Rubber packers

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rubber packers
sondaj pakeri

rubber packers

Test

Each inflatable element is tested with water in a test bench. After assembly, the tightness of each complete

packer is also tested. A test certificate is supplied with each order.

Safety and guarantee

Our packers are guaranteed free from any defect in material and workmanship. Our guarantee is limited to the repair

or replacement of any defective product or parts thereof. This guarantee is void if the products are used in other

circumstances than those described in our technical sheets. The decision of our technical department is final.

 

1 – Differential pressure and sizes

The range  of  packers  is  available  in  9 different diameters from 28mm up to 170mm OD.

These packers are reinforced with  two spiraled  layers of steel embedded into natural rubber. One layer is spiraled clockwise  and  the  other  one  is  anticlockwise.   The  two steel layers provide the resistance to the internal and external pressure. The maximum differential pressure decreases with the expansion of the packer as per table1.

Do not  use  the  packer  at  its  maximum  expansion  and keep a reasonnable clearance between the packer and the   borehole   unless   very   high   working    pressure   is requested.

2 – Inflation fluid a – Generalities

A major consideration is the choice of inflation fluid. Most inflatable packer manufacturers recommend inflation with water  for grouting  applications  whenever  possible. Generally the only time it’s not possible is in a dry hole or where the water level is too low. In these circumstances the column  of water  in the inflation  line  is too great to allow complete deflation of the packer. Even then, use of special  deflation  valves  (usually  requiring  two  inflation lines)   makes   use  of  water   inflation   possible.   We  will describe later the functionning of these deflation valves.

Water inflation is usually preferred because water inflated packer  ,  after  establishing   an  initial  seal  ,  will  remain inflated  up to the burst pressure of the packer owing  to the  incompressibility  of  the  water.  In  contrast  ,  a  gas inflated packer can only provide a seal if the gas pressure is maintained at a level above the sum of the sealing and grouting   pressures.   Leaks,   relaxation,   soil   movement, excess grouting pressure, etc… can all lead to bypass of the  inflated  packer  without  the  operator’s  knowledge. After  some  time    and  hardening  of  the  cement  ,  the packer will become difficult or impossible to retrieve. Moreover, quick pressure pulsation of the grout pump can also generate a packer movement  in the borehole if it’s inflated at a too low pressure    causing a fast destruction of the outer cover of the  rubber as the packer is not anchored properly. See figure 1

In fact, any liquid  provide the same inflation  benefits as water  and  in  sub-zero  temperatures   other  water/anti- freeze solutions (glycol) must be used. Where possible however, water is the preferred liquid since it’s non- polluting,   readily   available   and  will   not  damage  the rubber.  (Note  :  Packers  are  made  of  natural rubber and are not compatible with  oil inflation).

The major drawback with using water for inflation  is that deflation  is  slower  than when  using  gas and it  may  be more inconvenient to operate a manual inflation pump in some   circumstances.   When  gas  inflation  is    chosen, operators will use compressed air , nitrogen or any neutral gas.

3 – Inflation control

Suitable  inflation  fluid  , inflation  control  and  monitoring system , it’s time to connect it all up and trial inflate the packer. If gas inflating, trial inflations should only be performed in a pipe of adequate thickness and with appropriate safety precautions. If inflating with a fluid, trial inflations  may be performed free in air but are probably more usefully done in a pipe .Regardless   of  the   type   of  packer   or  the   inflation method,  it  is  critically  important  to  have  an  inflation system  that  provides  sufficient  control  and monitoring functions. The assembly shown in figure 4 (or equivalent set-up)  is  considered  to  be  the  minimum   for  safe, efficient operations. The system basically requires: a pressure source, an isolating valve, a vent valve, a pressure gauge, suitable hose to connect to the packer and between the other items.

Trial inflation allows the operator to check for system performance and leaks. Specifically,  the operator should be checking inflation pressure to firm contact with the test pipe wall and packer integrity at the maximum pressure.

 

It is best to perform trial  inflations  with  the full  length  of inflation  tube  that  will  be run in  the  hole  to  reach  the maximum setting depth of the packer. This allows the operateor to time inflation and deflation, get a indication of pumping  pressures  during  different  stages  of inflation and, for a liquid inflated packer, primes both the packer and the inflation tube

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