HYDRAULIC ACTUATION SYSTEM FOR DIVERLESS BELL MOUTH

Abstract

The present invention proposes a device capable of allowing remote unlocking operation and remaining compatible with the possibility of a mechanical and manual drive. The device is a hydraulic actuator (2) with hydraulic power supply through the lines coming from the platform. It also has a handle (4) for manual driving.

The invention allows cost reduction with PLSVs (waiting for diving and standby weather) and with diving activities themselves, in addition to greater agility in pull-out operations. Further, it promotes the diminishment of the need for diving and, consequently, lower MHRE (Man-Hour of risk exposure).

Claims

1. A hydraulic actuation system for diverless bell mouth, characterized in that it comprises an unlocking mechanism set that combines 3 forms of operation: mechanical, which works in the pull-in, hydraulic with a single-acting cylinder and removable handles (3), for pull-out, and manual with switch-type handle (4) operated by a diver, also in pull-out.

2. The hydraulic actuation system for diverless bell mouth according to claim 1, characterized in that it is used in bell mouths allowing diverless pull-in and pull-out operations without the aid of a ROV.

3. The hydraulic actuation system for diverless bell mouth according to claim 1, characterized in that the bell mouth has three sizes: 32″ for umbilicals, 46″ and 48″ for flexible risers for production, service, and injection of gas or water.

4. The hydraulic actuation system for diverless bell mouth according to claim 1, characterized in that the drive mechanism comprises a single-acting hydraulic actuator (2) for each bell mouth locking pawl, interconnected through a regenerative circuit, eliminating the need for a compensation system.

5. The hydraulic actuation system for diverless bell mouth according to claim 4, characterized in that the hydraulic actuator (2) has a hydraulic power supply by lines coming from the platform, eliminating the need for a ROV.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0010] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic form and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:

[0011] FIG. 1, which illustrates the hydraulic drive system of the present invention.

[0012] FIG. 2, which illustrates the mechanical drive mode in which the bend stiffener moves the pawls and locks;

[0013] FIG. 3, which illustrates the manual driving mode with diving. The removable handles (3) are identified by arrows, in addition to a second switch-type handle (4) that allows driving from the outside (by a diver).

[0014] FIG. 4, which illustrates components of the original

[0015] DLBM locking mechanism, being represented: handle (a), clamp (b), reaction block (c), shaft (d), centralizer (e), springs (f), pawls (g), eccentric (h), pin (i), pawl holder (j).

[0016] FIG. 5, which illustrates the operation of the DLBM, representing the entry of the helmet into the DLBM and the seat on the pawl.

[0017] FIG. 6, which illustrates the original components of the DLBM (1), together with the hydraulic actuator set (2) and removable handles (3), object of this invention.

[0018] FIG. 7, which illustrates the general diagram of the hydraulic circuit, object of this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0019] There follows below a detailed description of a preferred embodiment of the present invention, by way of example and in no way limiting. Nevertheless, there will become clear to a person skilled in the art, from reading this description, possible further embodiments of the present invention, still comprised by the essential and optional features below.

[0020] The invention comprises the development of a hydraulic drive system (FIG. 1) capable of releasing, without the need for divers, the locking pawls of the bend stiffener in pull-out operations of flexible risers and umbilicals, but which also allows driving by two more modes: mechanical (FIG. 2) and manual (FIG. 3).

[0021] The proposed system will be applied in bell mouths of three sizes: 32″ (81.28 cm) for umbilicals, 46″ (116.84 cm) and 48″ (121.92 cm) for flexible risers for production, service, and gas or water injection. The drive mechanism comprises a single-acting hydraulic actuator for each bell mouth locking pawl. A hydraulic circuit interconnects the actuators of each bell mouth with the platform driving system—FPSO (HPU-hydraulic power unit), by means of an arrangement of tubings (located on the upper and lower riser balconies) and an umbilical installed on the side of the platform. The number of actuators for each bell mouth depends on its diameter.

[0022] In the original locking (pull-in) mechanism of the Diverless Bell Mouth (DLBM), illustrated in FIG. 4, the pawl is the component on which the helmet of the bend stiffener (bend stiffener) is seated, and is responsible for transferring incoming loads to the DLBM body. The other internal components, such as springs, shaft, centralizer, form a set with the pawl, which allows the axial displacement when mechanically driven and the automatic return when the external driving force ceases. A reaction block is connected to the handle by means of an eccentric mechanism, allowing the manual retraction of the pawl by a diver's action. It also serves to anchor the end of the springs, and further as a guide for the rods. In the operation of the DLBM, represented in FIG. 5, the movement of the helmet retracts the locking pawl by means of a mechanical contact.

[0023] The DLBM operating mode with hydraulic actuation, object of this invention, is designed with the main objective of allowing the unlocking of the pawls that support the bend stiffener, during the pull-out operation. A single-acting spring-return hydraulic actuator is incorporated into the block that contains the original DLBM locking mechanism. FIG. 6 shows the original components of the DLBM (1), together with the hydraulic actuator (2), wherein the external view is shown on the left, and the internal components of both are shown on the right.

[0024] The adopted configuration uses a regenerative circuit, in which the hydraulic fluid inlet and outlet are connected in the same line, so that the piston moves by difference in areas between smaller and larger diameter rods. This configuration allows the use of a single hydraulic line for driving, without the need for a compensation system and without the entry of seawater into the cylinder.

[0025] It should be highlighted that the incorporation of the hydraulic cylinder does not interfere with the original operating mode of the DLBM for the pull-in operation. The same independence of drives occurs when the retraction of the pawls is performed by the diver, by using the handle for a manual drive.

[0026] In order to allow the path of the hydraulic circuit to the topside of the platform, as illustrated in FIG. 7, there has been used a branch of EHU (electro-hydraulic umbilical) was used, qualified for more aggressive scenarios in terms of fatigue (catenaries). In this way, it was designed that each EHU will be able to provide up to 4 drive rings to the DLBM.

[0027] At the ends of the umbilicals, terminations structures are installed, to ease the connections with path tubings connected to the upper and lower ends of the umbilical, in addition to protect the thermoplastic hoses from weather and ultraviolet rays.

[0028] On the topside of the platform, the circuit is interconnected in an individual drive panel, which in turn is powered by the platform's HPU, allowing the remote driving of each bell mouth individually. It is worth to highlight that said panel will be provided with mechanisms to avoid the spurious driving of the DLBM-SI (Standard Interface).