and temperatures as a result of either poor design or a pump operating a long way away from its design duty. This results in a drastically shorter bearing life, and the potential for a complete failure if not identified previously.

Whilst the improved bearing mounting further helps with bearing life, the main savings come from job specific thrust optimisation to ensure that bearings are optimally loaded at rated duty conditions. Many suppliers will fit the closest matched throttle and centre sleeve to obtain a close to balanced pump.

requested that ClydeUnion Pumps repair the spare pump in a very short time span, and re- install it on the process as soon as possible.

The project proved to be a challenge, as DEA processes are extremely aggressive towards steel materials – only a few metallurgies are able to resist (more or less) corrosion induced through DEA pumping. The pump was sent back to the factory without the rotor, as all the rotor parts displayed too much damage for repair. The pump casing showed high erosion/corrosion marks, leading to loss of material, particularly on the grooves for casing wear rings and volute tongues.

The solution was to carry out weld repair on all the damaged parts of the pump casing, and supply a new rotor. The difficulties were the accessibility of certain parts and the perfect control of intensity and temperature during the welding. A non-controlled welding can lead to a change in metal properties, and stress and strain on the casing.

Case study: diethyl amine pumping process overhaul

The ClydeUnion Pumps Aftermarket Technical Services team has experience across a range of services on critical rotating and reciprocating equipment to improve operational safety, reliability and efficiency. The team recently carried out an overhaul of a DVMx pump for a diethyl amine pumping process.

An operator possessed two DVMx pumps for a diethyl amine (DEA) pumping process.

The pump currently in operation showed worrying signs of wear, including collapse of characteristics and efficiency, while the other spare pump was already damaged. After several failed attempts at an overhaul carried out by another company, the operator

The project involved: the cleaning of all parts; a strip down and full dimensional inspection of parts; machining of eroded parts (Figure 3); the refurbishment of parts by weld deposition, heat treatment and the re-machining of the pump casing (Figures 4 and 5); the addition of grounding plates; the re-assembly with a new rotor, and hydrostatic and performance tests; and a clean down and paint.

Following the repair, the pump has regained its original characteristics and maintains very low vibration levels. The project was completed in 20 weeks and is operating well. In terms of investment, the cost of parts supplied amounted to 170 000 for the pump casing repair, complete rotor, and various parts and tests. The operator was able to avoid the losses in productivity linked to a total shutdown of the desulfurisation unit, as well as the unemployment of personnel working on the unit. The increase in efficiency will result in electrical consumption savings, and the decrease in vibration levels will lead

to a fall in routine maintenance cost. Conclusion

There are many detailed ways in which the running of multi-stage centrifugal pumps can be extended, and even existing equipment modified, to meet new performance requirements. The most important factor is ensuring that the end user and pump supplier cooperate to make sure a fit for purpose design is offered, and the end user can take advantage of the supplier’s experience with similar applications.

Originally published by Hydrocarbon Engineering.

April 2017 | | p33

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52