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Corrosion - A Life Cycle Challenge
- M Valliappan, We CAN Control Corrosion in India Network
The article highlights the corrosion issue which is one of the major challenges for pump manufacturers and users. The gradual destruction of metals not only hampers the smooth functioning of any plant but also increase the cost of project to a great extent.

Pump plays an integral role in fluid transportation for industrial purpose. Indian pumps have contributed to the nation’s economy significantly. Prominent sectors amongst them are agriculture, onshore and offshore production of oil and natural gas, petroleum refining, petrochemicals, mining, ship-building and marine duties, power generation, public water supply and sanitation, domestic and household utilities, process industries producing fertilisers, insecticides, pesticides, drugs and pharmaceuticals, textiles, soaps and detergents, cosmetic and health care products, dairies, vegetable oil and processed and packed food products, breweries, paints, etc.1

Pumps account for 30 per cent of the power consumption in the country. Thus, efficient operation of pump system can yield substantial savings. Selection of pump-motor system would differ from one industry to another due to changes in application parameters, process parameters and liquid characteristics.2

Pump Selection, a Puzzle for Public and Material Selection and a Challenge for Pump Manufacturers.

Pumps and valves are designed or chosen primarily for their mechanical performance i.e. containment of pressure, fluid sealing and, in the case of pumps, pumping capacity. For reasons of economy manufacturers offer their products in a limited range of materials. Each of these materials is suitable for a range of common fluids, and has the advantage of being available with relatively short delivery times. However, for corrosive and/or erosive fluids the user may require special designs (e.g. of seals) and/or special materials, which increase cost and delivery times. The balance of cost versus the likelihood of failure due to corrosion must be taken into account along with the criticality of the component, i.e. what are the consequences of a failure.3

When Pumps come to the minds of public for domestic application, the selection of pumps is always a puzzle for them. The moment the requirement is identified, the users merely check certifications like ISI mark, the only clue available for making a purchase decision. These ratings/ standards of manufacturing are the resultant effects of many strengths as well as weaknesses observed not only for the individual manufacturer, but also for the whole Industry.

The technical knowledge required for proper selection of pump set and pipe sizing is clearly out of the reach of public, especially farmers, who are the final consumers.

Material Selection for Chemical, Oil and Gas, Refining, Power and other industrial purpose is driven by the fact that how adequate these industries are equipped to follow appropriate selection criteria and choose the fit-for-purpose materials associated with design, apply, research and develop processes. This is again a puzzle for the manufacturers with least access for national and international standards and procedures. There are 43 Standards in MED 20, Mechanical Engineering: Pumps developed by Indian Standards Institution (ISI). How do these standards solve the puzzle on proper pump selection and help the general users to choose the efficient pumps of their interest without compromising any of life cycle drivers?

Agriculture sector consumes about 35 per cent of the total power generated. Most farmers use inefficient non ISI marked pump sets which consume more electricity and deliver less output. There is a potential of about 25 per cent to 35 per cent improvement in the efficiency of these pump sets by affecting minor/ major rectification and shifting to ISI marked pumps. The motors manufactured by unorganised units do not have ISI standards and is less efficient due to non-use of higher quality material resulting in iron loss and copper loss. The no load power factor is above 0.2 which is increasing the no load power consumption. There exists a mismatch in supply of pumps and motors by the unorganised sector as per operating load required by the client. There are many weaknesses associated with the development of pump manufacturing sector. Major contributors are: Absence of innovative approach to improve the existing processes and usage of lowgrade raw materials so as to produce cheaper products that are not efficient by unorganised sector.4

There is a wide gap between the minimum efficiency required for ISI certification and the efficiencies achieved by reputed manufacturers, which are very near international efficiencies. So, there is a big scope for improving the efficiencies of pumps manufactured in the country (Source: Indian Pump Manufacturers’ Association). Many factors that contribute for improvements in efficiency are often bypassed when the focus is made on initial investment and quick sale of items without acquiring the experience on proven performance of materials used for construction.

Industries worldwide depend upon pumping systems for their daily operation. These systems account for nearly 20 per cent of the world’s industrial electrical energy demand and range from 25-50 per cent of the energy usage in certain industrial plant operations. Purchase decisions for a pump and its related system components are typically based upon a low bid, rather than the cost to operate the system over its lifetime. Additionally, plant facilities personnel are typically focused on maintaining existing pumping system reliability rather than optimising the systems for best energy efficiency. It is a common practice for pumping system design and procurement to be based primarily upon the initial purchase cost of the equipment.5

Corrosion, the Neglected Concern
The manufacture of pumps requires a wide spectrum of materials metals and non-metals which would not only satisfy the design and functional requirements of the particular component but should also have reasonable assurance on its application in the environment surrounding the entire pumping process. Corrosion characteristics play an important role in deciding the proper materials of construction.

There is vast difference between the cost-intensive pumps imported for specialised applications from the manufacturers with access for the latest developments in materials and corrosion research and the low cost pumps manufactured locally without the involvement of appropriate material selection process. This difference is truly a life cycle challenge for the pump users as well as manufacturers in India.

References:
1. Chemical Engineering World, March 2000
2. Energy for Sustainable Development, Volume III No. 1, May 1996
3. National Physical Laboratory, UK
4. Coimbatore BDS
5. LBL 51042 Life Cycle Cost for industrial pumping)