JPH02190592A - Seal structure - Google Patents

Abstract

PURPOSE: To exert a large load on a resilient seal by small loading force, by screwing a follower assembly which consists of a first follower and a second follower on a hanger to rotate, and by moving downward the follower assembly to compress an elastic seal. CONSTITUTION: A seal assembly 30 is brought down on a determined position, and a first follower 36 is screwed around an outside screw 28 of a hanger. An elastic seal 32 is installed between a sealed surface 16 of a housing 12 and a sealed surface 20 of a hanger 14, and lower end parts 52, 72 of a first and a second followers 36, 38 are engaged with an upper surface 54 of the seal 32. When the follower 38 is rotated, the follower 36 is rotated along a screw 28 to move downward the follower assembly 34, whereby the seal 32 is compressed in an axial direction, and is expanded in a radial direction. When a load reaches a predetermined value, a large load is added on the seal 32 to move the assembly 34 further without enlarging a torque load together with shearing of a fixing equipment 40 which can be cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an improved elastomer seal in which the elastomer is pressed in two stages. The sealing structure of the present invention is particularly applicable to annular rings between multiple members, such as hanger back-off seals.

(b) Prior Art U.S. Pat. No. 4,008,898 discloses an annular elastomer seal provided between opposing cylindrical surfaces, in which a seal follower or actuator is held inactive by a shear pin and a seal support. The ring/ring is also shear pinned and the movement of the seal follower applies an initial seal load where the seal applies a light load to the seal support ring which moves downward within the annulus and seals as required. A seal configured to be moved to a sealing position is disclosed.

U.S. Pat. No. 4,138,144 discloses another wellhead annular seal assembly adapted to control the movement time of the first member 40 and locking sleeve 50 using a shear pin.

U.S. Patent No. 4,407,530, No. 4.408.78
No. 3 and No. 4,416,472 are both controlled so that the seals are set singly and in series.

This relates to the annular back-off of the hanger reservoir.

U.S. Pat. No. 3,004,776 discloses a sealing nut for a pipe fitting sump having a press ring 15 carried by the nut in a thin section that is sheared. Both the press ring and sleeve apply a sealing force to the resilient seal ring. The press ring and sleeve cooperate to fit the sealing ring around the pipe end thread 19 within the nut.

(...) OBJECTS OF THE INVENTION It is an object of the present invention to provide an improved annular elastic seal in which the seal follower can create a substantial sealing load.

Another object of the present invention is to provide an improved annular resilient seal in which the load bearing can be set with substantial seal loads without imposing high loading forces on the follower.

Still another object of the present invention is to provide a two-stage load application for an elastic annular seal that allows a large seal load to be applied with a small force load.

(d) Means for Solving the Problems The improved elastomeric seal of the present invention provides a well head annular seal between the inner surface of the well head housing and the outer surface of a hanger located therein and having an outer seal support shoulder. an elastic seal suitable for sealing a Uras, located on the support shoulder between the hanger and the housing, engaging a substantial area of the seal to support the seal; a first follower pushing toward the shoulder and a second follower engaging a substantially smaller area of the seal to push the seal toward the supporting shoulder and detachable from the first follower; A follower structure with fixing equipment is provided. The separable fastening device releases the second follower when the force on the seal reaches a predetermined value, whereupon the second follower is pressed against the seal independently of the first follower and due to its smaller contact area. It is possible to apply a heavy sealing load to the seal.

(e) Embodiment As shown in FIG. 1, the seal structure 10 of the present invention is installed in a well head housing 12 so as to surround a hanger 14. Well head housing 12 has an inner cylindrical sealing surface 16 surrounding hanger 14. The hanger 14 has a lower outer surface 1a which is slightly smaller in diameter than the housing sealing surface 16, an intermediate sealing surface 20 which is smaller in diameter than this surface 18, a shoulder 22 between the surfaces 18 and 20, an upper surface 24° which is smaller in diameter than the surface 20, and a lower outer surface 1a having a smaller diameter than the housing sealing surface 16. Shoulder 26. It also has an external thread 28 provided on the surface 24.

Seal assembly 60 is comprised of an annular resilient seal or ring 62 and a follower assembly 64 . Follower assembly 6
4 is the first follower 36. The second follower 3a and the second
It includes equipment 40 for detachably fixing the follower 68 to the first follower 3B.

The first follower 56 is connected to the screw 28 on the outer surface of the hanger 14.
A body 42 having internal threads 44 for engagement with the body 42 and a setting rim 46 extending downwardly from the body.

The rim 46 has an inner diameter surface 48. which is slightly larger than the diameter of the intermediate sealing surface 20. It has an outer diameter surface 50 that is smaller than the inner diameter of the housing sealing surface 16 and a lower seal engaging surface 52 that engages a substantial portion of the upper surface of the resilient seal 62. Body 42 has a reduced diameter outer surface 56 with threads 58 . The second follower 38 has an internal thread 6 that engages an external thread 58 of the main body 42.
Central body with 2 60. It has a lower rim 64 and an upper setting rim 66. The lower rim 64 has an inner surface 68 that is slightly larger than the outer surface of the first follower rim 48 and an outer surface 70 that is slightly smaller than the inner sealing surface of the housing 12. The lower rim 64 can then move easily between the outer surface of the first follower 66 and the inner surface of the nozzle 12. The lower rim 64 also has a lower end 72 that engages the upper surface 54 of the seal 32.
has. As shown in the drawings, the area in which the lower end 72 of the second follower 38 engages the upper sealing surface 54 is substantially greater than the area in which the lower end 52 of the first follower 66 engages the upper sealing surface 54. small. A suitable coupling arrangement 74, such as a J-slot, is provided on the upper exterior of the second follower 38 for running and setting the seal assembly 30. The releasable securing device 40 may be any suitable device, such as the illustrated shear pin.

In operation, seal assembly 60 is lowered into the position shown in FIG.
2 and the sealing surface 20 of the hanger 14. Lower ends 5 of first and second followers 36 and 68
2 and 72 engage the top surface 54 of the resilient seal 62. Second
When the follower 68 is turned, the first follower '56 is attached to the screw 28.
The follower assembly 64 is rotated upward to seal the follower assembly 64 downward.
2 relative to the top surface 54. This allows the seal 32
are axially compressed and radially expanded to engage surfaces 16 and 48 of housing 12 and hanger 14. When the load on the seal 62 reaches a predetermined value, the releasable retainer 40 is disengaged (the shear pin is sheared) and the second follower 68 is then rotated further, causing the second follower to engage the external thread 58 of the first follower 66. moving from top to bottom. Because the second follower lower rim 64 has a smaller area of engagement with the resilient seal 62, this additional movement of the second follower is more effective relative to the resilient seal 62 without increasing the torque loading of the follower assembly 64. Apply a large load. Second
The mechanical advantage afforded by the smaller contact area of the followers is the ability to create substantially greater sealing forces than would be possible with the same torque loading of the first follower 36. Second
As the rotation of the follower 68 continues, the first and second followers move downward relative to the first follower 66 until they reach the position shown in FIG. The resilient seal 62 is completely confined and cannot be forced out of its sealed position.

4 through 7 illustrate alternative embodiments of the seal assembly. In the drawings, assembly elements that are the same as those in the previous embodiments are designated by the same numerals plus the number "1" in the front matter, and changed elements are designated by new different numbers. The variation seal assembly 160 includes the housing 11
2 inner sealing surface 116 and inner sealing surface 1 of hanger 114
20. Seal assembly 160 includes a resilient seal ring 162 and a follower assembly 164.

The follower assembly 164 includes a first follower 166, a second follower 13a, and a releasable fixture 140, such as a shear pin, for securing the followers 156, 168 into a releasable assembly. 1st follower 166
is screwed onto the hanger outer screw 128, and the lower rim 175
Equipped with. This rim is the upper surface 1 of the elastic seal ring 162.
54. The lower rim 175 of the first follower 166 includes a plurality of apertures 176 extending axially therethrough, each aperture receiving a pin end 178 in the form of a cylindrical pin of the second follower 168. . Also, a resilient plug 180 is installed within the openings 176 of the lower rim 175 and connects the pin end 1 of the second follower 168.
78.

Therefore, the force created by the movement of the second follower 168 after the detachable fixture 140 is detached from the plug 1
80 to the elastic seal 162. Due to the small area of the pin end 178 and plug 180 compared to the contact area of the end of the lower rim 175 against the seal ring 162, the setting torque can be significantly increased due to its mechanical advantages without substantially increasing the setting torque. Sealing pressure can be obtained.

Seal assembly 160 is shown in FIG. 4 with its seal ring 162 set in place without sealing pressure being applied yet. In FIG. 5, an initial seal is performed by rotating the follower assembly 134;
When the rotation reaches a predetermined load, the separable fixing device 140 is separated. Thereafter, as the follower assembly 164 is further rotated, the second follower 168 will rotate over the first follower 136.
The upper part is moved axially to reach the position shown in FIG.

In both of the above-described embodiments of the invention, a follower assembly is provided which applies an initial load to the resilient seal until the locking device is severed and is then turned to the page. This substantially increases the sealing pressure applied to the resilient seal without substantially increasing its rotational torque. Although the seal assembly of the present invention as shown and described herein is intended for use in an annular seal between a well housing and a hanger, it may also be used with a variety of other annular seals without increasing the torque loading of the follower. It can be used as having the advantage of being able to create a sealing pressure of the required level.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a portion of the annular elastic seal of the present invention installed between the outer surface of the well hanger and the inner surface of the well housing. 2 is a cross-sectional view of a portion of the seal of FIG. 1 partially pressed into a set position by a follower assembly; FIG. 3 is a cross-sectional view of the portion of the seal of FIGS. 1 and 2 fully compressed by the second portion of the follower assembly; FIG. FIG. 4 is a cross-sectional view of a portion of another embodiment of the seal of the invention before being pressed; 5 is a cross-sectional view of a portion of the seal of FIG. 4 in a partially set position; FIG. 6 is a cross-sectional view of the portion of the seal of FIGS. 4 and 5 fully compressed by the second portion of the follower assembly; FIG. Figure 7 is 7- in Figure 4.
In a cross-sectional view along line 7. A drawing showing the position of the seal engagement extension equipment of the second follower. 10...Seal structure, 12,112...Well head housing, 14,114...71 ringer 16.
116... Housing sealing side 20, 120... Hanger sealing side 30, 130... Seal assembly. 32.132...Seal-34,134...Follower assembly, 36.136...First follower, 68°1
38... Second follower 40. 140... Separable fixing equipment, 64... Rim, 178... Pin end,
180...Plug.

Claims (1)

[Claims] 1. In the seal structure, an annular elastic seal installed in the annulus between the inner and outer cylindrical surfaces to be sealed, equipment for supporting the elastic seal within the annulus to be sealed, and a seal. a first follower comprising a follower structure, the seal follower structure engaging the resilient seal and moving relative to the seal to urge the seal into a hard sealing position; a second follower having an engaging extension and equipment for moving a second follower relative to the seal by movement relative to the first follower; and separating the second follower from the first follower. the second follower has an area of engagement with the seal that is substantially smaller than the area of engagement of the first follower with the seal. When the seal setting force reaches a predetermined maximum force, the releasable fixture is disengaged, whereupon the second follower moves further relative to the seal, and the first follower reaches a point at which the fixture is disengaged. Seal structure configured to remain in the same position. 2. The second follower comprises a thin lower rim extending around an outer surface of the first follower to engage the seal.
Seal structure as described. 6. The seal structure of claim 1, wherein the second follower includes a plurality of lower pin ends extending through the opening of the first follower to apply a sealing force to the seal. 4. A resilient plug is disposed within each opening of the first follower, the pin end extending into the first follower opening and engaging the plug, and the plug engaging the resilient seal. 4. The seal structure of claim 3, wherein said second follower transmits a force applied by said pin end to said resilient seal. 5. A sealing structure comprising: a well housing having an inner cylindrical sealing surface, an upwardly facing shoulder disposed within the well housing, and an outer sealing surface above the shoulder and facing the housing sealing surface; a seal assembly having a hanger, a resilient seal, a first follower, a second follower, and a releasable feature securing the second follower to the first follower, the first follower having a lower seal engaging rim; the second follower has a lower seal-engaging portion, the seal structure also comprising: means for moving both followers in an axial direction of the hanger relative to the resilient seal; equipment for moving the second follower in the axial direction of the first follower after the securing equipment is disengaged in response to the seal contact area of the first follower being equal to the seal contact area of the second follower; A seal structure configured to be substantially larger than its area. 6. The seal structure of claim 5, wherein the second follower has a lower rim surrounding the outer surface of the first follower and engaging the resilient seal. 7. the first follower having a plurality of apertures extending axially through the lower rim thereof, and the second follower extending axially through the first follower aperture; 6. The seal structure of claim 5, further comprising a plurality of pin ends that apply a load to the resilient seal independent of a load on the resilient seal by the first follower. a) The equipment for moving the first follower is a screw provided on the outer surface of the hanger above the sealing surface;
as well as. including a thread on an inner surface of the first follower that engages the hanger screw, so that when the first follower is rotated, the first follower is moved relative to the resilient seal and has an axial force thereon. The seal structure according to claim 5, wherein a load is applied. 9. The equipment for moving the second follower includes: a second screw provided on the outer surface of the first follower; and a screw provided on the second follower that engages with the second screw of the first follower. 9. The seal structure of claim 8, wherein when the second follower is rotated relative to the first follower, the second follower is moved axially on the second thread of the first follower. . 10. The separable fixed equipment connects the first follower and the second follower until the load reaches a predetermined value and transmits rotation between the followers, and after the load reaches the predetermined value, 6. The seal structure of claim 5 including a shear pin to enable independent rotation of said second follower.