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Instrumentation is a field, which is an eye or ear or brain in process industry to view and control the process parameters. The Instrumentation is a vital field, which link industry to management to take proper decision in profitability and safe operation of the Industry. So Instrument Engineers play a very important role in carrying out their role to satisfy the goals of Industry.

Basic requirement of Instrument engineer is as follows:

He should be well versed with Physics, Mathematics, Chemistry, Electronics and Other Science oriented subjects which are utilized well in the field.

An Instrument Engineer can divert himself in following fields

  1. As a Design Engineer
  2. As Maintenance Engineer
  3. As Construction Engineer
  4. As Marketing and Application Engineer
  5. As Manufacturing Engineer in Instrumentation Industry.

To become the successful Engineer in the above field the following will give a guidance. This is written based on the experience gained by the author. This will help the new students who has the flare to become an Instrument engineer.

Design Engineer

Terms used in Engineering Industry

P&I Piping and Instrumentation Diagram

PFD Process Flow Diagram

Instrument Index

Material Balance

Logic Narratives

Specifications

Piping Class

Hookup Diagram

Cable schedule

Junction Box diagram

Plot plan

Enquiry specification

Bill of Material

Vendor specification

1.0. P & I diagram

P & I diagram mean Piping and Instrument Diagram detailing the Location of Instruments and Pipe lines inter connected to the vessels, Columns and equipment like Compressors, pumps, coolers, tanks, and vessels, Safety valves etc in line diagram way. P & I run in many pages and the continuation is shown as links so that the line interconnections and process continuity can be identified.

The following are the details shown in the P& I diagram:

1.Pipe line size like 24",12", etc

2.The interconnecting Flanges, T joints, pipe Expanders, Pipe Reducers,

3.Vessels Sizes, Elevations Columns, Compressors, Pumps, spectacle Blinds, Traps etc.

4.The Instruments, Tapping points for Instruments, Control Schemes, Logic schemes, Alarm requirement, sizes of Control valves, and Failure Actions. Also Classifications like Pneumatic, Electronic DCS, PLC based are indicted.

5.P& I also show the directions of process flow, Insulation classes, Corrosion coupons etc.

6.P & Is are prepared as per Standards specified by the International standard Organizations like ASME,ANSI,ISA,IEEE,ISO ETC.

7.P & Is are prepared in different pages with basic sections like Utility, Interconnections, Basic Units, Vendor units like compressors sections, Different Units in plants,

8.The P&ID also reveals the control philosophy, on board, Filed, Type of instruments are shown.

9.The continuation of lines and reference to other P&Ids are also shown.

Please find the following drawing reflecting the P&ID.

 

 

2.0.Process Flow Diagram:

Process Flow diagram reflects the details of Energy and Material balance requirements.

The PFD details the process flow philosophy and is schematic diagram.

The basic vessel and pump and equipment tag Nos, Quantity and basic dimentions are shown.

The control philosophy in line diagram way.

The pipe line routing and the interconnections between vessels are shown. The line size and the valve sizes are not shown.

The spectacle blinds, Nonreturn valves are shown However the sizes are not shown.

The interlinking pipe routings are shown with connected page reference.

The capacity and the product details are shown.

PFD is the main document for developing the P&Ids.

 

 3.0 Instrument Index:

Instrument index details the complete Instrument package details the Tag no, Loop no, location, Type of instrument, Model no, Process description, location, type of control, indication, board mounted Instruments or DCS, Logic diagrams, Hookup and loop diagram details, Ranges, Alarm setpoints etc.

Instrument index is prepared based on the P&ID and revisions of P&ID is reflected in the Index.

Instrument index is the document for loop reference Material procurement of Field instruments and board and DCS instruments.

Instrument index is developed on the primary reference with Tag no as the key which I slated to other fields.

Tag numbers are developed on the basis process parameters such as Analysis, flow, pressure temperature, Level, weight and vibration etc.

Tag no also reflects the details of process such as Control, Indication, alarms requirements.

Tag number also reflects the locations such as unit numbers and stream or train.

The details of Instrument tag number details can be found from reference document ANSI/ISA-S5.1 OF Instrument Society of America.

Please find few examples:

05 LIC 101 mean unit 05 level indicating controller with number 101 of train 1

05 PALL 201 mean unit 05 pressure low low alarm with number 201 of train 2

11 IIC 104 MEAN Unit 11 current indicating controller with number 104 of train 1

12 UA 208 mean unit 12 unit alarm with number 208 of train 2

These can be understood easily with reference to P&ID.

Please find the example of Instrument Index.

TAG

LOOP_NO

SUB_JOB

INST_TYPE

SERVICE

PLANT_LC

LINE_NO

PIPESPEC

SIGNAL_TP

05MOV -0336

05M0336

102

MOTORIZED BALL VALVE

COKE DRUM VENT TO FLARE

FIELD-INLINE

5P2565-6"-CLC

CLC

05MOV -0338

05M0338

102

MOTORIZED BALL VALVE

COKE DRUM VENT TO FLARE

FIELD-INLINE

5P2564-6"-CLC

CLC

05MOV -0337

05M0337

102

MOTORIZED BALL VALVE

COKE DRUM VENT TO 5C-18

FIELD-INLINE

5P2563-12"-CLC

CLC

05MOV -0335

05M0335

102

MOTORIZED BALL VALVE

COKE DRUM VENT TO 5C-18

FIELD-INLINE

5P1161-12"-CLC

CLC

05HS -0335

05M0335

102

HAND SWITCH

LCL CTR PNL FOR MOV-0335

FIELD-LOCAL PANEL

E-DCS-DO

05HS -0336

05M0336

102

HAND SWITCH

LCL CTR PNL FOR MOV-0336

FIELD-LOCAL PANEL

E-DCS-DO

05HS -0337

05M0337

102

HAND SWITCH

LCL CTR PNL FOR MOV-0337

FIELD-LOCAL PANEL

E-DCS-DO

05HS -0338

05M0338

102

HAND SWITCH

LCL CTR PNL FOR MOV-0338

FIELD-LOCAL PANEL

E-DCS-DO

05TE -9004

05T9004

102

RTD ASSEMBLY

5E-103 WINTER CONTROL

FIELD-INLINE

5PXXX2-10"-CS

CS

05TT -9004

05T9004

102

TEMPERATURE TRANSM.

5E-103 WINTER CONTROL

FIELD-OFFLINE

5PXXX2-10"-CS

CS

05TY -9004

05T9004

102

I/P TRANSDUCER

5E-103 WINTER CONTROL

FIELD-INTEGRAL MTD

5PXXX2-10"-CS

CS

05TV -9004

05T9004

102

CONTROL VALVE

5E-103 WINTER CONTROL

FIELD-INTEGRAL MTD

5PXXX2-10"-CS

CS

05FE -9006

05F9006

102

ORIFICE PLATE

MED QUENCH WTR FLOW CTRL

FIELD-INLINE

5RW2018-8"-CA

CA

05FT -9006

05F9006

102

FLOW TRANSMITTER

MED QUENCH WTR FLOW CTRL

FIELD-OFFLINE

5RW2018-8"-CA

CA

05FY -9006

05F9006

102

I/P TRANSDUCER

MED QUENCH WTR FLOW CTRL

CONT BLDG-CONSOLE

05FV -9006

05F9006

102

CONTROL VALVE

MED QUENCH WTR FLOW CTRL

FIELD-INLINE

5RW2018-8"-CA

CA

05FE -9007

05F9007

102

ORIFICE PLATE

SML QUENCH WTR FLOW CTRL

FIELD-INLINE

5RW2019-3"-CA

CA

05FT -9007

05F9007

102

FLOW TRANSMITTER

SML QUENCH WTR FLOW CTRL

FIELD-OFFLINE

5RW2019-3"-CA

CA

05FY -9007

05F9007

102

I/P TRANSDUCER

SML QUENCH WTR FLOW CTRL

CONT BLDG-CONSOLE

05FV -9007

05F9007

102

CONTROL VALVE

SML QUENCH WTR FLOW CTRL

FIELD-INTEGRAL MTD

5RW2019-3"-CA

CA

05PI -9008

05P9008

102

PRESS GAUGE

PRESSURE OF OVERHEAD VAP

FIELD-OFFLINE

5P2566-24"-CS

CS

05TE -9009

05T9009

102

RTD ASSEMBLY

DESUPERHT WTR FLOW CNTRL

FIELD-INLINE

5P2566-24"-CS

CS

05TT -9009

05T9009

102

RTD TRANSMITTER

DESUPERHT WTR FLOW CNTRL

FIELD-OFFLINE

CS

05TY -9009B

05T9009

102

I/P TRANSDUCER

RAW WATER FLOW CONTROL

FIELD-INTEGRAL MTD

5RW2020-1 1/2"-CA

CA

05TV -9009B

05T9009

102

CONTROL VALVE

RAW WATER FLOW CONTROL

FIELD-INTEGRAL MTD

5RW2020-1 1/2"-CA

CA

05TY -9009A

05T9009

102

I/P TRANSDUCER

SOUR WATER FLOW CONTROL

FIELD-INTEGRAL MTD

5PW2054-1 1/2"-CLC

CLC

 

 

 5.0 Logic Narrative or Cause and effect diagram:

 

This document explains the cause and effect of any instrument abnormalities which can occur. One of the example is as follows;

In a plant the pump pumps liquid form a tank to another vessel.The logic condition