Q & A

It can operate continuously at pressures up to 25 bar 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 way in excess of the requirement.

The materials used in Boreline are particularly resistant to abrasion and have been shown to resist particulate matter such as sand extremely well.

Normal dragging and abrasion encountered during riser installation causes no visible damage. Care should, though, be taken to avoid any snagging of the hose on the well head or any sharp objects in the vicinity. (Contact with the ground, or other potential contaminants must be avoided for potable water applications.)

Boreline will safely handle water up to 53°C - this includes the vast majority of likely applications. ( 23°C is the maximum for potable water applications. ) Use of Boreline in water temperatures above 50°C will reduce its working life - For advice refer to your Boreline distributor.

A pH range of 4-9 can be safely tolerated for pumped water temperatures below 30°C. At temperatures between 30°C & 55°C the recommended range is from pH5 to pH9. Boreline is resistant to a wide variety of chemicals, details of which are available on request.

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 i.e. if the riser bursts it retains its longitudinal strength and the pump can be withdrawn attached to the riser.

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.

Boreline couplings are specifically designed for on-site attachment complementing the riser with good resistance to aggressive water and the benefits of long life with low maintenance. They are available in 316 grade stainless steel for all sizes and also in High Tensile Polymer for 1", 1½" & 2" sizes ( Other materials may be available on request ).

Couplings are double ribbed with clamps to ensure there can be no movement in any direction.

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.

Normally cables supplying submersible pumps are attached diametrically opposite to the ridge specifically provided along the outside of the riser. The cable is attached using straps tied in a clove hitch as shown on page 19. 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.

If sensor cables / 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 attached to the power cable itself. On lowering into the borehole care must be taken to ensure the Boreline takes all the load.

In order to minimise its weight, the riser should be empty when lifting the pump for inspection. This has often been done by removing the pump's non-return valve or drilling it through so that the water drains back at a controlled rate. Unfortunately, the life of the pump and motor can be reduced by this as they will suffer the repeated stresses of starting against zero head every time they are used. The Break-Off Plug System has been developed to avoid this : the non-return valve is retained intact and a hollow stainless steel drainer plug is fitted across the lower Boreline coupling. When it is necessary to drain the riser, the plug can be broken off, at a weak point, with a special 'torpedo' lowered down the hose.

This is not detrimental to performance but care must be taken on lifting the riser full as the standard lifting clamps may not be sufficiently rated for the loading. Details of pump weight, riser size and depth should be passed to your distributor who will advise on lifting methods.

Pump manufacturer's recommendations should be followed with regard to the equipment and its electrical safety. If no other guidance is given, we would recommend using a separate earth cable from the pump to a suitable surface earthing point.

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 and has major benefits in the resistance of shock loadings. It is imperative that the wellhead is designed and installed so that the pump hangs centrally in the borehole in order to avoid any chance of cable damage when the pump moves.

In operation Boreline will flex continually – though imperceptibly – preventing any solid encrustation from gaining a grip on the surface.

One feature of the Boreline material 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.

Pressure losses through Boreline are lower than with any other type of riser. This Super hydraulic performance is achieved by the avoidance of internal deposit build-up. ( i.e. Friction factors claimed for rigid pipe are valid only in new systems and corrosion / sedimentation in use will soon have a detrimental effect.) Being of flexible construction Boreline is designed to swell under pressure. This flexibility allows increases in the diameter, thus further reducing head loss as compared to rigid risers.

Extensive laboratory trials and many 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.

By careful design of the Boreline reinforcement, the extension of the riser has been minimised to balance the extension effect of axial loads against the reverse effect of internal pressure. The precise extension of the Boreline riser can be predicted with reasonable accuracy and, as a rule, will not exceed 2%. The riser can swell radially up to 15% at the maximum operating pressures which benefits hydraulic efficiency.

The ability of Boreline to safely expand under pressure minimises the effect of surge pressure. This is a major advantage over rigid risers where 'water hammer' can be a serious problem.

The potable water qualities of the riser have a number of national approvals including United Kingdom, Germany, South Africa 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.

Under known conditions of application to the well water, chlorine has no detrimental effect on the mechanical performance of the riser. Use of high concentrations should be discussed with your local distributor.

The manufacturer provides a warranty of 5 years against materials and manufacturing defects thus : If within this time from ex-works despatch any defect arising from faulty workmanship or material is discovered the goods will be replaced free of charge, provided that the customer notifies the supplier immediately. 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.

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. ( Where Boreline is to be used for a potable water application, measures should be taken to keep it clean at all times or to disinfect fully before use. )