Title:
BLOWOUT PREVENTER WITH RESISTANCE MEANS BETWEEN THE BODY AND THE PISTON
United States Patent 3670761


Abstract:
Blowout preventers each having at least one movable bonnet and an operating cylinder therewith which are movable together relative to a piston in the cylinder for exposing a ram mounted inwardly of the bonnet to effect the removal of the ram, wherein the preventer has detent or resistance means between the piston and an extension of the body to resist movement of the piston, the piston rod, and the ram connected therewith when fluid pressure is applied in the operating cylinder outwardly of the piston for thereby effecting an opening outward movement of the bonnet to the ram-exposed position.



Inventors:
LEROUAX ROBERT K
Application Number:
05/080294
Publication Date:
06/20/1972
Filing Date:
10/13/1970
Assignee:
HYDRIL CO.
Primary Class:
Other Classes:
251/1.3, 277/323, 277/325
International Classes:
E21B33/06; (IPC1-7): E21B33/06
Field of Search:
251/1 277
View Patent Images:
US Patent References:
3272222Blowout preventer1966-09-13Allen
2912214Blowout preventer1959-11-10Allen et al.
2752119Blowout preventer1956-06-26Allen et al.



Primary Examiner:
Nelson, Cary M.
Assistant Examiner:
Gerard, Richard
Claims:
I claim

1. A blowout preventer, comprising:

2. The structure set forth in claim 1, including:

3. The structure set forth in claim 1, wherein said resistance means includes:

4. The structure set forth in claim 3, wherein said detent means includes:

5. The structure set forth in claim 3, wherein:

6. The structure set forth in claim 5, wherein:

7. The structure set forth in claim 1, wherein said fluid pressure means includes:

8. The structure as set forth in claim 7, wherein at least one of said fluid conduits includes:

9. The structure set forth in claim 8, wherein said flexible conduit section comprises:

10. The structure set forth in claim 8, including:

11. The structure set forth in claim 1, wherein said body has a body extension extending into said operating cylinder and said resistance means includes:

12. The structure set forth in claim 11, wherein:

13. The structure set forth in claim 1, including:

14. The structure set forth in claim 13, wherein:

15. The structure set forth in claim 1, including:

16. The structure set forth in claim 15, wherein said fluid pressure means includes:

Description:
BACKGROUND OF THE INVENTION

The field of this invention is blowout preventers.

It often becomes necessary or desirable to replace the rams, or at least the sealing components thereof, in a blowout preventer while the preventer is in the field in its normally mounted position at a wellhead. In the past, various efforts have been made to facilitate such field removal of the rams for replacement and/or repair, examples of which are shown in U.S. Pat. Nos. 2,752,119; 2,912,214; and 3,272,222. In the blowout preventer constructions of such prior art, the rams were operated normally by the main hydraulic system, and a separate additional hydraulic system was required to move the bonnet away from and back to the preventer body. Such prior art constructions required telescoping tubes for carrying the hydraulic fluid to effect the movements of the bonnet relative to the head, which tubes have had polished or smooth external surfaces to maintain a fluid seal during the telescoping movements. Such smooth surfaces were exposed to damage such as scratches, indentations and nicks caused by tools and parts hitting the tubes when the bonnet and ram were in the open exposed position. If the damage was severe enough, destruction of the seals soon followed, with consequent leaks of hydraulic fluid, and causing the equipment to malfunction or become inoperative.

Furthermore, because of the use of the supplemental hydraulic system for moving the bonnet in such prior art blowout preventers, the overall weight of the preventer was excessive, and the force exerted in closing the bonnet in sealing contact with the head was relatively small. Also, an excessively large number of fluid seals was required in such constructions. Additionally, the location of such telescoping tubes in the prior art blowout preventers interfered with and prevented lateral removal of the rams from the preventer, so that it was very difficult, and often impossible, to remove the rams from a lower preventer in a vertically stacked double preventer assembly without first extending the bonnet in the upper preventer and removing the upper rams therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of one form of the apparatus of this invention, illustrating the left-hand bonnet in the ram-exposing position and the right-hand bonnet in the closed connected position;

FIG. 2 is a sectional view, partly in elevation, illustrating the left-hand portion of the apparatus of FIG. 1, but showing the bonnet in the closed position, with the ram in the closed position;

FIG. 2A is a view taken on line 2A--2A of FIG. 2;

FIG. 3 is a sectional view taken on line 3--3;

FIG. 4 is a view similar to FIG. 2, but showing the ram in the open or retracted position, but with the bonnet in the closed position, such view, like FIG. 2, being taken on line 2--2 of FIG. 3;

FIG. 5 is a view similar to FIGS. 2 and 4, but taken on line 5--5 of FIG. 3, and illustrating the bonnet in the ram-exposing position to permit the removal and replacement thereof;

FIG. 6 is a view similar to FIG. 1, but illustrating a modified form of the apparatus;

FIG. 7 is a view taken on line 7--7 of FIG. 8, and illustrating the left-hand portion of the apparatus of FIG. 6, but with the bonnet in the closed position, and with the ram in the closed position; and

FIG. 8 is a sectional view taken on line 8--8 of FIG. 7 to further illustrate the form of the invention shown in FIGS. 6 and 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, the letter A designates generally the blowout preventer of this invention which is connected in the usual way to well casing or pipe P, using bolts 10, or other suitable means, which extend through a flange 11 on each section of the casing P into a body B of the preventer A. The body B is of conventional construction and includes a central longitudinal opening 12 therethrough which is aligned with the vertical opening through the casing or pipe P. The body B also has laterally disposed ram openings 14 (one of which is illustrated in FIG. 2) which are disposed on diametrically opposite sides of the body B, extending entirely through the wall of such body B and communicating with the longitudinal opening 12. A ram R of any suitable construction is mounted so that it is laterally movable in one of the lateral ram openings 14, and each of such rams R has a suitable sealing assembly 15 formed of rubber or similar material in the usual manner. The rams R are adapted to be moved laterally from the closed position (FIG. 2) in which position they close off fluid flow through the central opening 12, to an open position (FIG. 4) in normal operation, wherein the central bore 12 is open for performing normal well operations therethrough.

Furthermore, as will be explained more in detail, the blowout preventer A of this invention is constructed with a bonnet H for each of the rams R so that each bonnet H encloses one of the rams R on each side of the preventer body B. Each of the bonnets or heads H is releasably connected to the body B with bolts 18 (FIG. 1) or any other suitable releasable securing means in the known manner. An operating cylinder C is secured to the bonnet H by bolts 20 (FIG. 1) or any other suitable securing means so that the cylinder C is secured to and movable with the bonnet H. A piston D is slidably positioned within the cylinder C (FIGS. 2-5), and each piston is connected to one of the rams R by a piston rod 22 so that movements of the piston D are transmitted to the ram R connected therewith. As will be more fully explained, hydraulic fluid under pressure is supplied to the cylinder C, preferably through fluid conduits F-1 (FIGS. 2 and 4) and F-2 (FIGS. 3 and 5) so as to move the piston D within the cylinder C for moving the ram R therewith to and from the closed and open positions. Also, when the bonnet H is disconnected from the body B by the release of the bolts 18, the fluid pressure in the cylinder C is utilized to move the cylinder C relative to the piston D (FIG. 5) for moving the bonnet H away from the preventer body B so as to expose the ram R for removal. The fluid pressure is also utilized for the return of the cylinder C relative to the piston D to return the bonnet H to the closed position (FIG. 4) for reconnecting the bonnet H to the preventer body B for subsequent normal operations of the ram R. It will be understood that throughout this description, the structure and operation for only the left-hand ram R and the parts therewith are explained in detail, since the structure and operation of the right-hand ram and the parts therewith are generally the same.

Considering first the form of the invention illustrated in FIGS. 1-5, the ram R preferably has a generally oval shape (as will be explained in connection with the ram R in FIG. 8), although it may be cylindrical or of any other suitable shape so as to properly function within its ram opening 14 in the body B. The ram R is releasably connected to the piston rod 22 by means of a connector button 22a which is disposed in a slot or slots such as the lateral or transverse slot 25 (FIG. 8) or the vertical slot 26. The diameter or dimensions of the button 22a are larger than the diameter or dimensions of the piston rod 22 so that the button 22a fits within a channel 25a to releasably retain the ram R on the rod 22. Using the connecting construction illustrated in the drawings, and particularly FIG. 8, the ram R may be removed in either lateral direction or vertically, depending upon the space available after the ram R has been moved to the ram-exposed position (FIG. 5). Although the button 22a is shown in FIG. 8 as having a square or rectangular shape, it may be round or of other shapes so long as it extends into the channel 25a when in the connected position with the ram R.

In the form of the invention illustrated in FIGS. 1-5, the preventer A is preferably constructed in an identical manner on each side of the body B. Thus, the left-hand bonnet H has extending therethrough a pair of body rods or extensions 30 and 31 which extend into the operating cylinder C, through the piston D, as will be more fully explained. The body rod 30 is connected by threads 30a to the body B and forms an extension thereof which serves as one of the supports for the bonnet H when it is in the open or ram-exposed position (FIG. 5). The body rod 31 is similarly connected to the body at threads 31a and forms the other support for the bonnet H in such ram-exposed position. Suitable seals such as 30' and 31' are provided as part of, or adjacent to, the threads 30a and 31a to prevent fluid leakage at such points.

The body rods 30 and 31 have enlargements 30b and 31b, respectively, which fit within bonnet cylinders 33 and 34, respectively. O-rings 30c and 31c, formed of rubber or similar sealing material are disposed in enlargements 30b and 31b, respectively, for sealing engagement with the inside surface of the cylinders 33 and 34, respectively.

The body rod 30 extends through an opening 35 in the piston D, and an O-ring 35a of rubber or other suitable material provides a seal with the external surface of the body rod 30 (FIG. 2). The hole 35 has an annular recess 35b formed therein which forms a part of a resistance means or detent means for resisting movement of the piston D relative to the body B, as will be more fully explained. The other part of the detent means or resistance means is a flexible split ring 36 (FIGS. 2 and 2A) which is mounted in a groove 30d in the rod 30. The ring 36 is split so that it can contract in its external diameter to enter the recess 35b. Its inherent resiliency normally urges it to a diameter which is greater than the diameter of the rod 30 so that when the ring 36 is in the recess 35b, it can engage either wall of the recess 35b to resist movement of the piston D inwardly or outwardly relative to the rod 30. It should be understood that any other suitable arrangement for providing a resiliently contractible and expansible member to enter the recess 35b to serve as the detent means or resistance means may be utilized.

Although the engagement of the ring 36 with the inner wall of the recess 35b may be the means used to prevent the piston D from moving outwardly when fluid is introduced into the operating cylinder C inwardly of the piston D for returning the bonnet H from the ram-exposed position (FIG. 5) to the closed position (FIG. 4), the outer end of the rod 30 preferably has a stop head 37 with a stop surface 37a formed thereon for engagement by a part of the outer surface 38 of the piston D for such purpose.

The body rod 31 is mounted in a similar manner to the mounting of the rod 30, and thus, it passes through an opening 40 in the piston D (FIG. 3 and FIG. 5), having a seal ring 40a mounted therein in sealing contact with the external surface of the rod 31. The opening 40 also has an annular detent recess 40b which corresponds with the annular detent recess 35b and which is adapted to receive a split resilient ring 41 which preferably has the same construction as the split ring 36 -9 (FIG. 2A). The ring 41 is disposed in a recess or groove 31d, and it is resiliently contractible from its normal external diameter which is greater than the external diameter of the rod 31 to a small enough diameter to enter the recess 40b. When the ring 41 is confined in the recess 40b, it serves with the recess 40b as a resistance means or detent means, as explained heretofore in connection with the ring 36 and the recess 35b. The rod 31 also has a stop head or member 42 which has a stop surface 42a which is engaged by the surface 38 of the piston D at the same time such surface 38 engages the stop surface 37a of the rod 30, as previously explained. The co-action between the split rings 36 and 41 and the walls of their respective recesses 35b and 40b provide a resistance to the movement of the piston D inwardly which is greater than the frictional resistance between the bonnet H and the tubes or rods 30 and 31 when hydraulic fluid pressure is exerted in the cylinder C outwardly of the piston D (FIG. 4) to thereby move the cylinder C and the bonnet H therewith outwardly to the ram-exposed position (FIG. 5).

The fluid conduit F-1 includes a passage 30e in the body rod or extension 30 which leads from the fluid passage 45 to the body B, which communicates through a suitable opening 45a (FIG. 7) with a source of hydraulic fluid under pressure. The passage 30e discharges through a port 30f into the area of the operating cylinder C inwardly of the piston D. The fluid conduit F-2 includes a longitudinal passage 31e through the body rod or extension 31 which is in communication with a fluid passage 46 (FIG. 5) in the body B and which is in communication with a source of hydraulic fluid under pressure. The passage 31e preferably extends to the outer end of the rod 31 and discharges into the area of the operating cylinder C outwardly of the piston D.

For locking the ram R in the closed position (FIG. 2), a locking assembly is provided, the essential components of which are illustrated in the drawing, and which includes a locking sleeve 60 with internal threads 60a in threaded engagement with external threads 61a on a lock screw rod 61. Under normal operating conditions, with the head or bonnet H secured to the body B, the lock sleeve 60 and the lock screw rod 61 are in the threaded or closed position illustrated in the drawings, and they move together with the piston D. The lock screw rod 61 is actually formed integrally as an extension of the rod 22 as illustrated in the drawings, although it will be appreciated that it may be a separate member which is welded or is otherwise attached to the piston D or parts connected therewith. The details of such construction may of course be varied and refined, as will be appreciated by those skilled in the art. The sleeve 60 moves through any suitable seal 62, preferably with a wiper (not shown) in the operating cylinder C. The outer end of the sleeve 60 is preferably a solid cap 60b which has wrench flats 60c thereon for engagement by a wrench or similar tool for rotating same. A protector tube (not shown) is normally mounted on the operating cylinder C so as to surround the cap 60b to protect same against damage when the sleeve 60 is in the extended position. When the sleeve 60 is rotated relative to the lock screw 61, it moves outwardly until a shoulder such as the shoulder 60d engages the inner surface 63 in the cylinder C. An anti-friction stop ring or washer (not shown) may be utilized together with the shoulder 60d to provide anti-friction and prevent galling between the surfaces 60d and 63 when they are in the extended locked position.

Since the apparatus of this invention is illustrated with its essential components rather than the refined construction and variations which may be utilized in actual manufacture, the details with respect to such things as the seal rings have been omitted in some cases, but seal rings are shown in the drawings to illustrate the separation of the various fluids that are present in the system. Thus, the piston ring D has an O-ring or other resilient sealing member 65 which engages with the inner wall of the cylinder C. A seal ring 66 is mounted in the bonnet H in the opening 67 through which the piston rod 22 moves for providing a fluid seal with the external surface of the rod 22. An O-ring 68 is also illustrated to show a seal between the bonnet H and the body B when the bonnet H is in the closed position. A seal 69 is also provided between the operating cylinder C and the bonnet H.

In the operation or use of the apparatus A of this invention, the bonnet or head H is normally secured to the body B by means of the connecting bolts 18 or other suitable attaching means. Therefore, for normal operation of each ram R, fluid under pressure is introduced into its respective cylinder C outwardly of the piston D for moving the ram R inwardly to completely close the longitudinal central opening 12 in the body B. It will be understood that when the ram R is a "blind" ram, it engages a ram of the same configuration in the diametrically opposite position for completing the closure of the opening 12, as will be well understood by those skilled in the art. If the ram R is shaped for fitting around the external surface of a well pipe in the bore or opening 12, then the two opposed rams will close off the opening 12 around such pipe, as will be also understood by those skilled in the art.

When it is desired to move each of the rams R to the open position so as to leave the bore or opening 12 completely open, fluid under pressure is introduced through each fluid conduit F-1 for each of the rams R, and therefore the following description will apply to only one of the rams R (left-hand ram as illustrated in the drawings), but it will be appreciated that such explanation applies also to the right-hand ram R.

Thus, hydraulic fluid under pressure is introduced through the fluid conduit F-1 into the cylinder C inwardly of the piston D to thereby move the piston D outwardly to the position shown in FIG. 4, wherein the ram R is displaced outwardly with its innermost edge beyond the edge of the body B. It will be understood that the hydraulic fluid which is used to accomplish such movement of the piston D is introduced from any suitable source of pressure (not shown) through a passage 45 in the body B and the passage 30e in the body rod 30 and ultimately through the port or ports 30f which discharge into the operating cylinder C inwardly of the piston D.

Under normal operations, the bonnet H thus remains connected to the body B, and the ram R is moved back and forth as desired for controlling the opening and closing of the central or longitudinal opening 12 through the body B. The piston D, and therefore, the ram R on each side of the body B may be locked in the closed position by the unthreading of the lock sleeve 60 relative to the threaded lock screw rod 61, as previously explained.

When it is desired to move the ram R to the exposed position (FIG. 5) for the removal of the ram R from the preventer A, the ram R is first moved to the open position illustrated in FIG. 4, forcing the resilient ring 36 to enter the recess 35b and forcing the resilient ring 41 to enter the recess 40b. In some instances, only one of such resistance means may be utilized. When the rings 36 and 41 are thus in the recesses 35b and 40b, respectively, the ram R is in a position so that its innermost edge is outwardly of the body B. Thereafter, the bolts 18 or other suitable connecting means between the bonnet H and the body B are disconnected, and fluid under pressure is supplied through the fluid conduit F-2, which includes the passage 46 and the passage 31e, to the operating cylinder C outwardly of the piston D. As previously explained, since the resistance provided by the rings 36 and 41 in their respective recesses 35b and 40b is greater than the frictional resistance between the bonnet H and the body rods or support rods 30 and 31, the fluid pressure acts to move the cylinder C outwardly while the piston D remains stationary. Since the operating cylinder C and the bonnet H are connected together by the bolts 20 or other suitable connecting means, the outward movement of the operating cylinder C moves the bonnet H outwardly therewith so as to fully expose the ram R (FIG. 5). The body rods 30 and 31 then provide support for the bonnet H and the other parts therewith. If desired, supplemental support may be provided by other means (not shown), such as an extension from the body upon which the ram R may rest.

When the ram R is in the ram-exposed position (FIG. 5), it may be removed either laterally in either direction or vertically, as previously explained.

To return the bonnet H to the closed position (FIG. 4), fluid under pressure is introduced through the fluid conduit F-1 so that such fluid enters the operating cylinder C inwardly of the piston D. Outward movement of the piston D is prevented by the engagement of the outer surface 38 of the piston D with the stop surfaces 37a and 42a, as previously explained. Only one of such stop surfaces 37a and 42a may be employed if desired, but the two surfaces together prevent a cocking of the piston D when subjected to the fluid forces. Since the piston D is thus prevented from moving outwardly by the engagement with the stop members 37 and 42 on the rods 30 and 31, respectively, the hydraulic fluid which is introduced under pressure through the fluid conduit F-1 forces the cylinder C and the bonnet H therewith inwardly from the outer open position (FIG. 5) to the inner closed position (FIG. 4). The bolts 18 or other suitable connecting means are then reattached to secure the bonnet or head H to the body B so that normal ram operations may thereafter be continued.

In FIGS. 6-8 a modified blowout preventer A-1 is illustrated, wherein the parts thereof which are the same as the parts of the preventer A bear the same letters and numerals. Thus, the body B is of the same general construction as the body B of the preventer A and it is connected in the same manner to the well casing C. The rams R, operating cylinders C and pistons D are the same in the preventers A and A-1, but the bonnet or heads H-1 are modified in the preventer A-1 as compared to the heads or bonnets H in the preventer A, as will be more fully explained.

Only the left-hand portion of the preventer A-1 will be described in detail, as explained heretofore in connection with the preventer A, since the right-hand preventer construction is basically the same as the left-hand portion. Thus, the modified head or bonnet H-1 includes a pair of chambers or hollow recesses 70 for receiving a pair of support tubes 71. The support tubes 71 are disposed on opposite sides of the ram R (FIG. 8) and the upper portions thereof are below the lower portion of the ram R so that the ram R may be removed in either lateral direction when the ram R is moved to the ram-exposed position (FIG. 6). The support tubes 71 also serve as means for protecting a flexible hose or conduit 72 mounted therein. Thus, the fluid conduit F-1 includes one of the flexible coiled hoses or tubes 72 and the flexible conduit F-2 likewise includes one of the flexible coiled hoses or conduits 72. One end of each of the flexible conduits 72 is connected to the body at 72a, and the other end thereof is connected to the bonnet at 72b so that as the bonnet H-1 is moved away from the body B, the flexible hoses expand or extend, and when the bonnet H-1 returns to the closed position (FIG. 7) with respect to the body B, the hoses or conduits 72 contract or retract due to their inherent resiliency. It will be appreciated that the hoses or conduits 72 may be formed of rubber tubing, which is reinforced with fabric, metal or other similar material, or any other similar type of hose construction. The fluid conduit F-1 includes the passage 45 in the body B which has connections at the opening 45a (FIG. 7) with a source of hydraulic fluid under pressure (not shown). The fluid entering through the passage 45 flows through the flexible tube 72 in the fluid conduit F-1 and then passes through a passage 75 in the bonnet H-1 which discharges into an annular space between the operating cylinder C and a liner 76 and finally enters the cylinder C outwardly of the piston D. It is to be noted that the liner 76 is spaced from the inner wall of the cylinder C which provides a passage for the entry of the hydraulic fluid from the passage 75 into the area of the cylinder C outwardly of the piston D.

The fluid conduit F-2 includes the passage 46 and the opening 46a in the body B which provides for the flow of hydraulic fluid from a suitable source (not shown) through the flexible tube 72 to a passage 77 in the bonnet H-1 for discharge into the area of the operating cylinder C inwardly of the piston D.

The preventer A-1 has a body rod 80 which is integral with or is connected to the body B and extends therefrom outwardly through a cylindrical opening or bonnet cylinder 81 in the bonnet H-1, and ultimately terminating a stop member 82 in the operating cylinder C outwardly of the piston D. The body rod or extension 80 has an enlargement 80a therewith, with a suitable seal ring 80b to form a seal between the rod 80 and the wall of the cylinder 81 during relative movement of the bonnet H-1 with respect to the rod 80. The rod 80 also passes through an opening 83 in the piston D, which is formed with a detent recess 83a which corresponds with the detent recess 35b in the preventer A. A seal ring 83b provides for sealing contact in the opening 83 with the external surface of the rod 80. A split resilient ring 85 corresponds with the ring 36 of the preventer A and it is mounted in a recess or groove 80c in the rod 80 so that it may contract to pass into the recess 83a for forming the resistance means or detent means in the same manner as heretofore described in connection with the ring 36 and the recess 35b. It is to be noted that there is only one body rod or extension 80 in the form of the invention shown in FIGS. 6-8, and it is preferably located directly below the piston rod 22 (FIG. 8). There may of course be additional body rods or extensions in addition to the rod 80, but one of such rods is normally sufficient to provide the resistance means for the normal operation of the preventer A-1.

The normal operation of the preventer A-1 is essentially the same as described heretofore in connection with the preventer A. Thus, the bonnet H-1 on the left-hand side of the body B remains connected by the bolts 118 so that as fluid pressure is introduced on either side of the piston D through the fluid conduits F-1 and F-2, the ram R is moved back and forth to and from the open and closed positions. When it is desired to move the bonnet H-1 to the open ram-exposed position (FIG. 6), the ram R is first moved to the retracted or open position with the piston D at the left-hand end of the cylinder C, in a position corresponding to that shown in FIG. 4 of the drawings for the preventer A. Thereafter, the bolts 118 are released or disconnected from the body B, and hydraulic fluid under pressure is introduced through the fluid conduit F-1 into the area outwardly of the piston D in the cylinder C so as to move the cylinder C and the bonnet H-1 therewith outwardly to expose the ram R as illustrated in FIG. 6. At that point, the ram R may be removed from the piston rod 22 in either lateral direction or vertically. When the fluid is introduced into the operating cylinder C outwardly of the piston D for moving the bonnet H-1 to the open position, the resistance means provided by the ring 85 in the recess 83a provides a greater resistance than the frictional resistance between the bonnet H-1 and the tubes 71 so that the piston D remains stationary while the cylinder C and the bonnet H-1 therewith move outwardly.

After the ram R has been replaced, the bonnet H-1 may be returned to the closed position by introducing hydraulic fluid under pressure through the fluid conduit F-2. At that time, the piston D is prevented from moving outwardly by the engagement of its outer face 38 with the surface 82a of the stop member 82, so that the bonnet H-1 and the operating cylinder C therewith are moved back to the closed position for the reconnection of the bolts 118 to the body B. Thereafter, normal movements of the ram R may occur.

The form of the invention shown in FIGS. 6-8 has a lock screw assembly (a portion of which is seen in FIGS. 6-8) which corresponds with the lock screw assembly described in detail in connection with the preventer A shown in FIGS. 1-5 and it operates in the same manner.

It will be understood that the foregoing description of the operation of the left-hand bonnet H-1 and the parts associated therewith applies equally well to the right-hand bonnet H-1 and the parts associated therewith.

From the foregoing description, it can be seen that the blowout preventers described herein provide for a means to resist movement of each piston D relative to the body B and therefore to resist movement of each ram R relative to the body B for the opening and the closing of each bonnet or head. The operating cylinder C for each ram R is utilized in applying the hydraulic power for the opening and closing of the bonnets rather than auxiliary or supplemental cylinder with separate hydraulic systems.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape, and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.