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Specifications serve three purposes. They:
All other objectives are subordinate to these three. Because they
are the basis of all engineering and scientific contracts, technical
specifications must be written with care. Conversely, badly-written
specifications cost time, money and effort.
This article deals with specifications in all their aspects and explains
their purpose, content, development and types. For brevity, whenever
the word 'specification' or its plural form is used, the meaning 'technical
specification' is intended.
The preparation of specifications is the first and most important step
in any contract negotiation. Without them, cost studies, estimates,
schedules and contract responsibilities are difficult to define. Well-written
specifications must:
GENERAL
A specification is a detailed description of the particulars of some
projected work in any scientific, manufacturing process or engineering
discipline by stating the dimensions, material content, quantities,
and performance of the work. The technical specifications also give
the directions to be followed by the designer, builder or constructor.
A specification defines the items that are to be produced, services
provided, and the performance required of them.
They do not specify how the work is to be done; this is the purpose
of procedures (see HOW TO WRITE PROCEDURES). Well-written specifications
may make reference to the procedures necessary when certain processes
are to be followed. When specifications refer to 'items' they include
not only the hardware including machinery, buildings, and installations,
but the software as well. Software includes documents, computer programmes
and, often, the item design calculations.
In view of the North American Free Trade Agreement (NAFTA) and resulting
increased cross-border commerce, a last general observation regarding
the preparation of specifications is well worth making. This is that
although the phrase 'or equal' is commonly included in specifications,
those who prepare specifications in the U.S.A. can include or omit
the phrase as they wish. Whatever they decide, U.S. law is on their
side.
In a 1974 decision* (see the end note), the U.S. Supreme Court upheld
the right of those who write specifications to choose those invited
to bid as they wished. The ruling was an important one. It has implications
for Canadian contractors and owners doing business across the U.S.-Canada
border. The Supreme Court handed down four principal rulings:
PURPOSE
To some degree, the purpose of specifications was discussed in the
introduction. A technical specification must provide the contracting
parties with clear knowledge of the expectations of both the end
user and the supplier. A graphic example of a badly-written specification
occurred in the heyday of travel by rail.
A British railway company wrote a specification for drinking glasses
for use in its dining cars. The law required that beer be served in
glasses that would hold half a pint. The successful supplier was able
to put in a bid ten per cent lower than competitors when it read the
specification. The glass thickness, top and bottom diameters of the
glass, and the glass height were specified. By producing a glass with
curved, not straight, sides, the supplier was able to reduce the material
needed by ten per cent. The glass met the specification but did not
hold half a pint. The specification writer had omitted to specify the
volume requirement.
Bearing this example in mind, specification writers should have a good
knowledge and understanding of five things:
Additional time spent in writing, reviewing and approving the specification reduces the chances of additional costs and equally costly delay of completion. TYPES OF SPECIFICATIONS
Specifications may be grouped in one or more categories and can exist
under different names. For example, design requirements themselves
can be specified for the direction of system and equipment designers.
These are used by designers to evolve a given equipment or system
design. As such, design specifications do not necessarily result
in the production of hardware. Here is an explanation of the various
groups of specification types to be found in industry. 1. CONCEPT SPECIFICATIONS
These are written in general terms to define a product or major undertaking.
They serve as a foundation for conducting an investigation, feasibility
study, and the probable life cycle cost of an undertaking.
For example, this type of specification might apply to a manufacturing
plant required to begin production of a commodity at a given time.
The concept specification might, and often does, state transportation
needs, lines of communication, market requirements, raw material markets,
security, waste disposal criteria, and required soil conditions. 2. DESIGN
Design specifications are used to define system or equipment performance,
output capacity, and the range of design licence open to the designer.
For example, a designer may be restricted to the use of electrical
or hydraulic means for a power-operated mechanism. This rules out
the use of, for instance, pneumatic means. Similarly, an architect
may be limited to concrete in the use of materials in a building
design.
The design specification writer must know what design restrictions
apply before writing the document. The actual structure of form of
specifications will be dealt with later in the chapter.
3. DESIGN DESCRIPTION
4. CONSTRUCTION AND MANUFACTURING 5. PROCESS
Process specifications describe the technical processes that will be
used in the manufacture of a product, or construction of a building
or system. These processes include the heat treatment of foundry
castings, rules for pre-stressing concrete beams, bolt torques on
bridge anchors, seismic measurements, and specific chemical processes
to name a few.
In many ways, process specifications are specified procedures and are
often regarded as procedures as opposed to specifications. For example,
the American Society of Mechanical Engineers (ASME) Boiler and Pressure
Vessel Code contains specifications that include process procedures. 6. STANDARDS
The use of standards has already been mentioned in conjunction with
construction and manufacturing specifications. Nevertheless, standards
are specifications in a category of their own. They are written by
national and international bodies (the ASME Boiler and Pressure
Vessel Code is used internationally), by industries, and even by large corporations.
There are many examples of standards as specifications. The U.S. Military
Specifications, the Canadian Federal Department of Works Master Construction
Specification, and Ontario Power's extensive welding standards fall
into this category. Standards, however, can be one of three types:
Specification writers need to be familiar with each type of standard
to avoid the mistake of unnecessarily restricting the sources of supply.
A too rigid specification can limit competition and lead to over-priced
goods and services. In summary, the first type is rigid in its definition;
the second allows greater flexibility of supply; and the third is more
general in nature, allowing for various configurations in which goods
and services can be supplied.
Here are some points worth remembering in the use and application of
standards.
In retrospect, the use of standards is beneficial and their use also helps reduce the size of originally-written specifications. ANATOMY OF A SPECIFICATION 1. IDENTITY 2. REVISION REFERENCE 3. TITLE 4. INTRODUCTION 5. DESCRIPTION 6. PERFORMANCE
7. CONSTRUCTION 8. RELIABILITY 9. QUALITY ASSURANCE
The purpose of imposing quality assurance standards, as opposed to
standards in general, is to provide an organizing framework within
which the contract is carried out. The specifications define the
quality of the service. Inspection and test requirements, forming
part of the quality assurance programme, do not improve the quality
of product or service, but provide objective evidence of the quality
of goods or services provided.
The choice of what level of QA programme to specify is an economic
one. Such programmes are expensive to develop and apply. The more detailed
the programme, the greater the assurance that the service provided
is of the required quality. The cost of the programme specified however
must be assessed against the consequences of defective goods and services
supplied to a less intensive programme. Increased costs stem from the
rejection of parts during construction or their re-work.
10. PACKAGING AND STORAGE 11. STANDARDS AND SPECIFICATIONS 12. RECORDS
The retention of accounting records is required by law. The retention
of manufacturing, inspection and performance test records is what
any manufacturing or service contractor observes for self-protection.
Clients who issue specifications frequently have to meet national
and industry regulatory controls by maintaining manufacturing as
well as operating records.
Equipment manufacturing and maintenance records, sometimes referred
to as history dockets, are essential when something goes wrong. They
are equally essential for maintenance supervisors and operators who
were not present when the equipment was received and commissioned.
For these reasons, specifications should include:
SPECIFICATION WRITING
The objectives for which specifications are written were dealt with
in the introduction to this session. Specification writing as used
here includes the text, drawings, illustrations and sketches.
The basis for development of a specification is the same as that described
for writing a technical report or procedure. To reiterate the advice
given throughout these articles, the steps are:
It is not necessary to dwell on each of these steps in detail. Advice,
however, that applies in particular to specifications is:
REVIEW AND APPROVAL
* George R. Whitten, Jr.,Inc,. d/b/a Whitten Corporation, Plaintiff-Appellant v Paddock Pool Builders, Inc., et al., Defendants-Appellees. No. 74-1169 (Decided Dec. 17, 1974). Ref. 424 Federal Reporter, 2nd Series, pages 25-36; 376 Federal Supplement, pages 125-138; 508 Federal Reporter, 2d Series, pages 547-562. |
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