26.6 Engineering and design

Engineering and design are the processes of applying the principles of physics to achieve the desired output from the constructed work and the process of creating drawings and details to communicate to suppliers and constructors exactly how the facility should be constructed or assembled to achieve the desired results. Engineering and design are complicated processes that brings together a vast array of components and elements to create a constructed work or utility. This text specifically separates the engineering process from the design process although they are often performed by the same person. Engineering is science. Design is art.

26.6.1 Standards, Best Practices, and Codes

Since the first use of manufactured gas for lighting over 200 years ago, engineers and operators have merged the laws of physics with practical experience to produce engineering standards and accrediting organizations for those standards, all in the interest of assisting and advancing the industry. The American Society of Mechanical Engineers formed in 1880 did much to further pipeline standards. Since that time the name has been changed to ASME International as a way to downplay the fact that this association for much of its history had an American base. ASME International defines standards as follows:

A standard can be defined as a set of technical definitions and guidelines, “how to” instructions for designers, manufacturers and users. Standards promote safety, reliability, productivity and efficiency in almost every industry that relies on engineering components or equipment. Standards can run from a few paragraphs to hundreds of pages, and are written by experts with knowledge and expertise in a particular field who sit on many committees.

When a standard is adopted by a governmental body, it assumes the force of law and achieves code status. The distinction between standards and codes is important and so merits a bit more discussion. Standards are based on universal laws of physics. For example, the determination of maximum allowable pressure in a pipeline is the application of a hoop stress analysis, the same the world over. This is a standard. When the hoop stress calculation is applied to determine the maximum allowable operating pressure, however, different regulatory bodies will set different factors of safety. This is a code.

Some of the standards-issuing organizations include the following:

- American National Standards Institute (ANSI)

- American Petroleum Institute (API)

- American Society for Testing and Materials (ASTM)

- ASME International (ASME)

- ASTM International (ASTM)

- British Standards Institution (BSI)

- European Committee for Standardization (CEN)

- Gas Technology Institute (GTI)

- International Organization for Standardization (ISO)

- Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. (MSS)

- NACE International (NASE)

- National Fire Protection Association (NFPA)

- Pipeline Research Council International (PRCI)

- Plastics Pipe Institute, Inc. (PPI)

- Russian Industry Standards (SNIP)

Providing a complete listing of standards is beyond the scope of this text, but two widely used standards for the pipeline industry are ASME B31.8, Gas Transmission and Distribution Piping Systems, and ASME B31.4, Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids. These standards are certainly the longest standing, and referring to them will cover the vast majority of designs anywhere in the world.

Codes often incorporate standards by reference, but codes—rules and regulations—vary depending on the country involved. The primary code governing natural gas transmission and distribution safety in the United States is contained in CFR Title 49, Part 192—“Transportation of Natural and Other Gas by Pipeline,” enforced by the Department of Transportation. The U.S regulations for oil are contained in CFR Title 49, Part 195—“Transportation of Hazardous Liquids by Pipeline.” In the United Kingdom, the regulations are Statutory Instrument 1996 No. 825, “The Pipeline Regulations of 1996,” enforced by the Health and Safety Executive. Engineers are advised to determine the particular codes applicable to the country in which the pipeline they are designing will operate.

One final note, standards and codes are not design manuals and do not take the place of experience and operating knowledge. Engineers cannot just “take the standards off the shelf” and design an effective system, but they may be able to properly engineer a system using only standards.

Standards and codes define the constraints or boundaries on design, and only a competent engineer can in consultation with knowledgeable operators determine the most effective design elements.