Revisions and Updates of Engineering Codes and Standards
Engineering codes are active, dynamic, and constantly evolving. They are subject to changes as new information becomes available, whether from research or practical experience, and are modified accordingly. They are also reviewed for their precision and for possible inconsistencies, keeping in mind the generally complex relationship interlinking different codes and standards. As cross-referencing is the norm for these types of documents, it’s important to make sure that any possible mismatches between them are avoided, and if they do occur, that they be promptly remedied.
Codes and standards provide us with information based on the best knowledge and information available at the time of each edition and revision. They allow us to design safe and economical equipment, applying best practices and ensuring the efficiency, safety, and integrity of both the system and the personnel involved in its fabrication, construction, and maintenance. That’s why it’s imperative that they be periodically revised and updated.
Codes and standards issued by world-renowned organizations such as ASME and API are regularly reviewed and amended, sometimes undergoing only minor changes, such as updating an address, and other times undergoing major, game-changing modifications such as completely renovated allowable stresses for equipment with previously less conservative requirements. These adjustments, both big and small, are all part of the general process of updating and correcting the information provided. It is also important to note that before publishing a completely new revision of a code or standard, organizations such as ASME and API often issue amendments or addenda. These are partial updates that address some specific and urgent changes that must be taken into account prior to the release of the next complete edition.
Two editions of ASME B31.3 for Process Piping
The types of changes implemented in engineering codes and standards, which in some cases reach nearly 100 total changes per edition, range from minor modifications such as the renumeration of footnotes or section title revisions, to the adjustment of minimum preheat temperatures, or are even as far as the modification of the established compatibility of different service fluids with various materials. Changes such as these are made to ensure clarity and precision when reading and interpreting the guidelines set forth in each section of the code, as well as to update said guidelines in accordance with new information gathered from research about fluids and experience with equipment such as piping and pipeline systems, pressure vessels, or heat exchangers, to name a few.
These changes can also cause a lot of headaches, especially regarding equipment design, maintenance, and repair. For example, many codes in their newer editions include reduced values for allowable stress criteria or establish different compatibilities of materials with certain fluids such as gas or liquid hydrogen. There are tables that list such compatibilities that have undergone complete renovations, changing entirely the previously accepted materials for certain services based on the discovery of their incompatibility or tendency to cause materials to become susceptible to embrittlement, for example. Another example is the removal of mandatory appendices, sometimes leaving them completely eliminated and out of play, and in other cases, reclassifying them as non-mandatory, meaning they no longer are obligatory, but rather are provided as guidelines.
Example of a deleted Mandatory Appendix in ASME PCC-2-2022 Repair of Pressure Equipment and Piping
As mentioned, sometimes the changes are based on conclusions gathered from ongoing research. As more information is discovered by researchers in up-and-coming fields such as hydrogen, which is being studied due to its potential as a massive and previously underutilized source of energy, (especially as it has become a clear intermediate vector in the energy transition towards a net-zero carbon emission goal), this new information must be taken into account as far as it can affect the safety, efficiency, or reliability of equipment.
Other times, changes are due to experience, which may include observations about the behavior or interaction of certain materials, or the practicality of equipment and accessory layouts and configurations. Unfortunately, they sometimes also stem from catastrophic, and at times, even lethal accidents due to critical equipment failure. In such cases, the root cause of the failure must be investigated, identified, and analyzed in order to be remedied and prevented in the future. This, of course, is the main goal of all codes and standards, though often times these valuable lessons come at a tragically steep price. There are many notable incidents, well known in the engineering community and beyond, that highlight this point and demonstrate just how important it is to properly and concisely adhere to the rules laid out by codes.
Knowing that codes undergo such revisions leads us to the question of how we can know what differences are present between each edition. Fortunately, each new edition includes a summary of changes that lists and specifies all the modifications made from the previous edition to the current one, allowing users to easily identify changes that will possibly affect the application of the code they plan to implement. These summaries list the page and location of each change, as well as a description of the change that was made, providing transparency and in a way, a record of the advances that were made in engineering knowledge and best practices.
Example of a Summary of Changes found in an ASME Standard
Since each code and standard has various revisions, when designing and implementing repairs and/or alterations to any equipment or system, it’s important to refer to the version of the code that was used for the initial design, as to ensure compatibility of such repairs and alterations. This is standard practice with codes in general and is important to keep in mind as a rule of thumb any time a repair or alteration is to be performed. Such information should be specified in the records of each system, as to facilitate the process of determining which edition of the code should be used as a reference for designing and implementing the repairs and alterations.
In conclusion, it’s clear that engineering codes and standards must be treated as the active, dynamic documents they are, subject to ongoing modifications as advancements are made in the many fields of engineering. This means that utmost care must be taken when determining which editions of the codes must be referenced, which is vital to ensure the safety of all individuals involved in the design, fabrication, repair, and maintenance of equipment, as well as to ensure maximum efficiency and integrity of the equipment itself.
For more information:
ASME B31.12 | Design of Hydrogen Piping and Pipelines
Intro. to ASME B31.12 Hydrogen Piping and Pipelines
ASME B31 | Design of Piping Systems for Industrial Plants
ASME VIII | Design of Pressure Vessels for Industrial Plants
TEMA | Design of shell & tube heat exchangers for Industrial Plants
API 650 | Design of Aboveground Storage Tanks
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