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- Will the riser withstand the forces and stresses involved
in pumping?
It can thus operate continuously at pressures up to 25 bars
with a good safety factor over its life while also maintaining
its design tensile load. In practice most wells operate
far below the design pressure and tensile loadings of Boreline
thus giving safety factors far in excess of the requirement.
^ back to questions
- How must Boreline be stored?
Boreline should be stored out of direct sunlight between
- 20 °C and + 40 °C to ensure maximum working life. Exposure
to humid or damp conditions is not detrimental.
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- Abrasion resistance. Will Boreline cope with sand in
the pumped water?
The materials used in Boreline are particularly resistant
to abrasion and have been shown to resist particulate matter
such as sand extremely well.
^ back to questions
- Can Boreline tolerate dragging across the ground?
Normal dragging and abrasion encountered during riser installation
causes no visible damage.
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- Temperature of Operation. What water temperatures can
be tolerated?
Water up to 53°C can be pumped safely with Boreline, which
includes most of the wells encountered in the sphere of
Boreline operation. Use of Boreline in water temperatures
above 50°C will reduce its working life. For advice refer
to your Boreline distributor.
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- Water Quality. Is Boreline restricted with respect
to Water Quality?
A pH range of 4-9 at temperatures below 30°C can be safely
tolerated for the pumped water.
At temperatures in the 30°C to 55°C the recommended pH range
is from pH.5 to pH.9.
The riser is resistant to a wide variety of chemicals, details
of which are available on request.
^ back to questions
- Failure of the Riser. How can I retrieve the pump if
the riser fails?
In the event of very severe riser misuse, Boreline is designed
to fail safe. i.e. if the riser bursts it retains its longitudinal
strength and the pump can be withdrawn attached to the riser.
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- Can I use the riser for applications other than rising
mains?
Boreline can be used for most submersible pump operations
and may also be used as a delivery hose for a wide range
of fluids. However, Boreline is designed to a higher specification
than most other delivery requirements and for more general
application you should contact your local Flexible Pipeline
distributor, or the manufacturer for advice on the most
economic systems.
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- What couplings are available?
A range of couplings is available
specifically designed for on-site attachment and to be reusable.
The stainless steel range complements the riser, both having
a wide resistance to aggressive water and the benefits of
long life and low maintenance.
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- How do the couplings work?
Double ribbed with clamps ensure no movement in any direction.
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- How strong are the couplings? Can the riser pullout?
Provided the manufacturer's instructions are followed, the
couplings are stronger than
the riser. The riser will tear or burst before the couplings
lose their grip.
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- How's the power cable attached?
Normally cables supplying submersible pumps are attached
diametrically opposite to the ridge specially provided along
the outside of the riser. The cable is attached using straps
wrapped around the cable and fastened to the riser with
corrosion resistant links.
When the pump and riser assembly are a tight fit within
the casing or in dog-leg wells. the power cable should be
protected particularly as it passes over the top of the
pump. For absolute stability the use of a spider or centralising
device is recommended.
^ back to questions
- What if the cable is heavy or I have several items
to attach?
If a safety cable/dosing tube/dip tubes, etc. are included
in any installation these may be secured to the riser in
the same way as the power cable or, if preferred, attached
to the power cable. On lowering into the borehole care must
be taken to ensure Boreline takes all the load.
^ back to questions
- Can I retain the pump's non-return valve?
It is important to assist lifting of the pump and riser
that the following changes are made:
The removal of the pump's non-return valve alows the riser
to drain, thus making removal of the pump from the well
easier. A non-return valve fitted at the wellhead will stop
the surface system draining back through the pump.
Providing you do not contravene the pump warranty, we recommend
that a 6 mm hole is drilled in the non-return valve, it
retained in the pump, or that it is removed entirely. It
further advice is required consult your distributor.
^ back to questions
- What if I forget to drill or remove the non-return
valve and the riser remains full of water?
This is not detrimental to performance but care must be
taken on lifting the riser full. On the occasions this may
be necessary the standard fittings clamps may not be sufficient.
Details of pump weight, riser size and depth should be passed
to your distributor who will advise on lifting methods.
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- How can I earth my pump with your riser?
Pump manufacturer's recommendations should be followed with
regard to the and its electrical safety. In the absence
of these, we recommend using a separate earth cable from
the pump to a suitable surface earthing point.
^ back to questions
- Does the pump torque twist the riser?
At pump start-up there is a partial rotation of the riser
in the area of the pump which ceases immediately the pump
speed increases and the riser fills to become a rigid system.
This is not detrimental to the performance of the system,
merely a consequence of the elastic nature of the riser.
This property has major benefits in the resistance of shock
loadings.
^ back to questions
- Steel risers sometimes suffer from solid deposits building
up-how does Boreline perform?
In operation the riser will be continually minutely flexing.
On stopping the pump the riser will drain and collapse to
its original lay-flat state provided the non-return valve
has been removed or drilled out. Because of these features
solid encrustation cannot gain a grip on the Boreline.
^ back to questions
- Does slime and other algae-based deposit build-up inside
Boreline?
One feature of the riser's material construction is that
it does not support algae growth.
Tests performed by the manufacturer and repeated by the
Water Research Centre (U.K.) have shown that algae will
not grow on the riser material.
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- What pressure losses can be expected with Boreline?
Pressure losses with Boreline are lower than with any other
type of riser. This Super hydraulic performance is achieved
by:
a non build-up of internal deposits. i.e. friction factors
claimed for rigid pipe are valid only prior to use. Sedimentation
in use affects the stated levels of the rigid product.
Being of flexible construction Boreline is designed to swell
under pressure. This flexibility allows increases in the
diameter, thus diminishing head loss as compared to rigid
risers.
^ back to questions
- Will Boreline and its couplings stand up to long term
use?
Extensive laboratory trials and several years practical
experience in hundreds of wells world-wide has shown that
Boreline and its couplings are
capable of long life in conditions where steel riser would
quickly fail.
The recommendations made in this literature generally assume
that the most extreme conditions will apply simultaneously
and continuously. In practice this is generally not the
case. Safety margins are therefore very high.
^ back to questions
- How can you be sure of the precise pump setting?
By careful design of the Boreline reinforcement, the extension
of the riser has been minimised by balancing the extension
effect of axial loads against the reverse effect of internal
pressure.
The precise extension of the Boreline riser can be predicted
with accuracy, but as a rule, this will not exceed 2%.
The riser swell can be up to 15% at the maximum operating
pressures which benefits hydraulic efficiency.
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- Can the Boreline withstand the surge pressure due to
sudden valve operation?
The ability of Boreline to safely expand under pressure
minimises the effect of surge pressure. This is a major
advantage over rigid risers.
^ back to questions
- Who has approved the riser?
The potable water qualities of the riser have a number of
national approvals including U.K., Germany, SA and Australia.
Boreline, has been installed in many countries and in a
wide range of operating conditions over the last few years.
It has proved to be a revolutionary solution to aggressive
water problems and when the additional installation and
handling costs of steel pipe are considered, it is a cost
effective solution in most water well applications.
^ back to questions
- Boreline - Does Chlorine affect its properties?
In situations where Chlorine is present in the water no
physical damage to the Boreline occurs. Fading can occur
in situations of higher concentrations of Chlorine. Where
dosages are high please contact your local supplier for
more information.
^ back to questions
- What guarantees do we have with Boreline?
Boreline and its accessories are covered by our normal product
warranty which is:
If within six months of ex-works delivery and provided that
the customer notifies the company immediately of any defect
arising from faulty workmanship or material will result
in free of charge replacement of the goods. Departure from
recommended operational usage and use of materials not supplied
by the company will invalidate this.
The warranty does not cover incidental costs incurred in
removal and installation of the riser.
^ back to questions
- Must I use the Boreline ancillary equipment?
A roller assembly and clamps (light and heavy duty) are
available. These are designed to handle the riser when empty,
i.e. if you have not followed instructions regarding the
non-return valve (see Q. 13) you should
not attempt to lift the riser full using this equipment,
consult your distributor for advice. Under normal circumstances
of installing and raising, the Boreline roller and clamps
are specifically designed for the purpose and properly used
will not damage the riser. While alternatives exist for
installation we recommend this equipment for maximising
the cost benefits of the product.
^ back to questions
- How much water is stored in hard rock?
The volume of water stored in fractured hard rocks near
the surface is estimated to less than 2 percent of the rock
volume. The percentage decreases with depth as fractured
become narrower and farther apart. The total amount of water
in storage in the rocks surrounding a hard rock well is
small, so that groundwater levels and the well's yield can
decline dramatically during the summers of dry years.
The volume of water stored in many alluvial soils can amount
to 10-15 percent of the volume of the alluvium. In areas
where alluvium overlying the hard rock is saturated with
water, the alluvium provides additional water storage for
nearby wells in the hard rock. The situation most often
occurs in valleys or meadows.
^ back to questions
- How much water will a well yield in hard rock?
When conditions are good, wells drilled in fractured rock
may yield good quantities of water.
Good conditions included;
- large amounts of fractures;
- good interconnection between fractures;
- wide, large clean fractures;
- a source of recharge;
- a large quantity of water in storage; and
- proper installation of the well, including removal
of granular debris that may clog the fractures.
Some wells may be dry if the above conditions are not met.
^ back to questions
- How do you know if you'll get a high-yielding well?
You don't. While exploration of the site may help to assure
a high-yield well in fractured rock you will still face
some trial and error that you seldom face when drilling
in an alluvial aquifer.
Wells that are drilled close together in alluvial aquifers
will probably have similar yields. However, wells drilled
close together in hard rock may not have similar yields.
You have to be able to drill to a very specific point in
a major fracture zone that has a lot of water in it. The
water must also be continuously recharged. If these conditions
aren't met, then you can easily have a dry hole that is
drilled right next to a producing well.
Also, keep in mind that a neighboring well can interfere
with your well. How much water passes through fractured
rock varies greatly depending on connections between fractures.
As a result, interference between neighboring wells is difficult
or impossible to advance.
^ back to questions
- What is Water Hammer?
Water hammer occurs any time you have a high flow velocity,
particularly in a long pipe run, and there is a sudden
change in velocity.
The resulting pressure wave is transmitted throughout
the system, subjecting every component to pressures close
to 10 times the normal system pressure. The pressure returns
to normal only when it is dissipated by friction loss,
pipe expansion or if something gives - a valve or section
of pipe.
For water hammer to occur, several conditions have to
be present, namely, sufficient velocity, a sufficiently
long pipe run or an abrupt change in velocity in a rigid
pipe system. Regarding flow velocity, it has been generally
agreed that water flowing less than 5 feet per second
(1,5 m/sec) will not create a water hammer.
Water hammer can be caused by an abrupt change in velocity.
This can be either a rapid acceleration, experienced at
pump start-up or valve opening, or a rapid deceleration,
which can occur when a pump is stopped or a valve closed
suddenly.
To avoid water hammer, you have to begin with a good
system design. Size the piping so that the velocity does
not exceed 5 fps. (1,5 m/s) If using a pressure tank,
ensure it is checked regularly and fixed or replaced at
the first sign of air loss.
Consider using a flow control valve to reduce the peak
flow velocity to below 5 fps. Electronic soft starts and
variable speed motors are also a good solution to water
hammer as they are used to ramp-up the pump speed slowly.
With an understanding of the factors contributing to
the problem, and access to the necessary tools, water
hammer can be controlled and even eliminated.
^ back to questions
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