Case Studies in Maintenance and Reliability: A Wealth of Best Practices. V. Narayan
70 production supervisors and their managers, in groups of 10–12 people. In these sessions, I listened to them and recorded their requests and complaints. There were additional meetings with the main service department staff as well, including those in the stores and main canteen. The canteen staff had several requests, some of which appeared quite important for staff welfare. During factory rounds, I spoke to production and maintenance workers and union representatives. My own discipline engineers, supervisors, and contractors also provided their inputs. It appeared that many of the issues were related to stresses on the infrastructure. The company had seen rapid growth over the initial 15 years of its existence, but the infrastructure had not kept pace with the growth in production volume.
Analysis of the feedback highlighted some common problems. These included complaints about the utilities: provision of electricity, water, and air. Factory ventilation, dust levels in the ceramics department, and fume extraction in the plating department were also significant issues.
The main canteen provided food to more than 4000 people in the daytime, about 2500 in the second shift, and about 1500 people at night. Food was served in batches, as the seating was limited to 1500 people. Electrical heating was used for cooking, for which they needed a secure electricity supply.
These issues did not appear in the GM’s list, which generally covered current projects, some staff issues, and a list of complaints from production managers.
I applied the first two project selection hurdles. Were these expectations related to production or welfare or safety, and were they feasible? This process narrowed the list down to about 10 items that could be handled as stand-alone projects. The next step was to evaluate them for importance. We had to find the money for items that affected health, safety, and environment (HSE) and staff welfare. Items that were critical to production were clearly important. We will not go into the details of how funds were obtained; that is a long story in itself. Suffice to say it needed lateral thinking and agile maneuvering.
The lead time for completing some of the items was two–three years. This allowed us to phase the work within a three-year budget window. The company had an annual budgeting system. This imposed additional challenges of phasing, accruals, and other familiar accounting handcuffs with which most engineers will be familiar.
3.3 Selected Projects
We selected the following projects based on the criteria discussed earlier. A brief description of the work is given along with its justification and timing.
1.Factory Ventilation (HSE)
With conventional north light roof trusses, the temperature inside the large factory buildings reached 85–90°F in summer. There were a few large column-mounted air circulators to provide artificial ventilation. We planned to install 40 additional air circulators to alleviate the problem. The lead time was 6 weeks and we could get 10–12 units per month. Summer was approaching, so this became a high-profile HSE issue. The costs involved were relatively low and people on the shop floor would see action being taken. The workers representatives helped decide the sequence in which the new units would be installed, giving them a role in decision making. The sequence was something I preferred they decided themselves, as it would minimize arguments. The project was justified as an HSE item.
2.Electricity Supply
The public electricity supply system was unreliable, due to a serious mismatch between supply and demand. There were frequent power cuts; to overcome this difficulty, the company had installed four 350 kW diesel generators, with a fifth on order. These worked as stand-alone units, supplying isolated sections of the factory. This limited our flexibility to provide power where it was needed to suit the (variable) production demand. With stand-alone units, we could never load the machines fully. To overcome these limitations, we planned to synchronize the generators and connect them to the distribution network. The latter was currently not a ring main; this was another shortcoming needing correction.
This project required major investment in new transformers, circuit breakers, and feeders. Due to the lead time required for procuring the hardware, this project was phased over three years. The cost of the project was high, but so were the expected returns. We expected to reduce the value of lost production due to electrical supply problems by 50–60%, giving a benefit-to-cost ratio of 5:1.
A different issue related to the cost of electricity purchased from the public supply system. The electricity supplier applied a three-part tariff, with charges for the connected load (kW), energy consumed (kWhrs), and a surcharge for power factor below 0.96 (kVA charge). In addition to the thousands of induction motors in service, there were large induction furnaces in the factory. Without correction, the power factor could drop as low as 0.91. We already had a number of power factor correction capacitor banks, which brought it up to 0.94–0.95. We planned a separate project to increase the power factor to a maximum of 0.98. This upper limit was set by the possibility of a large induction furnace trip when we could end up with a leading power factor. The new capacitor banks would be brought into service or disconnected so that the power factor never exceeded 0.98 or went below 0.96. The project was phased over two years, based on hardware availability. The costs were relatively low and the expected benefit-to-cost ratio was 5:1.
3.Air Supply
There were two problems, one relating to pressure fluctuations and the other to entrained water. The latter issue had been so serious in the past that the main air supply lines in the factory buildings were sloped in a saw-tooth fashion, with manual drains at the low points (see Figure 3.1).
Pressure fluctuations were due to peak demands exceeding installed capacity and because of pressure drops in the pipelines. The entrained water came from the humid air. The water should have condensed in the after coolers of the air compressors, but a simple calculation showed that the cooling water temperature was far too high to be effective. In turn, this was due to an overload on the closed circuit cooling system. The original cooling pond was suitable for two diesel engines and three air compressors. The equipment numbers had grown to four diesel engines and four compressors. One more generator and two compressors were on order.
Figure 3.1 Original design of 4” air mains.
The air compression capacity was marginal and the projected demand increase was 30 percent. We decided that a third one would be needed to provide buffer capacity. In order to reduce the pressure drop in the pipeline distribution network, we planned to add four new air receivers located close to the main consumers. Peak demands could then be met from these receivers. They would also act as additional knock-out vessels to trap entrained water.
We planned to install industrial cooling towers to absorb heat from the cooling water used in the engine and compressor cooling jackets and after-coolers. This would eliminate the bulk of the entrained water at source.
These two projects were planned for completion in 18 months. The cost of the third compressor, air receivers, and cooling towers was in the medium-range. We expected to reduce the value of lost production due to air supply problems by 90%, giving a benefit-to-cost ratio of 15: 1.
4.Water Supply
The city municipal water supply system provided about 70% of the factory’s requirements. The company had installed many bore wells to draw groundwater to meet the remaining requirements. The city accepted our justification for requesting additional water supply, but were not willing to invest in a new pipeline from an existing reservoir about four miles away. We offered to underwrite the capital costs while the ownership remained with the municipality. I convinced the finance manager that we should pay a grant towards the capital cost of a city asset that would benefit the company.
We also decided to accelerate investment in additional bore wells in plots of land owned by the company in the vicinity of the existing factory site.
These projects were also in the medium-range of costs. Most of the additional water requirements were for welfare facilities. Without these projects, production levels would eventually have to be drastically curtailed, but we justified the