Patent Publication Number: US-2010116071-A1

Title: Device for installation of a probe and probe accommodating arrangement

Description:
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. U.S. Pat. No. 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. 
     U.S. Pat. No. 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. 
     U.S. Pat. No. 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 
       FIG. 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, 
       FIG. 2  shows a cross section through a revolving turret arrangement corresponding to  FIG. 1 , with a probe in the lower bore, 
       FIG. 3  shows a plan view of a connector assembly according to the invention, 
       FIG. 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, 
       FIG. 5  shows an enlarged part of  FIG. 4 , including the probe mounting, and 
       FIG. 6  shows an axial cross section through a further embodiment of the invention. 
    
    
       FIG. 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  FIGS. 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  FIG. 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  FIGS. 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. 
       FIG. 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  FIG. 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  FIG. 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 .