carried out during well work. A square cross-section neck is provided between the collars for the rods to make and break.
While in operation sucker rods undergo a complex cyclic loading. Since they operate in the liquid pumped out of the well, they are exposed to the effect of corrodents contained in the liquid. In addition, sucker rods are subjected to bending, especially when operating in directionally drilled or inclined wells, and their threaded joints undergo wear during their making and breaking.
All this is causative of premature wear and break-downs, largely, of the sucker-rod threaded joints, especially in wells containing corrosive fluids.
There is known commonly a method for making sucker rods composed of a central stem or rod body and threaded end heads, incorporating upsetting the heads at the both ends of the long-length bar stock, followed by heat-treatment of the sucker rod and mechanical treatment or machining of the threaded ends to obtain a solid sucker rod (cf., e.g., U.S. Standard API Spec. 11B).
However, making sucker rods according to said method involves the use of expensive, predominantly alloyed steels containing Cr, Ni, Mo which is due to strict requirements to threaded end heads, since thread is a stress concentrator that affects adversely serviceability of sucker rods, especially those operating in wells containing corrosive fluids.
Another prior-art method for making sucker rods composed of a central stem or rod body and end heads is known to comprise upsetting and pressure-welding (cf., e.g., British Pat. No. 2,104,936A, CL. E21B 17/00 published Mar. 16, 1983).
According to said method, the sucker-rod production process consists in upsetting the end heads, their machining and subjecting to pressure welding, in particular, to friction welding to attach them to the central rod body, whereupon the resultant flush is eliminated from the weld joint obtained.
With such a method of making sucker rods the weld joint is located at a minimum rod cross-sectional area, which is of danger due to the effect of possible lack of penetration and other weld-joint defects impairing its strength. Furthermore, the fact that the weld joint is established at the place where the rod cross-sectional area changes in transition from the rod body to the head calls forth the constructional stress concentrator, which is operationally unreliable, especially when the sucker rod is subjected to bending during operation in directionally drilled or inclined wells.
In addition, it is due to unavoidable mutual displacement of the rod body and end heads in the course of welding that flash resulting from the welding process cannot be removed completely and flash residues affect adversely corrosion-fatigue strength of the material the rod body and the end heads are made from.
High-temperature heating of the weld-joint zone modifies the original structure of the metal of the rod body and of the end heads and causes residual heat stresses to arise, which impairs serviceability of a suckered rod.
The fact that the heads are made from a harder steel as compared to the steel from which the rod body is made, contributes to a lower c
REFERENCES:
patent: 3295613 (1967-01-01), Anderson
patent: 4073474 (1978-02-01), Hashimoto et al.
patent: 4205926 (1980-06-01), Carlson
patent: 4367838 (1983-01-01), Yoshida
patent: 4487357 (1984-12-01), Simon
patent: 4522529 (1985-06-01), Conley
patent: 4594020 (1986-06-01), Hughes
Metals Handbook Ninth Edition, vol. 6, pp. 719-728, 1983.
Ibragimov, deceased Oktai I. O.
Kakhramanov Khalid T.
Karaev Islam K. O.
Kurbanov Nariman G. O.
Rabinovich Avraam M.
Azerbaidzhansky Nauchno-Issledovatelsky I Proektno-Konstruktorsk
Godici Nicholas P.
Heinrich Samuel M.
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