Mass Flow Measurements of Liquids _1082ch1_1

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1

Overall Plant Design

1

1.1

AUDITING EXISTING PLANTS FOR UPGRADING 5

Prerequisites to Auditing 5

Goals 5

Functionality 6

Plant Standards 6

Identify Key Areas for Special Attention 7Who Audits the Plant? 7

The Audit 8

Upgrading Existing Systems 9

Evolution 9

Audit the Installation and Process 10

Process Information and System Integration 11

System Diagnostics and Redundancy 12

References 13

Bibliography 13

1.2

PROJECT MANAGEMENT AND DOCUMENTATION 14

Good Documentation Practices 14

Project Criteria Document 15

The Preferred Vendors/Technology List 15

I&C Documentation System 15

DocumentsPurpose, Contents, and Standard

Formats 18

Process/Mechanical Flow Diagrams 18

Piping and Instrumentation Diagrams 18

The Instrument Schedule 18

Instrument Data Sheets (Specification

Forms) 18System Architecture/Network Diagram 19

Control System Documentation 19

Instrument and Junction Box Layout

Drawings 20

Cable Block Diagrams 20

Control Room Layout Drawings 20

Panel Layouts and General Arrangement 20

Interconnection or Wiring Diagrams 20

Cable Routing, Cableway Sections, and

Details 20

Grounding System Drawings 20

Instrument Loop Diagrams 21

Logic Diagrams 21

Instrument Installation Checkout and

Calibration/Configuration Procedure 21

Decommissioning Documents 21

DocumentationAn Information Management

Perspective 21

Commercial Instrumentation Documentation

Tools 23Project ManagementAn I&C Perspective 23

Project Integration Management 25

Project Scope Management 25

Time Management 26

Cost Management 26

Quality Management 26

Human Resources Management 26

Project Communications 27

Risk Management 27

Procurement 27

Conclusions 27

References 27Bibliography 28

2002 by Bla G. Liptk
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2 Overall Plant Design

1.3

OPERATOR TRAINING, COMMISSIONING,

AND START-UP 29

Commissioning 29

Clear Goals and Objectives 29

Staffing 29

Schedule 32

Communications 32

Pre-Start-Up Inspection 32

Partial Operation and Water Runs 33

Documentation 35

Operator Training 35

Operating Procedures 35

Approach to Training 38

Simulation 38

On-the-Job Training 39

Start-Up 40

Field Changes 40Turnover 40

Post-Start-Up 40

Conclusions 41

Bibliography 41

1.4

FLOWSHEET SYMBOLS AND FUNCTIONAL

DIAGRAMMING FOR DIGITALLY IMPLEMENTED

LOOPS 42

Scope 42

General 42

Application to Industries 42Application to Work Activities 43

Application to Classes of Instrumentation and to

Instrument Functions 43

Extent of Loop and Functional Identification 43

Extent of Symbolization 43

Inclusion of the New S5.1 Standard (now

ANSI/ISA-5.01.01) in User/Owner

Documents 43

Definitions Related to Flowsheet Diagram

Symbology 44

General 44

Definitions 44Identification System Guidelines 47

General 47

Instrument Index 48

Guideline Modifications 48

Multipoint, Multifunction, and Multivariable

Devices 48

Systems Identification 48

Loop Identification Number 49

Typical Instrument Identification/Tag

Number 49

Identification Letter Tables 49

General 50

Graphic Symbol System Guidelines 51

General 51

Guideline Modifications 51

Instrument Line Symbols 51

Measurement and Control Devices and/or

Function Symbols 51

Multipoint, Multifunction, and Multivariable

Devices and Loops 59Fieldbus Devices, Loops, and Networks 61

Comments and Exceptions (Including

Non-ISA Industrial Practice) 61

Fieldbus P&ID Examples: DeviceNet 63

Functional Diagramming for Digital Systems

(ex-SAMA) 63

Instrument and Control Systems Functional

Diagramming 63

Equivalent Loop, Functional Instrument, and

Electrical Diagrams 64

Functional Diagramming Symbol Tables 64

1.5

HISTORICAL DATA STORAGE AND EVALUATION 79

Clarifying the Purpose of the Data System 79

Interactions and Integration with Other

Systems 80

Integration with Maintenance 80

Integration with Management 80

Data Collection 81

Event Data 81

Data Loggers 82

Data Collection Frequencies 82

Architecture of a Data Historian System 83Data Storage 84

Where to Store Data 85

Data Compression 86

Meta-Data 86

The Cost of Data Storage 86

Hardware Selection 87

Backup Media 87

Analysis and Evaluation 88

Data Filtering and Editing 89

System Testing 89

Support of the Data Historian System 89

Security 90Backup, Archive, and Retrieval 90

Bibliography 90

1.6

INTEGRATION OF PROCESS DATA WITH

MAINTENANCE SYSTEMS 91

Plant Floor Systems 91

Maintenance 92

Computerized Maintenance Management

System 92

Condition Monitoring and Predictive

Maintenance 93

Operation and Maintenance Needs 93

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Contents of Chapter 1 3

CMMS Integration 95

Integration Techniques and Business Alliances 96

Summary 97

References 97

1.7

APPLICATIONS, STANDARDS, AND PRODUCTSFOR GROUNDING AND SHIELDING 98

Grounding- and Shielding-Related Standards 98

Power Grounding Basics 99

Grounding, Bonding, and Overload Protection 102

Grounding Electrode Resistance 102

Power Grounding Definitions 102

NEC Article 250 103

Grounding Examples 104

Service Entrance 104

Separately Derived Instrumentation Power

System 105

Single-Point Grounding of Power Supplies 105

The Ungrounded System 106

Resistance Grounding 106

Shielding Theory 106

Lightning 109

Electrostatic Instrument Shielding 110

Differential Amplifiers and Isolators 111

Instrument Power Transformer Shielding 111

Floating vs. Grounded Instruments 111

Isolation Transformers 112

Power Supply Shielding 112

Digital Communications Shielding 112

Magnetic Field Influences 112

EMI and RF Shielding 112

Shielded Cable 113

Intrinsic Safety Grounding and Shielding 113

The Static Electricity Problem 114

Products 114

Conclusion 114

References 115

Bibliography 115

1.8

CONCEPTS OF HIERARCHICAL CONTROL 116Functionality 116

Measurements and Basic Controls (Functional

Section 1) 116

Advanced/Supervisory Controls (Functional

Section 2) 116

Management (Functional Section 3) 117

Hardware Architecture 117

Input/Output Systems 117

Controllers 117

Workstations 118

Communications 118

Architectural Concepts 119Structural Configuration 119

Hardware/Software Interplay 119

Hardware 119

Operating Systems 119

Communication Protocols 120

Application Software 120

System Hierarchy Interplay 121

System Specification, Selection, Design, andImplementation 121

Conclusions 122

Bibliography 122

1.9

ANALOG AND DISCRETE INPUT/OUTPUT, COSTS

AND SIGNAL PROCESSING 123

A/D and D/A Signal Conversions 127

D/A Converters 127

Weighted Current D/A Converter 127

A/D Converters 128

Counter Ramp ADCs 128

Successive Approximation ADC

(Serial) 129

Flash ADCs (Parallel) 129

Data-Acquisition Systems 130

Single-Channel Systems 130

Analog Signal Conditioning 130

Sample-and-Hold Circuits 131

Multichannel Systems 131

Analog Multiplexing 131

Digital Multiplexing 132

Data-Acquisition Boards 132

Digital to Digital I/O 133

Distributed Systems and Networks 133

RS-232-C 133

The GPIB (IEEE 488) 135

VXIbus 136

The Fieldbuses 136

Virtual Instruments 136

Software for Virtual Instrumentation 137

Theory of Signal Acquisition 137

The Sampling Process 137

Quantization 138

Coding 139Unipolar Codes 139

Bipolar Codes 140

Conclusions and Comments 140

Bibliography 140

1.10

ESTIMATING THE COST OF CONTROL SYSTEM

PACKAGES 142

Suppliers 142

Desired Accuracy of the Estimate 142

Clarify Scope and Objectives of This Control

System 143Estimating Techniques 143

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Software Tools 144

Controller Costs 144

Operator Station Costs 145

Instrumentation 145

Control Valves 145

Motors and Drives 146

Software Costs 146Maintenance Costs 148

Engineering Costs 148

Training and Start-Up Costs 148

Installation Costs 149

Control Room Incidental Costs 149

Taxes 149

Working with Vendors 149

Contingency Costs 149

Estimating vs. Bidding 150Submitting the Budget 150

Bibliography 150

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5

1.1 Auditing Existing Plants for Upgrading

G. K. TOTHEROW

Manufacturing is only one part of a business. The needs of the

business can change rapidly from forces outside manufacturing

and the control and information systems must follow and sup-

port the short-term and long-term business goals and needs of

the business. The process of auditing and upgrading control

systems is primarily one of determining engineering solutions

for business problems. Many companies embrace the concept

of continual improvement. These companies constantly review

and evolve plant systems to support their continued improve-

ment in manufacturing.1However, most companies only review

their automation systems in connection with a major project.

There is a good reason for this behavior. It is expensive and

disruptive to the plant operation to upgrade control systems.

Some people recommend auditing existing plant sys-

tems compared with world-class or best-practices stan-

dards. These audits have their place, but the value realized

by upgrading existing systems is in achieving business

needs and goals. The time to stop upgrading plant automa-

tion and information systems is when it is not a good finan-

cial decision as a way to meet the business needs. The only

way to determine if the upgrade to the existing systems is

a good financial decision is to audit the existing systems

against the functionality needed to achieve company and

plant goals. The purpose of this chapter is to provide a

methodology to audit a plant for upgrading systems. A side

benefit to the methodology given is that the justification for

the upgrade project is written from the audit information.

There are two types of plant upgrades. First, there is

what could be described as the maintenance audit to avoid

obsolete components, eliminate worn-out components, or

conform to new regulatory requirements to keep the plant

operating. Then, there is the upgrade for process improve-

ment or manufacturing cost savings that will show a return-

on-investment from the upgrade. Both share the common

theme of keeping the plant achieving business goals. The

goals and the project funding are different but the prerequisites

to the audit, the methodology of the audit, the integration

of old and new components, and the recommendation report

are the same when reviewing a plant system for upgrade.

There are five prerequisites to a meaningful consistent

automation system audit:

1. Understand the company and plant goals.

2. Determine the functionality that is needed from plant-systems to achieve or contribute to those goals.

3. Establish or communicate the plant standard compo-

nents and systems that can be maintained effectively

with the available support personnel and spare parts.

4. Identify key processes, machinery, or areas of the plant

for special attention.

5. Choose the best person to perform the audit.

This section first discusses the five prerequisites to the audits,the methodology for conducting the audits, and particular

issues of integrating new technology into existing plants.

PREREQUISITES TO AUDITING

Every plant and every industry has different equipment, raw

materials, and personnel. It stands to reason that every plant

and industry will have a different recipe to optimize profits.

State-of-the-art controls that reduce variation will not provide

the same return on the investment in one process, one line,

one plant, or one company, as they will in another. The sameis true with respect to head count reduction, reducing main-

tenance costs, and increasing reliability. All these factors are

very important to every manufacturer, but the degree to which

they are important varies between plants, industries, company

financial standing, and the general economy. For this reason

it is of foremost importance to fully understand plant and

company goals and audit systems against those goals.

Plant personnel, corporate experts, or outside consultants

may conduct system audits and make recommendations. The

degree to which they understand the plant will certainly be

different so the purpose of the five prerequisites to an audit is

to ensure that pertinent background information and goals of

the audit are clearly understood. Specific prerequisites to an

audit will need to be contracted or expanded based on the

industry and the scope of the project. The prerequisites here will

give the outside expert a good idea of how to meet the needs

of the company and will help the plant technical person con-

vince others to share the direction and success of the upgrade.

Goals

If this entire section were devoted to the importance of under-

standing company and plant goals, it would still not be enough.

The importance of focusing on project goals and the comple-menting company goals and initiatives cannot be overstated.



6/13


Manufacturing is only one facet of a business, and it seldom

drives the company; it swings to the demands of marketing,

sales, design, and other business factors. Manufacturing may

be asked to produce greater quantities, increase quality,

decrease delivery, shave costs, reduce downtime, add grades,

change packaging, or any number of other things to meet

business demands. Understanding the current business goalsis highly important prior to modifying manufacturing systems.

There was a time when only the highest-level people in

the company knew the corporate goals. And under them only

a few people knew the business and manufacturing goals of

the plants. And lower still only a few clearly understood the

department goals. Today, most companies have a mission

statement and a policy of passing down written goals so that

those below can establish supporting goals. Whether easy or

difficult to attain, the company, plant, and area goals are

important to auditing an existing plant because these goals

and company initiatives will be the basis for justifying the

audit recommendations.It is good to be given company, plant, and specific goal

information, but it must be understood that many business

decisions and business information will only be disclosed on

a need to know basis. It is also a fact of some businesses

that goals change rapidly and they may not be communicated

effectively. So, the first work that we do is to write a specific

goal for the audit in terms of the company or plant goal to

communicate effectively the basis for the audit. The audit of

an existing plant for upgrading should always have a specific,

stated goal. The following are some likely goals for the audit:

Reduce variation of product Increase throughput

Increase reliability

Avoid obsolescence

Adhere to safety or environmental regulations

Reduce maintenance costs

Decrease manufacturing changeover or process mod-

ification time

Functionality

The world of plant and process automation is changing very

rapidly. Whereas 25 years ago an operator interface devicemight be a panel with a gauge and push buttons, today the

operator interface device might be a wireless hand-held com-

puter. It is far too easy and common to jump from the project

goal or problem statement to looking for equipment or sys-

tems that a vendor says will solve the problem. An important

intermediate step is to obtain a laypersons description writ-

ten in simple language that tells what the ideal systems

must do for the operators, maintenance mechanics, and man-

agers to allow them to accomplish the stated goal or solve

the problem. Most of the functional description should come

from the users and area process managers along with an

estimate of the financial payback for solving the problem orachieving the goal. The functional description and the esti-

mated return on that functionality are often acquired by inter-

viewing the appropriate operating and maintenance personnel.

One purpose of the written functionality description is that

it breaks the components of the existing plant into digestible

pieces and describes the ideal as established from the goals.

It does so in terms of the functionality rather than component

descriptions. This is necessary because the physical componentoften provides several functionalities. A control system may

provide the controls, operator interface device, alarming, and

other functionality. The system may perform near the level of

the ideal functionality in one or two areas and may perform

far below the ideal functionality in others. The audit recom-

mendations could advocate replacement of the system or it

might recommend add-on components to enhance the system

capability in the poorly performing functional areas.

A second reason for the ideal functionality and the

estimated financial payback for the functionality is that it will

provide an estimate for the preliminary return on investment

for the upgrade project. Better yet, the return for providingthe functionality comes from the plant personnel who must

support the project.

The functional description should address:

Process measurement

Final control element

Input/output system wiring

Control needs

Redundancy

Operator interface needs

Alarm handling needs

Historical process data needs Management information needs

Production/cost/scheduling needs

Maintenance needs

Customer information needs

Plant Standards

Manufacturing and process facilities should establish and main-

tain a list of preferred components and vendors that have the

functionality needed to achieve plant and project goals. Plant

standards are useful to set a general direction in the components

and ways a facility will try to meet company and plant goalsand avoid obsolete components. Other common uses of a stan-

dard is to establish better vendor relationships, minimize spare

parts, minimize decision making, minimize training costs, and

ensure consistent and predictable results. That standards help

in all the ways listed above needs no explanation; however,

using standards to establish general direction and the period of

review of standards needs further clarification.

Few plants can justify the capital financing or the pro-

duction downtime to replace components across the facility

when new devices are proved better to meet the needed func-

tionality or when new industry trends and standards are estab-

lished. Innovation must be integrated into the facility. Theplant standard should lead in setting the direction to keep the



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1.1 Auditing Existing Plants for Upgrading 7

components from becoming obsolete and promoting devices

that will better satisfy the functionality desired. When should

the existing standards be reviewed and modified? The answer

is more often than is done for most plants. Any of the fol-

lowing events signal a time to review plant standards:

The manufacturer announces a discontinuation of theproduct.

An organizational or industry standards committee

selects another standard.

The plant is planning a major expansion or revision.

A problem of service develops with established ven-

dors or manufacturers.

Consider the example below, which shows a company that sets

and changes its plant standards to establish a strategic direction.

A chemical plant built in 1961 installed Foxboro transmit-

ters using 1050 mA DC current signals. Once installed, the

transmitters and wiring worked well and met the functionalitycriteria for field instrumentation and field wiring. Some time

after the ISA standards committee adopted 420 mA DC as

the standard for field signal wiring (ISA S50.1-1972) the plant

decided to adopt the 420 mA transmitters as their new stan-

dard. The next major opportunity to install transmitters was

during a major expansion and renovation project in 1975. The

plant replaced 100 of the old transmitters in the area of the

renovation and put them in the storeroom for spares for the

rest of the plant that kept the old 1050 mA DC transmitters.

In 1999, the plant had another major renovation project.

This time the project convinced the plant to use Foundation

Fieldbus for the signal wiring. The plant adopted FoundationFieldbus as its new standard field wiring. By 2000, 30% of the

plant was using new smart transmitters and Foundation Field-

bus, 65% of the plant was using transmitters with 420 mA DC

signal wiring, and 5% of the transmitters were the old 1050

mA DC Foxboro transmitters. The company will continue to

install the Foundation Fieldbus standard with each project.

The hypothetical plant used the plant standard to set an

appropriate direction to avoid obsolescence and integrated the

new standard along with the old where both met the required

functionality. The 420 mA DC only transmitters and signal

cable will not meet necessary functionality requirements when

the plant demands smart transmitters with online diagnostics.

A final word concerning standards is to guard against

using the standard to thwart innovation that meets the func-

tionality of its intended use and achieves company or project

goals better, faster, or cheaper.

Identify Key Areas for Special Attention

There are key areas, processes, and control loops in every

plant that are crucial to quality, production, or profitability.

They will be referred to as key success areas. These key

success areas and their impact on the operation should be

noted and understood by the auditors prior to reviewing thesystems for upgrading.

The purpose of this prerequisite item is to ensure that

audit recommendations address any issues that might affect

the process or operations at these points. These key areas

may be ISO (International Standards Organization) tagged

control loops, OSHA (Occupational Safety and Health

Administration) regulated areas, FDA (Food and Drug

Administration) certified processes, or just important areasof the plant. The audit to upgrade existing systems in the

plant should specifically address the potential impact to these

regulated areas. The importance of the key success areas of

the plant will be well understood by the operations and man-

agement people that will be curious about how any changes

may affect their operations. There may be some merit in

specifically addressing these areas in the upgrade recommen-

dations even to note that there is no effect on the process or

operation at that point.

The important point to remember is that the information

about these key success areas of plant operation should be

communicated to those responsible for the audit. It is certainthat if the potential impact on these areas is not addressed

up-front, the issue will be questioned later.

Who Audits the Plant?

The last prerequisite before performing the audit is to deter-

mine who should perform the audit. There are several persons

or groups that can be made responsible for the auditing so

the recommendations of this section may be a little difficult

to understand as we have not yet defined all of the steps and

expectations of the audit. This subsection should be reread

after the audit steps are reviewed if the reader disagrees withthe authors opinion.

Websters New World Dictionary2defines audit as follows:

5.any thorough examination and evaluation of a

problem.

The person, or group, conducting the plant review and

making upgrade recommendations should have the time to

dedicate to doing a thorough examination of the existing

systems, experience in evaluating and making appropriate

recommendations to resolve problems, and ability to write a

report that will show the value of implementing the recom-

mendations. Choosing the best person to perform the jobamong the several who regularly perform such tasks is as

important as successful accomplishment of the goals.

Figure 1.1a is a subjective chart showing a rating of the

qualifications of the persons who regularly conduct such

work. The chart shows the ranking of the various people on

a scale of 1 to 5, with 5 the best.

The categories on the chart are explained below.

Plant engineerA technical person at the plant with

3 to 7 years automation experience

Corporate engineerA senior-level engineer who

travels between various plants providing technicaltroubleshooting and project support



8/13


VendorA technical salesperson who might be called

to assess the existing systems and make recommen-

dations

Engineering firmAn outside engineer from a firm

that does detail engineering and project management

ConsultantAn individual with extensive technicalbackground and experience who is a specialist in

that process industry or is an expert in the technical

area of the upgrade project

Process knowledgeKnowledge of the plant process

in the area of the audit

Plant knowledgeUnderstanding of the plant, goals,

systems, and personnel

Industry knowledgeUnderstanding of the business,

regulations, projects, and trends for that process

industry

Problem resolutionCapability of determining equip-

ment and system changes that will resolve the tech-nical problems and add the functionality that the

audit reveals

TimeThe dedicated time to study the problem, deter-

mine resolution, and write reports

ExperienceGeneric estimate of the experience each

has in this type of audit and problem resolution

InfluenceAssessment of the capabilities of the per-

son or group to have the recommendations imple-

mented at the plant

CostThe cost of the audit

Project costThe degree to which the auditor will work

without bias on the companys behalf to gain return-on-investment and save capital money on the project

Four of the audit prerequisites are listed to give the out-

side experts the detail plant knowledge that they need to do

a very thorough audit. Unfortunately, there is no efficient

way to transfer the knowledge and experience of the outside

expert to plant personnel. Even if the plant had a technical

person with the time and experience to adequately examineand evaluate systems for upgrading, that plant person may

not have the political influence to be the catalyst for change

that is needed to convince the plant to implement the recom-

mendations.

THE AUDIT

The introduction to this chapter mentioned that there are two

types of projects: the maintenance upgrades to avoid obsolete

components, eliminate problem components, or conform to

new regulatory requirements to keep the plant operating; andthe capital project for process improvement or manufacturing

cost savings that will show a return on investment from the

upgrade. The primary differences between these types of

audits are perhaps the scale of the job and the internal funding

differences. Otherwise, both audits are essentially the same

and share the same characteristics and steps. Either type of

project will require finding the best place to replace the

functionality of the old components with new. Both projects

will require the new components to integrate with old com-

ponents. The maintenance project to replace individual com-

ponents relies more on the plant standards that set strategic

directions to ensure the solutions are synchronized with theplant long-term goals.

Plant Engineer Corporate Engineer Vendor Engineering Firm Consultant

Process

Knowledge5 5 3 4 4

Plant

Knowledge5 5 3 4 4

Industry

Knowledge4 5 3 3 5

Problem

Resolution2 3 4 4 5

Time 2 3 2 5 5

Experience 3 4 3 3 5

Influence 2 3 2 5 5

Cost 4 3 5 2 1

ProjectCost

3 4 2 2 5

FIG. 1.1a

Chart showing a subjective ranking of the relative strengths of persons who might perform a plant audit: 5 is best, 1 is worst.



9/13


Now, we understand the company, plant, process area,

and upgrade project goals. We interviewed operations and

management personnel and we know the functional specifi-

cations for an ideal system that would allow operations

achieve the project goals. We have estimates from operators,

managers, and maintenance personnel of the time, product,rework, quality, and other tangible savings that they can

achieve with functionality discussed. We understand the plant

standards for various components in the audited systems. We

identified the key success areas of the plant and noted their

impact on profitability. We selected an auditor and gave him

or her all our background material. So, now what methodol-

ogy should our expert follow?

1. The first step of the audit is to review the prerequisites

with the auditor. Remember that the purpose of the

prerequisites is to share plant-specific knowledge and

establish a functionality that would enable the plantto accomplish the goals.

2. Perform a physical audit of the systems (Figure 1.1b).

Thoroughly examine the existing systems auditing

functionality, models of components, and operating

procedures. Take special notice of communication

ports and communication capability of electronic

devices. Look carefully at the physical condition of

signal wiring and input/output (I/O) systems as well

as the installation of the existing equipment. Note

again that the systems should be audited in functional

groups rather than physical components. The operator

interface device includes at least three functionalgroups: interface to process data and control, alarm

management, and historical data.

3. Define the gap that exists between the functionality

needed and the functionality in the present systems.

Consider submitting this gap analysis for review and

approval by operations and management as an inter-

mediate step.

4. Evaluate the upgrades needed to close or eliminate the

functional gap using plant standard equipment where

applicable.

5. Evaluate the modifications to the operation and main-

tenance practices needed with the system upgrades toachieve and sustain the project goals.

6. Make a formal recommendation of the most effective

upgrade that will evolve the present systems and sup-

ply the functionality needed to achieve the goals of

the project. Recommend the changes needed to oper-

ation and maintenance practices that are necessary to

achieve and sustain improvements. Provide a cost esti-

mate of the upgrade and a rough return on investmentfrom the information gathered in the ideal functional

specification. Define the operating performance goals

that can be achieved by following the recommenda-

tions, and determine the measurable results that will

be the success criteria for the project. The recommen-

dation should also state the estimated length of time

that the system will remain viable.

7. Audit the system performance as compared to the

project goals and the agreed-upon project success cri-

teria approximately 6 months after the upgrade project

is complete.

These seven steps constitute an outline for auditing a

plant for automation system upgrades. The procedure does

not address what to look for or how to evaluate the selection

of various components. Other sections of the Instrument

Engineers Handbook adequately address the selection and

installation of control elements and transmitters, networking,

control systems, operator interface devices, and other tech-

nical information. The last part of this section focuses on a

few of the fundamental issues of the integration of new and

old components in upgrading existing systems.

UPGRADING EXISTING SYSTEMS

The person performing the audit should have knowledge

beyond that of the typical plant personnel of the trends,

alliances, and evolving technologies that will provide a great

return on investment for manufacturing and process industries.

These items may not be in the functional specification. The

auditor has an obligation to make the plant aware of trends,

evolving technologies, and integration issues so that the plant

can determine the value of an immediate investment. The rest

of this section on auditing an existing plant for upgrades

addresses some of the issues of integration of old and newand other items that the auditor should include in the upgrade

recommendation report.

Evolution

Systems should evolve, not become extinct.

Evolution should be the plan while auditing existing sys-

tems and should definitely be a primary consideration in the

evaluation phase of the system upgrade. In the 1980s and

1990s a distributed control system (DCS) meant proprietary

I/O systems, controllers, data highways, operator interface

devices, and process historians from a single vendor. Initialinvestment to purchase these systems was high, and the cost

FIG. 1.1b

List of some of the items that should be noted by observation or

discussions with operators during a control system audit.

Check Sheet for Control System Audits

Model numbers of components

Instrument installation

Communication capability of electronic devices

Physical condition of instruments, valves, controllers, and wiring

Valve position, cycling at typical conditions

Operating procedures, problems, suggestions

Documentation

Problems with regulatory control

Multiple operator interface devices to various systems



10/13


of outages and disturbance to operations installing them were

even greater. Suppliers replaced components and had major

new releases often because the systems encompassed both

the hardware and software in many areas of functionality and

because competition and development were very active. A

result is that it is common for customers to have two sys-

tems from the same vendor with new operator interfacedevices that cannot communicate with old controllers, or new

controllers that will not communicate with old operator

devices. Today, many companies operate with independent

systems from various suppliers on the same plant site.

Like others, Fisher Controls, now part of Emerson Process

Management, began assisting customers with life-cycle plan-

ning for the DCS in the early 1990s. These life-cycle programs

provide migration paths to keep systems current and provide

notification of new products and manufacturing changes and

supply of older products.3

(Honeywell offers several options

of LifeCycle Management (LCM) to help its customers inte-

grate new technology with predictable costs.4

) These pro-grams help successfully avoid component obsolescence and

assure that the components interface through several vintages,

but they do not always lessen the cost and disruption to plant

operations. There is another option to supply the evolution

needed.

In the late 1990s open standards, increased functionality,

and reliability of personal computers and the need for process

information combined to enable, and force, vendors to create

access to their systems. Today, a plant system can be defined

as an arrangement of independent components connected to

form a unity for the achievement of specified functionality.

The components do not need to be from one vendor. Archi-tecture of the system is very important. Hardware and phys-

ical connectivity to the proper data highway systems enable

very highly flexible and upgradable functionality through

upgrading software. The components can be selected because

they are the best of breed, or selected on the basis of lowest

cost to fill the functional requirement. With the proper archi-

tecture, the hardware and software components that comprise

the process control and information system can evolve at

different speeds over many years with minimal impact onoperations and minimum cost.

The audit should identify existing components supporting

interfaces to open systems as well as existing components from

suppliers that refuse to provide open interfaces. Figure 1.1c

shows a typical 1990-vintage DCS with a good, high-speed

interface to other systems. Figure 1.1d shows PCs as new

operator interface devices connected with redundant links to

the DCS and PLCs (programmable logic controllers). Addi-

tional functionality is added to the operator interface device

through software to allow retrieval of grade specifications

from the specification management system and downloading

of grade set points and tuning parameters to the existingcontrol systems.

Audit the Installation and Process

Few situations are more frustrating or more futile than trying

to correct process design problems with process control. Sim-

ilarly, changing manufacturers or styles of instruments will

hardly improve the control problems caused by instrument

installation errors. Every control and system upgrade project

should strive to correct the physical process and instrument

installation problem of past projects. Physical problems

involve piping and mechanical work that is usually expensive,and controls engineers are always under pressure to make the

existing system work without modification. However, the best

FIG. 1.1c

Typical DCS architecture circa 1990.



11/13


approach is to address the problems directly. Allowing oper-

ations and management to think that a new controller or new

instrumentation will resolve a physical problem is as great a

disservice as failing to recognize the physical problem. Theaudit is the time to recognize and note process and instrument

installation problems.

Sometimes it is not feasible to conduct an audit to scru-

tinize every process and every instrument and control valve

installation looking for installation problems. The process

design problems are particularly difficult to see without ana-

lyzing Process and Instrument Diagrams (P&ID) and yet with

existing systems this is not something that is typically part

of the control system upgrade project. Scrutiny of the process

and control system designs must be focused on certain areas

prior to the field audit.One way to identify process areas for extra scrutiny is

through recognizing indicators of process problems from

other parts of the audit. Figure 1.1e lists some of the key

indicators that a control problem is more involved than just

needing a new controller or upgraded system.

Process Information and System Integration

Great process control is not enough. Process information is

more valuable than control in many industries today. This is

not totally without reason or justification since the information

is needed for product tracking, product genealogy, offline

statistical analysis, regulatory compliance, and marketing andcustomer relations. Process information increasingly interfaces

to enterprise resource planning (ERP) systems, enterprise

asset management (EAM) systems, manufacturing execution

systems (MES), and data historians. Every system audit andrecommendation should address these issues.

The functional specification in the prerequisites to the

audit should contain a statement about the desired interfaces

to other systems. Today, any audit should address this issue

whether it is in the functional specification or not. The trend

is clear that more process information and process system

health information are desired by higher-level systems. It is

also true that the process control system and the operator, or

process manager as the position is often called, increasingly

need access to many more systems than just a process con-

troller. The integration between the management systems will

be bidirectional where quality control persons may need tosee the key information about the current product and the

FIG. 1.1d

Illustration of the same DCS as Figure 1.1c with a new DCS controller, PLC, new operator interfaces, and supervisory controls added.

FIG. 1.1e

Do not try to correct problems and disturbances introduced by poor

process design and nonfunctional process equipment when the best

solution is to recognize and correct the process.

Indications of Physical Process Problems

Control of process was always poor.

Periodic or seasonal fluctuations in controllability of the process.

Instruments and valves that work in other places are not working. Fast oscillations in process characteristic properties after mixing.

Fast process transients and oscillations while in manual mode.

Control valves that operate at extremes of their range.

Excessive process equipment and control component failures.



12/13


operator may need to see, approve, and download the spec-

ification for the next run in the plant. Operators, or their

systems, need access to the maintenance system, e-mail,

upstream and downstream processes information, historical

data, time and attendance systems, possibly accounting to

show real-time cost of production, and various other systems

in the future. Figure 1.1f shows the connectivity for the

operator interface devices to integrate to the other plant infor-

mation systems.

System Diagnostics and Redundancy

System diagnostics and redundancy, like process informationand system integration, is an area that the auditor may under-

stand better than the plant personnel. So too, the auditor

making recommendations for upgrading systems should

include recommendations on the system diagnostics and

redundancy even when the functional specification does not

address the issues.

System diagnostics begins with the transmitters and final

control elements in the field. Smart transmitters, valves, and

a device network are the basis for a system to alert folks of

process and instrument problems and provide the diagnostics

to isolate the problem.

The 420 mA DC has been the standard for signal wiringsince the 1960s but it now looks extravagant to run a pair of

copper wires in a plant to every instrument for just one piece of

information. Fieldbus technologies are discussed in Section 4.7.

The plant may need direction and recommendations on the

diagnostic and quality information available.

Regulatory control is as important as ever, but supervi-

sory controls and coordinating plant controls are needed in

most plants to make a step change in quality and productivity.

Changing one regulatory controller for another is not a recipe

for success. Section 1.8 of this chapter discusses hierarchical

control. The auditor must consider that recommendations

address virtual sensors, automatic loop tuning, statistical pro-

cess control, and model-based control. Also, the control sys-

tems recommendations should make the plant aware of

redundancy options, diagnostic capabilities, and automatic

telephone dialing system alarms.

Redundancy of control systems, where it is required, is

often considered a dreaded but necessary expense. Where

applicable, the control system upgrade recommendation

should address the advantages of redundancy for purely eco-

nomic reasons. Systems that continue to function through a

component failure avoid forced downtime, lost product, the

cost of emergency maintenance support, interruptions to pro-

duction scheduling, and other problems. As systems are inte-

grated, redundancy may be needed in communication net-

works, interface devices, and software to ensure that thesystems continue to function through a failure. The technical

FIG. 1.1f

Illustration of the same DCS as in the previous figures with direct operator interface communication to the PLC, and the addition of

interfaces to other plant information systems that need process data.

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expert must make the plant aware of opportunities. Section 2.9

discusses system architecture for increased reliability.

References

1. Walton, M., The Deming Management Method, New York: Dodd, Mead

& Company, 1986.

2. Websters New World Dictionary, 2nd college ed., New York: World

Publishing Company, 1970.

3. Proceedings 1992 PROVOX Users Group Meeting Report, Austin, TX:

Fisher Controls Company, 1992.

4. Honeywell Web Site, 2001, http://www.iac.honeywell.com/

pulp_paper/Services/InternetServiceLifeCycleMgtContent.htm.

Bibliography

McMillan, G. K., Process Industrial Instruments and Controls Handbook,

5th ed., New York: McGraw-Hill, 1999.
http://1082ch2_9.pdf/http://1082ch2_9.pdf/