US3915426A

US3915426A - Blowout preventer with variable inside diameter

Info

Publication number: US3915426A
Application number: US412771A
Authority: US
Inventors: Robert K Lerouax
Original assignee: Hydril LLC
Current assignee: Hydril LLC
Priority date: 1973-01-26
Filing date: 1973-11-05
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28

Abstract

A variable inside diameter blowout preventer capable of sealing off a bore or around an object against high well pressures, and which may be either a ram-type preventer or an annular preventer, and wherein a plurality of upper and lower anti-extrusion members are each disposed in two overlapping layers and are mounted for radial movement to and from a sealing position and an open position, with the anti-extrusion members inhibiting extrusion of a resilient sealing member therewith throughout a predetermined range of variable inside diameters of the sealing member and anti-extrusion members.

Description

United States Patent LeRouax *Oct. 28, 1975 BLOWOUT PREVENTER WITH VARIABLE 2,368,928 2/1949 King 166/10 INSIDE DIAMETER 2,609,836 9/1952 Knox 277/73 2,780,294 2/l957 Lo0mis.... l66/203 Inventor: Robert o Houston. 2,846,178 8/1958 Minor 251/229 x 3,038,542 6/1962 L0omis.... 166/204 [73] Asslgnee' Company 3,572,628 3/1971 Jones 251/1 Notice: The portion of the term of this Patent Subequ9m to y 29, 1992 Primary Examiner-Martin P. Schwadron has been dlsclalmed' Assistant Examiner-Richard Gerard 2 Filed; 5, 1973 Attorney, Agent, or FirmPravel & Wilson [2]] Appl. No.: 412,771 ABSTRACT 57 Related US. Application Data 1 [63] Continuationin a t f S N 326 965 J 26 A var1able 1ns1de d1ameter blowout preventer capable 1973 abandon-g r 0 of sealing off a bore or around an object against high well pressures, and which may be either a ram-type 52 US. Cl 251/1- 277/127 Prevent an annular Prevent", and wherein [51] Int. Cl. E21B 33/06 rality of upper and lower anti-extrusion members are [58] Field Of Search 251 /1; 277/73, 126, 127, each disposed in verlappmg layers and are 277/129 181 185 188 166/81 82 84 mounted for radial movement to and from a sealing position and an open position, with the anti-extrusion members inhibiting extrusion of a resilient sealing [56] References Cited member therewith throughout a predetermined range of variable inside diameters of the sealing member and UNITED STATES PATENTS anti-extrusion members. 2,035,925 3/1936 Seamark 277/34 2,246,709 6/1941 Allen 277/129 11 Claims, 10 Drawing Figures US. Patent Oct. 28, 1975 Sheet 1 of 4 Sheet 2 of 4 3,915,426

US. Patent Oct. 28, 1975 U.S. Patent Oct. 28, 1975 Sheet 3 of4 3,915,426

US. Patent Oct. 28, 1975 Sheet 4 of4 3,915,426

BLOWOUT PREVENTER WITH VARIABLE INSIDE DIAMETER CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. patent application Ser. No. 326,965 filed Jan. 26, 1973, copending herewith, and now abandoned.

BACKGROUND OF THE INVENTION The field of this invention is blowout preventers for oil wells and the like.

Annular blowout preventers made by the Hydril Company, an example of which is shown on page 2742 of the Composite Catalog for 1970-71, have been in extensive commercial use for a number of years. Such blowout preventers provide a fully-open bore therethrough so that drill bits, reamers, casing hangers and other large diameter tools can freely pass therethrough, but when actuated to the closed position, the packing of each such preventer is forced inwardly to reduce its bore and automatically adjust its size and shape in sealing contact with whatever object happens to then be in the bore of the preventer, thereby closing off the annular space around such object to prevent a blowout of well pressure from below. If no tool is in the well, the bore of the preventer can be fully closed to prevent a blowout.

Although such Hydril blowout preventers are very satisfactory for relatively low well pressures in the range of from about 2,000 psi. to 5,000 p.s.i., it is generally desirable to use a ram type blowout preventer above such pressures, and above 10,000 psi. well pressure, it has heretofore been considered essential to use a ram type blowout preventer of a predetermined opening size because of the inability to satisfactorily prevent extrusion of the rubber of the preventers at such higher pressures.

SUMMARY OF THE INVENTION The present invention relates to blowout preventers wherein a resilient sealing member or members are provided for closing a well bore or sealing with a pipe or other object disposed in the bore and wherein antiextrusion means are mounted with the sealing member or members to prevent extrusion thereof over a' relatively large variable range of bore diamters for the preventer, and wherein the blowout preventers of this invention may be of the ram type or the annular type, and are yet capable of sealing off much higher well pressures than with prior known annular blowout preventers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, is a vertical sectional view illustrating one embodiment of the blowout preventer of this invention in the retracted or opened position;

FIG. 2 is a view similar to that of FIG. 1 illustrating the blowout preventer in the closed or sealing position with a pipe in the well bore;

FIG. 3 is a view taken on line 33 of FIG. 1 to illustrate in particular the anti-extrusion means of the blowout preventer of this invention;

FIG. 4 is a view taken on line 44 to further illustrate the anti-extrusion means of FIG. 3 when in the contracted position with the sealing means in sealing contact with the well pipe;

FIG. 5 is a view taken online 5-5 of FIG. 3;

FIG. 5A is a view taken on line 5ASA of FIG. 4;

FIG. 6 is an isometric view of the upper antiextrusion means used with the blowout preventer of this invention in the annular or cylindrical form thereof;

FIG, 7 is a vertical sectional view of the blowout preventer of this invention in the ram type preventer;

FIG. 8 is a view taken on line 88 and illustrating a portion of the blowout preventer of this invention in the ram type; and

FIG. 9 is an isometric view, partly exploded, illustrating the upper anti-extrusion means used with the ram type blowout preventer of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, the letter B refers generally to the form of the blowout preventer of this invention shown in FIGS. l6.

Briefly, the preventer B includes a housing H which has a central longitudinal bore 10 through which a pipe P or other object is adapted to extend in the known manner for well operations. The housing H is constructed so that it is positioned in a stack of blowout preventers or in a string of well casing or pipe in any suitable manner, as will be understood by those skilled in the art. The blowout preventer B has a replaceable assembly A, the details of which will be described hereinafter, which has a central bore 11 which is preferably at least as large as the central opening or bore 10 and which is likewise substantially the same size or at least as large as the bore of the casing or pipe above and below the preventer B so that a full opening bore 11 is available for the passage of the pipe P and other well tools during normal operations.

Considering the details of the blowout preventer B,

the housing Hmay take numerous forms, but as illus-' trated in the drawings, it includes a lower housing section 12 having a housing recess 12a for receiving the blowout preventer assembly A and an annular piston 14 formed of rubber or similar material, as will be further explained. The recess 12a is further defined by a housing section or cover 15 which is secured to the housing section 12 by bolts 15a (FIG. 1) or other suitable securing means. A fluid line 12b and a fluid relief line 15b communicates through the housing H with the recess 12a for the inlet and relief of hydraulic or other fluid pressure with respect to the resilient piston 14 to control the opening and closing of the blowout preventer B, as will be more evident hereinafter. For connecting the housing H in a stack of blowout preventers, or to suitable flanges of the well pipe or casing above and below the blowout preventer B, connecting threaded studs 12c and 150 are preferably provided, although any other suitable connecting means may be employed. Connecting studs 150 are preferably dis- I posed longitudinally in alignment with the connecting means M is also provided with the seal member 30, as will be more fully explained. The upper anti-extrusion means M is preferably identical to the lower antiextrusion means M in the preferred form of the invention, except that they are upside down with respect to each other. Therefore, the details of the anti-extrusion means M will be hereinafter explained and the same parts will be identified with the same numerals and/or letters followed by a prime mark for the lower antiextrusion means M.

The upper anti-extrusion means M is illustrated in detail in FIGS. 3-6. Such anti-extrusion means M includes an upper or first set of anti-extrusion members 35 which together form an annular or cylindrical assembly (FIG. 6). In fact, the members 35 may be cut or otherwise formed from a single solid cylindrical member or ring. The radial edges or sides 35a of each of the members or segments 35 are disposed radially and if extended would all converge at a single point in the center of the bore or opening defined by such segments 35. The inner surfaces 35b of the segments or members 35 form the inner bore of the upper or first set of the antiextrusion members 35, which bore may vary from its smallest diameter (FIG. 6) to a larger retracted diameter (FIGS. 1 and 3).

The outer surface 35c of each of the members or segments 35 is likewise formed in a cylindrical surface with the other surfaces 350 and in the preferred form of the invention, a pair of threaded openings 35d are provided in such surface 350 of each segment 35 for a purpose to be hereinafter explained.

The upper anti-extrusion means M also includes a second or lower set of anti-extrusion members or segments 36 which are likewise formed in a substantially cylindrical or annular shape as a ring when assembled in their innermost contracted position (FIG. 6) and which are adapted to move outwardly to a larger inner bore diameter as shown in FIGS. 1 and 3. The members 36 are staggered or are spaced alternately with respect to the members 35 so that the radial edges 35a of the segments 35 are disposed substantially midway of the segments or members 36 when the segments 35 are in their retracted position of FIG. 6. The sides or edges 36a of the segments 36 extend substantially radially although they are also preferably inclined as shown in the drawings since the lowermost surface 36d of each segment 36 is bonded or is otherwise secured to the rubber or other material of the sealing element 30, and such inclined surfaces 36a provides room for some distortion of the rubber of the sealing element 30 without binding the movements of the members 36. The inner surfaces 36b of the segments 36 are preferably disposed coextensively with the surfaces 35b so as to form a bore which is of the same diameter as the bore formed by the surfaces 35b. Also, as will be explained, the

surfaces

35b and 36b remain vertically aligned during the radial movement of the

segments

35 and 36 from the open position to the closed position of the blowout preventer B and vice versa. Each of the segments 36 has an outer surface 36c which is formed with one or more openings 36e, the purpose of which will be hereinafter explained.

The

segments

35 and 36 are connected together so that they may move radially from the enlarged or retracted position of FIGS. 1 and 3 to the maximum closed position of FIGS. 4 and 6 by connectors 40. Each connector 40 also serves to prevent extrusion of the ring 14 and/or the sealing member 30 radially and horizontally between the edges 35a of adjacent segments 35. Each connector 40 is secured to one of the segments 36 by a screw or other fastener 41 which extends into the threaded opening 36e. Each connector 40 is connected to a pair of segments or anti-extrusion members 35 disposed above the segment 36 with which the connector 40 is secured, by a slidable connection which includes lateral or circumferential slots 40a in the connector 40 through which connector screws or pins 42 are disposed. Each connector pin 42 extends into one of the openings 35d on the outer surface of one of the segments 35, and each pin 42 has a head 42a which is larger than the slot 40a so that the segments 35 are forced to move radially with the segments 36 while permitting relative circumferential movements of the members 35 with respect to the member 36 with which it is connected, within the limits provided by the length of the slots 40a.

In the operation or use of the blowout preventer B of FIGS. 1-6 of this invention, the normal undistorted shape of the sealing member 30 is illustrated in FIG. 1 and in that position, the segments 35 are circumferentially spaced from each other so that there is a space between the sides 35a of the adjacent segments 35. The segments 36 below the segments 35 cover the gap thus present between the edges 35a of the segments 35 and prevent extrusion of rubber upwardly into the spaces between the segments 35. When it is desired to seal with the pipe P or other object in the well bore, hydraulic pressure or the like is introduced through the line 12b to urge the annular piston 14 inwardly to thus force the sealing element 30 into a smaller diameter and finally into sealing contact with the external surface of the pipe P. During such inward distortion of the sealing element 30 to its sealing position with the pipe P, the segments 36 are carried with the rubber or other material of the sealing element 30 and they thus move radially inwardly to reduce the inner bore diameter of the inner surfaces 36b until they engage the pipe P. The connectors 40 urge the segments 35 radially inwardly with the segments 36 and permit them to move closer to each other to close the gap between their side edges 35a until the surfaces 35b engage the pipe P also. It will be understood that the

surfaces

35b and 36b remain substantially vertically aligned at all times and normally are also substantially vertically aligned with the inner bore 30a of the sealing member or element 30 so that extrustion of the sealing element 30 longitudinally of the pipe P is prevented by the overlapping

segments

35 and 36 at all times.

The lower anti-extension means M has segments 35' and 36 which correspond with the

segments

35 and 36 and they are connected together by connectors 40' in 55 the same manner as the connectors 40 serve to connect the

segments

35 and 36 as previously explained. The lower anti-extrusion means M functions in the same manner as the upper anti-extrusion means M and both work simultaneously above and below the sealing element 30 to thus confine the sealing element 30 against extrusion in either longitudinal direction with respect to the pipe P.

When it is desired to retract the blowout preventer B from its sealing position (FIG. 2) to its open or retracted position (FIG. 1) the pressure in the recess 12a is relieved through the relief line b or other suitable means so that the annular piston 14 returns to its normal undistorted condition by its own inherent resiliency or other suitable means. Likewise, the sealing element returns to its normal undistorted position of FIG. 1, carrying with it the

segments

36 and 36, which through connectors 40 and pins 42 carry with them the segments 35 and 35', respectively, so that they move to their fully open position (FIGS. 1 and 3).

In the modified form of this invention illustrated in FIGS. 7-9, a blowout preventer 3-1 of the ram type is illustrated, utilizing the same anti-extrusion means M and M and modified only to accommodate the semicylindrical configuration of the rams R of the blowout preventer B-l rather than annular shape of the preventer B.

The blowout preventer B-l has a housing H-l of any suitable construction which is adapted to be connected in a stack of blowout preventers or in a string of well casing or pipe in the conventional manner. Thus, the housing H-l has a longitudinal central bore therethrough for the passage of the pipe P or other well tools in the known manner. The housing H-l also has upper and lower flanges 51 with bolt openings 51a or other suitable means for connecting the preventer 13-1 in the stack of the preventers or in the well casing. The rams R are adapted to fit within lateral recesses 50a in the housing H which communicate with the longitudinal bore 50 in the known manner.

A conventional head or bonnet 52 is connected to each side of the housing H, and each of such heads or bonnets 52 has a recess 52a (one of which is shown in FIG. 7) and each of which is aligned with the lateral openings 50a in the housing H-l, so as to form a continuation thereof. The rams R are received in their respective recesses 52a when they are in the retracted position (FIG. 8). A piston rod 54 extends through a suitable seal 52b in the bonnet 52 and is connected to a piston 56 disposed in the cylinder 57 in the known manner. The cylinder 57 is closed by a cap 58 having a fluid inlet line 58a therewith for the introduction of hydraulic fluid or other fluid for operating the piston 56. Another fluid line 520 is provided for communicating with the opposite side of the piston 56 for introducing hydraulic fluid or other fluid to move the piston 56 to the right or outwardly from the position shown in FIG. 7. It will be understood that the piston 56 is merely exemplary of any suitable power means for moving the rams R, and a similar power means is provided for each of the rams R, although only the piston 56 is illustrated for the right-hand ram R in FIG. 7.

To facilitate the description, the details of only one of the rams R will be described hereinafter, and only wnen it is necessary to show the interaction of the two rams will the other ram be specifically identified. However, it will be understood that the two rams R are preferably made in the same manner and bear like numerals and/or letters for identification purposes.

Thus, each ram R has a ram carrier 60 which is connected to the piston rod or stem 54 preferably in the conventional releasable manner, utilizing a button 54a on the rod 54 fitting into a suitable slot in the ram carrier 60. The ram carrier 60 is preferably formed of steel or other relatively rigid material and is substantially semi-cylindrical in cross-sectional shape (FIG. 8). The ram carrier 60 is provided with an internal recess or surface 60a which is likewise substantially semicylindrical in cross-sectional shape and which is adapted to receive a seal element 61 formed or rubber or other suitable resilient material and preferably having an external convex surface 61a which substantially conforms with the internal surface of the recess 60a (FIG. 8). Side anti-extrusion plates 62 formed of steel or other metal are disposed so as to engage the inside surface of an inwardly extending lip 50b on the housing H-L'During movement of the carrier 60 from the position of FIG. 8 to the stop position of FIG. 7, there is a sliding movement between the carrier 60 and the side plates 62 as the seal element 61 deforms and urges the semi-cylindrical sealing member S into sealing contact with the pipe P.

The seal member 61 is confined at its upper end between the ram carrier 60 and an upper ram confining and alignment plate 64 which is also preferably semicylindrical (FIG. 1) which plate 64 is secured to the carrier 60 by one or more cap screws 66 or other suitable securing means. It is to be noted that the upper surface 60b of the ram carrier 60 engages and slides relative to the upper surface of the recess 50a and the recess 52a. The upper surface 61b of the seal member 61 engages and seals with the upper surface of the recess 50a.

Each ram R also has a lower ram confining and alignment plate which preferably extends for the full depth of the ram and which is provided with a shoulder 65a or other suitable engaging means for enabling the carrier 60 to retract the plate 65 outwardly therewith but permitting inward movement of the carrier 60 relative to the plate 65 after inward movement of the plate 65 is stopped by engagement with the opposite plate 65 on the other ram R.

It is to be noted that the vertical or longitudinal area between the upper alignment plate 64 and the lower alignment plate 65, and inwardly of the seal member 61, forms a pocket or recess which is generally semicylindrical for receiving the parts of the ram R which are normally the primary replaceable parts. Such parts may be preassembled and inserted initially into position as will be more evident hereinafter.

Also, replacement assemblies including such parts may be used when necessary.

Such replaceable assembly of the ram R includes the yieldable sealing element or member S formed of rubber or other similar resilient yieldable material. The upper anti-extrusion means M shown in FIGS. 7-9 is provided above the sealing element S for each of the rams R and likewise, the lower anti-extrusion means M is provided below the sealing element S for each of the rams R.

As best seen in FIG. 9, the anti-extrusion means M for each ram R includes the segments or

anti-extrusion members

35 and 36 which are disposed in the two layers in the same manner as described heretofore in connection with FIGS. 1-6, the only difference being that the segments 35 are arranged in a semi-circular or semi-cylindrical form when used with the rams R of FIGS. 7 and 8. It should also be noted that the end segments in the upper anti-extrusion means M for each ram R are modified so as to be only partial segments as compared to the other segments 35 so that the identical to that heretofore described for the antiextrusion means M, except that they are upside down with respect to each other as is evident from FIG. 7.

In the operation or use of the form of the invention shown in FIGS. 7-9, the rams R are operated in the conventional manner, utilizing hydraulic pressure supplied to the line 58a for moving the piston 56 for each ram R inwardly from the open or retracted position (FIG. 8) to the inner or sealing position (FIG. 7). When the rams contact each other at the

radial surfaces

64a and 65a, the inward momvement of the confining

plates

64 and 65 is prevented, but the carrier can still exert an inward radial force on the seal member 61 and the sealing element S for each of the rams R. Such distortion of the sealing member S continues until it is in full sealing contact with the external surface of the pipe P.

During the inward radial movement or distortion of the sealing element S, the

segments

36 and 36 are moved with the material of the sealing element S radially inwardly so as to constantly maintain a metallic barrier to prevent longitudinal extrusion of the flexible material of the sealing element S. The extrusion members 35 move with the elements S by reason of the connectors 40 and likewise the segments 35 move with the segments 36 by reason of the connectors 40 so as to avoid any extrusion of the rubber or other material of the sealing element S between the

segments

36 and 36, respectively. Ultimately, the segments of the extrusion means M and M also contact the external surface of the pipe P and thus block longitudinal extrusion of the sealing element S in either longitudinal direction relative to the pipe P. Upon a release of the pressure acting on the piston 56 and the application of pressure to move same outwardly for each of the rams R, the rams R are retracted and are moved to the position of FIG. 8 so as to provide the full open bore corresponding to the bore 50 of the housing H-l in the known manner.

Instead of the dished out or concave surface 30a, the shape of the surface 30a or other portions of the sealing member 30 may be modified, or recesses or the like in the member 30 may be provided, the purpose of which is to compensate, or partially compensate, for the smaller volume of the space available for the rubber of the member 30 when it is in its sealing position (FIG. 2) as compared to the volume of the space available for such member 30 in its retracted position (FIG. I).

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.

I claim:

1. A blowout preventer adapted to seal with a pipe or other object in a well bore or to close same in the absence of any object in the well bore, comprising:

a resilient sealing member having an inner curved surface adapted to engage a pipe or the like in a well bore;

means for urging said sealing member radially inwardly for effecting a seal with a pipe or the like in a well bore or with itself for closing a well bore; and

first anti-extrusion means mounted with said sealing member and movable radially therewith in response to radial inward movement of said sealing member for preventing extrustion of the sealing member longitudinally when fluid pressure acts on said sealing member, said first anti-extrusion means comprising:

a first set of anti-extrusion members circumferentially disposed with respect to each other and mounted for radial movement;

a second set of anti-extrusion members, mounted below said first set and staggered circumferentially with respect to said anti-extrusion members in said first set to close radial spaces therebetween; and

separate connector means connecting said first set of anti-extrusion members to said second set for effecting radial movement thereof together.

2. The blowout preventer set forth in claim 1,

wherein:

said sealing member is substantially semi-cylindrical and is adapted to be mounted as a part of a blowout preventer ram.

3. The blowout preventer set forth in claim 1,

wherein said sealing member is annular.

4. The blowout preventer set forth in claim I, including:

second anti-extrusion means mounted with said sealing member on the opposite side longitudinally of said sealing member from said first anti-extrusion means and movable radially relative to said sealing member in response to radial inward movement of said sealing member for inhibiting extrusion of the sealing member longitudinally when fluid pressure acts on said sealing member from either longitudinal direction.

5. The structure set forth in claim 4, wherein said second anti-extrusion means includes:

a second set of anti-extrusion members mounted below said first set and staggered circumferentially with respect to said anti-extrusion members in said first set to close radial spaces therebetween; and

said anti-extrusion members in such first and second sets having overlapping surfaces, the extent of overlap of which increases as the anti-extrusion members move radially inwardly.

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

each of said anti-extrusion members in said second set of anti-extrusion members of said second antiextrusion means is bonded to said sealing member and is movable therewith; and

connector means connecting said first set of antiextrusion members in said second anti-extrusion means to said second set for effecting radial movement thereof together.

7. The structure set forth in claim 6, wherein said connector means includes:

a connector plate secured to each of said antiextrusion members in said second set for movement therewith; and

circumferential slide connection means connecting said connector plate to each of two of the antiextrusion members in said first set above the antiextrusion member in said second set to which said plate is secured for thereby providing limited circumferential movement of said connected members relative to each other as they move together radially.

8. The structure set forth in claim 1, wherein:

said anti-extrusion members in said first and second sets having overlapping surfaces, the extent of overlap of which increases as the anti-extrusion members move radially inwardly.

9. The structure set forth in claim 8, wherein:

each of said anti-extrusion members in said second set of anti-extrusion members of said first antiextrusion means is bonded to said sealing member and is movable therewith.

10. The structure set forth in claim 1 wherein said separate connector means includes:

11. The structure set forth in claim 10, wherein said circumferential slide connection means includes:

a circumferential slot in each said connector plate for each of said two anti-extrusion members in said first set; and

a pin with each of said two anti-extrusion members in said first set extending through said slot and having a head thereon to force the anti-extrusion members in said first set to move radially with the antiextrusion members in said second set while permitting relative circumferential movement during such radial movement.

Claims

1. A blowout preventer adapted to seal with a pipe or other object in a well bore or to close same in the absence of any object in the well bore, comprising: a resilient sealing member having an inner curved surface adapted to engage a pipe or the like in a well bore; means for urging said sealing member radially inwardly for effecting a seal with a pipe or the like in a well bore or with itself for closing a well bore; and first anti-extrusion means mounted with said sealing member and movable radially therewith in response to radial inward movement of said sealing member for preventing extrusion of the sealing member longitudinally when fluid pressure acts on said sealing member, said first anti-extrusion means comprising: a first set of anti-extrusion members circumferentially disposed with respect to each other and mounted for radial movement; a second set of anti-extrusion members, mounted below said first set and staggered circumferentially with respect to said antiextrusion members in said first set to close radial spaces therebetween; and separate connector means connecting said first set of antiextrusion members to said second set for effecting radial movement thereof together.

2. The blowout preventer set forth in claim 1, wherein: said sealing member is substantially semi-cylindrical and is adapted to be mounted as a part of a blowout preventer ram.

3. The blowout preventer set forth in claim 1, wherein said sealing member is annular.

4. The blowout preventer set forth in claim 1, including: second anti-extrusion means mounted with said sealing member on the opposite side longitudinally of said sealing member from said first anti-extrusion means and movable radially relative to said sealing member in response to radial inward movement of said sealing member for inhibiting extrusion of the sealing member longitudinally when fluid pressure acts on said sealing member from either longitudinal direction.

5. The structure set forth in claim 4, wherein said second anti-extrusion means includes: a first set of anti-extrusion members circumferentially disposed with respect to each other and mounted for radial movement; a second set of anti-extrusion members mounted below said first set and staggered circumferentially with respect to said anti-extrusion members in said first set to close radial spaces therebetween; and said anti-extrusion members in such first and second sets having overlapping surfaces, the extent of overlap of which increases as the anti-extrusion members move radially inwardly.

6. The structure set forth in claim 5, wherein: each of said anti-extrusion members in said second set of anti-extrusion members of said second anti-extrusion means is bonded to said sealing member and is movable therewith; and connector means connecting said first set of anti-extrusion members in said second anti-extrusion means to said second set for effecting radial movement thereof together.

7. The structure seT forth in claim 6, wherein said connector means includes: a connector plate secured to each of said anti-extrusion members in said second set for movement therewith; and circumferential slide connection means connecting said connector plate to each of two of the anti-extrusion members in said first set above the anti-extrusion member in said second set to which said plate is secured for thereby providing limited circumferential movement of said connected members relative to each other as they move together radially.

8. The structure set forth in claim 1, wherein: said anti-extrusion members in said first and second sets having overlapping surfaces, the extent of overlap of which increases as the anti-extrusion members move radially inwardly.

9. The structure set forth in claim 8, wherein: each of said anti-extrusion members in said second set of anti-extrusion members of said first anti-extrusion means is bonded to said sealing member and is movable therewith.

10. The structure set forth in claim 1, wherein said separate connector means includes: a connector plate secured to each of said anti-extrusion members in said second set for movement therewith; and circumferential slide connection means connecting said connector plate to each of two of the anti-extrusion members in said first set above the anti-extrusion member in said second set to which said plate is secured for thereby providing limited circumferential movement of said connected members relative to each other as they move together radially.

11. The structure set forth in claim 10, wherein said circumferential slide connection means includes: a circumferential slot in each said connector plate for each of said two anti-extrusion members in said first set; and a pin with each of said two anti-extrusion members in said first set extending through said slot and having a head thereon to force the anti-extrusion members in said first set to move radially with the anti-extrusion members in said second set while permitting relative circumferential movement during such radial movement.