WO1996013706A1

WO1996013706A1 - Device for installation and removal of a probe

Info

Publication number: WO1996013706A1
Application number: PCT/NO1995/000191
Authority: WO
Inventors: Kaare Halvorsen; Kjetil Wang
Original assignee: Corrocean A/S
Priority date: 1994-10-28
Filing date: 1995-10-18
Publication date: 1996-05-09
Also published as: ITMI952207A1; GB2309505A; GB2309505B; IT1275806B1; ITMI952207A0; GB9708549D0; NO303248B1; NO944130D0; NO944130L

Abstract

It is disclosed a device for installation and removal of probes in process tubes, tanks, etc. The device comprises a lower valve body (2), having a lower valve ball (5) with corresponding lower valve seats (6). Furthermore, and a lower valve handle (12) is provided for opening, respectively closing said lower valve ball (5). Said device further comprises an end section (4), provided for connexion of a retriever tool. An upper valve body (3) is located between lower valve body (2) and said end section (4), which upper valve body (3) holds an upper valve ball (7) with corresponding upper valve seats (8). Said upper valve ball (7) is arranged for opening and closing, respectively, by an upper valve handle (13).

Description

Device for installation and removal of a probe

The present invention concerns a device for installation and removal of probes in process tubes, tanks, etc., as stated in the introductory part of claim 1.

Probes, sounds and similar devices are e. g. used in oil, gas and process industry for monitoring i. a. corrosion within the system. By means of a short access fitting, a probe may be installed in the tube so that it comes in direct contact with the process medium through a hole in the process equipment. The access fitting is normally welded or flenged to the process equipment.

Installation and removal of probes should preferably be done under normal working conditions, that is without the system being shut down. This will for example for process tubes mean that the normal working pressure should be maintained, and draining off liquid/gas is not necessary.

For performing replacement of probes are previously known so called retrievers, for example hydraulic retrievers referred to in NO-patent 162832 and NO-patent 174942. The use of hydraulic and/or mechanic retrievers involves a large cost saving, as the probes can be installed, respectively removed, without altering the process. However, this known method will involve a leakage risk. Furthermore, the valve could be opened comparatively easily by accident. This can have great consequences, as the process medium may leak to the environments. It is therefore an object with present invention to provide a device of the above mention kind, which represent an increased safety compared to today's equipment. The object of the invention is achieved by a device having features as stated in the characterizing part of claim 1. Further features are stated in the dependent claims. The invention will now be described more in detail by means of an example of embodiment and with referance to the enclosed drawing, showing a device according to present invention, partly in section.

In the drawing is shown a valve unit 1 , comprising a lower valve body 2 and an upper valve body 3. Lower valve body 2 contains a lower valve ball 5 with associated lower valve seats 6. Correspondingly, the upper valve body 3 contain an upper valve ball 7 and associated upper valve seats 8. Above upper valve body 3 is located an end section 4 which is fasten by means of fasten pins 9. A not shown retriever of mechanical, hydraulic or other type is adapted to be installed to the end section 4. Between lower ball 5 and upper ball 7 is located a lower pressure equalizing valve 10. Between upper ball 7 and the not shown retriever is located an upper pressure equalizing valve 11. I order to control closure of lower, respectively upper valve ball 5, 7, a lower valve handle 12, respectively an upper valve handle 13 are provided. A person skilled in the art will understand that the handles 12, 13 can be replaced by automatical control means.

In operation, the valve unit, i. e. lover valve body 2, is attached to the not shown access fitting, after both lower valve ball 5 and upper valve ball 7 are set in open position by means of respective valve handle 12, 13. This is being done so that the valve stem in the retriever, which shall retrieve sealing plug and probe, must be screwed in the threaded section of the rear end of the plug, and thus guided in the valve in order to get contact with the sealing plug. After the retriever tool is attached to the end section 4, the removal of the probe can be made. When the operation is completed, both balls 5, 7 are closed by means of the valve handles 12, 13. Lower pressure equalizing valve 10 is used in order to balance any difference in pressure between lower and upper ball. In the same way, upper pressure equalizing valve 11 may be opened in order to balance any difference in pressure between upper valve body 7 and the retriever. According to the present invention, the bottom of upper valve body 3 constitutes an end section for lower valve body 2. In this way, substantial!) building height is saved, compared to what would be the case if two known valves were connected in series. This is of great value in this kind of operations, as the length of the retriever tool is dependent upon the length of the valve unit 1. Thus, a length reduction of the valve unit 1 will give approximately a double length reduction of the complete equipment for installation and removal of probes.

The fact that upper valve body 3 will fill the function of end section for lower valve body 2, implies a substantial reduction in the total weight of the tool.

In retriever operations, there is always a possibility that something can go wrong, and that the valve unit 1 again should be set, and thus be the only barrier against the process medium. According to the present invention, a double safety measure is achieved , which involves a substantial safety gain. In a simple ball valve, an accident could easier arise than in a device according to present invention. The statistical probability for such an accident to occur, will basically correspond to the squared probability that an accident should occur in a one ball valve.

In addition, opening of one of the ball valves will easily be spotted at inspection, whereupon the open valve can be closed. It is a very small chance that both ball valves by an accident can be opened si oultanously.

A ball valve is basically intended to be used in connection with fluids, and may leak gas. By use in gas systems, a double ball valve can involve an increased safety against leakage. A particular advantage is achieved in that the pressure from a gas leakage will be substantially reduced against the upper ball valve.

Claims

Claims:

1. Device for installation and removal of probes in process tubes, tanks, etc., comprising a lower valve body (2), having a lower valve ball (5) with corresponding lower valve seats (6) and a lower valve handle (12), said handle (12) being provided for opening, respectively closing siad lower valve ball (5), said device further comprising an end section (4), provided for connection of a retriever tool, characterized in that an upper valve body (3) is located between lower valve body (2) and said end section (4), which upper valve body (3) holds an upper valve ball (7) with corresponding upper valve seats (8), which upper valve ball (7) is arranged for opening and closing, respectively, by an upper valve handle (13).

2. Device according to claim 1 , characterized in that said upper valve body (3) is arranged to form end section for said lower valve body (2).

3. Device according to claim 1-2, characterized in that a lower pressure equalizing valve (10) is arranged between lower and upper valve ball (5, 7).

4. Device according to claim 1-3, characterized in that an upper pressure equalizing valve (1 1) is arranged by said end section (4).