US2709091A - Locking screw for well head - Google Patents

Description

y 24, 1,955 I 1.. L. RECTOR 2,709,091

LOCKING SCREW FOR WELL HEAD Filed April -25, 1952 LfiUREA/CE L. R5005 A TTORNEY United rates Patent LOCKING SCREW FOR WELL HEAD Laurence L. Rector, Fort Worth, Tex.

Application April 25, 1952, Serial No. 284,335

3 Claims. (Cl. 285-22) This invention relates to well head assemblies for oil and gas wells, and has reference to improvements in locking screws, such as those for engaging and securing mandrel hangers, strippers or the like, in well heads.

An object of the invention is to provide a locking screw construction of the described class which may be re packed without loosing the well gas pressures.

A particular object of the invention is to avoid killing the well (that is, filling the same with a heavy mud to overcome formation pressures) when replacing packing around the locking screw.

Another object of the invention is to eliminate the fire hazard, due to escaping well gases, ordinarily present when replacing the referred to packing.

A further object of the invention is to prevent corrosion of threads on a locking screw of the described class by effectively sealing the inner or forward end of the screw so as to prevent the corrosive agents ordinarily present in a well from reaching such threads.

The invention will be more readily understood by reference to the accompanying drawing wherein:

Figure l is an enlarged broken vertical sectional view of a well head and showing a locking screw construction embodying the present invention positioned therein.

Figure 2 is a broken elevational view of a mandrel hanger type tubing head and showing locking screws made in accordance with the invention engaging a mandrel hanger supported therein.

It is to be understood that the locking screw referred to may be employed in connection with tubing strippers or the like, not shown, but, for the purpose of describing the present invention, the same is illustrated in connection with a mandrel hanger type tubing head having a body 11 and upper and lower flanges l2 and 13. The lower surface of the lower flange 13 is provided with annular grooves 14 for receiving sealing rings, not shown, which in turn engage the upper surface of a casing head. The tubing head 10 includes a bonnet 15 which is secured to the upper flange 12 of the body 1.1 by means of bolts 16. The upper inside diameter of the body 11 is tapered, as at 17, to receive and support a correspondingly shaped mandrel hanger 1.8 which threadedly supports the well tubing depending therefrom. A ring seal 21 of metal or the like is provided between the bonnet 15 and the ad joining peripheries of the body 11 and the mandrel hanger 18. The lower surface of the bonnet 15 and the adjoining upper surfaces of the body 11 and the mandrel hanger 18 are grooved, not numbered, to receive the ring seal Horizontal bores 22 are radially disposed in the upper body flange 12 to slidably receive the cylindrical heads 23 of locking bolts 24 which are a part of the construction comprising the present invention. The tapered sur face of the mandrel hanger 18 is provided with conical recesses 25 to receive the pointed ends 26 integral with the forward or inner ends of the locking screw heads 23. At least one groove 27 is provided around each head 23 to receive an O ring 28 for engagement with the bore 22 in the body 11. The shank 29 of the screw 24 is threaded,

2,709,091 Patented May 24, 1955 as at 30, outwardly of the cylindrical head 23 and a tapered ground surface 31 is provided between said threads and said head. A threaded seating element 32, having a diameter larger than the bore 22, is threadedly engaged in an enlarged portion 33 of said bore, and which element is provided with a seat 34 for receiving the tapered ground surface 31. The inside diameter of the element 32 is threaded, as at 35, to receive the threads 30 on the screw shank 29. The outer end of the screw 24- extends beyond the outer surface of the upper body flange 12 and is provided with wrench surfaces 36 for turning the shank 29 and moving the screw head 23 inwardly or outwardly as required. A packing 37 is provided in the enlarged portion 33 of the bore 22, and a packing gland 38 is threadedly engaged in the peripheral surface of the upper body flange 12. Flat rings 39 and 40 are positioned on opposite ends of the packing 37 and respectively engage the ends of the threaded element 32 and the packing gland 38.

In operation, after the tubing 24) has been landed, the locking screws 24 are turned to cause their pointed ends 26 to engage the conical recesses 25 in the mandrel hanger 18. The 0 ring 28 prevents corrosive fluids from the well from reaching the threads 30 on the screw stem 29. When new packing 37 is required, the lock screw shanks 29 are turned in a direction so as to cause the ground surface 31 on the head 23 to engage the seat 34 in the threaded element 32. Thus, the gland 38 can be removed while the gas pressure is retained within the well, eliminating the fire hazard hereinbefore referred to, and avoiding killing the well as described in the foregoing.

The present invention is not limited to the construction herein shown and described, but may be made in many ways within the scope of the appended claims.

What is claimed is:

l. in combination with a well head body and a mandrel hanger supported therein, a locking screw construction comprising a shank within a horizontal radial opening in said well head body, a cylindrical head secured to the inner end of said shank and having a tapered end on the inner end thereof adapted to be received within a cor responding recess in the side of said mandrel hanger, an internally threaded valve seat element fixedly mounted within said opening and outwardly of said head, threads on said shank engaging the internal threads of said element, a packing gland around said shank and detachably secured in the outer end of said opening, a packing between said internally threaded element and said packing gland, and coengageable surfaces on the opposing ends of said cylindrical head and said valve seat element.

2. In combination with a well 'nead body and a man drel hanger supported therein, a locking screw construction as defined in claim 1 and wherein an annular groove is provided around said cylindrical head, and an O-ring is received in said groove for coaction with said radial opening.

3. In combination with a Well head body and a mandrel hanger supported therein, a locking screw construction as defined in claim 1 and wherein said valve seat element is threadedly engaged in said opening in said well head body, and wherein the said coengageable surfaces are correspondingly tapered and provided with ground finish surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 2,083,089 Rector June 3, 1937 2,274,477 Howard et al Feb. 24, 1942 2,312,487 Roach et al Mar. 2, 1943 2,532,662 Eckel et a1 Dec. 5, 1950

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