This invention relates to a method for installing a gasket. It relates, more particularly, to a method for installing a gasket between two pipe-flange halves, the pipe-flange halves being designed to be brought together by means of bolts extending through boltholes in the pipe-flange halves. The invention also includes a system for installing a gasket.

When conventional pipe-flange connections are being installed, wherein a gasket is placed between two pipe-flange halves and clamped by means of the bolts of the flange connection, it is a considerable problem that the gasket is being misplaced during the installation. This may result in the gasket being damaged during the torquing or in it not sealing because it sits incorrectly. The problem is greatest where the flange connection is placed somewhere with limited access, like under water or in a confined place.

It is known to place the gasket in a tool before inserting it between the pipe-flange halves. US2011/0167607 discloses such a tool. It has turned out that the use of such tools does not always give the correct positioning of the gasket relative to the pipe- flange halves.

From US3730537 A, a seal body is known, which is provided with two radially projecting, plate-shaped portions which form a centring means or web oriented in a plane perpendicular to the centre axis of the seal body and which constitute part of the seal body and extend outwards from the periphery of the actual seal ring. A projecting portion is provided with a pair of fingers arranged symmetrically, forming an abutment against a first bolt, and a further, diametrically opposite portion of the centring means is provided with a handle and an opening for receiving a second bolt. The gasket is thereby fixed on two bolts before the flanges are brought together.

EP2505313A1 discloses a handle, which, at one end portion, is provided with a magnetic shoe arranged to rest against the periphery of a ferromagnetic sealing ring dur- ing the insertion and centring of the sealing ring between flanges.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through the features, which are specified in the description below and in the claims that follow.

According to the invention, at least two installation bodies are placed between two pipe-flange halves. The installation bodies have gasket stops at a desired radial distance from the centre axis of the pipe-flange halves, which is ensured by placing the installation bodies on bolts that are in corresponding boltholes in the pipe-flange halves.

The gasket may then be inserted between the pipe-flange halves until it hits the installation bodies. The use of two installation bodies arranged on respective bolts ensures that the gasket will come into the correct position.

After the pipe-flange halves have been brought sufficiently together, the installation bodies may be removed.

The invention is defined by the independent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect, the invention relates more specifically to a method for installing a gasket between two pipe-flange halves, the pipe-flange halves being designed to be brought together by means of bolts extending through bolt holes in the pipe-flange halves, the method comprising :

arranging at least two installation bodies between the pipe-flange halves; attaching the installation bodies to respective bolts,

letting the installation bodies form a gasket stop which is at a desired radial distance from a centre axis of the pipe-flange halves;

inserting a gasket between the pipe-flange halves until it hits the installation bodies; and

clamping the gasket between the pipe-flange halves by means of the bolts.

By bolts are meant, here, the bolts that are used for bringing the pipe-flange halves together.

The method may include removing the installation bodies from the flange halves. In a second aspect, the invention relates more specifically to a system for installing a gasket between two pipe-flange halves, the pipe-flange halves being designed to be brought together by means of bolts extending through boltholes in the pipe-flange halves, and the system including at least two installation bodies that are between the pipe-flange halves and that are attached to respective bolts and form gasket stops at a desired radial distance from the centre axis of the pipe-flange halves.

The fact that the installation bodies are attached to the bolts ensures that the installation bodies are in correct positions relative to the pipe-flange halves. Letting the installation bodies just abut against the bolts will not ensure that the installation bodies are in the right positions.

In some cases, the installation bodies may be held in position by means of axle pieces, for example, which are placed in the relevant boltholes. This is to be considered as covered by the set of claims even though the pipe-flange halves are pulled together by means of other bolts.

The installation bodies may be provided with through openings for the bolts. This gives the best guarantee of the installation bodies being in the desired positions. By the installation bodies being formed as annular discs, the gasket stop will remain in the right position regardless of the rotational angles of the installation bodies around the bolts. The installation bodies may, with advantage, be provided with handles. In this connection, the term handle covers an ROV attachment (ROV = Remotely Operated Vehicle), for example.

The pipe-flange halves may be unlike; one of them may be a blind flange, for example.

The method and the system according to the invention enables a reliable relative positioning of the gasket between two flange halves by the very fact of the installation bodies' being fixed between the flange halves also in the radial direction. Leakage problems that are due to incorrect positioning of the gasket during the installation or damage caused to the gasket because it was not correctly positioned at the start of the torquing are thereby avoided. The method and the system are equally well suited for groove gaskets as for flat gaskets.

In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which : Figure 1 shows an axial section II-II according to figure 2 of a groove gasket during insertion between two flange halves in a pipe-flange connection;

Figure 2 shows a radial section I-I according to figure 1 of the groove gasket during insertion between the pipe-flange halves in the pipe-flange connection;

Figure 3 shows an axial section of the pipe-flange connection after the gasket has hit an installation body and is fixed between the pipe-flange halves; and

Figure 4 shows the same as figure 3, but after the installation body has been removed and the pipe-flange halves have been pulled together.

In the drawings, the reference numeral 1 indicates a pipe-flange connection comprising two pipe-flange halves 2. The pipe-flange halves 2 are fixed to pipes not shown. The pipe-flange halves 2 are provided, in a manner known per se, with a number of boltholes 4 which are distributed around a centre axis 6 of the pipe-flange connection 1. The pipe-flange halves 2 are brought together by means of bolts 8 extending through their respective boltholes 4.

In this embodiment shown, a gasket 10 consists of a groove gasket, which is arranged to seal against annular grooves 12 in the pipe-flange halves 2.

In figure 1, an installation body 14 is arranged between the pipe-flange halves 2, and the installation body 14 is attached to one of the bolts 8. Here, the installation body 14 consists of an annular disc with a through opening 16 for the bolt 8. Externally, the periphery of the installation body 14 constitutes a gasket stop 18. The gasket stop 18 is at a desired radial distance from the centre axis 6. The installation body 14 is provided with a handle 20.

In figure 2, an example in which two installation bodies 14 are arranged on respective bolts 8 is shown. The gasket 10 is inserted between the pipe-flange halves 2 by means of an auxiliary tool 22 until it hits the gasket stop 18 formed by the installation bodies 14. The gasket 10 is then in the correct radial position relative to the pipe-flange halves 2.

The bolts 8 are then tightened until the gasket 10 enters the annular grooves 12. Those of the bolts 8 that hold installation bodies 14 are then removed so that the installation bodies 14 can be removed. The pipe-flange halves 2 are then brought together to give a satisfactory seal. In an embodiment not shown, in which a flat gasket is used, the pipe-flange halves 2 must be pulled together sufficiently for the flat gasket to be held in position before the installation bodies 14 are removed.

The use of the verb "to comprise" and its different forms does not exclude the pres- ence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" before an element does not exclude the presence of several such elements.

The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.