10.1 Introduction

In Chapter 2, it is pointed out that standards are generally written to achieve safety and reliability, to reduce cost and increase flexibility, to promote business, and to help society function. A well-written standard will accomplish these goals effectively. A poorly written one will accomplish them less well, and may even impede them. This chapter identifies those characteristics that make for an effective standard. These characteristics help in selection when there is a choice of standards, development when a new standard is needed, and effectively supplementing an existing standard with proper text in a specification, statement of work, or other contract documents.

10.2 Clarity and Understanding

In order to achieve its intent, a standard must first be understood. This seems obvious, but since this discussion is related particularly to engineering standards, it may be more difficult to accomplish than it first appears. The nature of many engineering standards is technical, sometimes highly so. While not everyone will be able to understand fully the content of a technical document, a standard should be written, and provided with sufficient definitions so that a technically competent user can understand it. Further, it should be written such that a person not well versed in the field, but taking time to read it carefully, can comprehend the general concepts and requirements, if not the technical details. In some cases this can be a challenge, as when a standard of limited scope in a specialized field makes reference to and has requirements for compliance with one or more similarly technical and specialized documents.

If a standard assigns responsibilities to a person or organization, the responsible party should be clearly designated. If there are special qualifications that go with assigned duties, these should be clearly indicated. While a number of standards developing organizations make a practice of using “shall” for requirements, “should” for recommendations, “will” for expected consequences, and “may” for permissions, some organizations have other conventions. Whatever terms are selected must be clearly defined and assiduously used.

Many organizations lean toward performance standards over prescriptive ones, the idea being that this allows the performing organization the greatest flexibility to implement better or cheaper ideas. Also, standards are written to aid in accomplishing something, and a well-written performance standard is closer to defining what is needed, rather than a solution that may not be the best one. On the other hand, it is often difficult to define every requirement. If every requirement has not been well thought out and documented, then prescribing a known successful solution is often safer than trying to identify every detail needed for an effective performance standard.

10.3 Scope

The scope of a standard ranges from very narrow and specialized to very broad. Whatever be the case, it should be clear and well defined. The following two examples illustrate this:

1. Example 1: ASME SA-20, Specification for General Requirements for Steel Plates for Pressure Vessels, consisting of only 41 pages of the ASME BPVC Section IIA, includes common requirements that apply to 33 steel plate specifications for fabrication of pressure vessels. It references 50 standards, including the 33 plate specifications as well as 17 standards related to terminology, testing and inspection, welding, marking, and handling. This standard defines within itself the requirements for how plate should be ordered and manufactured, test methods and reporting and retests, quality and rejection criteria, tolerances, marking, packaging requirements, etc. It leaves to the individual plate specification the actual chemical and physical properties, whether certain tests are required, and it leaves to the purchaser identification of any supplementary requirements, although it specifies many details for the case where supplementary requirements are specified. This standard has a fairly narrow scope.
2. Example 2: ASME B31.3, Process Piping (originally the Chemical and Petroleum Refinery Piping code), at over 500 pages, was developed “considering piping typically found in petroleum refineries; chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants and related processing plants and terminals.” It applies to all fluids, but has clearly defined exclusions. It references hundreds of other standards and hundreds more by references within those. It includes by reference the ASME SA-20 specification referred to above. This standard has a wide scope.

The difference in scope between these two standards is immense, but a study of each document reveals that the scope is clearly defined, and that each document addresses its scope without straying beyond. Further, across the scope of each document, the depth of treatment is relatively consistent. ASME SA-20 covers only the general requirements for certain steel plate material, while ASME B31.3 addresses the production of piping systems for a wide variety of applications and using a wide range of product forms. In order to maintain a consistent level of detail and to avoid a document running to thousands of pages, B31.3 makes reference to plate, bar, forging, pipe and tube, and other standards. These standards, in turn, reference others, including ASME SA-20, and SA-20, in its turn, requires compliance with other standards dealing with the rolling process, nondestructive evaluation, etc.

This approach allows a fairly concise document addressing the specific concerns of those involved with production of steel plates (in the case of ASME SA-20) or production of process piping (ASME B31.3). The details of how to perform NDE of the steel plates in the case of SA-20, or, tolerances, NDE, etc. of those plates, in the case of B31.3, are included in reference standards that address the specific needs of those involved in those particular specialties.

By constructing what might be referred to as a system of standards, the creators of ASME B31.3 have produced an efficient document that can be used in conjunction with whatever reference standards are appropriate for a particular situation (and the particular business that a company might choose to pursue). This provides an efficient way of managing a vast number of requirements.

10.4 Terminology

Use of specialized terminology, and of terms with a meaning different in the context of the document than in common speech, should be clarified. In this respect the document should be able to stand on its own. Specialized terms and expressions may be unfamiliar to the general reader, yet may need to be used in order to convey accurately the intent of the document. The process of standard development typically includes discussions of which terms require definitions, and which ones are sufficiently understood from the common use of language or from definitions understood in the engineering field in general.

10.5 Structure and Organization

The structure of a standard is dependent in part on its content, but just as there is more than one way of structuring a corporation, there is more than one way of arranging information.

To provide for their efficient use, engineering standards are most often constructed in a modular manner, whether internal to a single standard or as what might be considered a system of standards. A top level standard may refer to a number of other standards that help in the definition of an overall product. Although some repetition may occur, this approach minimizes the need to repeat common requirements.

For a standard addressing the design and fabrication of a product, it is usual to provide a design section distinct from those sections addressing fabrication, inspection, testing, qualification, etc. It would, however, be possible to place the inspection requirements in a standard next to the aspect of fabrication to which each applies. Most standards follow the former organization. This approach seems to work well, although its use is partly for historical reasons (this is the way many standards have been written for the last century) and partly because so many of the supporting standards fit better with a document that is arranged this way.

For ease of use, it is usual to keep related information together in a standard. Consistent with the strategy, the standard developer should strive to place all text, figures, tables, and equations for a given topic, say, earthquake analysis, in one section rather than spread it out over many chapters. An organization that requires the user to flip back and forth between chapters to extract information makes the use of that standard inefficient for the engineer and increases the likelihood of errors.

An example of effective placement of information is found in Mandatory Appendix 2, Rules for Bolted Flange Connections with Ring Type Gaskets, of the ASME BPVC Section VIII, Division 1. Everything from bolt loading to gasket type to figures for use in calculating stress, is found in this single appendix, generally in the order in which it will be used by the engineer.

Once a structure and organization is selected, it is important that it be followed, and whatever structure is followed, it should be logical, such that once a person becomes familiar with the standard he/she will find information where it is expected. There should be no need to go on an extended search for requirements that clearly “must be there somewhere.” At least one standard exists in which not all the design requirements are found in the design section (some are in the testing section), and not all the testing requirements are found in the testing section (some are in the design section). This leads to confusion, much searching around, and the possibility that requirements will be missed by a user who is not thoroughly acquainted with the document. There are plans to correct this situation in the next revision of this particular standard, but a little more thought given to the structure of the standard and placement of information within it could have avoided the problem.

10.6 Consistency

Just as it is important to follow the selected structure of a standard, it is important that the standard be consistent. In developing a standard, particularly a complex one of any length, it is not unusual to address different aspects of an item in different places or sections of the document. Because these sections may be separated by a large amount of text, and may in fact be written by different authors because of the way work is divided, care must be taken to examine the document as a whole to ensure consistency. Standards developing organizations often find themselves in the position of addressing inquiries inspired by apparent inconsistencies, and at times even making changes to correct such inconsistencies. A particularly helpful aspect of organization of the ASME B31 piping codes is that each follows the same structure, so that the requirements for a particular aspect of piping design or fabrication are found in the same paragraph in each of the codes, differing only in the first digit of the paragraph number, which reflects the “.X” designation of the respective standards (e.g., for ASME B31.3, paragraph numbers begin with 3).

10.7 References to Other Standards

Most engineering standards will require references to other documents and standards. This need should not prevent a standard being consistent, unambiguous, and fully covering its stated scope. As can be seen from the examples above, a standard need not explain every detail. Further, standards are designed to be used together to achieve their goals. When other standards addressing a particular aspect of the scope of a standard already exist, those other standards can help fill out the scope if properly referenced. This approach avoids both redundancy and contradictions. It saves development time and minimizes the need for deciding among multiple standards covering the same topic; and finally, it allows those already familiar with the referenced standard to proceed without the need to study another document.

10.8 Attention to Details

It should perhaps not need mentioning, but the spelling, grammar and syntax, references and cross references, and every other detail of a standard should be thoroughly checked and rechecked. If “shall” has been selected as the term for an imperative, for example, then a word search should be made for every other likely term that may have slipped in, so that each can be corrected if needed. Many people will be depending on the quality of the product.

10.9 Supplementing a Standard

When a standard is cited or otherwise put into effect by an organization, there may be a need either to provide additional guidance or to take exception to certain aspects. Whatever contractual terms are used should hew to the same level of quality that is expected of the standard itself. There is little value in having a clear, well-thought-out, and documented standard which is not clearly invoked, leaving it unclear as to what the actual requirements for a project or task are.

10.10 Timeliness

Often a standard is released for distribution prior to it being completely finished owing to time constraints. This results in confusion on the part of the user and the end result is a reluctance of the targeted audience to use the standard. When this situation occurs, the organization in charge of the standard scrambles to rewrite the standard, filling in the voids and restructuring it as needed. The end result is that it takes longer to release an incomplete standard and fix it than to wait and release a complete standard. Sufficient schedule time must be allowed in order to avoid this situation.

10.11 Sample Standard Structure

For a standard to be widely accepted, it must be easy to use. Accordingly, good organization of a standard is of an utmost importance and the topics must flow smoothly in order to avoid having the user go back and forth in the document. The following is a summary of the essential elements of a standard:

1. Table of Contents. A detailed Table of Contents is very helpful in pinpointing the topic of interest. It, or the index, is normally the first place the user visits prior to using the Standard.
2. Foreword. The foreword normally explains the reason for developing the Standard and the process by which it is developed.
3. Scope/Preamble. The scope or preamble defines the applicability of the Standard as well as its limitations, exceptions, and assumptions. It helps the user understand the applicability of the Standard. Sometimes there are two or more standards that cover the same subject but the applicability is quite different. An example of this situation includes the repair standard for pressure vessels published by the National Board (NBIC) and that published by ASME (ASME FFS-1). They both cover the same subject but are vastly different in their applicability. The NBIC has general repair rules but references other standards for design and analytical parameters. ASME FFS-1 on the other hand has detailed design and technical parameters and methodology for handling repairs. Accordingly, the technical ability of the NBIC code user might be different from the technical ability of the ASME FFS-1 user even though the end result tends to be the same.
4. Terms, Definitions, Acronyms. There is no need for definition of commonly used and understood terminology, but definitions unique to the standard should be provided. This section is sometimes found early in the document, or sometimes as an appendix or a glossary at the end.
5. Reference documents. The need for this section varies, as does its placement, but most often it is not only helpful but also necessary.
6. Topics. Sequence of the topics in a standard varies greatly depending on the type of standard. The following list of topics might be typical for a design standard for fabricated products, and is not intended to represent an exhaustive list:
   1. Design conditions
      1. Dimensional requirements (volumetric minimum and/or maximum, envelope dimensions, etc.)
      2. Materials (if specified)
      3. Loads (force, pressure, moment, etc.)
      4. Life (cycles, years, etc.)
      5. Environments (internal and external, as applicable)
      6. Cleanliness, etc.
   2. Design criteria (may range from fairly prescriptive to fairly broad)
      1. Safety factors or allowable stresses
      2. Stress analysis
      3. Fatigue analysis
   3. Materials (might specify acceptable materials, define characteristics of materials to be accepted, or define processes for determining material properties to be used; may not be applicable in some process standards)
   4. Fabrication
      1. Forming
      2. Welding
      3. Post weld heat treatment
      4. Surface finish
   5. Inspection
      1. Dimensional
      2. Visual
      3. NDT
   6. Testing
      1. Qualification testing (used to qualify a design)
      2. Acceptance testing (less stringent than qualification testing, used to determine acceptability of an individual article)
   7. In-service inspection
   8. Refurbishment and/or repairs
   9. Documentation
7. Appendices. These typically provide information that can stand separate from the rest of the document. They may include information that applies only in special cases or applications, or may provide guidance on topics that are not the main thrust of the document (considerations in performing a pneumatic test on a piping system, for example, in order to ensure a safe and effective test).
8. Index. A detailed index is an important tool in a Standard for helping the users find specific topics and details.

10.12 Summary

The quality of a standard is critical to its usefulness. The characteristics listed above are the basics needed to ensure a useful and effective standard. Each person or group developing a standard should give careful thought to every aspect of the product being produced, and then follow through to ensure that their standard is of a quality such that they, and any other users, will find it effective and easy to use.

10.13 Case Studies

Case Study 1

Using a bicycle to go back and forth to work is becoming more prevalent throughout various metropolitan areas in the industrial world. It is a good exercise and saves natural energy resources. Write the outline of a standard for minimum bicycle requirements when used on major streets and highways with automobile traffic. Outline a standard defining the mechanical, safety, and electrical requirements.

Case Study 2

Select a product or process from your field of interest, and (1) determine what type of standard is most appropriate for it and (2) provide an outline of that standard.