35th Anniversary
ANNIVERSARY SUPPLEMENT FEATURE
MAINTENANCE-IN-PLACE makes pumps ‘beautifully reliable’
He added: “For the screw pumps we’d
Fitted with ‘Optimum rotors’, the 18.5kW Börger units pump out 40m3
70m head (7.5 BAR vertical discharge), and have a suction lift of -5.5m
For Börger, one of the biggest breakthroughs in pumping technology has been the introduction of its Maintenance-In- Place system, which drastically reduces downtime during repair
D
uring the past 35 years, Börger began making rotary lobe pumps, which are
designed with large-scale geometry and short passage to enable the medium to be pumped efficiently. Self-priming and valve-less, the even rotation of the rotor pair creates a vacuum on the priming side of the pump, which can be defined by the direction of rotation of the drive. This vacuum draws the liquid into the pump chamber. With further rotation, the pumped medium is conveyed past the pump wall into the pressure area. Up to six chamber charges are displaced with each drive rotation – depending on the rotor type. When the rotor is at a standstill, the pump seals off almost completely. Since producing its first pumps over 20 years ago, Börger recognised just how costly downtime could be during repairs and routine maintenance, leading them to develop a MIP (‘Maintenance in Place’) system. MIP allows all wear parts to be replaced very easily with basic tools. David Brown, Börger UK’s managing
director, said: “Before Maintenance-In- Place, many sites could find themselves hours or even days offline. Rebuilding old pumps or just servicing them was invariably a difficult task because they are often awkward, heavy and located in a very tricky place. For those installing pumps with MIP, those headaches and downtime have gone.” The following case study shows just how popular this innovation has been. As the first Severn Bridge approaches its
50th anniversary, the millions of drivers that cross it each year will be blissfully unaware of just how crucial the pumping operation is some 70m below the land in the tunnel that connects a vital National Grid cable from England to Wales. Valued at £80M, the 2.2 mile tunnel is protected by Börger pumps that remove one million litres per day of water ingress from underground springs. A total pump failure is estimated to cost around £1M to £1.25M - per day. Just to be clear, we’re talking here about
the first Severn Bridge (slightly further up the river than the more famous construction that hosts part of the M4). The tunnel housing the National Grid cable is a warm, damp, noisy environment where corrosion is a challenge. Following a refurbishment of the tunnel a decade ago when the pumping out of the spring water was reduced from two points to just one (at Aust on the English side of the Severn), National Grid has been working towards the best possible solution for automated control of the tunnel’s pumping system, as Substation Engineer, Steve Parker, explained: “We’ve gone from what could be described as ‘panic breakdown maintenance’ – to a controlled, managed quarterly program. “This has come on the back of switching
from two screw pumps to four rotary lobe pumps made by Börger. Although this upgrade has involved a capital cost, we’re already well on our way to getting that back by the huge amount of time and labour we save on servicing.”
/ PROCESS&CONTROL /h at
need a minimum of three personnel just to go down into the tunnel to carry out an inspection that could take at least two and half hours. To bring one of the pumps out for repair or maintenance required winches, which then became an extremely time-consuming health and safety event, lasting up to two and half days! Including the cost of two full-time fitters, we’d have to jack the screw pump apart in order to cut the main rotor in half, which overall, was a costly and sacrificial exercise that I considered no longer manageable. Removal of one of the two screw pumps also left us vulnerable with a single point of failure. We needed a much smaller, more reliable, more cost- effective and easier to maintain pump regime, which is where Börger came in.” The installation of four stainless steel Börger pumps, carried out by Almax Technologies, has reduced inspection time to just 40 minutes. For servicing, the MIP feature of the factory-tested pumps means that all four can be stripped down, oil changed, rotors checked, in a day (or less), right back to the gearbox seals. Only two pumps are in action at any one time, operating alternately on a 20 minute shift system so as to preserve their lifetime. In the event of a flood, then all four pumps would automatically leap into action. Also, removal of a Börger unit would still leave three working if needed. Soft-start inverters get the variable-drive pumps up and running so as not to shock the pipework, which is now being changed from plastic to stainless steel to reduce vibration. National Grid is also introducing a new control and monitoring system, which Parker says he held back on until the performance and maintenance of the pumps could be firmly established. Flow meters currently check on the pumps’ typical 63m3
per hour of water, but the
new smart system will help improve efficiency further because a complete history will be available, with graphics to study trends and much more – accessible via a smart phone if required. Parker concluded: “Compared to the saga of servicing our screw pumps, all we need to get at the Börger pumps are basic tools, which can be taken down into the tunnel with ease in a small holdall. The simplicity of the Maintenance-In-Place feature is a real benefit - four Eye-bolts on the front of each pump – and the pumps themselves are rock solid, despite being in such a harsh, almost oil-rig type environment. They have taken massive hammerings – but been totally resilient. Beautifully reliable.”
Börger
www.boerger.com
Enter 233 PROCESS & CONTROL | JUNE 2015 S7
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