Oilfield Consultant in Surface and Subsea Wellheads Equipment,Christmas Trees,Flow Control Equipment,Seals(Elastomerics & Metal-to-Metal)                     Contact me NEW E-mail: country45ve@yahoo.com

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  Tubing heads are the part of the wellheads that suspend the tubing string, by using a device called tubing hanger, it may come in various shapes and sizes and depends on the well's condition and tube program, as well as the most convenient way to hook-up the well.

Tubing heads has generally studded outlets and several valve attached, as well as a threaded internal 2" VR (Valve Removal ) for the convenient removal of any damaged valve. In the bottom of this element has an accessory called : Secondary Seal Pack-Off, it comes in many sizes and shapes, as well as each company's technology develops, and it's function is to isolate the casing string suspended by the casing hanger down below. Some Pack-Off models are shown ahead and left side shows a model DMC-P-OO Assembled with two inner O-rings and Back-up rings, outer O-ring and snap ring as well. Right figure is a Pack-Off model DMC-S-OO suitable for short casing cut-off and Working Pressures up to 5,000 PSI WP.

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Tubing heads uses a set, of lockdown screws (see figure ahead in blue color) , or tiedawns, or set screws, etc, etc, every company, or wellheads manufacturer has it's own way to call this elements, but the function is to keep the tubing hanger safe landed in the tubing head's bowl, and for that reason is a point of concern about the integrity of the tubing head working conditions.

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There are several arrangements of the tubing heads bowls as well as the lockdown screws, and pack-off, it depends of the working conditions, and of course PSL/PR of the element, for instance a service for high concentrations of H2S is mandatory the use of SS materials with controlled hardness, and exotics materials like Inconel, Cladding and so on.




Some TUBING HANGERS ahead, in left position a Tubing Hanger DMC-WA Wrap Around Style, in the right a Tubing Hanger DMC-EN-OO assembled with annulus and neck seals, prepared with the H-BPV profile thread for accommodate the back-pressure valve like figure below in the right position(Ref. Fig. 4)

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The Tubing Hanger at the left side is a model DMC-EN-CS it has an annular compression seal that is energized by the weight of the supported threaded string at the bottom and also it can be secured by the lockdown screws of the tubing head, also it has an H-BPV internal preparation for accommodate the H-BPV Back Pressure Valve, shown in right below position(Ref. Fig.4)

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This configuration is simple, clever, and special, it has a continuous control line attached to the tubing hanger body, and also a transition sub-seal for seal interface with the tubing bonnet above.


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Updated on:01/13/04Copyright @2003 Daniele Molaro Consulting

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