codification

Codification

DEFINITION:

“A code may be defined as a brief title comprised of either letter or number or both and is used to identify an item of data and express its relationship to other items of same or similar nature.

- The complexity of relationship governs

complexity of coding structure”

Types of Codes-Sequence Codes

Sequence Code:This is simplest method of coding. It is assignment of consecutive numbers beginning with 1 to a list of items as they occur, - just as Account No given by Banks to its

customers.

• Advantage of sequence code is its ability to accommodate unlimited number of items by using fewest possible digits.


- As new items occur they are simply given next higher unused number in sequence.

• Sequence code always requires directory for decoding.

• There is no provision for classifying group of like items according to specific characteristics and cannot be used where such requirements exist.


- It is practical only for coding lists or for numbering longer lists where code serves only as a convenient title as in account No. by banks.

• Sequence plan of coding, however, is an inherent part of almost all other more specialized and sophisticated coding methods.

– Division of data set forth by most classification plans is arranged in sequence & individual data items within division are arranged with use of simple sequence code.

Types of Codes-Block Codes

Block Codes:• It is minor refinement of sequence code i.e. a

series of consecutive code number is divided into block and

- each block of numbers being reserved for identification of group of item which have some common characteristics,

- plus some unassigned nos for new items


• Block coding provides a data classification system,

- which uses a few code digits to identify each item,

- expansion of code to include additional items within each block is confined to those numbers left unassigned when plan is originally established.


• New blocks of any quantity of code nos for new classification may be added as required, beginning with next higher unreserved code No in sequence

• As in case of sequence code, decoding in this method also requires some form of cross-reference directory.

• However, decoding is comparatively easy to accomplish as reference is directed to a range of code nos within blocks thus narrowing scope of search.

Types of Codes- Group Classification codes

Group Classification Codes: • Group classification codes are those which

designate major and minor data classification by successively lower order group of code of digits.

• Number of different classifications, sub-classifications, type, kinds and sizes, necessary for data identification, determines quantity of digit, groups required in code.

Types of Codes- Group Classification codes

• A scientific and rationalized materials coding is based on group classification code system

• Group code is readily construed and easy to understand and apply.

• Capacity of expansion is also very large. • Machine processing is facilitated since a sort on

specific digit groups causes separation on desired class of data for processing.

Types of codes- Mnemonic

Mnemonic codes:

• Mnemonic code construction is characterized by use of letters and number combination, which describe items coded, combination having been derived from description of items themselves.

• Combinations are designed to be an aid to memorizing codes and associating them with items they represent.

Types of codes- Mnemonic

• There are no definite rules to follow in constructing a mnemonic code except that an effort be made to select combination which best suggest item, they represent.

- Letter I, O & Q should be avoided because of their similarity to number 1 and 0.

Type of Codes-Numeric Alphabetic

Numeric Alphabetic codes:

• Numerical alphabetic codes are designed to maintain data they identify in some form of alphabetic sequence without use of alphabetic characters in codes.

• This system is used for individuals or company names.

Type of Codes-Numeric Alphabetic

• Numerical construction of these codes is particularly advantageous for machine processing, rather then an unwieldy alphabetic code.

• Numerical alphabetic code is constructed in such a way that two high order digits are 01 to 26 correspond to the letters of alphabetic.

Advantages of coding system:

• Accurate identification.• Prevents duplication

• Assistance in standardization & variety reduction• Facilitate efficient/economical buying.

• Basis for sorting stores documents• Simplification of mechanical recording

• Central analysis of unit store house records.

Characteristics of a good coding system:

• Covers whole range of stores in use & likely to be used

• Classifications are designed to meet requirements of organization

• No. of digits is constant.

• Sufficient room for future expansion or amendments

Method of coding-Group Classification Code

Coding by nature of items:• Inherent characteristics of all stock items are

reviewed and in first instance similar items are collected into series of Main Group such as raw materials, tools, machinery spares etc.

• Each of these groups is then divided into Sub-groups of section.


• A 10 digits code system in line with the above may work as under: _______________________________________________Main Group

____________________________________________Sub-Group

_________________________________________Sub-sub- groups

______________________________________Item serial number

__________________________________Check digit

XX XX XX XXX X


• For purpose of inventory control & grouping of related items on purchase requisition or order, number is tied to system of 100 basic classifications or Main Groups (00-99) of all materials.

• The first two digits represent number assigned to any class and identify an individual item in that class or group or family.


• Each class/ Main Group is sub-divided into 100 sub-classes/Sub-groups arranged preferably alphabetically and represented third and fourth digits (Total 10,000 Sub-groups)

• Each sub-group can further be assigned 100 sub-sub groups, representing fifth and sixth digits. Here again sub-sub-group classification is arranged preferably in an alphabetic manner.


• This implies that the entire stock holding can be divided into 10,00,000 sub-sub-groups.

• Individual items falling into a Main-group, sub and sub-sub group are assigned item serial number, using 7th, 8th and 9th digits.

NTPC’ Main Group classification

Main Group DescriptionCode----------------------------------------------------------00 Scrap01 Metal Ferrous02 Metal Non-ferrous03 Non-Metallic Materials04 Refractory & Thermal Insulation

Materials05 Packing07 Surface Coating Materials10 Chemical & Gases


Main Group DescriptionCode----------------------------------------------------------11 Oil & Lubricants14 Medicines & Medical Equipments 15 Fasteners 16 Pipes & Hoses17 Pipe Fittings & Flanges18 Valves, Strainers, Traps19 Bearings & Accessories20 Tech Power Transmission System


Main Group DescriptionCode---------------------------------------------------------------------------

21 Building Hardware22 Tools, Tackles & Accessories23 Cutting Tools, Abrasives &

Accessories24 Welding Electrodes & Accessories26 Laboratory Items27 Furniture28 Office Stationery29 Personal use/Domestic item


Main Group DescriptionCode--------------------------------------------------------------------------

31 Pumps- I32 Pumps- II33 Pumps- III34 Compressors35 Industrial Fans & Blowers37 Spares for Valves



40 Boiler 250 MW41 Turbine 250 MW42 Auxiliary Boiler43 Turbo Generator 660 MW44 Boiler 660 MW45 Boiler 60 - 110MW46 Boiler 200/ 210 MW47 Boiler 500 MW



Construction Equipments



49 Turbo Generator 60 - 190 MW50 Turbo Generator 200/210 Mw51 Turbo Generator 500 MW52 Gas Turbine Generator53 Diesel Generator Set



54 Fuel Management & Lube Handling System

55 Coal Handling Plant56 Ash Handling & ash Utilization System57 C. W. System58 Water Treatment System59 Hydrogen Generation Plant

•



62 Workshop items63 Crane, Hoisting, Lifting & Materials

Handling65 Construction, Earth Moving &

Automotive vehicles66 Air Conditioning & Ventilation System70 Engines (Without vehicles) 71 Locomotives 74 Wagons75 Rail Track & Signaling System76 Hydro Electric Project



81 Cable, Conductor & Accessories82 Electrical Lamps, Fitting & Installation Materials83 Electrical Circuit Components85 Switch Gears86 Motors87 Transformers90 Relays92 UPS& Power Back Units



94 Control & Instrument95 DAS/ DCS & PLC System96 Communication Systems97 IT & Communication


• Check Digit:• With introduction of computerized stores

accounting system, it has now become usual to add as last digit, 10th digit in code scheme, as check digit.

• This is a self- checking device, to ensure correctness of code numbers fed to computer.

• If there is an error in writing/reading/capturing code no, this shall immediately be highlighted by computer by not accepting code.

Method of coding- check digit

• One of systems ‘Modulus 11’ for calculating check digit is as under.

• Check digit is remainder by multiplying all the digits in the code number from right to left by 1, 2, 3, etc. respectively, adding products and dividing sum by 11, for example:

Method of coding- check digit

_____________________________________________________ X9=00

________________________________________________ __ X8=24

_______________________________________________ X7=00

__________________________________ ---- X6=30

__________________________________________ X5=00

______________________________________X4=08

___________________________________X3=00

_______________________________ X2=02 ____________________________X1=05

69

0 3 0 5 0 2 0 1 5

The check digit for code 030502015 shall 3 i.e. by dividing 69 with 11 we get remainder of 3.

Method of coding- check digitAnother method of calculating check digit, which is followed in NTPC is as under: ________________________________________________________ X 7=14

_____________________________________________________ X 3= 6

________________________________________________ X 1= 7

_ _____________________________________________ X 7= 0

__________________________________________ X 3=12

_______________________________________ X 1= 0

__ ___________________________________ X 7=21

____________________________________X 3= 0

_________________________________X 1= 6

66

2 2 7 0 4 0 3 0 6Dividing 66 by 10 we get remainder of 6 and by subtracting 6 from 10 we get remainder 4 i.e. check digit. Check digit for first time to be generated through computer and later form integral part of code

Code by End use

This means arranging code to correspond purpose for which various items are eventually used.

In a motor- car unit first division of materials would be into production stores and non-production stores.

Further sub-divisions may be arranged in line with somewhat as follows.

Code by End use

• Production Engine, Body, transmission, Stores steering, suspension.

• Engine: Ignition, valve gear, fuel system, cylinder block, cylinder Head.

• Valve GearIndividual items such as inlet valve and exhaust valve etc.

Code scheme –Common use items

• We shall seldom come across with suppliers ‘O&M Spare Parts List’ which includes many items which are not manufactured by them.

• Such items are bearing, V-belts, oil seals, pipes and pipe fittings, nut and bolts, electrical fuses, relays, contactors, indicating lamps, bulbs etc. and these are their “Bought Out Items”


• These might have already been included in our vocabulary in some other classification because they are also in use for other purposes.

• In these instances, it is advisable to indicate in catalogue for equipment spares that these items are ‘Common User’ items and can be bought more cheaply from the actual manufacturers than from OEM, who himself has to treat them as bought out parts.


• By buying items from actual manufacturers, lead- time also is drastically reduced and so are inventory levels.

- In addition, if they are not so identified, same will appear under several vocabulary No, will be stocked separately and may have effect of increasing stock-holdings unnecessarily ` involving duplicate locations in store house. If a particular common item is used in many types of equipment, advantage of bulk purchasing can also be availed of.


• If a particular common item is used in many types of equipment, advantage of bulk purchasing can also be availed of.

• In beginning when consumption data are not available, it is advisable to incorporate on the stock cards the details of such equipments for which the particular common item is required.


• This information helps in materials planning. A particular bearing may be used in 2 equipments and another in 10 machines. Quantities to be requisitioned may vary based on above information.

Three Basic Stages of Scientific Codification

Three basic stages of scientific codification are: IdentificationClassification and

Codification

Identification: is the process of assigning correct nomenclature to each item which must take into consideration complete specification including technical nomenclature. Identification system shall be uniform for all items. Most commonly


Used method is to begin the nomenclature withNoun i. e. name of item, followed by distinguishing

(distinctive) features and ending dimensional details for example:

A 20 mm DIA drill may be described as“Drill HSS, Taper Shank, 20mm DIA

standard length”A bolt may be described as “Bolt Hex M. S. (grade of MS) 1inch X 3 inches BSW


A 200mm dia side and face cutter may be described as“Cutter milling. Side and face, HSS 200mm (OD), x 40mm (ID) x 25mm (thick)

Item is not a nose pliers- it is pliers nose, pliers cutting etc.

Item is not a ring spanner- it is rather spanner ring,Spanner box, spanner open jaw etc


Classification- is arrangement of items into groupsaccording to a pre-determined pattern, governed by the common features of the items held in stock and likely to be added in future. Grouping of stores item had to be organization specific i.e.a grouping which good for X organization, may not meet the requirement of Y organization. - This may however be done on basis of ‘description’, ‘nature of items, ‘sources of purchase’ or ‘function of the items’ etc


Description classification: refers to grouping of items of similar description irrespective of end use, into one class.- bearings are put under one class- oil seals & O rings another category- pipes and pipe fittings

Nature of materials: items are classified according to nature such as raw materials, machinery and equipment, consumables, chemicals, fuel stock, furniture, packing material


Codification: is allocation of specific code to items within broader framework of selected system

- A codification system is usually tailor made to satisfy specific needs of the organization.

-Usual approach is to employ general principles of one of the standard systems & design specific codes to suit need of organizationHowever, codes should have following characteristics.


• System shall be as simple as possible in its form to make it user friendly.

• There is one and only one place for an item in catalogue i.e. each item should have one unique identification code and there is no scope of duplication

• Avoidance of descriptive nomenclature.


• Unit of measurement is standardized & given against each code

• Apart from identifying and classifying all existingitems, it should have enough unassigned codes to absorb from time to time items added in futurewithout necessitating any changes in already assigned numbers or sequence of numbers.

- that is the system should be capable of expansion


• If possible, in code catalogue, it may be reflected against each item,

- whether it is stock/ non-stock item. - If feasible it may further be added if it is an Insurance or UR or consumable spare.

• Descriptions are brief but accurate.


• It should be suitable to method of processing data, if machine processing is to be adopted, use of letter should be avoided.

• However if alpha-numerical system is adopted, characters with similar appearance shall not be used. Letters O, Z, S, I & V can be confused with number Zero, 2, 5, 1 and U

• Least possible number of digit should be used to adequately describe each item.


• As far as possible, code itself should indicate some of characteristics of the items i.e. significant code system.

• Codes shall be symmetrical i.e. number of digits used are consistent or all the items in catalogues

• Codes as far possible shall be capable of being easily detoxified i. e. user shall get maximum information of item without referring to catalogue

Process of codification

Preparation of code catalogues:Best system of coding, if not implemented properly, may prove an utter failure. It is necessary to study process of compilation of catalogues. Following are brief out-lines of a typical procedure to be followed:

Constituting of task force:A task force is to be constituted which should include those persons who have fairly good knowledge of subject & are made responsible for accomplishing the job. They may be from Materials, O&M, System and MIS Groups.


Study of present system:This task force needs to study current system of identification and to record full particulars of this system, visits all Store units & record offices.

It is advisable to collect copies of stock verification sheets, - Which apart from giving fairly large no. of various items in use, shall ensure that all items stocked presently are definitely

coded.


Consultation with other departments:Other deptts viz. Finance, Purchasing, Stores, O&M and Design etc. are consulted and with them, it is agreed:

• The general contents of catalogue

• Type of coding system to be adopted i.e. whether the coding system is based upon nature of items or end use to which they are put or any other system.

Process of codification• Broad classification and sub-classification to be

used.

• System of numbering and number of digits.

• Estimated dates for the preparation and ultimate issue of each catalogue & process of switching over to new code.


Preparation of originating sheets:

• Task force prepares list of items in respect of each classification from lists in hand which include stock-taking sheets, catalogues of suppliers, OEM part list etc.

• All such items are listed in the sub-group giving a description and quoting sizes & specifications.


• No item numbers are allotted at this stage. Lists are sent to stock holding units and user departments and their comments are obtained in the appropriate columns.

• Stock holding units may suggest inclusion of new items or removal of some of the items so listed. Changes in specification may also be recorded.

Process of codificationCompilation of data:

• When all originating sheets are received back, those are analyzed.

• All items, which are apparently not required, are removed.

- New items are added at appropriate places, if necessary items are rearranged.

Process of codification• Once the final list is ready, the details are broken

into sub-sub-groups and start assigning code numbers.

• It is very laborious task. - Effort should be made to restrict varieties of items stocked by limiting size ranges,

- by eliminating alternatives and omitting items, which are used occasionally.


• Allocation of numbering is made in a way that there is sufficient room for future expansion/ adjustments.

• Items shall be arranged alphabetically, if sizes are there, starting from the lowest size and proceeding further.

• Catalogues so prepared are sent for printing or multiplication, depending upon requirement of copies


• While distributing copies, care to be taken to ensure that complete sets are issued to only those who really require them.

- Individual volumes are issued to various stock holding groups. Record of distribution is kept

Amendments-additions:• During course of operation, some new items are

added in catalogue and amendments are issued periodically, say quarterly.


• If organization is new, there may be frequent amendments, which may make it essential to reprint Cats. taking care of all such supplements.

• As far as possible, changes should not be made in Main Group unless these are absolutely necessary.

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codification

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