Plugged hot tap tee

1. A T-pipe piece ( 1 ) designed for transfer of fluids under high pressure through a main passage ( 1 a ) thereof, a branch pipe ( 1 b ) remains in standby use position, said T-pipe piece comprising:

said branch pipe ( 1 b ) having an opening being sealed by a material which is continuous with the main passage ( 1 a ) and having a seal, and when required, forming an opening and fluid flow in the branch pipe ( 1 b ) while the main passage ( 1 a ) is in production and remains under full pressure; and

the seal includes a metal diaphragm ( 2 ) which remains in contact with the fluid flowing in the main passage ( 1 a ), which metal diaphragm ( 2 ) being thinner than a wall thickness of the T-pipe piece and being, in use, supported by a solid body of a plug ( 3 ) inserted in the branch pipe.

2. The T-pipe piece as defined in claim 1 , the metal diaphragm ( 2 ) has a thickness approximately from 1/20 to ½ of the wall thickness of the T-pipe piece ( 1 ).

3. The T-pipe piece as defined in claim 1 , the metal diaphragm ( 2 ) includes a rupture nicking (B) which is activated when the plug ( 3 ) is pulled out.

4. The T-pipe piece as defined in claim 1 , the metal diaphragm ( 2 ) is connected to the plug ( 3 ) and is pulled therewith when the plug ( 3 ) is pulled out.

5. The T-pipe piece as defined in claim 1 , the plug ( 3 ) includes internal activating mechanism which can be manipulated by a tool to retain, alternatively release, the plug ( 3 ) from the branch pipe ( 1 b ).

6. The T-pipe piece as defined in claim 5 , the activating mechanism includes a conical mandrel body able to expand a locking ring.

7. A tool ( 5 ) for opening up of said branch pipe of said T-pipe piece as defined in claim 1 , opening up of the branch pipe taking place under complete control during full production pressure and fluid flow, the tool being used together with a valve assembly which is being first installed in a sealed way to the branch pipe, the tool includes a connection means in a lower end thereof for engagement with the plug.

8. A method for controlled opening of a branch pipe of a T-pipe piece which transfers fluid under pressure through a main passage thereof, where the branch pipe is sealed off in its opening by a material that is continuous with the main passage and has, until opening thereof, remained in standby position for possible future use, where an opening and fluid flow in the branch pipe is created while the main passage is under production and remains under full pressure, and a seal comprises a thin metal diaphragm which is in contact with the fluid flowing through the main passage and the diaphragm is supported by a plug inserted in the branch pipe, said method comprising the following steps:

mounting a valve assembly to the branch pipe;

installing a tool assembly onto the valve assembly, a valve being opened and a cavity of the valve pressurized such that pressure differential between the pipe and said cavity is balanced;

lowering a plug retrieving tool through the valve assembly and establishing a mechanical connection with the plug;

retrieving the plug tool together with the plug and metal diaphragm as the metal diaphragm is torn loose from the T-pipe piece, the plug tool, the plug and the diaphragm being parked within the tool assembly;

closing the valve and isolating the pipe from environments; and

disconnecting the tool assembly from the valve assembly and removing the tool assembly, said T-pipe piece now stands ready for connection of a pipeline.

9. The method as defined in claim 8 , the metal diaphragm is torn loose from the T-pipe piece along a prefabricated nick.