Success Factors for Pipe Design and Stress Analysis in Heavy Industrial Facilities

 

 

Contributed by Brian C. Gray, P.E., Lead Mechanical Engineer

_____________________________________________________________

Success Factors for Pipe Design and Stress Analysis in Heavy Industrial Facilities

Drive by or walk into any refinery, power plant, chemical plant, or petrochemical facility anywhere in the U.S. or abroad, and you invariably notice one of the most predominant and common features between them all:  the systems of piping.  While steel structures, mechanical and electrical equipment, and buildings fill in most of the other available space, these facilities are often defined and characterized by the miles of sophisticated networks of piping that form the arteries of production and ultimately equate to revenue and cash flow for the owner of the plant.  How this piping is designed and constructed has a direct correlation to the successful operation, maintenance, and reliability of the facility, and also to the profitability and performance of the engineering, procurement, and construction entities responsible for its design.

The Foundation of Successful Piping Design and Stress Analysis

From the standpoint of design, a piping system must meet the following tenets and be:

  • Structurally safe for the facility personnel and the public at large,
  • Materially compatible with the solids, liquids, or gases for the process in the associated external environment,
  • Economically constructible,
  • Accessible for maintenance and operations around equipment and structures, and
  • In full compliance with all requirements and provisions of the appropriate American Society of Mechanical Engineers (ASME) or other construction codes and pertinent client standards.

It is this last bullet where piping designers and engineers spend much of their time to physically layout the piping systems and analytically evaluate them for flexibility, structural integrity, and their impacts on other structures, equipment, and components.  Pipe stress analysis is the primary mechanism to determine the acceptability of the piping system along its extent and at all of its connections.  Conversely, the pipe stress analysis phase is often where some of the most costly oversights and critical misses occur on a design/build project.

The Business Impacts of Pipe Stress Analysis

On a typical medium (>$10 million) or large (>$100 million) heavy industrial project, it is not uncommon for the piping to represent anywhere from 40% to 50% of the total installed cost of the project factoring in the engineering, materials, labor, inspection, and turnover/commissioning involved.  If equipment size, layout, or accessibility is not appropriately taken into consideration, the pipe stress analysis efforts can take considerably longer to complete and result in an overly complicated and more expensive piping system to fabricate, install, and inspect, not to mention cause delays or busts in the overall project schedule.

From past, personal experience, I can say without hesitation that it is a very humbling experience to listen to a client’s project team deeply and sharply criticize a final constructed piping arrangement and require extensive modifications prior to system turnover and acceptance.  At that point, the entire EPC team has failed the client, and even if the “redo” meets their needs, the stigma and bad feelings will linger and can impact the financial performance on that project and even eliminate any opportunity to perform future work for them.  Also, the heavy industrial world is a lot smaller than it seems, and word of mouth (or email, text, etc.) can travel fast and potentially jeopardize opportunities with other current or potential clients.

Collaborate and Engage to Ensure Pipe Stress Analysis Success

A successful pipe stress analysis begins early in a project and affects all parties associated with the job.  The piping designers and engineers must be fully engaged with the Project Team at the onset of a project to evaluate the proposed general arrangement for a new facility or how the piping or new equipment will be introduced into an existing facility.  The piping designers and engineers must work closely with the process engineers to understand the overall P&IDs—especially any piping configuration vital to the process itself—and correctly integrate the piping into the facility tie points.  Interaction with the civil/structural group on foundation locations, pipe racks, and miscellaneous steel is critical to the routing and proper support of the piping system.  Additionally, coordinating the pipe routing with the electrical and instrumentation group is essential for the proper layout and spacing of cable trays, quantifying material and layout for heat tracing, and ensuring correct piping arrangement for in-line instrumentation and instrument connections.

The working relationship between piping designers and engineers must be seamless and involve collaboration early in the job to address critical piping and the incorporation of flexibility into the design during initial routing, rather than cycling through numerous iterations of the piping layout later in the project when schedule and the impact of change management becomes much more critical.  It is equally essential to keep Project Management aware of piping progress and to review issues before they happen or as early as possible.  Such collaboration can head off potential problems and may even serve to get the client involved to provide insights and recommendations based on past experiences that incorporate a more holistic approach to the piping design.  Lastly, the pipe stress analysis may require an equipment vendor to structurally modify or augment its equipment to handle loads that exceed allowable values.  Such a solution can often be more economical and better for the project schedule as opposed to modifying the piping system directly, especially in areas of high constraint or limited spacing.

Pipe stress analysis is a complicated and time-consuming process that requires competent and experienced personnel working with the right tools and collaborating effectively with many other disciplines and project stakeholders.  If involved early in the design phase of a project, the piping team can properly account for the complexity and known variables of the process, layout, and constraints present to best ensure that the piping portion of a job is executed safely, is done correctly per the construction code and client’s standards, and can directly lead to a satisfied customer ready to work with you again on the next project.

_____________________________________________________________

Brian Gray, P.E. – Lead Mechanical Engineer

B.S. in Mechanical Engineering, MBA w/ Project Management

Brian has more than 20 years of industrial engineering experience in engineering and project settings. His past experiences includes detailed mechanical equipment design and specifications, piping system designs, and extensive project engineering in the power, chemical, and refinery industries, from simple engineering-only projects up to and including full EPC turnkey deliveries, and key management roles in engineering for Lauren Engineers & Constructors, Inc., in Dallas, TX.

Leave a Reply

Your email address will not be published. Required fields are marked *