Saturday, 27 January 2018

Maintenance Definition? | | What is maintenance? | | Types of maintenance? | |

Image Courtesy: Google
The definition of maintenance according to the Dictionary of International Trade (Global Negotiator) is:
          The Actions (Repairing and replacing) necessary for keeping a piece of article in correct condition (or) taking steps to avoid something breakdown (Preventive Maintenance) and bringing back to precise operable conditions (Corrective Maintenance) to achieve its maximum useful life. 


Generally, the maintenance is distinguished into 4 types, which are differ by the nature of tasks we perform. They are

1. Corrective Maintenance
2. Preventive Maintenance
     (a) Periodic Maintenance (Time based maintenance -- TBM)
     (b) Predictive Maintenance
            (i) Condition Monitoring
3. Zero Hour Maintenance (Overhaul)
4. Breakdown Maintenance
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1. Corrective Maintenance:

          Whenever the machine is in breakdown, repair/Maintenance is required instantly. The set of activities designed to identify, isolate and rectify a defect so that the failed equipment or machine can be restored to proper working order.  The difficulties that are faced during operation are communicated to the maintenance department by the operators or users of the equipment. It improves the equipment and its components (parts) so that preventive maintenance can be done reliably. Equipment with design weak points ought to be redesigned to improve reliability or enhancing maintainability.

2. Preventive Maintenance (PM):

          Preventive maintenance refers to regular or daily maintenance (Equipment cleaning, Inspection, Lubrication and Re-tightening), performed to retain the healthy condition of system and prevent failure through the prevention of deterioration. It requires periodic examination or instrument condition diagnosis, to measure deterioration. This can serve as a scientific feature, that is, the device will be checked even if it does not provide any signals that contain the problem. It protects the device from unplanned downtime and costs due to sudden failure. Preventive management is very complicated, especially for companies with a lot of equipment. It is further divided into two types, they are periodic maintenance and predictive maintenance. As human life is extended by medicine, the instrument remediation is long lasting through preventive maintenance.

2 (a). Periodic Maintenance (Time Based Maintenance - TBM):

          The basic maintenance of apparatus created by the users of it. Time based maintenance carried out regularly according to predetermined schedule. Time based maintenance consists of periodically analyzing, servicing and cleaning equipment and replacing parts to prevent unexpected failure and process issues. It consists of a sequence of basic tasks (i.e., Data collection, visual inspections, cleaning, lubrication, re-tightening of bolts, etc.....,) for which no in-depth training is necessary. This type of maintenance relies on TPM (Total Productive Maintenance). 

2 (b). Predictive Maintenance:

          The service life of essential components is predicted based on inspection or analysis, in order to use the parts to the limit of their service life. Predictive maintenance is completely condition based maintenance compared to periodic maintenance. For this maintenance application, it is important to know the physical variables (Temperature, motion, vibration, power consumption, and so on) by measuring and analyzing statistics bout degradation. Which variation is indicative of problems that will be showing on the equipment. This maintenance is highly technical, requiring advanced technology resources and requires at times of mathematical, physical and/or technologies. 

2 (b).(i) Condition Monitoring:

          Condition monitoring is the method of figuring out the condition of machinery while in operation. Machine condition monitoring is very important as a result of it gives data regarding the health of the machine. You'll use this data to notice warning signs early and facilitate your organization forestall unexpected outages, optimize machine performance, and reduce repair time and maintenance expenses. Condition monitoring not only helps to reduce the chances of catastrophic failure, however conjointly permits them to order component parts in advance, schedule workforce, and plan other repairs during the downtime. Typically Vibration, noise and temperature measurements are used as key signs of the state of machines. Successfully using this programme enables to stumble the faults early, and permits to repair of drawback parts prior to failure.
The key to a succesful condition monitoring programme includes:
1. Knowing what to listen for
2. How to interpret it
3. When to put this information to use

3. Zero Hour Maintenance (Overhauling):

          Normally the best degree of maintenance performed by any industry is overhauling. The set of tasks whose purpose is to study the equipment at scheduled periods before showing any failure, either once the the reliablity of the equipment has been reduced significantly therefore it is risky to make forecasts of production capasity. This review has been anticipated to have been deserted for zero hours operation, that is devices are new. All these things meant to replace or repair all things subject to wer. The purpose is to make sure, with high probablity, a good operating time fixed in advance. 

4. Breakdown Maintenance:

          Breakdown maintenance means that people waits until equipment fails or brokendown and later repair it. Such a factor can be used when the breakdown doesn't considerably have an effect on the operation or production or generate any vital loss other than repair cost. This maintenance could be planned or un-planned.

Also refer to :

Monday, 15 January 2018

Reducer | | Function of Reducer | | Types of Reducer | |

          A reducer is a kind of pipe fitting component in a pipe line that reduces the pipeline size from a bigger to smaller diameter.
          Typically, the length of reduction is the average of larger and smaller pipe diameters. There are two varieties of Reducers are employed in pipe lines, they are (1) Concentric reducer   (2) Eccentric reducer.

          Depending on the Mach Number of the flow reducer is used as Diffuser or as Nozzle. 
          Design guidelines and operational manuals often123 prescribe the choice or selection of reducer. A reducer permits for a modification in pipe size to satisfy the system's needs, or to adapt to existing piping of a different size. Usually we have a tendency to use concentric reducer however eccentric reducer are used once there is requirement to maintain the same-top or bottom of pipe level. These are also manufactured in inches and metric units too.

You can refer to this link for check the reducer size based on ANSI B 16.9.

          Generally in pumps the suction line is larger than inlet nozzle and also the delivery nozzle is smaller or same size as delivery line. Therefore, a reducer is needed in both suction and delivery lines. However some folks generally confuse that what kind of reducer is used? Concentric or eccentric? And within which position?
          During this topic we will share our experience concerning what kind of reducer is used. We hope it will assist you a lot.

Concentric Reducer or Conical Reducer :

          Concentric reducer is also known as Conical reducer. Concentric reducers are used to join pipe or tube sections whose ends are on same axis. It maintains center line elevation. When larger pipe and smaller pipe center lines to be maintained on same axis therein case we use Concentric reducers. These are more economical reducer fittings.

Uses of Concentric reducer:
1. Concentric reducers facilitate in transporting slurries and abrasive liquids.
2. They're helpful in the service of cavitation.
3. Concentric reducers are used Within the discharge lines of pumps.

Eccentric Reducer :

          In Eccentric reducers fittings the center of both ends of pipe or tube sections  are not present on the same axis. Unlike concentric reducers, these have an edge that is parallel to the connecting line. This parallel edge leads to two pipes having offset center lines. For eccentric expander or increaser same fitting is employed in reverse. 

          Horizantal liquid reducers are always eccentric, having top flat (unless on control set, same as PV, TV, HV, LV) or pipe rack, that prevents the build up of air bubbles within the system. Eccentric reducers are used at the suction side of the pumps to make sure that air does not accumulate within the pipe. The gradual accumulation of air in a concentric reducer might lead to a large bubble that might eventually cause the pump to stall or cause cavitation when drawn into the pump.

          Horizontal gas reducers are always eccentric, having flat side at bottom, that permits condensed water or oil to drain at low points.

          In vertical lines we typically use concentric reducers only unless the layout dictates otherwise.

Uses of Eccentric reducer:
1. These systems have less turbulence or material entrapment
2. Absorbs pipe wall and fluid borne noise and vibrations
3. These are used with flat side up in pump suction to avoid cavitation (when negative suction there).
4. Less installation space is required


Eccentric reducers installation instructions:

Case 1: When the source of supply is present below the pump, the eccentric reducers should be placed with the flat side at the top and vice versa. 
Eccentric reducers installation when source of supply is below or above the pump suction nozzle -- Source:

Case 2: Within the case of horizontal pipe runs, air pockets are avoided by installing the eccentric reducer with the flat side up.

 Eccentric reducers installation in case of long horizontal pipe runs -- Source:



Friday, 12 January 2018

Pulpers | | Function of Pulper in Pulp Making

          Pulper is employed in numoreous industries (Agriculture, paper plants) at different workplaces however here in this topic we discuss regarding the pulper which is employed in Paper Industry. 
Image Courtesy : Google
          Pulper is a mechanical machine which is used to produce pulp from cellulose fibrePulper is the heart of the re-pulping operation. Paper pulper is employed for different opeartions like crushing virgin pulp (Slabs and sheets), Waste paper process, machine broke, deinking and pulp purification. The bales of wood pulp or waste paper is loaded on conveyors and passed into a pulper (circular tank) containing water, it breaks the fiber by the action of mechanical operation (by using impellor).           

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          Among different raw materials waste paper processing is important because it contains a lot of dirt, stapler pins, metalic pieces, adhesive tapes, un-dissolved coating and alternative foreign materials like wax, plastic etc., This waste paper ought to be free from these types of undesirable materials. Before entering into pulper these materials are segregated from raw materials however some may remains. If these materials are present in pulp and move into wire section; they harm to wire as well as poor quality of paper occurs. Moreover centi cleaners is also block, increase the paper web breaks, reduces the performance of press felt and dryer screen. Therefore the pulper must has the ability to get rid of most of the contraries like wire, plastic etc.,
          Based on operation pulpers can be classified into two types they are Batch pulper and Continous pulper. In batch mode operation pulp formation is done in batches, by this we can control the size, dry strength of paper, and color by adding some chemicals. For stock deinking and change the color we use Surfacants. The suppliment chemicals of surfacants are Disparcent, Anti-foming agent, Caustic soda, Borax, and Sodium silicates. Waste Paper contains written papers and news paper too, the ink present on them change the color of the paper. Dispercent prevent the ink to diposit on the fibre. While pulper running a lot of foam will form, to reduce foam we use foaming agent. Rest of the three chemicals i.e., Caustic soda, Borax and Sodium silicates enhance the activity of Surfacants.
Pulpers can be classified into a lot of types.

a) Based on power consumption
          1.  Low power consumption 
          2.  Medium power consumption
          3.  High power consumption

b) Based on Consistancy of pulp
          1. Low consistancy
          2. High consistancy

c) Based on model
           1) Hydra pulper
                    a) D-type
                    b) Horizantal
                    c) Vertical
          2) Drum Hydra pulper
          3)  Broke pulper 

Broke pulper: We use these type of pulpers in wet end and dry end of paper machine floor. "Broke is the paper that partially or fully manufactured paper or board". The purpose of broke pulper is dissolving broke from the machine to make the broke suitable for reuse. Broke system is an important fibre source for paper plant because it is fully finished product and also financially helpful. Paper broke form continously while process. The main area's of Broke forming are:

1. Trim cutting in wire section (Coutch pit rolls)
2. During web breaks in paper machine (Presses, size press)
3. While rewinding operation : as trim 
4. Rejected rolls
5. In cutting operations of paper (Sheeters)
Image Courtesy: Google

Hydrapulper: Hydra pulpers uses less power and also maintenance is simple. These type of pulpers are dynamically balanced. The impellors use both mechanical and hydro dynamical systems for dissolving pulp. Hydra pulprs again classified into many types for example Vertical Hydra pulper, Horizantal, D-type etc.,
Image courtesy: Google
          D-type pulper is mainly used for old corrugated carton, waste paper and boxes. These type of puplers are present in D-type structure. Compared to traditional hydrapulpers these type of pulpers increases productivity without increasing the volume and momentum. Because of its D-type design it reduces the time of breaking pulp by incresing contact of pulp in less time in a rotation.
Image Credits : Google

Drum pulper: The more gentle mechanical action of Drumpulpers maintain maximum physical properties of fibre. This is a batch type pulper. This type of pulpers use less water and power.
Image Credits :

Friday, 5 January 2018

Tips for Industrial Gearbox Inspection and Maintenance

          To extend the lifetime of industrial gearbox, regular inspection and maintenance is must. On the other hand, for complete inspection and possible overhauling dismantling the gearbox and inspecting is time consuming and also causes undesirable downtime and breaks in production lines.   
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1. Gearbox Rating:

          Every gearbox have its own manufacture ratings both thermal and mechanical. It is vital to examine and conform that the gearbox is running withing it's manufacture specified ratings. On several cases it is seen that gearboxes are put in application surpassing its ratings, it'll cause gearbox failure.

2. Good housekeeping

          It looks simple but gives good results,  often gearboxes are operated at dirty and dusty environments. It is very important requirement to keep gearboxes in clean and dry areas. Regular cleaning of storage place and equipment is required. Keep the working environment and equipment dust and debris free unless contamination will increases the operating temperature of gearbox.

3. Oil (Shaft) Seals

          Any oil leakages at input and output shafts indicates that oil seals are damaged. With this we tend to loose lubrication and also chances of admittance of dirt, water and debris, so keep an eye on it.

4. Breathers

          It is seen that water and dust always enter into the gearbox through breather. It ought be of correct shape, style and type. Keep this breather always clean to allow the gearbox to breath easily. 

5. Regular lubrication

          This is one of the major step in preventive maintenance. Use manufacture recommended lubricating substance grade, type and quantity only. The selection of lubricant depends on temperature and season.

6. Check the temperature regularly

          Check the temperature fluctuations regularly to avoid overheating. Look for any signs of oil burnt smell, Foamed sight glass, discoloration of housings, burnt paint marks on housings. We could check the overheating of gearbox by sprinkling water on it. Spray water on gearbox and notice that it evaporates, boils or crackles. 

7. Gear Wear / Contacts

          Inspect Gears for any wear or misalignment. By using engineers blue we will find the gear wear.

8. Backlash and Shaft play

          Check the backlash between gears and also wear of shafts. We can check the backlash increase by using a dial gauge, it can't be noticeable with naked eye. End play causes gears wear.

9. Conduct Vibration Analysis

          Most gearboxes operate in noisy environments, at that environments we cant notice those vibrations. Vibrations are the cause of gears misalignment, bearing defects, shaft misalignment etc., 
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