RU2763154C1 - Fastening a flange connection at the wellhead - Google Patents

Abstract

FIELD: wellhead equipment.

SUBSTANCE: invention relates to fastening a flange connection at a wellhead. Fastening the flange connection at the wellhead contains a support and wellhead flanges with holes for fastening, a sealing ring installed between the flanges in grooves with tapered surfaces, studs, nuts. The support and wellhead flanges are made with six holes for fastening, six studs are made with lateral blind holes, at the end of the studs there are six segment elements with lateral threaded holes. The segment elements are screwed onto studs and rigidly fixed with screws screwed into the side threaded holes of the segment elements until they stop against the ends of the side blind holes. In the side threaded holes of the segment elements above the screwed-in screws, there are internal annular grooves, into which the split spring retaining rings are inserted, fixing the screws in the side threaded holes of the segment elements from spontaneous flap. Studs with segment elements and nuts are made of material of strength class 12.8 with a thread pitch of 2.5-4 mm. Studs with segment elements from below are inserted into holes for attaching the support and wellhead flanges and form a ring in contact with the support flange, and the nuts on the studs are wrapped from above.

EFFECT: reducing the duration of the assembly of the flange connection of the wellhead equipment, simplifying the maintenance of the device in operation, reducing the duration of fastening the nuts on the studs or bolts, reducing the metal consumption of the structure, reducing the overhaul period and periodic inspections of the fastening of the flange connection at the wellhead for tightness.

1 cl, 5 dwg

Description

The invention relates to the field of mining, in particular to the oil and gas industry, and can be used when repairing wells for the purpose of attaching various wellhead equipment to the supporting flange of the well, as well as for fastening the wellhead flange during well operation.

Known flange connection of parts (patent RU No. 2150041, publ. 27.05.2000), including two flanges tightened by pins together and a sealing element made of a metal ring with two end grooves - grooves for elastic, for example polyurethane, gaskets installed in the chamber, formed by the annular grooves of the trapezoidal profile on the flanges connected to each other, and the sealing element with its end sections is located in the grooves of the flanges in such a way that half of the end sections, including the elastic gasket protruding from the ring and a part of the ring in the area of the groove location, corresponds to their shape, the other half of the end sections sections is made with a gap, and its middle part, connected to the end sections, has a rectangular profile.

The disadvantages of the device are:

- the duration of the assembly of the flange connection of the wellhead equipment during well workover, due to the need to seal the wellhead almost after each technological operation (flushing, perforation, etc.), i.e. fix and fasten the wellhead and support flanges with each other using 12 studs and 24 nuts;

- a requirement for service due to the need to use two wrenches to tighten the studs when attaching the device;

- long duration of fastening of nuts on a stud. This is due to the fact that the studs and nuts used have a small thread pitch, usually 1.0-1.5, which increases the number of turns of the nuts when tightening them onto the studs;

- high metal content of the structure, associated with the use of 12 pins and 24 nuts.

Known device for connecting flanges during well workover (patent RU No. 2749686, publ. 06/16/2021), containing tightened together through aligned holes support and wellhead flanges, and a sealing ring installed between the flanges in grooves with tapered surfaces. In this case, the support and wellhead flanges are pulled together from 4 to 12 clamps. Moreover, each retainer consists of a rod equipped with a bottom thread, an eccentric handle pivotally attached to the upper end of the rod, a support washer and an adjusting nut located below the support washer and screwed onto the thread of the rod. In the initial position, the rods of the retainers are installed in the combined holes of the support and wellhead flanges, and the adjusting nuts are screwed into the threads of the rods. In this case, the upper ends of the adjusting nuts interact with the lower end of the support flange, and the lower ends of the eccentric handles interact through the support washers with the upper end of the wellhead flange. In the working position, to tighten the support and wellhead flanges together by means of aligned holes, the eccentric handles of the latches are sequentially turned until the side ends of the eccentric handles stop through the support washer into the upper end of the wellhead flange with a limited upward movement of the rods and sealing the sealing ring in the grooves with tapered surfaces of the support and wellhead flanges.

Disadvantages of the device:

- low tightness of the flange connection, since the clamps are attached to the flange connection by turning the handles by hand, which does not ensure tightness at a pressure of over 5.0 MPa. As a result, fluid begins to pass through the O-ring;

- the complexity of the design of the retainer for fastening the flange connection;

- high cost of manufacturing clamps for fastening flange connections;

- high metal consumption of the structure, associated with a large number of parts for fastening the flange connection.

The closest in technical essence and the achieved result is a flange connection of the wellhead equipment containing the wellhead and support flanges, an O-ring installed between the flanges in grooves with tapered surfaces (patent RU No. 2170807, publ. 20.07.2001). The sealing ring is made of an elastic material with an allowance for deformation, taking into account the presence of an additional ring, and the wellhead and support flanges are pulled together by studs, while the additional ring is made of metal, connected to the sealing ring of an elastic material and has concentric conical symmetric ribs located on its inner part for centering the grooves in contact with their tapered surfaces, while the outer part of the additional ring is made flat for support outside the grooves of the end surfaces of the flanges and serves as a closing dimensional link in the connection elements.

The disadvantages of the device are:

- long duration of assembly of a flange connection of wellhead equipment during well workover, due to the need to seal the wellhead practically after each technological operation (flushing, perforation, etc.), i.e. fix and fasten the wellhead and support flanges with each other using 12 studs and 24 nuts;

- high maintenance requirements due to the need to use two wrenches to tighten the nuts on the studs when sealing the flange connection;

- high duration of the fastening of the nuts on the stud. This is due to the fact that the studs and nuts used have a small thread pitch, usually 1.0-1.5, which increases the number of turns of the nuts when tightening them onto the studs;

- high metal content of the structure, associated with the use of 12 pins and 24 nuts;

- it is necessary to periodically monitor the condition of the nuts screwed onto the studs due to the possibility of their loosening during operation, requiring tightening to ensure the tightness of the flange connection, and this increases the interoperative period of periodic inspections of the fastening of the flange connection at the wellhead for tightness.

The technical objectives of the invention are to reduce the duration of the assembly of the flange connection of the wellhead equipment, to simplify the maintenance of the device in operation, as well as to reduce the duration of the fastening of the nuts on the studs or bolts, to reduce the metal consumption of the structure and to reduce the turnaround time - periodic inspections of the fastening of the flange connection at the wellhead for tightness.

The posed technical problems are solved by fastening a flange connection at the wellhead, containing support and wellhead flanges with holes for fastening, a sealing ring installed between the flanges in grooves with tapered surfaces, studs, nuts.

What is new is that the support and wellhead flanges are made with six holes for fastening, six studs are made with lateral blind holes, at the end of the studs there are six segment elements with side threaded holes, while the segment elements are screwed onto the studs and rigidly fixed with screws, of the segment elements screwed into the side threaded holes until they stop against the ends of the side blind holes, while in the side threaded holes of the segment elements above the screwed-in screws, internal annular grooves are made, into which the split spring retaining rings are inserted, fixing the screws in the side threaded holes of the segment elements from spontaneous opening , moreover, the studs with segment elements and nuts are made of material of strength group 12.8 with a step of 2.5-4, while the studs with segment elements from the bottom are inserted into the holes for attaching the support and wellhead flange and form a ring in contact with the support flange, and the nuts on the studs are wrapped at the top.

FIG. 1 schematically depicts the fastening of a flange connection at the wellhead.

FIG. 2 shows a bottom view - A of fastening a flange connection at the wellhead.

FIG. 3 shows a top view - B of fastening a flange connection at the wellhead.

FIG. 4 schematically shows an enlarged view I of the fastening elements of the flange connection at the wellhead.

FIG. 5 shows a side view - C of a segment element.

The flange connection of the wellhead equipment contains support 1 (see Fig. 1 and 2) and wellhead 2 (see Fig. 1 and 3) flanges with holes (Fig. 1 is shown conditionally). As a wellhead flange, for example, a faceplate 2 is used (shown schematically in Fig. 1), which is attached to the support flange during well operation.

The supporting flange 1 and the faceplate 2 are equipped with grooves with a tapered surface for the sealing ring 3 (see Fig. 1).

The outer diameters of the supporting 1 flange and the faceplate 2 are equal to each other and are, for example, D _f = 300 mm.

To attach the support 1 flange and faceplate 2, six studs 4 (see Figs. 1-5) with side blind holes 5 (see Figs. 2 and 4) made at the ends of the studs 4 are used.

Also, the fastening of the flange connection at the wellhead contains six segment elements 6 (see Fig. 1-2) with side threaded holes 7 (see Fig. 2).

Segment elements 6 are screwed onto pins 4 and rigidly fixed with screws 8 (see Figs. 2, 4, 5) screwed into the side threaded holes 7 of the segment elements 6 until they stop against the ends of the side blind holes 5.

In the side threaded holes 7 of the segment elements 6 above the screwed-in screws 8, internal annular grooves 9 are made (see Fig. 4), into which the split spring rings 10 (see Fig. 4-5) are inserted, fixing the screws 8 in the side threaded holes 7 segmented elements 6 from spontaneous lapel.

Studs 4 (see Fig. 1 and 3) with segment elements 6 and nuts 11 (see Fig. 1-3) are made of material of strength group 12.8 according to GOST R 52627-2006 with a step of 2.5-4, for example 2, 5.

After aligning and installing the pins 4 in the holes of the supporting 1 flange and the lower flange of the faceplate 2, the segment elements 6 of the pins 4 form a ring 12 between themselves (see Fig. 2) with an outer diameter - D _n and an inner diameter - D _in ,

The outer diameter of the ring 12 is determined by the formula:

where D _mts - center-to-center diameter of the installation circle of studs 4, mm,

k ₁ = 1.12 - coefficient obtained experimentally.

The inner diameter of the ring 12 is determined by the formula:

where D _mts is the center-to-center diameter of the stud installation circle,

k ₂ = 0.88 - coefficient obtained experimentally.

Outer and outer diameters D_n and D_v rings 12 are determined by the value of the coefficients k_oneand k₂, determined empirically, depending on the diameter of the studs, which on the one hand excludes the rupture of the segment elements 6 and the studs 4 when tightening the supporting 1 flange and the faceplate 2, and on the other hand eliminates the excessive metal consumption of the segment elements 6 of the studs 4.

The outer circumference - L _{1 of} one of the equal segment elements 6, the corresponding studs 4 are determined by the dependence:

where π = 3.14;

L ₁ - outer circumference of one of the equal segment

elements 6 pins 4;

D _n - outer diameter of segment elements 6 forming a ring 12, mm;

n - number of studs 4 with segment elements 6: n = 6 pieces.

The inner circumference - L _{2 of} one of the equal segment heads of the bolts is determined by the dependence

where π = 3.14;

L ₂ - outer circumference of one of the equal segment

elements 6 pins 4;

D _in - the inner diameter of the segment elements 6 forming a ring 12, mm;

n - number of studs 4 with segment elements 6: n = 6 pieces.

The angle α between the segment elements of the studs is equal to:

where, 360 is the value of the angle of the circumference of the ring 12, °

n - number of studs 4 with segment elements 6: n = 6 pieces.

Substituting numerical values in formulas 3-5 we get:

L ₁ = π × D _n / n = (3.14 × 280 mm) / 6 = 219.8 mm.

L ₂ = π × D _in / n = (3.14 × 220 mm) / 6 = 172.7 mm.

α = 360 ° / n = 360 ° / 6 = 60 °

Studs 4 with segment elements 6 are inserted from below into holes for attaching the support 1 and wellhead 2 flanges and form a ring 12 in contact with the support flange 1. Nuts 11 on the studs 4 are wrapped from above.

In the side threaded holes 7 of the segment elements 6 at a depth h, for example, at a depth of h = 10 mm, internal annular grooves 9 are made, into which split retaining rings 10 are inserted.

Fixation with split retaining spring rings 10 completely eliminates the turning of the screws 8 and provides a rigid connection between the pins 4 and the segment elements 6 under operating conditions and vibration. Studs 4 and segment elements 6, for example, have a metric thread M22.

The device works as follows.

Before assembling the device, six pins 4 and six segment elements 6 are made, depending on the center-to-center diameter of the circle - D _{mts of the} support flange 1 and faceplate 2, in the holes of which pins 4 are installed according to formulas (1-5).

Let's take: D _mts = 250 mm. Then, substituting the numerical values into formulas 1-5, we get:

D _n = k ₁ × D _mts = 1.12 × 250 mm = 280 mm.

D _in = k ₂ × Dmts = 0.88 × 250 mm = 220 mm.

L ₁ = π × D _n / n = (3.14 × 280 mm) / 6 = 146.53 mm.

L ₂ = π × D _in / n = (3.14 × 220 mm) / 6 = 115.13 mm.

α = 360 ° / n = 360 ° / 6 = 60 °.

From the condition of the equally strong connection of the segment element 6 and the nut 11 on the thread of the stud 4, we take the height - H of the segment elements 6 is taken equal to the height of the nut 11, for example equal to 22 mm.

After the manufacture of segment elements 6 with side threaded holes 7 (see Fig. 2) and pins 4 with side blind holes 5 and inner annular grooves 9 (see Fig. 4), as well as six screws 8, for example, metric thread M6, and split spring retaining rings 10. All elements are made in an amount of 6 pieces.

Next, the pin 4 and the segment element 6 are rigidly connected to each other. First, the segment element 6 is screwed onto the pin 4 until its threaded hole 7 is aligned with the side blind hole of the pin 4. Next, the screw 8 is screwed into the threaded hole 7 of the segment element until the end of the screw 6 stops at the end lateral blind hole 5 of the stud 4. Then insert the split snap ring 10 into the inner annular groove 9 of the stud 4.

Next, proceed to fastening the flange connection at the wellhead.

In the groove (in Fig. 1, 2 is shown conditionally) with the tapered surface of the support flange 1 (see Fig. 1), an O-ring 3 is installed. support flange 1 align their holes for fastening.

Further, in the aligned holes of the supporting flange 1 and the flange of the faceplate 2, first insert the pin 4 from below (see Figs. 1 and 2), rigidly connected from below with the segment element 6, and then from above (above the faceplate 2) screw the nut 11 onto the pin 4, while the outer surface (circumference L ₂ ) of the segment element 6 is in a position on the periphery (parallel to the diameter) of the support flange 1 (see Fig. 2). The remaining five studs 4 with segment elements 6 with nuts 11 are fastened in a similar way. Then, using one wrench, all nuts 11 are tightened.

The flange connection at the wellhead has been completed. If necessary, for example, to remove the sucker rod pump, disassemble in the reverse order.

The duration of fastening the flange connection at the wellhead is 4 times reduced, since to seal the wellhead, it is necessary to tighten 6 nuts, and not 24, as in the prototype.

Due to the presence of a large thread pitch (on all studs, segment elements and nuts) due to a decrease in the number of revolutions of rotation of the nuts relative to the studs during the fastening of the flange connection, the duration of the fastening of the nuts on the studs is reduced by 1.5-3 times;

The maintenance of the device in operation is simplified, since only one wrench is used, and not two, as described in the prototype, since from above the segment elements of the studs forming the ring 12 are self-fixed to each other from rotation.

The metal consumption of the flange joint fastening structure decreases, so

as the device contains 6 studs, 6 segment elements and 6 nuts, and not 12 bolts and 24 nuts, as in the prototype.

In the proposed device, the frequency of monitoring the fastening of the flange joint is halved, since only one row of nuts 6 needs to be inspected and tightened and, accordingly, the number of nuts 11 to be inspected and tightened during the operation of the flange joint is reduced by 4 times in comparison with the prototype. Reducing the frequency of checking the fastening of the flange joint increases the interoperative period of periodic inspections of the fastening of the flange joint at the wellhead for tightness, and this, in turn, reduces the costs of the maintenance personnel.

The proposed flange connection at the wellhead allows:

- to reduce the duration of the assembly of the flange connection of the wellhead equipment;

- to simplify the maintenance of the device in operation;

- to reduce the duration of the fastening of nuts on studs or bolts;

- to reduce the metal consumption of the structure;

- to increase the interoperative period of periodic inspections of the flange joint fastening at the wellhead for tightness.

Claims (1)

Fastening a flange connection at the wellhead, containing a support and wellhead flanges with holes for fastening, an O-ring installed between the flanges in grooves with tapered surfaces, studs, nuts, characterized in that the support and wellhead flanges are made with six holes for fastening, six studs are made with side blind holes, at the end of the studs there are six segment elements with side threaded holes, while the segment elements are screwed onto the studs and rigidly fixed with screws screwed into the side threaded holes of the segment elements until they stop against the ends of the side blind holes, while in side threaded holes of the segment elements above the screwed-in screws, there are internal annular grooves, into which split spring retaining rings are inserted, fixing the screws in the side threaded holes of the segment elements from spontaneous flap, and the studs with segment elements and nuts are made of material of strength class 12.8 with a thread pitch of 2.5-4 mm, while the studs with segment elements from below are inserted into the holes for attaching the support and wellhead flanges and form a ring in contact with the support flange, and the nuts on the studs are wrapped from above.

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