Faced with an obsolete pump, AxFlow’s answer was to rebuild it
4 Oct 2017
When a Scotland-based manufacturer of electrical conductors was faced with a failing, obsolete pump, one company was on hand to repair and rebuild the original one.
Hydrostatic Extrusions in Perth manufactures the copper-clad aluminium (CCA) electrical conductor, the Cuponal, used in the production of busbars for power transmission systems.
Traditionally busbars have been made of copper – highly conductive but neither light nor cheap.
The Cuponal, comprising a solid core of electrical grade aluminium with a pressure bonded seamless outer layer of high-conductivity copper, is manufactured by hydrostatically extruding copper and aluminium billets from which the busbars are manufactured.
This offers 60% lower weight, 40% cost reduction and 60% lowersurface resistance.
The hydrostatic extrusion process uses oil at high pressure around the billet to effect the extrusion, which eliminates any friction between the billet and press container.
At the company site, oil was delivered by two high-pressure reciprocating Holden & Brooke T50 Trimax pumps applying 1500 psi pressure to the main ram using castor oil as the hydrostatic medium.
Situation critical
Their performance was critical to the entire process, but last year the No 1 suffered a catastrophic failure due to being over pressurised. The second pump enabled production to continue, but having two functioning pumps was essential for system resilience.
Unfortunately, the Holden & Brooke Trimax pump was obsolete. Hydrostatic Extrusions MD Stuart Elliott dispatched his team to seek alternatives, but the company concluded it was too difficult and costly to purchase a pump that delivered a low flow and high pressure that matched the performance of the original.
The other option was to look at the feasibility and costs of getting the pump repaired and this led to AxFlow’s Huddersfield Service Base being called in for advice.
Tom Cooper, manager of the service base, recalls: “It was in a very poor state of repair and needed some serious work if it was to re-enter service and perform to the customer’s requirements.
We estimated that the pump could be rebuilt to the original operating specification, pressure tested before spray painting, and dispatched for refitting and commissioning in eight weeks
Tom Cooper, manager of AxFlow’s Huddersfield Service Base
“However, we considered that extensive repair work, which included making completely new components, could be performed.
“We prepared a full report, supported by extensive photographs, the associated costs and a timeframe in which the work would be carried out, and this was accepted by the customer.”
The report identified many key failings, the most obvious being the crankshaft. This had sheared, causing excessive force on the bearing housing, which had resulted in the casting cracking. Both items had to be completely replaced.
In addition, the pinion wheel, worm shaft, conrod bearings and crankshaft bearings had to be replaced.
AxFlow’s final recommendation was to replace all the seals, packings and gaskets, as well as the tapered roller Timken bearings for the worm shaft.
“We estimated that the pump could be rebuilt to the original operating specification, pressure tested before spray painting, and dispatched for refitting and commissioning in eight weeks,” said Cooper.
“We achieved a complete repair and rebuild in the eight weeks and since commissioning the pump has run perfectly. Such has been the customer’s satisfaction that we have now taken delivery of the second pump for repair and maintenance.”
