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 Bimbar 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 Bimbar 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 : Bimbar 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
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.
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 .
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.
The general characteristics of packers whether inflated with liquid or gas is that the bulk of the inflation volume is placed into the packer at relatively low pressure and it is only the last little bit of volume that is placed at increasingly higher pressure. Charting inflation pressure against time leads a curve showing low, steady pressure increase over an extended period followed by a rapid pressure increase (after wall contact is achieved) in a relatively very short time. This characteristic takes some time to getting used to and operators should be
? The pressure gauge cannot be accidentally isoled from the packer and so always indicates the packer pressure.
? The pressure source is independently isolated from the packer. This is of great importance with gas regulator since they can easely be set at very high pressures or not be properly shut down. In fact, the temptation is to leave the regulated gas connected to the packer at pressure which may lead to packer over-expansion and sub-sequent failure.
? The vent valve ensures that the packer can be safely deflated.
? Being small, self contained and portable (if provided with suitable hose lengths), the gauge set can be moved to the most convenient location to control and monitor the packer during inflation and grouting operations.
Clearly, all components used in the inflation control system must be adequate pressure rating. In the case of gas inflation, if operating deep in a water filled hole the surface gas pressure may easely be over 70 bar and adequate precautions are required. The pressure gauge should be chosen such that the maximum inflation pressure lies in the middle third of the gauge’s scale. Pressure gauges are delicate instruments that require careful treatment and regular calibration to ensure their reliable operation.
4 – Inflating the packer
Once the packer size has been chosen along with a
encouraged to use the trial inflations to accustom themselves to the pressure, volumes and times involved.
5 – Deploying the packer
The usual deployment methods are via a rigid pipe or a hose. The later is quicker but provides limited depth control, no packer hold-down capacity and limited support for inflation tubes. It’s also depth limited by the self-supporting capacity of the hose and it’s connection to the packer for which reason a safety wire is sometimes used along with the hose. Depth limitations may also be due to the handling capacity of the hose raising and lowering system which is frequently manual.
Using a rigid pipe for running the packers offers good depth control, good support for inflation tubes and some hold-down capacity. However it generally requires a mechanized system (drill rig or crane) to handle the rods due to their length and weigth and thus is much slower and more cumbersome.