Device for installation of a probe and probe accommodating arrangement

The present invention relates to a device for mounting and dismounting of a probe in process pipelines, tanks etc., as stated in the introductory part of claim 1. It also comprises a probe accommodating arrangement.

Background

Several suggestions exist for mounting and dismounting probes in process pipelines, tanks etc. Such probes are used for measuring corrosion, pressure, temperature etc, inside a system, such as in oil, gas and process industries. With a nipple, a probe can be mounted through a hole in the equipment into a tube to contact the medium of the process.

The mounting and demounting of probes is preferably conducted at normal operating conditions, which means that the system is not shut down when probes are to be changed or inspected. In connection with process a pipeline, this means that the normal operating pressure is maintained, and that draining of fluid/gas will not be necessary. This means a substantial reduction of the maintenance costs.

The disadvantage of prior art hydraulic and/or mechanical retrievers is the risk of leakage upon the mounting and demounting of the probes. This may be detrimental to the environment.

In the offshore oil industry, process pipelines and transport pipeliness are placed on the sea bottom. The condition for such pipeline needs surveillance and probes have to be mounted and demounted for maintenance and upgrading. For various reasons it is desirable to use remote operated vehicles (ROVs) to conduct this operation. The depth of the sea bottom may make the use of divers dangerous and even impossible, and it is more economical to use a ROV. The security of such work has to be high, as a leakage can have large economic and environmental consequences.

Prior art technology is largely based on mechanically operations, such as use of threaded connections between a retriever and the probe and between an access tube and the retriever, and use of mechanically operated handles for opening and closing valves.

Such mechanical operation can be difficult to accomplish by a ROV.

Efforts have been made to reduce the number of operations and to replace some of the threaded connections with more simple mechanisms. US patent specification

3,589,388 (Haneline 1971) shows a pressure operated retriever to withdraw an injector nozzle from a high pressure environment. This structure comprises a ball valve which in its open condition has an opening for introducing the injector nozzle. Further it comprises a partly hollow or tubular connection device with two or three grooves for defining a plurality

of fingers. A radially protruding tongue is arranged on each finger to be accommodated in an opening behind an injector needle. The fingers are resilient to enable connection to the opening. The probe can be pulled out by the retriever due to this connection,

A disadvantage of this retriever system is the need for a screw connection radially to the access tube to fasten the injector needle. The connector device can only be pulled out of the opening without the injector needle when the screw is tightened.

US patent specification 4,275,592 (Atwood et al 1981) shows a retriever utilizing fingers with lips to pull a probe. A number of threaded connections are shown. This retriever will not be suitable for exchanging probes in sub sea pipelines. US patent specification 4,002,059 (Jeffers et al 1977) shows a retriever for mounting and demounting of probes with corrosion coupons in process pipelines. During operation, the probe is locked in grooves in the access tube by spring-loaded locking means on the probe. The retriever can be lowered over the probe by a wire comprising a grappling means and a rod like body. As the retriever is lowered over the probe, the rodlike body is lowered through an opening in the upper part of the probe to release the spring- loaded locking means. The grappling means comprises arms catching a circular groove at the top of the probe, before the probe can be lifted from the access tube.

The disadvantage of this retriever is the need for two different tools for mounting and for demounting the probe. Additionally, a weight and wire are used for lowering and pulling the probe. Neither of these arrangements will be suitable for ROV operation.

From Norwegian patent specification 317390 (CorrOcean 2004) a device for mounting a probe in a process pipeline or a process tank is known, which device is not provided for remote operation by a ROV.

From PCT application NO06/00163 (CorrOcean 2006) a device for mounting and demounting of a probe is known, which is arranged in an access tube to a process pipeline and/or a tank. This device requires a valve housing with a ball valve with opening for handling of the probe at mounting and demounting.

Object The main object of the invention is to provide a device for mounting and demounting of probes, which is suitable for use with a ROV. The device should be able to remove and/or install a probe without stopping the operation. The device should comprise means for operating locking means for locking the probe to the access tube in a safe and simple way. A secure sealing between the probe and the access tube is also important. Further it is an object to provide a probe accommodating arrangement.

The invention

The invention is stated in claim 1. Claim 7 describes a probe mounting arrangement suitable for use with such a device, to connect a probe to a structure to be monitored and disconnecting this arrangement.

Particularly favorable embodiments are described in the claims 2 - 6 and 8 - 10. In the following, the invention is further described with reference to two embodiments.

Example The following examples of embodiments of the invention are described with reference to the enclosed drawings, in which

Figure 1 shows an axial section through an embodiment of a device according to the invention, showing an arrangement for changing probes in a retriever device,

Figure 2 shows a cross section through a revolving turret arrangement corresponding to Figure 1 , with a probe in the lower bore,

Figure 3 shows a plan view of a connector assembly according to the invention, Figure 4 shows an axial cross section of the sensor mounted on a guiding tube, with handle for ROV-operation, together with an axial cross section of the guiding funnel arranged on a fundament which is integrated with a structure to be monitored, Figure 5 shows an enlarged part of Figure 4, including the probe mounting, and

Figure 6 shows an axial cross section through a further embodiment of the invention.

Figure 1 shows five main parts: - a turret arrangement 11 with

- a probe or sensor 12

- a valve 13 for revolving the turret arrangement 11

- a retrieving cylinder 14 with

- a retrieving head 15.

The turret arrangement 11 comprises a cylindrical housing 16 with a turret unit 17 inside. The cylindrical housing 16 is closed by an inner head 18 and an outer head 19, each having a central bore 20, 21 for a shaft stub 22, 23 of the turret unit 17. The housing heads 18 and 19 have axially aligned circular openings 24, 25 for passing a probe 12 through the turret unit 17. The openings 24, 25 are further axially aligned with a tubular bushing 26 provided for releasable mounting on a structure to be monitored. An example of an

embodiment of such a structure will be described in connection with Figures 3 - 5 showing a connector assembly to be operated by a ROV.

The turret unit 17 has two symmetrically arranged bores 27, 28 for accommodating a probe 12. The bores 27, 28 can be axially aligned with the openings 24, 25 in the housing heads 18, 19 by revolving the turret unit 17. The outer part 29 of each bore 27, 28 is enlarged with a larger diameter to accommodate a gripping device described below.

The rotation of the turret unit 17 is operated by an hydraulic motor provided by a protruding foil 30 acting as a piston in a housing 31 enclosing 180° of the circumference of the turret unit. At each end of this arched housing 31 , a combined inlet and outlet 32, 33 is arranged with connection to the revolving valve 13.

The probe or sensor 12 is designed according to prior art, with an operating probe element 34 carried by a generally cylindrical body 35 with sealing rings 36 and with a protruding shaft 37 arranged for engagement by a mating gripping head 38 connected to the retrieving cylinder 14 as described below.

The valve 13 comprises an hydraulic valve element 39 arranged in a tubular housing 40, with a remotely controlled activator 41. The valve 13 is connected to a supply line 42 for hydraulic fluid.

The activator 41 is connected to a handle 43 for being handled by a ROV.

The retrieving cylinder 14 has an outer tubular housing 44 with an outer head 45 and a piston 46 carrying a tubular piston rod 47. The piston rod 47 carries the retrieving head 15 at the end facing the turret arrangement 11 , the retrieving head being designed according to prior art to catch and move the protruding shaft 37 of a probe 12.

The tubular housing 44 is provided with inlets 49, 50 for hydraulic fluid.

In Figure 3 - 5 an embodiment of a probe connector assembly is shown. The assembly is based on a fundament 51 integrated with the structure to be monitored, e.g. a process pipeline. Access to the inside of the structure is through a bore 52.

A probe 53 is arranged in the bore 52, with sealing rings and an annular series of locking dogs 54 arranged for release with a locking bushing 55 which is slidable on the probe 53. The structure and operation of said dogs may be according to prior art.

The fundament 51 carries a tubular funnel 56 with an upper diverging collar 57 for guiding the connector assembly to be engaged into the funnel 56. An axial slot 58 extends from a V-notch 59 in the diverging collar 57, down to the lower third of the funnel 56. Below the end of the axial slot 58 an inner groove 60 provides a recess for a sealing ring to be described below.

The connector assembly of this embodiment comprises a central housing 61 for hardware included in the connection circuit, with a lower female connector element 62 for connection with the corresponding male connector element 63 at the end of the probe 53.

The outer end of the central housing 61 , is extended by a handle 64 for ROV operation.

The central housing 61 carries a coaxial guiding tube 65 mating with the inner side of the guiding funnel 56, these parts being connected with an axial arm 66. The axial arm 66 has an extension with a protruding tab 67 mating with the slot 58 to be guided by this. The arm 66 is also connected to a ROV-handle 68.

At the lower end of the guiding tube 65, a sealing ring 69 is arranged in a corresponding groove. In the mounted position of the connector assembly, the sealing ring 69 will mate with the groove 60 in the guiding funnel 56.

A first passage 70 is arranged to extend from the inner part of the bore 52 to the outside of the fundament 51 for monitoring the pressure of the pipeline. A second passage 71 is arranged from the part of the bore 52 between the inner and the next sealing ring, for connection to a monitoring system, which is provided to detect leakages in the sealing system.

The probe installation arrangement of Figures 3 - 5 is particularly advantageous in connection with a device according to claim 1. This arrangement can, however, also be adapted for use with other systems for exchange of probes.

Figure 6 shows an embodiment with a turret arrangement 72 with a probe or sensor 73, a retrieving cylinder 74 with a retrieving head 75. The elements 72 - 75 are similar to the corresponding elements of the previous embodiment. To a cylindrical socket 76 corresponding to the bushing 26 of Figure 1 , an annular series of catching elements or "locking dogs" 77 are arranged in an array. The locking dogs 77 are activated or released by a longitudinally slidable, tubular activator 78 with a chamfered activating surface 79 at the front end, for cooperation with a corresponding bevelled outer surface 80 of the locking dogs 77, and with an annular piston 81 to be powered by hydraulic pressure from a valve not shown.

The annular assembly of locking dogs 76 is catching a holding ring 82 cooperating with the probe connector assembly shown in Figure 5.

To manoeuvre this device, a handle 83 for a ROV is provided at the turret arrangement 72. At the front end of the turret arrangement 72, a connector 84 is protruding to engage with a mating socket 85.