Thursday 19 May 2011

Pulsation Dampeners For Oil and Gas Industry

Pulsation dampeners can be used for the following cases:
  • It can be used for leakages in a hydraulic system. Also it can be used for any pressure changes due to thermal expansion.
  • It can be used as an energy storage device (Accumulator) in a hydraulic system. It supplies hydraulic power for a short period of time. This property is crucial for lube oil system which has to supply lube oil to critical rotating equipment wherein slightest delay may result in a costly failure to the equipment.
  • Pulsation Dampeners installed close to the valves is used to absorb the surge which is risen from the sudden pump shut-downs when the fluid flows back slamming into the pump or check valve.
  • It can be used in absorbing the surges like water hammer results from the sudden change of kinetic energy (of the flowing fluid) to pressure energy and thus saves costly equipment failures or replacements
  • Pulsations dampeners can be used in dampening the pressure surges/pulses on the discharge side of the pump, thus prolonging the life of the pump fluid end components.
      
    Expanding gate valves are used in various industrial areas like isolation valves in power plants, ESD valves in production, block valves in process systems, high temperature valves in refineries, and pipeline valves in critical areas. These expanding gate valves manufactured by various manufacturers are available in all the sizes, pressure ranges, and trims used in piping systems requiring the positive shut off of liquid or gas.
    The expanding gate valves are full bore through conduit valves with rising stem and parallel expanding gate and segment for tight mechanical seal and positive shut-off, both upstream and downstream, and under both low and high differential pressure.
    An API 6A expanding gate valve should have the following features:
  • Parallel expanding gate design creates positive mechanical seal across both seats, both upstream and downstream, with or without line pressure.
  • Non-rising stem permits valve installation in pressure drop.
  • A double row roller thrust bearing on the stem makes operation easy, even under full pressure.
  • Upper and lower roller thrust bearings are used to minimize torque and are isolated from well-bore fluid.
    So this is all about  Pulsations dampeners and Expanding gate valves.

Monday 16 May 2011

Wellhead Equipment


Wellhead equipment are used in connecting the casing and  tubing  to an oil or gas pipeline. These are useful in suspending the casing strings and help seal the well. The casing is a permanently-installed pipe for lining the well hole to provide pressure containment and prevent collapse. The wellhead equipments are known as the flanged devices that are attached to the casing.
Wellhead equipments include a number of other components such as casing heads, casing spools, tubing head spools, tees, and crosses. The casing head is part of the connection between the casing and the wellhead equipment itself. Usually, many pieces of wellhead equipments are assembled together into one wellhead equipment that is called a "Christmas tree". These wellhead equipments are important for the tubes to be placed into the well while valves and chokes are used to control the flow of oil and/or gas at the surface. Wellheads and wellhead equipment may be located on offshore platforms, in sub-sea locations, or onshore.
A typical Wellhead Equipment -X-mas Tree Caps is shown below.



Casing Head Spool-Bottom Slip Connection characteristics:
(1) Connect surface casing by type WD slip.
(2) Adopt type BT secondary seal structure.
(3) Accurately calculate casing string's length is not necessary.
(4) Can not be affected by surrounding environment, climate, etc.
(5) Easy, rapid, safe and reliable in installation that can be applied to different sizes casing, such as: 30",20",13-3/8",12-1/4",9-5/8",7",5-1/2". It can also be applied to different sizes casing as: 13-3/8",9-5/8",7",5-1/2"etc.
A variety of bottom thread such as CSG, LCSG, BCSG, TM, for the connection between casing head and surface casing can be manufactured.

Casing Head Spool-Bottom thread connection
(1) Bottom of the casing head connects surface casing by various types of threads, such as CSG,LCSG,BCSG,TM,ETC.
(2) Convenience and rapid in installation, safe and reliable in operation.

Casing Head Spool-Bottom welded connection
(1)Bottom of the casing head connects surface casing by welding.
(2)There’s pressure test hole, which can test welding effect, in welding annular space.
Bottom can be connected to surface casing by the method of sleeve welding. Pressure testing holes are designed for the test of welding effect.
Applied Casing Program: 20", 13-3/8",9-5/8",7",5-1/2", etc.
Casing hanger is classified into two kinds,
  • The threaded (mandrel) and
  • The slipped; slip casing hanger consists of G, W, WD, WE and other types. WD hanger is applicable for connection of casing head and surface casing and keeps the slip closing the casing fast in use of outer force, W hanger adopts self-weight energized sealing structure and WE & G hanger is manual-energized sealing structure.
 
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