[0001] In use the resilient packer of an annular blowout preventer can wear and be damaged.
Changing the packer in present annular blowout preventers requires the removal of
the upper end connection plus other elements of the BOP stack which are above the
annular preventer such as the bell nipple, stripper, or rotating head. To do this
clearance must be provided between the rig floor substructure and the top of he BOP
to allow the top to be lifted clear to provide access to the packer. This is very
inconvenient in snubbing operations. Also the top portion of most present annular
blowout preventers is large and heavy which reduces the clearance and increases the
difficulty of replacing the packer.
[0002] U.S. Patent No. 2,154,955 discloses a well casing control valve having removable
side plates allowing access for ram changes.
[0003] U.S. Patent No. 2,320,974 discloses a ram type blowout . preventer with. removable
side plates for changing internal ram operating mechanisms and rams.
[0004] U.S. Patent.No. 2,592,197 discloses a ram type blowout preventer with side windows
for each ram for insertion and removal of the rams with covers secured over the windows
for each ram for insertion and removal of the rams with covers secured over the windows.
[0005] None of the known prior art recognizes the problem of changing the annular packer
in an annular blowout preventer. Flat door covering windows for access to rams in
a ram type blowout preventer do not teach that the packer of an annular blowout preventer
could be removed in a manner other than through the top.
Summary
[0006] An improved annular blowout preventer having a body with a central bore therethrough,
a split annular packer recess surrounding and opening onto the bore, an annular packer
positioned in said recess, means for axially loading the packer, at least one opening
through the side of the body into the packer recess of sufficient size for the removal
of the packer therethrough, a plug removably positioned in the opening to close the
opening and form the exterior of said packer recess, a ring surrounding said body
to retain said plug in position in said opening and means supporting said ring in
position surrounding said body and retaining said plug in said opening.
[0007] An object of the present invention is to provide an improved annular blowout preventer
in which the annular packer may be changed without regard to the vertical clearance
available.
[0008] Another object is to provide an improved annular blowout preventer having simple
and easy means for changing the annular packer.
[0009] A further object is to provide an improved annular blowout preventer with a side
access to the annular packer. without sacrificing the strength of the preventer body.
Description of the Drawings
[0010] These and other objects and advantages of the present invention are hereinafter set
forth and explained with respect to the drawings wherein:
FIGURE 1 is a partial sectional partial elevation view of the improved annular blowout
preventer of the present invention.
FIGURE 2 is a sectional view through the packer taken along line 2-2 in FIGURE 1.
FIGURE 3 is a view similar to FIGURE 1 with the retaining sleeve lowered below the
body plug.
FIGURE 4 is an end view of the plug.
FIGURE 5 is a plan view of the.plug.
FIGURE 6 is a sectional view similar to FIGURE 2, but of a modified form of the present
invention.
Description of the Preferred Embodiments
[0011] Annular blowout preventer 10, as shown in FIGURE 1, includes body 12 having central
bore 14 extending therethrough with packer recess 16 surrounding and opening onto
bore 14. Body 12 includes lower flange 18, inner upstanding rim 20 and outer upstanding
rim 22. Upper end closure 24 is threaded into rim 22 and has depending rim 26 extending
to a position between rims 20 and 22, and forming annular chamber 28. Upper end closure
24 extends inward as flange 30 to proved shoulder 32-at the upper end of packer recess
16. Annular packer 34 is positioned in packer recess 16 between shoulder 32 and annular
actuating plate 36. Means for axially loading annular packer 34 is provided by piston
38 which is slidable in chamber 28 responsive to pressure through port 38a and port
38b and connected to annular actuating plate 36 by annular arm 40.
[0012] Annular packer 34 includes resilient annulus 41 with upper insert plates 42 and lower
insert plates 44 embedded therein. Annular packer 34 is split and preferably has two
semi-annular sections 34a and 34b. as shown in FIGURE 2. Ring 46 is embedded in the
exterior of resilient annulus 41 and has a plurality of tapped holes 48 to allow firm
engagement of packer 34 during removal. Annular packer 34 is split as described and
shown to allow it to be removed easily from recess 16 through opening 50 in rim 22
and depending rim 26 of end closure 24 as best seen in FIGURE 2.
[0013] Opening 50 includes inner rectangular opening 52 with shoulder 54 at its inner end
and outer rectangular opening 56 with shoulder 58 facing outward at the inner end
of opening 56. Plug 60 is shaped to fit closely into opening 52 and 56, to engage
shoulder 54 and capture seal ring 62 between shoulder 64 on plug 60 and shoulder 58.
The inner surface 66 of plug 60 is cylindrical to form a portion of the wall of recess
16. Plug 60 is retained in opening 50 by sleeve 68 which surrounds outer rim 22 of
body 12 from a position above opening 50 to a position below opening 50. Suitable
means for supporting sleeve 68 in its plug retaining position is provided in the form
of lugs 70 secured to outer rim 22 by screws 72.
[0014] Whenever it is desired to replace packer 34 then screws 72 are removed and sleeve
68 is lowered to the position shown in FIGURE 3 so that plug 60 can be removed. With
plug 60 removed packer sections 34a and 34b can be removed even with a pipe extending
through bore 14.
[0015] In the modified form shown in FIGURE 4, annular blowout preventer 80 includes outer
rim 82 and depending rim 84 of end closure with inner rectangular opening 86 extending
transversely thereof and outer rectangular openings 88 and 90 provide shoulders 92
and 94. Plugs 96 and 98 are positioned therein and seal rings 100 and 102 are positioned
between shoulders 104 and 106 on plugs 96 and 98 and shoulders 92 and 94. Sleeve 108
surrounds rim 82 and retains plugs 96 and 98 in position sealing both ends of bore
86. Packer 110 includes sections 112 and 114 and has ring 116 embedded therein with
tapped holes 118 to assist in removal of packer sections 112 and 114 through opposite
sides of bore 86 after plugs 96 and -98 are removed.
1. An annular blowout preventer including a body having a central bore extending therethrough
with an annular packer recess surrounding and opening to said bore, an annular split
packer positioned in said recess, means for loading said packer to seal within said
bore, and characterized by an opening through the side of said body into said packer
recess, a plug for sealing said opening, and means for retaining said plug in said
opening.
2. An annular blowout preventer according to claim 1 wherein said packer includes
two sections.
3. An annular blowout preventer according to claim 1 or 2 including means in said
packer allowing engagement therewith to pull said packer through said opening.
4. An annular blowout preventer according to claim 3 wherein said engagement means
includes a ring embedded in the outer exterior of said packer, and threaded holes
in said ring.
5. An annular blowout preventer according to any of the preceding claims wherein said
retain includes a sleeve surrounding said body and engaging the exterior of said plug.
6. An annular blowout preventer according to claim 5 including means for retaining
said sleeve in engagement with the exterior of said plug.
7. An annular blowout preventer according to claim 1, 2, 3 or 4 wherein said opening
extends through both sides of said body with a plug in each side of said opening,
and said packer is divided into two sections.
8. An annular blowout preventer according to any of the preceding claims wherein said
loading means includes a piston movable vertically in said body, and an annular actuating
plate engaging the underside of said packer, movement of said piston in one direction
axially loading said packer to move inward into sealing position and in the other
direction unloading said packer to allow it to relax from sealing position.
9. An annular blowout preventer comprising a body having a central bore therethrough
and a recess surrounding and opening on said central bore, a split packer having a
resilient annulus with a series of upper insert plates embedded in the upper surface
of the annulus and a series of lower insert plates embedded in the lower surface of
said annulus, said packer positioned in said recess, an annular piston chamber in
said body with a piston movable therein responsive to pressure admitted to said chamber
on opposite sides of said piston, said piston axially loading said packer, and characterized
by an opening through the side of said body into said packer recess, a plug removable
positioned in said opening, and a sleeve surrounding said body.and retaining said
plug in position within said opening.