When looking at a Production Plant as a system that takes in raw materials and outputs Dollar Notes, the concept of criticality can be defined in a simple way. Imagine the plant has 100 equipment items labeled from 1 to 100, with various connections and functions. The output could be anything from cartons of cola to medicine tablets, all equating to a daily value of $100k.
Consider what happens when we incrementally increase the output of each equipment item by 1%. For example, some items may see a slight increase in output, while others remain unchanged. This exercise helps identify critical items within the plant.
In addition to production considerations, safety and environmental impacts play a crucial role in determining criticality. Equipment failures that lead to safety hazards or environmental damage can halt production entirely. Therefore, all failures are considered financial losses in this context.
To analyze the impact of these 1% changes, factors such as nameplate capacity, reliability, maintainability, and planned downtime need to be considered. Mathematical modeling techniques like Reliability Block Diagrams and Fault Tree analysis can help in determining sensitivity figures.
Overall, factors like redundancy, buffer storage, low MTTRs, and high MTBFs play a role in reducing criticality. It is important to keep shutdowns short and infrequent to avoid them becoming critical issues. While this information may seem complex, a day in a classroom setting is usually needed to explain it thoroughly.
Terry, have you considered the importance of developing criticality? Depending on your goals, there are various approaches you can take. It's essential to distinguish between true criticality methods and prioritization strategies. Some mistakenly use criticality for maintenance frequency decisions, which goes against fundamental physics principles. Criticality is often misunderstood and misapplied in the field of reliability, as demonstrated by this discussion. So, what is your motivation for creating a criticality matrix?
In the world of reliability, there are various approaches to consider depending on the task at hand. Some focus on real criticality methods, while others lean towards prioritization strategies. It's important not to confuse the two, as using criticality to determine maintenance frequencies goes against the laws of physics. Criticality plays a vital role in establishing maintenance schedules and overall equipment strategies. Without it, what other methods could be utilized? It's crucial to understand each perspective to gain a comprehensive view. Many people mistakenly associate criticality with prioritization, but they are distinct concepts. The misuse and misunderstanding of criticality in reliability are evident in discussions like this one. I'm eager to hear more about your thoughts on this matter.
Hello James F., you are correct in mentioning that criticality is a key factor in determining maintenance strategies. However, it is not the sole factor to consider. Criticality provides a foundation for prioritizing maintenance actions when issues arise. By incorporating production data into the calculation of criticality, you can further refine this process. The dynamic assessment of criticality in relation to current production levels aids in pinpointing essential equipment for maintenance.
- 08-10-2024
- Rebecca Murphy
Vee, I have a few questions for clarification: Is it feasible to achieve a 1% increase in equipment output in actual plant operations? I've come across the concept of plant optimization, which can reveal catalyst limitations but may not address equipment criticality. Is this method commonly used in other facilities? While redundancy and buffer storage can be easily identified, obtaining data on Mean Time To Repair (MTTR) and Mean Time Between Failures (MTBF) can be challenging without proper data analysis using a Computerized Maintenance Management System (CMMS). Can we rely on simple averages of repair times and durations between breakdowns as reliable indicators of equipment performance?
Josh, understanding the impact of a 1% change in equipment productivity is crucial for assessing the sensitivity of the overall plant output to small adjustments. The more significant the change in plant output in relation to a specific equipment item, the more vital that item becomes. These sensitivity analyses are typically conducted in mathematical models since it is impractical to make individual changes in a real plant. However, the accuracy of the model should closely reflect real-life scenarios.
In practical terms, there are multiple ways to enhance equipment performance, including improving reliability through measures like monitoring MTBF and failures per month. Additionally, enhancing maintainability by swiftly addressing faults and getting the equipment back in operation is key. Capacity improvements can be achieved through redesign, such as utilizing a larger impeller for a pump or increasing the speed of a packing machine. Other strategies include reducing setup times, prolonging intervals between shutdowns/overhauls, and minimizing shutdown durations.
In processes involving catalysts, there is a noticeable degradation over time resulting in decreased performance. While this is a natural occurrence, compensating for these losses can be achieved by focusing on the aforementioned improvement factors. Catalyst technology is advancing rapidly, offering longer-lasting options for various applications, albeit at a potentially higher cost. Consider the life cycle costs before investing in these catalysts.
Improving reliability, maintainability, and other factors is essential for optimizing plant performance. By conducting sensitivity studies and modeling the plant, you can identify critical equipment or sub-systems that require attention. For more in-depth information on MTBF, MTTR calculations, look out for my upcoming book "100 Years of Maintenance," set to be published later this year.
- 08-10-2024
- Jasmine Howard
Thank you for bringing up the topic of computer simulation, Vee. It's possible to create these simulations, and I assume the licensor has access to such a computer model for the process.
It is highly unlikely that the model will be able to function without your crucial inputs. These include details on the mode of operation, loading density, reliability, maintainability, availability of spares and logistics, actual capacity (not just nominal nameplate capacity), consequences of failure, and more. As the operator, only you have access to this critical information, not the designer. Therefore, the responsibility falls on your shoulders. It may be beneficial to seek guidance from Consultants who specialize in this area. While software packages like MAROS, MIRIAM, WITNESS, SPAR, and SPARC can help with reliability models, they come at a hefty licensing cost and building/running the model can also be expensive. Thus, it is a decision that should not be taken lightly.
In a typical petrochemical plant, around 10% of the equipment is considered critical, such as fire water pumps, ESD systems, pressure relief valves, and essential single line equipment. These critical components are categorized as "C" for spares, with backup pumps being labeled as either "B" or "C", and the rest classified as "D". The definition of criticality can vary between organizations depending on their risk tolerance, adherence to local safety and health regulations, and the overall reputation of the company.
There are numerous systems available, but one crucial aspect for large facilities is the implementation of a comprehensive database to record all component classifications. This database should be easily accessible to all staff members as it is essential for various tasks within the plant. For instance, the vibration analyst needs it to determine monitoring frequencies, while the work scheduler relies on it to prioritize tasks and schedule preventative maintenance and overhauls. Instead of each individual trying to understand the systems and develop rankings on their own, having a centralized database is much more efficient. In our plant, the risk-ranking process involved advanced computer simulations and expert input. Although I wasn't directly involved in the process, I utilize the results daily to make informed decisions regarding resource allocation for different equipment. This database proves to be a valuable tool in ensuring optimal performance and maintenance efficiency.
Do you have any articles or sample reports on computer simulations for assessing asset criticality? I believe choosing between a simple and quick approach, like generic and vendor strategies, versus a more complex and thorough one, such as RCM, RBI, IPF, is key in developing a maintenance strategy. It's important to consider the evolution from a simple approach to a more complex one over time.
At my job at a nuclear power plant, determining the criticality of equipment is a complex process due to the interconnected systems present. In the past, I would spend a significant amount of time analyzing how components fit into the system and the potential consequences of failure. While this knowledge is valuable, it can be time-consuming and non-productive for me to be an expert on every aspect of the system. Having risk rankings conducted by expert panels and accessible in our plant database has proven to be extremely beneficial in streamlining this process. This streamlined approach has been invaluable in improving efficiency and decision-making in addressing equipment issues.
- 08-10-2024
- Heather Coleman
Josh inquired about acquiring more information regarding computer simulation for asset criticality. Vee suggested checking out the websites of relevant software products for articles or sample reports to grasp the concept better. While such resources may not be readily available in the public domain, Vee recommended exploring these software products' websites. Additionally, Josh mentioned that a chapter on this topic will be included in his upcoming book "100 Years of Maintenance."
Hello James, I apologize for not being in touch recently. I am currently overwhelmed with work, but I am eager to keep the conversation going and appreciate your participation. I will make an effort to provide some clarifications in the next few days. However, I am still awaiting a response to the question I raised with Terry. Can you explain the reason for wanting to utilize criticality, Terry? Thank you.
Thank you Oz for your input. I value hearing different perspectives on determining maintenance strategies. Criticality is important, but not the only factor to consider. Other key factors include spare parts availability, lead time, cost, environmental impact, safety, fire risk, accessibility (especially in remote locations), and political considerations. It's worth noting that political factors can also influence the criticality of equipment. However, let's strive to keep politics out of our workplaces. Your mention of physics caught my interest, and I'm curious to learn more. No rush though, I appreciate your insights and am happy to wait. Thank you!
Hello Daryl, when it comes to determining criticality in reliability, it appears to be a highly established practice with various methods available for analysis. Do you believe that criticality is unnecessary, or are we possibly directing our focus in the wrong direction? Your input would be greatly valued. To others reading this post, feel free to join the conversation and share how you handle criticality in your plant operations. Thank you, Terry O. Let's engage in a discussion on the importance of criticality in plant maintenance.
quote: Josh inquired about any articles or sample reports on computer simulations for asset criticality. To gain a better understanding of the concept, Vee mentioned a methodology for the quantitative risk ranking of components of the space shuttle in a document available at http://foia.msfc.nasa.gov/docs/SAFIE.PDF. Although the link does not include a sample report, it provides detailed information on the methodology. Our plant also utilizes a computer model for similar analyses, albeit less advanced than the one described in the NASA document. Additionally, we rely on input from an expert human panel. The final ranking is determined by a combination of the computer model and expert panel rankings.
Happy New Year, Terry! I want to clarify that I never said criticality wasn't necessary; rather, it is often misunderstood. My query was about the purpose of determining criticality. Criticality is frequently misapplied, leading to overly complex approaches and overlooking underlying failure mechanisms driving maintenance activities. So, why do you want to utilize criticality? Is it to prioritize assets for maintenance activities, identify at-risk assets in real-time, or assist in selecting tasks based on failure modes? I sometimes use criticality methods, typically relying on fuzzy logic with a mix of qualitative methods, choosing the best approach for each situation. Consultants offering criticality analyses often fail to mention that it can only be conducted at the failure mode level, requiring a comprehensive analysis of functions, failures, and effects before determining further analysis. While this process may seem extensive, there are specific applications where it is beneficial. For a quicker asset prioritization method, consider using Analytical Hierarchical Process. Integrating criticality post-RCM implementation can serve as a common reference point for discussing maintenance priorities. Maintenance selection activities inherently address criticality, as it represents the probability and consequences of failure, essentially serving as a risk indicator. However, criticality matrices are not essential for task selection, as demonstrated by the RCM approach. While criticality is valuable when properly applied, it should not solely dictate task frequencies. High criticality does not always warrant more frequent tasks; instead, decisions should be based on the physical science behind failure mechanisms. Ultimately, criticality is beneficial when considering various factors in task selection and can be a valuable tool for implementing maintenance improvements. So, Terry, how do you intend to utilize criticality? Cheers!
Terry, I wanted to emphasize another important aspect of applying criticality that I didn't mention previously: evaluating the criticality of works in progress. This approach is crucial for effectively managing maintenance backlogs and reducing emotional biases that often drive work prioritization. I highly recommend incorporating this practice into your workflow for increased efficiency and effectiveness. Cheers!
James, I appreciate your patience and hope that my previous posts have provided some context for my comments in this conversation. I have some familiarity with RCM turbo from my involvement with it during its time as MPDS for BHP Engineering before it was acquired by Strategic. Many maintenance engineers in Australia were also familiar with it during that period. To address your questions directly, let's consider the example of on-condition maintenance: When assessing stock levels and deciding which items to keep in stock, there are factors beyond just criticality to consider. The key issue with on-condition tasks is the lead time between detecting a failure and the actual failure, known as the P-F interval. If this interval allows enough time for the component to be sourced, planned, and replaced, then there may be no need to keep it in stock. However, if the P-F interval is shorter than the lead time, it becomes clear that the item should be stocked. I hope this clarifies my perspective. While I believe criticality is important and has its place, it is not a cure-all for all plant maintenance challenges.
Daryl, you have mentioned that criticality analyses can only be done at the failure mode level, but I respectfully disagree. Criticality assessments can be applied at various levels such as system, sub-system, equipment, or failure mode. In industries like offshore Oil & Gas, Safety Critical SYSTEMS are acknowledged, and the HSE in the UK recognizes up to 13 such systems. Identifying system criticality is crucial as it helps determine where to focus resources and efforts. While some critical systems may be apparent, conducting a system criticality study can reveal the need for redundant equipment. It is possible to eliminate low criticality equipment without impacting the overall plant significantly. The top-down approach of criticality assessment involves identifying systems, sub-systems, and equipment that could potentially lead to losses in terms of safety, financial, or reputation. Performing a sanity check is essential to ensure nothing is overlooked, for example, inspecting relief valves on low criticality systems may require a quick P&ID review instead of a detailed analysis like RCM. Evaluating physical failure mode criticality aids in determining maintenance tasks and frequencies, as well as identifying degradation mechanisms. While a basic RBD or FTA analysis can identify system-level criticality, more detailed assessments may require mathematical modeling tools such as Monte Carlo or Markov simulators for accuracy. It is important to be well-informed about these processes, and I appreciate Terry for raising this important question.
Which safety critical systems are recognized by the HSE UK? What is the official name of the HSE UK organization that was mentioned earlier? Would it be the UK Occupational Safety and Health Act? It is acknowledged that assigning criticality can be done from systems to parts, but not at the platform level in the oil & gas industry. Some preventive maintenance tasks, such as SDS/ESD instrument input checks, vibration surveys, valve greasing, and lubrication, are tagged to the platform and span across multiple systems. All preventive maintenance tasks are given a work priority of three (3) and are prioritized based on asset criticality. Since the platform is not given a criticality rating, PM tasks located in areas with platform tags will not have a criticality value. How can this issue be resolved? Asset criticality is utilized to identify safety critical PM tasks, as safety critical systems and equipment should have a higher criticality level and ideally require 100% PM compliance.
Analyzing the criticality of a running unit is not as crucial as conducting it during the design phase. Nowadays, designs are becoming increasingly intricate, with few teams prioritizing Reliability-Centered Maintenance (RCM) during the initial stages of a project. Despite numerous complex criticality analyses on various applications, no groundbreaking discoveries have been made that would revolutionize the traditional maintenance models. This suggests that RCM is still in its early stages and requires time to evolve and improve. Do you share this belief? In the offshore Oil & Gas industry, up to 13 Safety Critical Systems are acknowledged, and it is not always necessary to conduct a comprehensive RCM analysis to determine system criticality. Identifying critical systems can help streamline resources and efforts towards areas that require immediate attention. System criticality studies can also highlight the importance of redundant equipment. By utilizing a top-down approach, starting from system level down to equipment level, potential risks that could lead to business losses are identified. While system and sub-system criticality can be apparent in some cases, analyzing failure modes can pinpoint maintenance tasks and frequencies. Employing tools like Monte Carlo or Markov simulators can enhance the accuracy of detailed criticality analysis. It is essential to conduct a thorough review, such as a P&ID assessment, to ensure all critical components are addressed. In conclusion, focusing on criticality at various levels is crucial for effective maintenance planning and decision-making.
In response to your post, it is important to note that conducting a criticality analysis during the initial design phase is just as crucial as during the operational stage. Present-day designs are becoming increasingly intricate, with few teams focusing on Reliability Centered Maintenance (RCM) during the project's design phase. However, this hasn't been my personal experience. I have been directly involved in the mathematical modeling of numerous projects, including conducting RCM activities during the design phase. In fact, some projects had all maintenance tasks, procedures, drawings, spare parts, tools lists, etc., integrated into the Computerized Maintenance Management System (CMMS) before the Plant was even operational. This proactive approach, in my opinion, is vital for achieving top performance. Notably, by conducting criticality analysis early on in the design process, several projects have realized significant cost savings.
It seems there may be some confusion regarding my previous statements, so let me clarify once more. It's essential to understand the concept I'm discussing before continuing the conversation. I have reservations about using criticality alone to determine frequency without considering the underlying failure mode. As an example, I recently completed a significant project in Asia that focused on this aspect. Terry, what are your intentions behind applying criticality? My repeated queries stem from the fact that there are various methodologies for applying criticality or other prioritization techniques. When discussing criticality, it's crucial to establish a common understanding. Criticality typically involves assessing the likelihood and consequences of failure, whether through numerical values, criticality matrices, or qualitative grades. To comprehend the risks associated with asset failure, we must also understand how the asset can fail. This bottom-up approach to criticality ensures a thorough analysis of failure probabilities and consequences.
Additionally, the distinction between criticality and prioritization is essential. Prioritization, based on criteria other than criticality factors, is often used for sequencing efforts and resource allocation. Approaching asset management from a top-down perspective for decision-making purposes may not accurately account for failure probabilities. Decisions made at higher levels may be influenced more by operational significance and economic considerations rather than the potential failure consequences. Therefore, it's crucial to base criticality assessments on detailed information at the failure mode level.
I recommend referring to a document by Expert Choice for further insight on prioritization and criticality: [link]. This systematic approach, incorporating sensitivity analysis and aligning with corporate objectives, has been successfully implemented in various industries, including rail and petrochemical sectors. Emphasizing the importance of conducting criticality assessments at the failure mode level, I believe this method is crucial for making informed decisions in safety-critical industries such as munitions, electricity, and rail transportation. Let's ensure we are clear on the distinction between criticality and prioritization, acknowledging the value of each within the asset management context.
Thank you for taking the time to share your insights on Criticality/Priority. While I may not be a consultant, I aspire to become one in order to delve deeper into the craft and explore its various applications across different industries and levels. Each of us may have different perspectives and approaches, but that doesn't invalidate our insights. It's interesting to see how personal experiences shape our viewpoints. I focus on the core principles of Reliability/RCM/Root Cause and how they can be effectively implemented at a plant maintenance level. Your detailed explanations have sparked my curiosity, and I need some time to digest them before responding thoughtfully. I appreciate your willingness to engage with the questions raised here. Sharing our experiences and knowledge is key to helping others grow. I'm always eager to learn and adapt, even if certain concepts may not be directly applicable to my current work environment. Thank you once again for your valuable input.
Thank you, James. I am grateful for the opportunity to pursue a career that I am passionate about, just like many others in this field.
In today's complex design environment, it is often overlooked that conducting a criticality analysis during the design stage is more vital than for a running unit. Many teams neglect to incorporate Reliability Centered Maintenance (RCM) practices during the initial phases of a project. It's important to note that RCM and criticality are not synonymous. The RCM standard (SAE JA1011) does not specifically address criticality as a key component.
Hey, have you had a chance to review my explanations regarding the 13 essential safety critical systems mentioned earlier?
- 08-10-2024
- Yvonne Mitchell
Josh, I have compiled a list of essential systems commonly used in industrial settings. This list includes structural integrity systems, ignition control systems, process containment systems, fire, smoke, and gas detection systems, fire protection systems, shutdown systems, blowdown and relief systems, emergency response systems, life-saving systems, heating, ventilation, and air conditioning systems, communication systems, and blow-out prevention systems. These systems are crucial for ensuring safety and efficiency in various industries.
HSE, short for Health & Safety Executive, is the regulatory body in the United Kingdom responsible for ensuring health and safety standards are upheld.
Could the 13th item on the list be related to the critical potable water system used for drinking? I suspect this because someone designated a criticality level of 1 for potable water pumps. Is this list officially published in the UK Safety and Health Act or detailed in a specific circular or guideline? I am eager to obtain a copy of this list. Will it possibly be included in your upcoming 100 years Maintenance guidebook?
- 08-10-2024
- Gregory Hughes
It is no surprise that during a telecom system outage, all hot work activities were halted until the system was fully restored. The significance of the HVAC system's role as a critical safety component was brought to my attention. The importance of these safety measures is evident in ensuring the overall safety of the work environment.
It is crucial to understand that HVAC systems play a pivotal role in detecting and containing smoke within a building, such as in control rooms and radio rooms. Fire-dampers are essential components that isolate different sections of a building to prevent the spread of smoke in case of a fire. Regular testing of these fire-dampers is necessary to ensure their effectiveness in emergency situations.
There is a room for interpretation when it comes to assessing the criticality of assets, but in my experience, we have implemented a rigorous assessment process to ensure that all team members are aligned. We use a straightforward database that evaluates specific criteria for each asset in the analysis, including safety, environmental impact, sales, production, and maintenance. By asking key questions related to each criterion, we determine the potential impact of equipment failure. While there are various failure modes to consider, we focus on assessing the design function of equipment as part of our analysis. Consistency is crucial in ranking assets, and having a designated facilitator helps maintain uniformity in the results. The database assigns a score ranging from 0 to 1000 to each asset based on its criticality, which is then leveraged in our CMMS for planning, scheduling, and prioritizing equipment maintenance tasks. This method, which some may call prioritization or criticality, has proven effective for our team and ensures that our objectives are met.
Which document lists the safety critical systems approved by the HSE in the oil and gas industry? I searched the HSE website and came across the UKOOA EHS04 Management of Safety Critical Elements. Is this the official document that outlines the safety critical systems for the oil and gas sector?
It has been some time since I last worked on this topic, but UKOOA is a reputable representative in the Oil and Gas industry. The document title seems familiar, so I recommend taking a closer look to see if it resonates with you.
Josh, I'm not entirely certain if that is the exact document you are searching for. The HSE, known as the Health and Safety Executive, functions as both an advisory and regulatory body, operating under a multitude of laws and regulations. This results in numerous definitions and layers surrounding various aspects of safety. For instance, the Safety Case Regulations define "safety-critical elements" as parts of an installation or plant whose failure could lead to or significantly contribute to a major accident. It is important to note that not every element of a system is considered safety-critical solely based on one component. Additionally, a safety critical element differs from a safety critical system. If my memory serves me correctly, these distinctions are crucial when considering safety protocols. Cheers!
- 08-10-2024
- Quentin Foster
Vee, can we confirm if the Electrical Protection System Integrity is one of the 13 safety critical systems in place?
When discussing Safety Critical Systems versus Safety Critical Elements, Daryl is absolutely correct in his differentiation. Systems are composed of various elements, each playing a crucial role in ensuring the overall safety. In the Offshore Oil & Gas industry, certain systems are deemed critical, such as Fire Protection Systems, without the need for a detailed RCM analysis to determine their criticality at the failure mode level. In non-safety critical systems, there may be individual elements, like relief valves, that are considered critical. While power generation is a key Safety Critical System within the Offshore Oil & Gas industry, Distribution systems are typically not classified as such. The term "electrical protection system" may refer to components like circuit breakers, which are considered elements within the broader system.
- 08-10-2024
- Shawn Thompson
Protective relays are essential components of an electrical protection system.
- 08-10-2024
- Frances Fisher
Relays performing protective functions can have hidden failures that are crucial for safety-critical systems. Identifying these failures through methodologies like IPF or RCM studies is important in order to implement mitigation tasks. Safety Critical Systems are those that can pose serious risks to the overall facility operation. In the event of system failure, it is necessary to shut down the facility until the issue is resolved. For instance, in a fire protection system, components such as Fire Pumps, Fire Water Piping, Deluge Valves, and Sprinkler Heads must be fully functional. Analyzing the entire fire protection system is essential using tools like RCM, while also examining specific subsystems like the deluge system. Regular inspections and maintenance tasks are crucial for elements within a safety critical system to prevent potential failures. It is vital to assess the condition of all protective elements, even those not part of safety critical systems, such as relief valves and reverse-current relays. The reliability and functionality of these components play a significant role in the overall operational safety of the facility.
Protective relays are vital for motor control centers (MCC) and switchboards.
When it comes to MCC and switchboard protective relays, it is important to consider their importance in terms of safety within the power distribution system. These relays can be critical components depending on the risk they present, which is determined by the probability and consequences of failure. However, due to the high level of redundancy in power distribution systems, the overall risk is usually low. If it is determined that these relays are indeed critical, it is necessary to follow the appropriate maintenance tasks outlined in the RCM decision tree or other suitable methods.