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African Petrochemicals- Mar/April Edition 15_2 {2018}

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Backup power - why site

Backup power - why site surveys are a win-win By Kevin Norris, Consulting Solutions Architect: Renewable Energy, Jasco Intelligent Technologies. Winter is approaching and with it, brings the inevitable likelihood of power outages. Many South African organisations are gearing up by investing in alternative power solutions or, at the very least a UPS system to manage the safe shut down of systems in the event of an outage. It’s important however, to ensure that the solution you choose is the best fit for your business - or it will fail you when you need it most. Kevin Norris. Selecting the best UPS to meet your requirements isn’t as simple as choosing one from a catalogue or going with the solution that works best for another company. Your business has unique requirements and there are a lot of factors that go into planning the right solution. These include calculating the exact power load and ensuring that there are not external problems which could impact the functionality of the system. Incorrect planning could result in a system that is unequal to the task. You could end up overspending on a system that over-caters for your requirements. Price has no impact on the suitability of a solution. Your chosen solution in fact, could end up costing more in the long run due to damages caused by incompatibility or additional components required later. For these reasons, it is essential to ensure a proper site survey is carried out before investing in a UPS or generator solution. Site surveys are often seen as unnecessary spending, however, UPS and generator power systems can be exorbitantly expensive, and the costs of site surveys are often negligible when weighted against the overall solution. The benefits of conducting a proper site survey extend beyond saving money on your solution. -They can help identify inefficiencies in your business’s power environment, the correction of which could save you even more money. Proper site surveys are more than simply visiting a site and quickly assessing what equipment requires power backup before proposing a solution. Quick surveys may be able to determine what the electrical load is, but will not be able to detect underlying power problems, invisible to the naked eye. Nor can they assess any events which may impact power delivery. For example, an industrial machine may cause a large power drain when it is switched on, and such activities need to be catered for in the event of a power outage. Typically, a quality site survey should include monitoring your business’s electrical environment for at least seven days, factoring in the parameters relevant to the equipment being catered for (which should be confirmed before starting). This will give an overview of factors such as poor power factor (inductive) loads, voltage fluctuations, harmonics, transience and any patterns which may impact a backup power system. A good power service provider will be able to provide you with a UPS solution that can operate easily and efficiently within the existing parameters of your organisation’s existing electrical environment and confine its output to fit within the tolerances of the equipment it supports. The surveyor should also inspect the electrical distribution within your site premises, tracing from the source of power to the load in order to check for any obvious flaws. These should be corrected before installing a UPS or taken into account with the proposed solution. Something as seemingly inconsequential as a bad power terminal can cause inefficiencies in the delivery of power to your entire organisation. It can also put unnecessary pressure on a UPS system. Over and above examining the existing electrical environment, the survey should also inspect the proposed area where the UPS is to be installed. Improper housing without the necessary cooling and filters can negatively impact the lifespan of a UPS system, and may well cause the system to fail before it even starts. Once the seven day (minimum) evaluation is completed, and the parameters of both the existing and proposed environments are confirmed, the service provider should be able to produce a report on the power status of your business. This report should detail the requirements as well as suggest any recommended corrections to be done before a UPS is installed. A site survey will also equip the service provider with all the information needed to specify the perfect solution options to meet your requirement. In so doing, you will be protected, knowing that your chosen solution will work, and that accountability for an incorrectly specified solution rests with the service provider. It’s a win-win. About the Jasco Group Jasco delivers end-to-end best-of-breed solutions across the entire ICT value chain. Our services include solution design, business consulting, project management and logistics to manage the supply, installation and commissioning of solutions; and professional services to provide integration and customisation of solutions; managed services, support and maintenance. Jasco’s operating divisions, namely Intelligent Technologies, Enterprise, Carriers and Electrical Manufacturers deliver a range of solutions and services. Intelligent Technologies delivers broadcast, power, data centres and Property Technology Management (PTM) solutions as well as Energy Optimisation and Co-location services, a carrier-neutral co-location telecommunications hub where the network infrastructure serves multiple service providers. The Carrier business provides solutions and components for access and transmission networks as well as hi-sites. The Enterprise business delivers contact centre solutions, Unified Communications, Cloud Solutions and security and fire solutions. Electrical Manufacturers delivers contract manufacturing of white goods. The Jasco Group has a national footprint with offices in Gauteng, Western Cape, Free State, Eastern Cape and Kwa-Zulu Natal. Other than South Africa, the organisation trade in many sub-Saharan African countries, with a special focus on the Southern African Development Community (SADC) region. For more information: www.jasco.co.za 30

Added reliability in triple offset valves Bearing failures are among the highest root causes of failure in triple offset valves (TOV) for tight shutoff applications. This issue is directly attributed to the need to have metal bearings with very tight tolerances when accepting the shaft diameter. Properly designed TOV’s are metal to metal torque seated type valves. Therefore, very little shaft deflection can be tolerated in order to torque the seal ring into the seat. Additionally, properly designed TOV’s should have the bearings located as close as possible to the centre line of the disc, which helps to deliver rigid support of the shaft on sealing. Triple offset valve. Potential problems in oil and gas applications In oil and gas and petrochemical applications, there are many potential problems associated with bearing failures. Many of these are obvious, such as sulphur tail gas and acid gas services within refineries and gas processing plants. Sulphur in the gas state will have a phase change to a solid at temperatures below 115°C. If the gas phase sulphur is trapped in the bearing cavities and there is a drop in the temperature, the sulphur will become a solid. This causes bearing to shaft seizure, locking the disc in one position. When this situation occurs, the end user must apply a heat gun of some sort in order to unlock the valve. This procedure is not the best practice when operating a modern process facility. Most TOV valve manufacturers offer a welded on steam jacket in order to deliver heat to the bearing area. While this is good design practice, human error can negate this benefit if plant personnel turn off the steam to the jacket, or unhook the connections to perform maintenance and then do not reconnect the steam to the fittings. Other chemical applications such as butadiene and styrene have the same issues as described above, except when these chemicals become trapped and dormant it causes a phase change and popcorn, or polymerisation, resulting in seizing of the bearings. Additional situations are also attributable to fouling, such as simple pipe scale. Furthermore, during the start-up phase in new constructions when the pipes have not been properly flushed, debris can migrate into the bearing cavities. Improper designs can also add to bearing failures once in service. If a certain design has not taken into account the thermal coefficients of both bearing material and the tolerances accompanied by the cross sectional thickness, then the bearing could lockup during fast changing thermal conditions. The Zwick solution TOV valve manufacturers are keenly aware of these potential problems and in the early ‘90s some manufacturers introduced the bearing protection ring, which has now become the industry standard. However, this feature has proven fallable. A single ring of die-form graphoil installed into a groove in the ID of the bearing without a compressive load will flatten out and quickly become ineffective, even after only a small amount of cycles under pressure – graphoil has no memory. Other manufacturers offer a dual packing set with a lantern ring sandwiched between them, in addition to a flush port with grease fitting located on the bonnet to allow for flushing of the bearings. Some even offer O-rings at the bottom of the bearing cavity. This design would be a good solution, but in the petrochemical market Fire-Safe designs are mandatory, and an O-ring in the bearing cavity would not be considered compliant. German-based Zwick, the manufacturer of the Tri-Con series, is particularly strong in special applications requiring several customised features. An example of this is a mechanical design which ensures that both the ID and OD of the bearings are protected without violating the Fire-Safe criteria. The design incorporates three rings of die-form graphoil packing at the very end of the bearing ID, and then three rings of the same on the OD, both are captured by machined edges and loaded by the packing, which keeps the graphoil rings from flattening out. This patented design is called the sealed bearing feature. Besides the fact that it prevents any media from entering the bearing cavity, the advantage of minimal shaft deflection is preserved by this special design, which also functions as an additional packing seal to keep fugitive emissions to a minimum. For more information contact: Desmond Delport Valve & Automation Tel: +27 (0)11 397 2833 Email: desmond.delport@valve.co.za Web: www.valve.co.za 31

Collection

December 2016 Edition 13.6
Sept / Oct 2016 Edition 13.5
July / August 2016 Edition 13.4
May / June 2016 Edition 13.3
March / April 2016 Edition13.2
Jan / Feb 2016 Edition 13.1
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