FR2461181A1 - Ball float with adjustable buoyancy - guides undersea pipe line launched from ship to depth dependent on proportions of contained water and air - Google Patents

Abstract

The spherical float (1) is used in the launching of a submarine pipeline (23) from a ship, being adjustable for buoyancy, and supporting pipe guides (6-8) on chains (4,5). Buoyancy is adjusted by varying the proportions of air and water in the float, a compressed air line being connected to a top aperture (2), and sea water ingress or egress being controlled through a bottom aperture (3). Rollers (7,8) or skid cradles may be used to guide the pipe, and are arranged to fit the particular pipe barrel. Floats with rollers may be connected by chains to form a train which extends from a launching ramp, the chain following a curved longitudinal profile to be weighted down on the sea bed.

Description

The object of the invention relates to a rolling float device for underwater pipelines.

 It is intended for laying industrial and other piping on all the seabed with support during 1 immersion of a correct elastic line.

 In the devices known to date, the laying of the underwater pipes was obtained either by pulling down, or by towing, tension abutment, or finally by the method of the S curve comprising fixed lighteners.

All these means use either lightening floats, which must be successively fixed and released, or devices
traction ges accessoiqsNwhose implementation requires significant manpower and time.

 The device according to the invention avoids these drawbacks and makes it possible to eliminate the tensile forces on the pipe as well as the fixing and the largaget of the lightening floats; so that the balanced immersion of the pipe is done in a way automatically and effortlessly.

 It is constituted by a floating capacity open at its upper part for the admission of compressed air and at its lower part for the evacuation or the admission of ballast fluid, it being specified that each float supports a movable frame in which slides the pipe to be submerged and, is connected to the previous one by a chain towed by the mooring boat.

In the appended drawings given by way of nonlimiting example of one of the embodiments of the subject of the invention:
Figure 1 shows seen in section and in elevation the rolling or sliding float.

 Figures 2 and 3 show the application of the device on different scales.

 The float is made up fig 1, by a lightener c 1, connected to its upper axial part by a nozzle 2 to a compressed air duct.

 Its axial lower part is provided with a free orifice 3 connecting the capacity 1 with the liquid element.

 The base of the float sphere supports by fasteners 4, 5, a rolling chassis 6. This rigid nacelle is provided with oriented rollers, mounted free 6, 7 which support the cable 8 which can slide freely.

 These floats are positioned at a distance determined by a connecting chain 9 fig 2, connected to the wetting boat 10 via the ramp It provided with sliding rollers 12, 13, 14.

 These rolling chassis 15, 16, 17 are maintained at a determined progressive immersion by adjusting the buoyancy of the capacities 18, 19, 20 and the like.

These capacities are ballasted by sending compressed air which more or less drives out the mass of compensating water.

 St> bilisation- of all the floats in their functional position is obtained by the arrangement of a trailing dead body 21, which follows the relief 22.

 The invention is characterized first of all by the design of the ballast lightening floats and then by the fact that these floats secured to the rolling chassis are connected together by cables, which allows a constant distribution of the support points.

 This device avoids the continuous handling of floats during advancement.

 The correct elastic line, represented by the curvature 3 of the cable fig 2, 3, is obtained by the good distribution of the lightening floats whose hydrostatic thrust can be remotely controlled by injection or air evacuation.

 However, the shapes, dimensions: and arrangements of the various elements may vary within the limit of the equivalents, as moreover the materials used for their manufacture without changing the general conception of the invention which has just been described.

Claims (3)

CLAIMS 1. Rolling float device for laying underwater pipes eliminating the traction forces on the pipe and laying, as well as the release of traditional lightening floats characterized by a sealed spherical capacity provided at its upper part with 'a connecting piece with a compressed air duct and at its lower part of a free orifice making it communicate with the surrounding fluid.  2 Device according to claim 1 characterized in that the lower part of the capacity is connected flexible or to a flexible links a chassis bearing oriented rollers, whose contact angle corresponds to the diameter of the pipe to immerse , or to a sliding cradle. 30 Device according to Claim 1, characterized in that the lightening floats with lower rolling chassis are interconnected by a spacing chain and connected with the wetting boat by the immersion ramp provided with bearing bearing members. 40 Device according to Claim 1, characterized in that the end of the chain is connected to a trailing dead body.