EP3194259B1 - Fairlead to guide a anchor chain, for a floating installation - Google Patents

Description

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

The present invention relates to systems for anchoring floating installations, in particular for ground anchoring oil well platforms or production, storage and unloading vessels (also referred to as "Floating Production Storage"). and Offloading (Unit) "or" FPSO ").

BACKGROUND

Conventionally, the offshore oil well installations consist of floating platforms connected to the wellhead and anchored to the ground by means of anchor chains.

Of a generally square horizontal section, these platforms may have sides of several tens of meters, and a weight likely to reach several tens of thousands of tons (even several hundred thousand tons).
They support all the means necessary for the extraction of oil, possibly also for its processing on site; sometimes they also include equipment intended to ensure a human presence on board.

For anchoring, it is very generally used several groups of chains (also called anchor lines), each of these groups being arranged at one of the corners of the platform.

Each anchor group has several chains (three to eight for example) which are arranged parallel to each other.

Each anchor chain consists of a chain with metal links each of which has a length of a few tens of centimeters and is made from a wire having for example 9 to 20 cm in diameter.

The lower end of each of these anchor chains comprises means for its attachment to the ground, via a solid sunken into the seabed. Their upper end extends to a maneuvering station which is arranged on the side of the platform, above its waterline, for operation by a tensioner winch.

Between their upper and lower ends, an intermediate section of these chains is associated with a device commonly referred to as "fairlead".

These fairleads are attached to the platform, usually below the waterline.

The tension applied to each anchor chain by the tensioner winch associated with it is locked by locking means, some of which may be provided within even the fairlead, in the form for example of a jaw composed of two jaws articulated around axes of rotation parallel to each other.

These fairleads also provide guidance for a change of direction of the associated anchoring chain between, on the one hand, an upstream section extending vertically from the operating station and, on the other hand, a downstream section extending in an inclined manner up to the sunken mass in the seabed.

1. (i) une structure amont pour la solidarisation du chaumard avec l'installation flottante, portant les moyens de renvoi pour guider un changement de direction de la chaîne d'ancrage entre le tronçon amont et le tronçon aval, et
2. (ii) une structure aval, comportant les moyens de blocage en translation de la chaîne d'ancrage.

Fairleads of this type, for example described in the documents U.S. 5,845,893 and WO-2013/088082 , have two structures:

1. (i) an upstream structure for joining the fairlead with the floating installation, carrying the return means for guiding a change of direction of the anchor chain between the upstream section and the downstream section, and
2. (ii) a downstream structure, comprising the locking means in translation of the anchor chain.

The downstream structure is assembled with the upstream structure by means of pivot connection means defining a horizontal axis of rotation.

This downstream structure is thus able to pivot about this horizontal axis of rotation, in an admissible angular sector, so as to adapt to the inclination of the downstream section of the anchor chain.

But, in practice, in the fairleads as described in these documents U.S. 5,845,893 and WO-2013/088082 , the intermediate section of the anchor chain is likely to undergo undesirable tensions depending on the angular position of the downstream structure.

Indeed, this intermediate section may be subject to inappropriate bending for certain inclinations of the downstream structure relative to the return means carried by the upstream structure.

1. (i) un support d'attache amont, solidaire du corps flottant que l'on souhaite ancrer,
   et
2. (ii) un élément arqué aval comportant des moyens de blocage de la chaine, en forme de cliquet, et des moyens de renvoi pour guider un changement de direction de la chaine.

We know, on the other hand, of the document FR-2 601 322 a fairlead for guiding an anchor chain comprising two structures:

1. (i) an upstream attachment support, integral with the floating body that is to be anchored,
   and
2. (ii) a downstream arcuate element comprising ratchet-shaped chain locking means and return means for guiding a change of direction of the chain.

The upstream attachment support and the downstream arcuate element are assembled by pivot connection means which define a horizontal axis of rotation.

However, these pivot connection means are deported under the line of passage of the chain to not hinder its movement; which makes the structure cumbersome and harms its strength.

OBJECT OF THE INVENTION

The present invention aims to overcome this drawback, by proposing a fairlead structure very compact and resistant, and which also reduces (or eliminate) voltage phenomena on the intermediate section, regardless of the angular position of its structure downstream.

1. (i) une structure amont, pour sa solidarisation avec l'installation flottante, et
2. (ii) une structure aval, comportant des moyens pour le blocage en translation de la chaîne d'ancrage associée,

laquelle structure aval est assemblée avec ladite structure amont par l'intermédiaire de moyens de liaison pivot définissant un axe de rotation horizontal,
et lequel chaumard comporte des moyens de renvoi, pour guider un changement de direction de la chaîne d'ancrage entre un tronçon amont et un tronçon aval, lesdits moyens de renvoi équipant ladite structure aval ;
en outre ladite structure aval comprend deux plaques latérales délimitant le passage de la chaîne d'ancrage et entre lesquelles sont ménagés les moyens de blocage et les moyens de renvoi ;
et conformément à l'invention, l'extrémité amont de chacune desdites plaques latérales comprend un palier en U recevant un bras complémentaire de ladite structure amont et coopérant ensemble par le biais d'un tourillon, pour former les moyens de liaison pivot, chaque palier comprenant deux branches en regard et à distance l'une de l'autre, lesdits moyens de renvoi s'étendant au moins entre les branches intérieures en regard des deux paliers.For this, this fairlead is of the type comprising:

1. (i) an upstream structure, for its attachment to the floating installation, and
2. (ii) a downstream structure, comprising means for locking in translation of the associated anchor chain,

which downstream structure is assembled with said upstream structure by means of pivot connection means defining a horizontal axis of rotation,
and which fairlead comprises return means for guiding a change of direction of the anchor chain between an upstream section and a downstream section, said return means equipping said downstream structure;
furthermore, said downstream structure comprises two lateral plates delimiting the passage of the anchor chain and between which the blocking means and the return means are formed;
and according to the invention, the upstream end of each of said side plates comprises a U-bearing receiving an arm complementary to said upstream structure and cooperating together via a trunnion, to form the pivot connection means, each bearing comprising two branches opposite and at a distance from each other, said return means extending at least between the inner branches opposite the two bearings.

In practice, such a fairlead is of a small footprint and is very resistant; it also allows a return of the anchor chain, without subjecting inappropriate bending to its intermediate section, regardless of the inclination of its downstream structure with respect to its upstream structure.

• les moyens de renvoi comprennent une surface inférieure destinée à constituer une surface de glissement pour un tronçon de la chaine d'ancrage s'étendant entre les tronçons amont et aval ; dans ce cas, la surface inférieure des moyens de renvoi comporte de préférence (i) une partie amont, dont la section longitudinale est courbe convexe, et (ii) un partie aval, dont la section longitudinale est rectiligne ; encore de préférence, la partie amont des moyens de renvoi s'étend de part et d'autre d'un plan radial qui, d'une part, passe par l'axe de rotation horizontal et, d'autre part, s'étend perpendiculairement à un axe longitudinal de la structure aval ;
• la surface inférieure comprend (i) une gorge longitudinale, destinée à recevoir des maillons de chaîne d'ancrage dont le plan général s'étend perpendiculairement à l'axe de rotation horizontal du chaumard, et (ii) deux bandes latérales, s'étendant de part et d'autre de ladite gorge longitudinale, pour servir de surface d'appui aux maillons de chaîne d'ancrage dont le plan général s'étend parallèlement audit axe de rotation horizontal ;
• l'extrémité amont des moyens de renvoi est évasée ;
• les moyens de blocage en translation comprennent une mâchoire composée de deux mors articulés autour d'axes de rotation parallèles entre eux, lesquels mors sont associés à des moyens pour leur manoeuvre en rotation en sens inverse entre lesdites positions active et inactive ; dans ce cas, de préférence, les moyens de manoeuvre comportent (i) une masse inerte, dite « contrepoids », qui est accouplée en mouvement avec lesdits mors et qui est manoeuvrable en hauteur entre une position basse et une position haute correspondant, respectivement, à la position active et à la position inactive des mors, de sorte à manoeuvrer et à tendre à maintenir lesdits mors dans ladite position active, et (ii) un moyen actionneur, piloté par des moyens de commande, pour la manoeuvre desdits mors depuis ladite position active jusqu'à ladite position inactive et pour la manoeuvre dudit contrepoids depuis ladite position basse jusqu'à ladite position haute.

According to other advantageous characteristics, which can be taken in combination or independently:

• the return means comprise a lower surface intended to constitute a sliding surface for a section of the anchor chain extending between the upstream and downstream sections; in this case, the lower surface of the return means preferably comprises (i) an upstream portion, the longitudinal section of which is convexly curved, and (ii) a downstream portion, the longitudinal section of which is rectilinear; more preferably, the upstream portion of the return means extends on either side of a radial plane which, on the one hand, passes through the horizontal axis of rotation and, on the other hand, extends perpendicular to a longitudinal axis of the downstream structure;
• the lower surface comprises (i) a longitudinal groove, intended to receive anchor chain links whose general plane extends perpendicular to the horizontal axis of rotation of the fairlead, and (ii) two lateral bands, extending on either side of said longitudinal groove, to serve as a bearing surface for the anchor chain links whose general plane extends parallel to said horizontal axis of rotation;
• the upstream end of the return means is flared;
• the locking means in translation comprise a jaw composed of two jaws articulated around axes of rotation parallel to each other, which jaws are associated with means for their operation in rotation in opposite directions between said active and inactive positions; in this case, preferably, the operating means comprise (i) an inert mass, called "counterweight", which is coupled in movement with said jaws and which is operable in height between a low position and a corresponding high position, respectively, at the active position and the inactive position of the jaws, so as to maneuver and tend to maintain said jaws in said active position, and (ii) an actuator means, controlled by control means, for the operation of said jaws from said active position up to said inactive position and for the operation of said counterweight from said low position to said high position.

• au moins un chaumard tel que décrit ci-dessus, et
• une chaîne d'ancrage apte à coopérer avec ledit chaumard,

la partie amont courbe de la surface inférieure des moyens de renvoi définissant un arc de cercle dont le diamètre correspond de 7 à 20 fois le diamètre du fil des maillons constituant ladite chaîne d'ancrage, de préférence de l'ordre de 15 à 18 fois.The present invention further relates to an anchoring system on the ground of a floating installation comprising:

• at least one fairlead as described above, and
• an anchor chain adapted to cooperate with said fairlead,

the curved upstream portion of the lower surface of the return means defining an arc whose diameter corresponds to 7 to 20 times the wire diameter of the links constituting said anchor chain, preferably of the order of 15 to 18 times .

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

• la figure 1 représente partiellement une plateforme flottante, équipée d'un système d'ancrage conforme à l'invention vu en légère perspective ;
• la figure 2 est une vue agrandie de la partie supérieure du système d'ancrage de la figure 1, selon une perspective permettant l'observation des chaînes d'ancrage juxtaposées ;
• la figure 3 montre, en perspective et de manière agrandie, l'un des chaumards équipant le système d'ancrage selon la figure 1 ;
• la figure 4 est une vue en coupe du chaumard de la figure 3, selon un plan de coupe longitudinal vertical ;
• la figure 5 est une vue en coupe de la structure aval du chaumard, selon un plan de coupe transversal passant par les moyens de renvoi ;
• la figure 6 représente en perspective, et de manière isolée, la structure aval du chaumard illustré sur les figures 3 à 5 ;
• la figure 7 montre cette même structure aval du chaumard, de manière isolée et du côté de son extrémité destinée à coopérer avec la structure amont ;
• les figures 8 et 9 sont des vues partielles de la structure aval du chaumard, selon un plan de coupe longitudinal, qui représentent les mors de la mâchoire respectivement en position active et en position inactive.

The invention will be further illustrated, without being limited in any way, by the following description of a particular embodiment shown in the accompanying drawings in which:

• the figure 1 partially represents a floating platform, equipped with an anchoring system according to the invention seen in slight perspective;
• the figure 2 is an enlarged view of the upper part of the anchoring system of the figure 1 , from a perspective allowing the observation of juxtaposed anchor chains;
• the figure 3 shows, in perspective and in an enlarged manner, one of the fairleads equipping the anchoring system according to the figure 1 ;
• the figure 4 is a sectional view of the fairlead of the figure 3 , according to a vertical longitudinal section plane;
• the figure 5 is a sectional view of the downstream structure of the fairlead, according to a transverse sectional plane passing through the return means;
• the figure 6 represents in perspective, and in isolation, the downstream structure of the fairlead shown on the Figures 3 to 5 ;
• the figure 7 shows the same structure downstream of the fairlead, isolated and the side of its end intended to cooperate with the upstream structure;
• the Figures 8 and 9 are partial views of the downstream structure of the fairlead, in a longitudinal sectional plane, which represent the jaws of the jaw respectively in the active position and in the inactive position.

As shown schematically on the figure 1 , fairleads 1 according to the invention are intended to be part of a system 2 for ground anchoring a floating platform P (this platform P is shown here only partially).

This platform P floats on the body of water M , above the soil S of the seabed, by defining a waterline F.

The anchoring system 2 consists of several anchoring groups G , for example each arranged at one of the corners of the platform P (on the figure 1 only one of these anchor groups G is shown).

As illustrated on the figure 2 , each anchor group G comprises a plurality of anchor chains C (here seven anchor chains C ) which are juxtaposed and arranged parallel or substantially parallel to each other.

Each anchor chain C is formed of a plurality of metal links M1 , M2 intertwined two by two (visible in particular on the figure 5 ).

These links M1 , M2 each define a general plane M1 ' , M2' respectively.

The general planes M1 ' , M2' of two successive links M1 , M2 extend perpendicularly with respect to each other.

These links M1 , M2 are made of steel; their length may be of the order of 50 to 120 cm and their width may be of the order of 30 to 80 cm. They are made from a wire whose diameter is for example between 9 and 20 cm.

The lower downstream end C1 of the anchoring chains C is fixed by any suitable means to a solid mass T placed on the ground S of the seabed, or preferably sunk into this soil S (on the figure 1 only the lower end C1 of one of the chains C is shown).

The upstream upper end C2 of the various chains C extends to a maneuvering station 3 equipping the platform P , above the waterline F , and in this case at the upper part of the platform P ( Figures 1 and 2 ).

• des moyens stoppeurs 4, aptes à assurer un blocage en translation de chacune des chaînes C, et
• des moyens tensionneurs 5, comprenant ici un treuil tensionneur unique monté mobile en translation au-dessus des moyens stoppeurs 4 pour la mise en tension de chacune des chaînes C constitutives du groupe d'ancrage G.

Within this maneuver station 3 (represented in particular on the figure 2 ), we find in particular:

• stopper means 4, able to ensure a locking in translation of each of the chains C , and
• tensioning means 5, here comprising a single tensioner winch mounted to move in translation over the stopper means 4 for tensioning each of the chains C constituting the anchor group G.

The stopper means 4 which cooperate with each chain C consist of jaw type mechanisms comprising two jaws articulated around horizontal axes.

These jaws are operable in opposite directions with respect to each other (for example by means of an operating wheel) between - an active position, for locking in translation of the anchor chain C associated in one direction upstream to downstream, and - an inactive position, in which they are spaced from each other so as to allow the translation of the chain C.

The tensioner winch 5 consists for example of an electric winch, able to maneuver in both directions the anchor chain C associated therewith.

This tensioning winch 5 is mounted here on a rolling chassis guided by a rail structure, which is arranged along a raceway parallel to the stopper means 4.

Alternatively and not shown, the upper end C2 of each anchor chain C is associated with its own fixed tensioner winch.

Each anchor chain C also has an intermediate section C3 extending between its lower end C1 and its upper end C2.

This intermediate section C3 cooperates with one of the fairleads 1, fixed here on the platform P and below the level of its water line F.

This fairlead 1 makes it possible to deport below the waterline F the point from which the associated anchoring chain C deviates from the platform P ( figure 1 ).

• un tronçon amont vertical C4 (ou brin amont vertical), s'étendant depuis le poste de manoeuvre 3 (plus précisément depuis les moyens stoppeurs 4 associés) et ce jusqu'au chaumard 1, et
• un tronçon aval incliné C5 (ou brin aval incliné), s'étendant selon une pente descendante depuis ce chaumard 1 jusqu'à son massif d'ancrage T au sol S.

Each fairlead 1 thus guards a change of direction of this intermediate section C3 of the anchor chain C , between:

• a vertical upstream section C4 (or upstream vertical strand), extending from the operating station 3 (more precisely from the stopper means 4 associated) and up to the fairlead 1, and
• an inclined downstream section C5 (or downstream inclined strand), extending in a downward slope from this fairlead 1 to its T ground anchor S.

As illustrated on Figures 1 and 2 , a chute section 6 participates in guiding and maintaining the vertical section C4 of each anchor chain C.

The structure and operation of the fairlead 1 according to the invention are described below in connection with the Figures 3 to 9 .

1. (a) une structure amont 10, pour la solidarisation de ce chaumard 1 avec l'installation flottante P, et
2. (b) une structure aval 11, libre en rotation autour d'un axe de rotation horizontal 12', qui comporte :
   • (b1) des moyens de renvoi 13, pour guider un changement de direction de la chaîne d'ancrage C entre son tronçon amont C4 et son tronçon aval C5, et
   • (b2) des moyens 14 pour le blocage en translation de la chaîne d'ancrage C.

As illustrated by Figures 3 and 4 , the fairlead 1 has two structures:

1. (a) an upstream structure 10, for securing this fairlead 1 with the floating installation P , and
2. (b) a downstream structure 11, free to rotate about a horizontal axis of rotation 12 ', which comprises:
   • (b1) return means 13 for guiding a change of direction of the anchoring chain C between its upstream section C4 and its downstream section C5 , and
   • (b2) means 14 for locking in translation of the anchor chain C.

Such a fairlead structure 1, and in particular the presence of the return means 13 on the downstream structure 11, makes it possible to reduce (or even eliminate) the possible voltage phenomena generated on the intermediate section C3 of the anchor chain C , regardless of the inclination of the downstream structure 11 around its axis of rotation 12 '.

In this case, the upstream structure 10 of the fairlead 1 is assembled with a support portion 15 which is detachably secured to a receiving portion 16 fixed to the floating platform P , for example by welding and / or by inserts (bolting , riveting, etc.).

The upstream structure 10 is secured to the support part 15 so as to give it a degree of freedom in rotation about an axis 17 extending vertically, or at least approximately vertically ( Figures 3 and 4 ).

For this, the support portion 15 comprises a cylindrical plain bearing (not visible in the figures) on which is fitted and guided in rotation a cylindrical rear portion 101 (forming a pin) of the upstream structure 10.

This upstream structure 10 also comprises a carrier portion 102 on which the downstream structure 11 is attached.

This carrier portion 102 here comprises two lateral arms 1021 (each in the form of a plate), which extend parallel and facing each other, each in a vertical plane.

• une extrémité arrière solidarisée avec la partie arrière cylindrique 101, et
• une extrémité avant solidarisée avec la structure aval 11, par l'intermédiaire de moyens de liaison pivot 12, de sorte à former l'axe de rotation horizontal 12'.

Each lateral arm 1021, cantilevered from the cylindrical rear portion 101, has two ends:

• a rear end secured to the cylindrical rear portion 101, and
• a front end secured to the downstream structure 11, via pivot connection means 12, so as to form the horizontal axis of rotation 12 '.

These two lateral arms 1021 have a spacing adapted to define, between them, a passage for the anchor chain C.

For its part, the downstream structure 11 comprises a support portion 111 which carries the return means 13 and the locking means 14.

The support portion 111 is constituted here by two metal side plates (designated by the same reference numeral 111) which are arranged parallel and at a distance from each other, on either side of a longitudinal axis 11 'of the downstream structure 11.

The side plates 111, arranged in vertical planes, define the passage of the anchor chain C.

• une extrémité amont 111a, montée pivotante sur l'un des bras latéraux 1021 de la structure amont 10, cela autour de l'axe de rotation horizontal 12', et
• une extrémité aval 111b portant, avec l'extrémité aval 111b de la plaque latérale 111 en regard, un organe tubulaire 112 à section carrée pour le guidage du tronçon aval C5 de la chaîne d'ancrage C.

Each side plate 111 has two ends:

• an upstream end 111, pivotally mounted on one of the lateral arms 1021 of the upstream structure 10, that around the horizontal axis of rotation 12 ', and
• a downstream end 111b bearing, with the downstream end 111b of the side plate 111 facing each other, a tubular member 112 of square cross section for guiding the downstream section C5 of the anchor chain C.

These upstream ends 111 and downstream 111 b still constitute, respectively, the upstream and downstream ends of the downstream structure 11 (respectively designated by the same reference numerals).

In this case, as represented in particular in figures 6 and 7 , The upstream end 111 of each of the side plates 111 consists of a bearing in U.

• une branche intérieure 111a1, s'étendant en regard de l'autre plaque latérale 111 de la structure aval 11, et
• une branche extérieure 111a2, s'étendant à distance de l'autre plaque latérale 111 de la structure aval 11.

Each bearing 111 has two branches opposite and at a distance from each other:

• an inner branch 111 to 1, extending facing the other side plate 111 of the downstream structure 11, and
• an outer branch 111 to 2, extending at a distance from the other side plate 111 of the downstream structure 11.

Each upstream end 111 thus receives one of the two lateral arms 1021 of the upstream structure 10, between its two branches 111a 1, 111a 2 and cooperate with each other through a pin 12 a.

The pivot connection means 12 of the downstream structure 11 thus comprise two journals 12a, arranged at a distance from one another and coaxially to define the horizontal axis of rotation 12 '.

Such a structure is particularly useful for defining the horizontal axis of rotation 12 'while preserving a passage for the anchor chain C within the downstream structure 11.

• les moyens de renvoi 13 sont ménagés entre les extrémités amont 111a en regard des plaques latérales 111, et
• les moyens de blocage 14 sont ménagés entre les extrémités aval 111b en regard des plaques latérales 111.

In this fairlead 1 according to the invention, the return means 13 and the locking means 14 are formed between the side plates 111 of the downstream structure 11:

• the return means 13 are provided between the upstream ends 111a facing the side plates 111, and
• the locking means 14 are provided between the downstream ends 111b facing the side plates 111.

The return means 13 are here formed by an elongate metal piece which is secured between the two side plates 111 of the downstream structure 11, and they extend over part of the length of this downstream structure 11.

The lower surface 131 of this elongated metal piece 13 constitutes a sliding surface for the intermediate portion C3 of the guide chain C.

• une partie amont 133 dont la section longitudinale est courbe convexe, du côté de la chaîne C, et
• un partie aval 134 dont la section longitudinale est rectiligne.

In this case, this lower surface 131 of the return means 13 comprises:

• an upstream portion 133 whose longitudinal section is convexly curved, on the side of the chain C , and
• a downstream portion 134 whose longitudinal section is rectilinear.

"Longitudinal section" in particular means a cutting plane extending parallel to the side plates 111 of the downstream structure 11 or perpendicularly to its horizontal axis of rotation 12 '.

In particular, the upstream portion 133 of the return means 13 extends opposite and at a distance from the horizontal axis of rotation 12 '.

This upstream portion 133 of the return means 13 thus extends on either side of a radial plane R which, on the one hand, passes through the horizontal axis of rotation 12 'and, on the other hand, extends perpendicularly to the longitudinal axis 11 'of the downstream structure 11 ( figure 4 ).

In this case, the deflecting means 13, and particularly the upstream arcuate portion 133, extending between the inner legs 111a 1 facing the two upstream ends 111 of the side plates 111.

This upstream portion 133 here defines a circular arc, extending over an angular sector of the order of 30 ° to 50 °.

The diameter of this upstream portion 133 advantageously corresponds to 7 to 20 times the diameter of the wire of the links constituting the anchor chain C , preferably of the order of 15 to 18 times.

This structural feature aims to impart optimum curvature to the intermediate portion C3 of the anchor chain C.

For example, for a wire of 157mm, the diameter of the upstream portion 133 is preferably 2680mm.

The downstream portion 134 extends parallel to the longitudinal axis 11 'of the downstream structure 11.

This downstream portion 134 extends over only a portion of the length of the downstream structure 11, and thus ends at a distance from the locking means 14.

• une gorge longitudinale 135, destinée à recevoir des maillons M1 de chaîne d'ancrage C dont le plan général M1' s'étend perpendiculairement à l'axe de rotation horizontal 12', et
• deux bandes latérales 136, s'étendant de part et d'autre de ladite gorge longitudinale 135, pour servir de surface d'appui aux maillons M2 de chaîne d'ancrage C dont le plan général M2' s'étend parallèlement à l'axe de rotation horizontal 12'.

As shown in detail on the figure 5 , the lower surface 131 of the return means 13 comprises, over its entire length:

• a longitudinal groove 135 intended to receive links M1 of anchor chain C whose general plane M1 ' extends perpendicularly to the horizontal axis of rotation 12', and
• two lateral strips 136, extending on either side of said longitudinal groove 135, to serve as a bearing surface for links M2 of anchor chain C whose general plane M2 ' extends parallel to the axis horizontal rotation 12 '.

The longitudinal groove 135 here consists of an inverted U-shaped horizontal cross section, which consists of a bottom wall 1351 extended by two side walls 1352 extending at a distance and facing each other. .

The two side strips 136 extend opposite each other and at right angles to the side walls 1352 of the longitudinal groove 135 and relative to the side plates 111.

• une bordure intérieure 1361 qui est raccordée à une bordure inférieure de l'une des parois latérales 1352 de la gorge longitudinale 135, et
• une bordure extérieure 1362 qui est raccordée à l'une des plaques latérales 111 de la structure aval 11.

These lateral strips 136 each comprise two borders:

• an inner edge 1361 which is connected to a lower edge of one of the side walls 1352 of the longitudinal groove 135, and
• an outer edge 1362 which is connected to one of the side plates 111 of the downstream structure 11.

As illustrated in particular on the figure 7 , the upstream end 137 of the return means 13 is flared, so as to facilitate the passage of the chain C at the level of the return means 13.

In general, the return means 13 are dimensioned according to the size of the links M1 , M2 constituting the anchor chain C.

In particular, the distance separating the two side plates 111 facing the downstream structure 11 is identical (with the clearance), or greater, to the width of the links M1 , M2 of the chain C.

The depth of the bottom wall 1351 of the return means 13 is slightly greater than half the width of the links M1 , M2 of the chain C.

The width of this bottom wall 1351 is, on the one hand, identical (with the clearance), or greater than the wire diameter of the links of the chain C , and on the other hand, less than the width of said links.

But in practice, these return means 13 are adapted to receive several dimensions of chain links, or even a useful cable during the installation of the anchor chain C.

For example, the depth of the bottom wall 1351 of the return means 13 is 200mm; the width of this bottom wall 1351 is 170mm.

The locking means 14 comprise in turn a jaw 141 (visible in particular on the Figures 8 and 9 ) associated with maneuvering means 142.

The jaw 141, located between the two side plates 111 of the downstream structure 11 (at their downstream ends 111b opposite) consists of two jaws 1411, 1411 has one lower and the other upper 1411 b.

• une extrémité aval 1412, articulée autour d'un axe de rotation 1413 (respectivement 1413a et 1413b), et
• une extrémité amont 1414, destinée à coopérer avec les maillons M1, M2 de la chaîne d'ancrage C (figure 8), en particulier avec l'extrémité aval des maillons M1 s'étendant dans un plan vertical.

These jaws 1411 each have two ends:

• a downstream end 1412, hinged about an axis of rotation 1413 (respectively 1413 and 1413 b), and
• an upstream end 1414, intended to cooperate with the links M1 , M2 of the anchor chain C ( figure 8 ), in particular with the downstream end of the links M1 extending in a vertical plane.

The axes of rotation 1413 of these two jaws 1411 extend horizontally, parallel to one another and also parallel to the horizontal axis of rotation 12 'of this downstream structure 11.

• une masse inerte 1421, dite « contrepoids », qui est mobile entre une position basse (figure 8) et une position haute (figure 9), et qui est accouplée en mouvement avec les mors 1411 pour leur mouvement dans un sens de rotation,
• un moyen actionneur 1422, pour une manoeuvre des mors 1411 dans un sens de rotation inverse, et
• des engrenages 1423, pour assurer une rotation synchrone des deux mors 1411, et dans un sens de rotation inverse l'un par rapport à l'autre.

The maneuvering means 142 comprise in turn:

• an inert mass 1421, called "counterweight", which is movable between a low position ( figure 8 ) and a high position ( figure 9 ), and which is coupled in motion with the jaws 1411 for their movement in a direction of rotation,
• an actuator means 1422 for operating the jaws 1411 in a reverse direction of rotation, and
• gears 1423, to ensure a synchronous rotation of the two jaws 1411, and in a direction of rotation opposite to each other.

The counterweight 1421 has the general shape of a Ve or U open downwards, intended in the lower position to overlap the tubular member 112 of the downstream structure 11 ( figure 8 - The horizontal link M2 downstream of the vertical link M1 in support blocks the closure of the jaws 1411 and thus the descent of the counterweight 1421 just above and without contact with the tubular member 112).

This counterweight 1421 has for example a mass of between 100 kg and 2000 kg.

This counterweight 1421 is carried by two arms 1424 ( figure 6 ) Connected with the lower jaw 1411 in the jaw 141.

Each arm 1424 comprises, on the one hand, a first end secured to a lateral end of the counterweight 1421, and on the other hand, a second end secured to the lower jaw 1411 a .

These arms 1424 are thus coupled to either side of the lower jaw 1411 has, ensuring maneuvering these arms 1424 and 1421 associated counterweight along the axis of rotation of said lower jaw 1413 in 1411 is associated.

The actuator means 1422 here consists of a linear actuator carried by the downstream structure 11, and in particular by its lower face.

The linear actuator 1422 consists in the species in a pneumatic cylinder, associated with a pneumatic supply and a pneumatic distributor (not shown) located at the operating station 3.

More specifically, the linear actuator 1422 is a simple pneumatic actuator, cooperating with a lower extension 1416 of the lower jaw 1411 in the jaw 141.

This linear actuator 1422 is here fixed without degree of freedom and it extends parallel, or at least approximately parallel, to the longitudinal axis 11 'of the downstream structure 11.

This linear actuator 1422 includes a cylinder 1422 and a movable rod 1422 b.

The rod 1422 b is deployable; its free end has the general shape of a spherical cap for cooperating with a rear face of the lower extension 1416 of the lower jaw 1411 a.

The gears 1423 here consist of two plates which are each integral in rotation with one of the jaws 211.

These plates 1423 extend in the same plane which is perpendicular to the axis of rotation 1413 of these jaws 1411.

These plates 1423 mesh with each other by means of a rack extending over an arc of a circle, thus forming a portion of wheel or pinion (visible on the figure 4 ).

The operation of this fairlead 1, as well as the operation of its jaws 1411 between the active and inactive positions, is described above in relation to the Figures 8 and 9 .

In particular, for the locking in translation of the anchor chain C , the rod 1422 b of the linear actuator 1422 is retracted into its cylinder 1422 a ( figure 8 ).

The counterweight 1421 is in the low position, ensuring the holding of the jaws 1411 in the active position due to the force exerted.

The upstream ends 1414 of these jaws 1411, brought closer to each other, then abut on one of the links of this anchor chain C (namely a link M1 extending here vertically, and parallel to plates 111); these jaws 1411 are thus converging from their downstream ends 1412 to their upstream ends 1414.

This active position is maintained thanks to 1421 counterweight in the low position, coupled to the lower jaw 1411 a.

The counterweight 1421 is here directly overlying the downstream duct 112, and thus extends just above the downstream section C5 of the anchor chain C.

This counterweight 1421 thus exerts a moment of force on the lower jaw 1411 has through its arm 1424 in a first rotational direction (here clockwise in the figures); the gear 1423 transmits a moment of force on the upper jaw 1411 b in a second direction of rotation (anti-clockwise).

The anchor chain C is thus suitably locked in translation by the locking means 14, in the upstream to downstream direction.

This anchor chain C is additionally supported on the lower surface 131 of the return means 13 of the downstream structure 11, as illustrated in FIG. figure 5 .

This arrangement of the return means 13 on the downstream structure 11 makes it possible to limit or even eliminate inappropriate bends of the intermediate section, as a function of the inclination of the downstream section 11, which would then be capable of generating undesirable tensions on the latter. .

For the operation of the anchor chain C , in particular in an upstream direction downstream, the control means are controlled so as to cause the extraction of the rod 1422 b of the linear actuator 1422, with respect to its cylinder 1422 has ( figure 9 ).

This operation then causes the movement of the end of rod 1422 b which presses on the lower extension 1416 of the lower jaw 1411 a, thereby generating the pivoting of the jaws 1411 has around its axis of rotation 1413 in the counterclockwise .

This movement is transmitted to the upper jaw 1411 b through the gear 1423, generating its pivoting in a reverse direction (clockwise on the figure 9 ).

This rotational movement in the opposite direction of the two jaws 1411 allows their operation from the active position to the inactive position.

During this maneuver, the counterweight 1421 is in turn maneuvered from its low position (near the downstream tubular section 112 - figure 8 ), up to a high position (at a distance from this same tubular section 112 - figure 9 ).

The counterweight 1421 operated in this high position allows the accumulation of a potential mechanical energy, in particular a potential energy of gravity.

It will be noted that the counterweight 1421 in the low position ( figure 8 ) and in the high position ( figure 9 ) Is offset downstream with respect to its axis of rotation 1413 (that is to say still offset downstream with respect to the axis of rotation of its associated arm 1424).

Its center of gravity always remains on the downstream side relative to the vertical plane passing through the rotation axis 1413, thereby promoting its pivoting in the clockwise direction according to the Figures 8 and 9 .

The anchor chain C can then be manipulated in translation in the fairlead 1, in both directions.

For the return of the jaws 1411 in the active position, simply remove the air pressure in the actuator 1422.

The counterweight 1421 then causes the retraction rod 1422 b in the cylinder 1422a and the pivoting of the associated jaw 1411 in the active position ( figure 8 ).

This embodiment with linear actuator 1422 has the advantage of being simple and reliable, with the use of a single actuator single effect (so with a single seal).

The presence of such a counterweight 1421 for the operation and maintenance of the jaws 1411 in the active position is also useful when tensioning the anchor chain C, or to tighten a slightly relaxed anchoring chain C.
Indeed, it is then sufficient to exert traction in the downstream direction upstream on the anchor chain C ; the jaws 1411 providing a ratchet phenomenon under the action of the associated counterweight 1421 (the jaws 1411 are spaced apart at the passage of each vertical link M1 of the chain C ).

In this embodiment, the counterweight 1421 is additionally equipped with a fastening plate 1421 has ( figure 3 ) on which a hook can be fixed so as to be able to pull upward on the counterweight 1421 and thus bring it from its low position to its high position.

1421 This platinum is particularly useful as redundant safety means, to allow the opening of the jaw 141 and release the chain C in the fairlead 1, in case of failure of the pneumatic system, for example.

The fairlead according to the invention thus provides a simple and effective solution for reducing or even eliminating the tensions during the angular variation of the downstream structure 11 about its horizontal axis of rotation 12 '.

The fairlead 1 according to the invention thus has the advantage of proposing an erased return at the intermediate section of the anchor chain, without exerting any additional tension generated by the variations of inclination of the downstream structure.

Claims (8)

1. A fairlead intended to cooperate with an anchoring chain (C), for a system for anchoring a floating installation (P) to the ground,
   wherein said fairlead (1) includes two structures (10, 11):

   (i) an upstream structure (10), for the fastening of said fairlead (1) with said floating installation (P), and

   (ii) a downstream structure (11), including means (14) for locking said anchoring chain (C) in translation,

   wherein said downstream structure (11) is assembled with said upstream structure (10) through pivot connection means (12) defining a horizontal axis of rotation (12'),
   and wherein which fairlead (1) includes guide means (13), for guiding a change of direction of the anchoring chain (C) between an upstream section (C4) and a downstream section (C5),
   wherein said guide means (13) equip said downstream structure (11),
   wherein said downstream structure (11) comprises two lateral plates (111) delimiting the passage of the anchoring chain (C) and between which are arranged the locking means (14) and the guide means (13),
   characterized in that the upstream end (111a) of each of said lateral plates (111) comprises a U-shaped bearing receiving an arm (1021) complementary of the upstream structure (10) and cooperating together through a stud (12a), to form the pivot connection means (12), each bearing (111a) comprising two opposite branches (111a1, 111a2), remote from each other, wherein said guide means (13) extend at least between the internal branches (111a1) opposite the two bearings (111a).
2. A fairlead according to claim 1, characterized in that the guide means (13) comprise a lower surface (131) intended to form a sliding surface for the intermediate section (C3) of the anchoring chain (C) extending between the upstream (C4) and downstream (C5) sections.
3. A fairlead according to claim 2, characterized in that the lower surface (131) of the guide means (13) includes:

   - an upstream part (133), whose longitudinal section is convexly curved, and

   - a downstream part (134), whose longitudinal section is rectilinear.
4. A fairlead according to claim 3, characterized in that the upstream part (133) of the guide means (13) extend on either side of a radial plane (R) that, on the one hand, passes through the horizontal axis of rotation (12'), and on the other hand, extends perpendicular to a longitudinal axis (11') of the downstream structure (11).
5. A fairlead according to any one of claims 2 to 4, characterized in that lower surface (131) comprises:

   - a longitudinal groove (135), intended to receive links (M1) of the anchoring chain (C) whose general plane (M1') extends perpendicularly to the horizontal axis of rotation (12'), and

   - two lateral bands (136), extending on either side of said longitudinal groove (135), to serve as a bearing surface for the links (M2) of the anchoring chain (C) whose general plane (M2') extends parallel to said horizontal axis of rotation (12).
6. A fairlead according to any one of claims 1 to 5, characterized in that the translation locking means (14) comprise a jaw (141) composed of two jaw members (1411) articulated about axes of rotation (1413) parallel to each other, said jaw members (1411) being associated with means (142) for the operation thereof in rotation in the reverse direction between said active and inactive positions.
7. A fairlead according to claim 6, characterized in that the operation means (142) include:

   (i) an inert mass (1421), called "counterweight", which is coupled in movement with said jaw members (1411) and which is operable in height between a lower position and an upper position corresponding to said active position and inactive position, respectively, of said jaw members (1411), so as to operate and tend to hold said jaw members (1411) in said active position, and

   (ii) an actuator means (1422), piloted by control means, for the operation of said jaw members (1411) from said active position to said inactive position and for the operation of said counterweight (1421) from said lower position to said upper position.
8. A system for anchoring a floating installation (P) to the ground, comprising:

   - at least one fairlead (1) according to claim 3, and

   - an anchoring chain (C) adapted to cooperate with said fairlead (1),

   characterized in that the curved upstream part (133) of the lower surface (131) of the guide means (13) defines an arc of a circle whose diameter corresponds to 7 to 20 times the diameter of the wire of the links (M1, M2) constituting said anchoring chain (C), preferably of the order of 15 to 18 times.

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