A. Parmar, Engineering Director, Corona, California; C. RENTSCHLER, Consultant, Lititz, Pennsylvania; and G. SHAHANI, Adjunct Professor, Allentown, Pennsylvania
In the chemical processing industry, plant maintenance is critical to achieving successful business outcomes regarding plant output, production efficiency, plant safety and environmental performance (FIG. 1). In developed economies, process plants are aging, and new investments are more complex to justify with the current relatively high capital costs and pricing pressures. Therefore, maintaining and upgrading existing assets have become even more critical in the current economic environment. The goal of a comprehensive maintenance program should always be tailored to maximize business performance rather than minimize maintenance costs.
In the past, maintenance was viewed as a necessary evil. Repairs were carried out only when equipment or machinery broke down. This led to unplanned downtime, which is expensive in terms of lost production and associated revenues. In addition, the repairs took longer and cost more due to the expedited shipment of parts and overtime labor costs.
A better and more proactive approach is preventive and predictive maintenance. This is the systematic practice of proactively carrying out maintenance before failure occurs. Preventive maintenance is more cost-effective and better in the long run. It also results in improved environmental performance due to reduced emissions and leaks. Equally important, safety is also improved with preventive maintenance. Furthermore, from a business perspective, maintenance costs and timing are predictable. In the maintenance world, keeping the basics in perspective is vital. Systems can be easily overwhelmed by spending money on projects and programs that may not add enough value. For example, operating a complex with a highly featured computerized maintenance system with a flashy dashboard will not improve a piece of equipment’s mean time between failures (MTBF), and overinvesting in reliability-centered maintenance may see diminishing returns on value added. Proactive maintenance practices for various systems are described in literature.1 Artificial intelligence (AI) is expected to enhance the development and execution of maintenance programs in the future.
This article will review various maintenance activities, including emergency repairs, routine preventive and predictive maintenance, annual turnaround and computerized maintenance management. Optimal results are achieved when design, engineering, operations and maintenance teams work together seamlessly. Plant maintenance must be considered early in the design stage of a processing plant for the best operational results.
Types of maintenance. Maintenance is broadly classified into two types: corrective and preventive (FIG. 2). Preventive maintenance is time priority- and risk-based, predictive and condition monitoring-based, while corrective maintenance is attending to an emergency or fixing an identified issue while performing preventive maintenance.
Corrective maintenance: This type of maintenance includes:
Emergency repairs—These repairs are unplanned and could arise from an emergency with an undesirable imminent safety or environmental impact. Emergency repairs may be needed for an equipment breakdown affecting production with consequential impact on revenue.
Preventive maintenance: This type of maintenance includes:
Priority-based repairs—These repairs are based on a defined priority (such as 1, 2, and 3), with the first category being the most important. The priority determines the schedule, ranging from a next-day fix to a fix that must occur within a couple of weeks.
Annual turnaround is considered a fixed-time period activity. This comprehensive program is scheduled several months in advance and requires up to several weeks of planned downtime for a large facility. Turnarounds require several weeks of planning.
Predictive and condition monitoring—These are generally proactive measures to prevent issues such as line stoppage or equipment failure. These programs could be based on a fixed or floating time period based on service hours and a usage-based trigger.
Plant design to facilitate maintenance. A plant’s project design phase is crucial for the success and ease of maintenance during operations. Maintenance personnel are often not involved in the design phase; subsequently, their job becomes more complex and time-consuming after a handover from projects to operations. Ultimately, this adds unneeded downtime and costs to plant operations. This would prove not only costly but also unsafe. For example, space for working on equipment and component removal is crucial for efficient maintenance. Maintenance personnel should be considered an integral part of the design phase, especially during the layout phase.
Decades ago, maintenance access and equipment removal were based on design work using 2D drawings. This worked, in general, but it was very challenging to ensure everything was considered. Then, as a next step, plastic or wooden plant models were used to ensure proper plant design. This usually worked but was cumbersome and costly. Often, the models were moved to the plant site once the plant began operation. Finally, the processing industries are utilizing detailed and efficient 3D computer models. In 3D modeling, one can zoom in on any corner of the model, get dimensional details, calculate space availability and conduct a virtual walkthrough of the space. This facilitates maintenance design and ensures a high degree of success. However, the detailed design is only as good as the requirements and oversight provided by maintenance, so it is crucial to involve this group early and often. Some of the critical issues to be considered in the design for efficient plant maintenance include:
Locate equipment and piping so they can be easily accessed: A mechanical designer locating a piece of equipment by considering space and proximity to connecting equipment may not consider the accessibility of the piece of equipment by maintenance personnel. What looks ideal from the standpoint of minimizing piping or conduit may create a nightmare for a maintenance worker. For example, putting equipment on a platform may be viewed as managing space efficiently. However, this would require a holistic review considering accessibility and required clearances for maintenance accessibility. Input from maintenance is vital to ensuring that equipment is placed optimally for ongoing maintenance.
Locate instruments and gauges where they can be easily read: With today’s technology, there are fewer field instruments. Most data is available in the control room. However, local data is often needed during maintenance activities, so this information should be readily available. When scanned through a mobile device, a barcode can fetch the required information at a particular location.
Ensure sufficient and convenient worker access and workspace: Getting to the equipment is only half the problem. Once there, it is frustrating for maintenance personnel to not have a sufficient workspace. Maintenance personnel should be requested to provide their desired “work envelope” around the equipment. This can then serve as dedicated space as maintenance is performed, and drawings should show this envelope so other components are kept out of this space.
Design for equipment and component removal: An essential aspect of designing for maintenance is to ensure that accommodation is made for equipment or component removal (e.g., the removal of a pump or the replacement of heat exchanger tubes). Removal “alleys” should be designated so sufficient space exists for removal. If there are walls, accommodation should also be made for going through these walls if needed in the future. Finally, ceiling and wall embedment or lifting beams should be located so the equipment can be easily moved using hoists and other mechanical tools. Piping flanges or equipment connecting locations should be considered, ensuring they are placed in the right location to help with maintenance and service.
Provide utility access, such as power outlets and instrument air: Maintenance personnel often require power or instrument air for their tools and tests. Instead of addressing these needs by running temporary power cables or hoses, it is more convenient to provide permanent sources for power and instrument air. Experienced maintenance people can identify plant locations that will benefit from these installations.
Input from maintenance and operations teams: Input from maintenance and operations teams is vital to identify redundant equipment for critical processes, process control, automation and operations. It is also essential to have employ maintenance personnel who can troubleshoot automation. This can be outsourced to a trusted partner, and this company can fix issues or make improvements as necessary. Think ahead of maintenance expectations. For example, when ordering a piece of equipment, it makes more business sense to get a good deal by lumping the critical spare parts for maintenance rather than at a later stage. When equipment is installed, or during construction, maintenance can initiate the review of original equipment manufacturer (OEM) manuals and create preventive maintenance plans. Such activities would ensure maintenance readiness before startup and commissioning.
Keys to success. The keys to success in maintenance are a combination of personnel skills, proper planning, and the right materials and tools.
People. Maintenance personnel should possess adequate knowledge, skills and a proper attitude. The goal is to create a culture of continuous learning and skills development. A mature maintenance organization can contribute and add value during the project design phase.
Planning. This includes a joint goal-oriented partnership between maintenance and production, with input from commercial and financial functions.
Material and tools. It is critical to have all necessary spare parts available. The right tools, such as a fit-for-purpose computerized maintenance management system for shutdown or turnaround activities, should be used. These tools should be able to measure performance (e.g., productivity and costs) and track, monitor and provide alert notifications to take appropriate action.
Design. It is important to consider maintenance during the design phase to ensure low lifecycle cost, maintainability, reliability and safety.
A sound maintenance organization is critical to operational sustainability. Begin with the basics to obtain a true understanding of the maintenance organization, crew teams and mechanical functions by asking the following key questions2:
What are you doing?
Is it getting better?
How do you know?
Can I help?
In addition, periodically auditing the maintenance department—with the joint efforts of operations, safety and maintenance personnel—is a good idea. Achieving common goals to optimize the manufacturing plant should also be a goal.
Takeaways. Effective and timely plant maintenance is the cornerstone of efficient plant operation and substantial profits. This involves both emergent maintenance issues and planned outages. In both cases, the plant staff must be prepared to address the challenges that could hinder operation. Proper maintenance also leads to a safer plant and one that produces fewer emissions. Detailed planning and budgeting ensure a solid maintenance program. Designing for maintenance is critical in the plant’s design phase and should involve maintenance personnel. Maintenance activities can be very efficient if sufficient space, access and outage utilities are considered in the design. Effective maintenance is the job of all those involved in plant design and operation and will lead to effective plant results when adequately coordinated. HP
LITERATURE CITED
Chemical Process Plants—Proactive Maintenance Practices, Chemical Engineering, online: https://store.chemengonline.com/shop/chemical-process-plants-proactive-maintenance-practices/
Lee, R., The “Maintenance Insanity” Cure: Practical Solutions to Improve Maintenance Work, Industrial Press Inc., October 7, 2017.
Ashim Parmar is Senior Director of Engineering at Del Real Foods Inc. He has more than 25 yr of experience in project management, operations, maintenance, reliability and start-ups. His primary responsibility is ensuring that projects are completed on time, in compliance and within budget. Parmar is focused on continuous improvement and digitizing with a value-added approach. He has previously worked for Eastman Chemicals, International Flavors and Fragrances, Symrise, Novartis and Pfizer Pharmaceuticals.
Carl Rentschler is a Senior Manager and Consultant specializing in project management, business development, construction, engineering management and talent acquisition related to the petrochemical and power industries. He has more than 40 yr of varied engineering and management experience with Parsons, Air Products and Linde. Rentschler is a licensed professional engineer, and earned a BS degree in civil engineering from Penn State University, and an MEng degree from Cornell University.
Goutam Shahani is an Adjunct Professor of finance and statistics. He retired as Vice President of Sales and Marketing at ShureLine Construction in 2020. Shahani has 40 yr of experience in industrial marketing, business development and asset management at Air Products, Linde and ShureLine Construction. He has over 60 publications and patents in the energy and environmental sectors. Shahani earned BS and MS degrees in chemical engineering and an MBA.