Comprehensive Stress Analysis for Pressure Safety Valve (PSV) Piping Systems: Ensuring Safety and Compliance
Comprehensive Stress Analysis for Pressure Safety Valve (PSV) Piping Systems: Ensuring Safety and Compliance Home / Learning In industrial piping systems, controlling pressure within safe limits is vital to prevent hazardous over-pressurization. Pressure Safety Valves (PSVs) are crucial in this regard, as they are designed to release pressure once it reaches a pre-set limit, protecting equipment, the surrounding environment, and personnel from potential harm. However, when a PSV activates, it exerts dynamic forces on the connected piping, creating stress-critical conditions. Therefore, a thorough stress analysis of PSV-connected piping systems is essential for both safety and compliance. This article provides an in-depth look at the stress analysis of PSV systems, from the fundamental PSV types and discharge classifications to the load cases needed for accurate modeling. Understanding the critical loads and forces involved enables engineers to design safer, more reliable systems that meet industry standards. Types of PSV Discharge Systems: Open vs. Closed Discharge The two primary PSV discharge systems—open discharge and closed discharge—handle fluid forces differently: Open Discharge: In this system, the PSV discharges directly into the atmosphere. This approach is often used for non-toxic or non-flammable gases, where environmental and safety risks are minimal. Closed Discharge: Here, the fluid from the PSV is directed to a closed system, such as a discharge header or drum, where it can be collected for disposal or recycling. This system is typically employed for hazardous or high-value fluids that require containment. Each discharge type imposes distinct forces on the piping, which must be accounted for during stress analysis to ensure stability and prevent failures under relief conditions. Design Principles for Pressure Relief Devices The key principle behind pressure relief devices is intrinsic safety; they must either “fail safe” or not fail at all. Solutions to issues in pressure relief piping should rely on solid design practices, as any failure is unacceptable. Prioritizing simplicity and established guidelines is vital for ensuring reliability. Here are four primary reasons to approach the engineering of pressure safety valves and discharge systems with precision: Flow Capacity Restrictions: The design of inlet and outlet piping can hinder flow, potentially compromising the valve’s ability to release pressure safely. Operational Performance: Poor design can negatively influence the operation of the PSV, altering its opening or closing pressures. Risk of Mechanical Failures: The thrust generated during valve discharge can result in mechanical failures within the piping system. Safety Valve Inlet Piping :To function effectively, safety valves should be mounted vertically, either directly on the vessel nozzle or via a short connection that allows for unobstructed flow. This principle should also apply to safety valves safeguarding piping systems.Pressure Drop:The pressure drop between the vessel and the safety valve inlet should be minimal to prevent starving the valve or causing it to chatter.Preventing Piping Overstress :It is crucial to avoid overstressing the inlet piping or mounting nozzle on the vessel. Consider the reaction force during valve operation along with forces from the discharge piping; minimizing the length of the inlet piping can help reduce strain.Safety Valve Discharge Piping :The allowable back-pressure on a safety valve depends on several factors, including its back-pressure rating, which may differ from the ASA rating of the outlet flange. This should be verified with the manufacturer. Conventional safety valves should not experience back-pressure exceeding 10 percent of the net setting, and it must always remain at least 5 psi lower than the opening pressure.Drain Hole Management :In applications where liquids may accumulate at the valve discharge, it’s essential to remove the drain hole plug. This applies in scenarios where condensate can form or precipitation may enter the discharge line. If the plug is removed, the drain must be piped safely for disposal, particularly if the fluid poses a hazard or if sudden discharges could endanger personnel. Piping Support Design Safety valves need to measure pressure within a 3% accuracy and fulfill specific control functions. Excessive strain on the valve body can hinder its performance. Therefore, piping supports should be designed to minimize load on the valve. In high-temperature applications, excessive loads can cause permanent deformation, and even at lower temperatures, distortion may result in leaks below the set pressure. Discharge piping should be supported independently from the valve and carefully aligned to reduce forces during normal operation. Properly designed expansion joints or long-radius bends should be included to prevent excessive strain. Discharge Piping Stress Analysis is mainly subjected to stresses from thermal expansion and discharge reaction forces. The rapid release of compressible fluids can create impact loads and bourdon effects at directional changes, necessitating adequate anchoring to prevent sway or vibration during discharge. Minimizing Pressure Loss To limit pressure loss in discharge piping, the system should be as direct as possible, employing long-radius bends and avoiding tight-fitting connections. The discharge pipe’s cross-sectional area must never be smaller than that of the valve outlet. Main Load Cases for PSV Stress Analysis Effective PSV stress analysis involves defining load cases that accurately capture the operational and occasional forces exerted on the system. Below are essential load cases typically evaluated for PSV piping systems: Sustained Load Case (Operating Condition): This load case models sustained forces that occur under normal operating conditions, including: Weight (W): Accounts for the weight of the piping, insulation, and fluid. Internal Pressure (P): The pressure within the piping during standard operation. Thermal Load Case (Expansion): Thermal expansion or contraction occurs as the piping temperature changes. It is essential to account for this to prevent excessive stress during temperature fluctuations. Key Component: Thermal Expansion (T1): Thermal forces associated with the operating temperature. Occasional Load Case (Relief Scenario): During PSV activation, sudden pressure release generates dynamic jet forces, which classify as occasional loads. These forces need to be considered along with sustained loads to simulate a PSV relief event. Key Component: Relief Reaction Forces (F): Resulting from the rapid release of gas or liquid. Thermal Expansion with Relief Forces: If the PSV is triggered while the system operates at high temperatures, combining thermal expansion with relief forces becomes necessary
Piping Design and Stress Analysis for Hydrogen Pipelines: A Technical Perspective
Piping Design and Stress Analysis for Hydrogen Pipelines: A Technical Perspective Home / Learning As hydrogen becomes an increasingly important energy carrier in the global push for clean energy, the design and analysis of hydrogen pipelines are paramount to ensuring both efficiency and safety. Hydrogen poses unique challenges to piping systems due to its low molecular weight, high diffusivity, and flammability. These characteristics necessitate advanced piping design principles and stress analysis techniques to minimize risks such as leaks, embrittlement, and system failure. MECS Engineering is at the forefront of addressing these challenges by applying cutting-edge methodologies for piping stress analysis and design tailored for hydrogen transportation. The Challenges of Hydrogen Pipelines Hydrogen is highly volatile and flammable, requiring careful design to prevent hazards when transported through pipelines. Hydrogen’s small molecular size makes it prone to diffusion through materials, increasing the risk of leaks. It can cause embrittlement in certain materials, which increases the likelihood of fractures and leaks. It often operates under high pressures, necessitating durable pipeline design to ensure structural integrity and safety. Due to the unique characteristics of hydrogen, effective stress management is crucial to maintain the pipeline’s operational efficiency and prevent failure. Stress analysis is vital in ensuring that the pipeline can withstand the stresses induced by hydrogen flow without compromising safety or structural integrity. Codes and Regulatory Compliance: ASME B31 series encompasses ASME B31.12 code dedicated to hydrogen piping systems. It covers the specific challenges posed by Hydrogen and provides essential guidelines for the design, construction and maintenance of hydrogen pipelines, covering factors like material selection, pressure ratings, and safety measures. In conclusion, this article has explored the common causes of pipe failures in industrial plants, emphasizing the critical role of stress analysis in preventing such failures. By identifying weak points, ensuring safety, optimizing design, and maintaining compliance with industry standards, stress analysis serves as a cornerstone in achieving reliable and efficient piping systems. At MECS Engineering, we specialize in piping stress analysis to help clients protect the integrity of their piping systems. Our team of expert engineers ensures that your systems are designed to withstand operational stresses, reduce costs, and meet all safety and regulatory requirements. Key Considerations in Piping Design for Hydrogen Pipelines 1. Material Selection Material selection is one of the most critical factors in hydrogen pipeline design. To prevent the cracks and fractures, materials with high resistance to hydrogen embrittlement are selected, including: Stainless Steel (300 series): Stainless steel is commonly used for hydrogen pipelines due to its resistance to hydrogen embrittlement and its high strength. However, material selection must take into account hydrogen pressure and temperature conditions, as hydrogen can cause embrittlement at higher pressures. High-Strength Low-Alloy (HSLA) Steel: HSLA steels are used when high strength is required for pipeline construction. These materials offer good resistance to hydrogen-induced cracking (HIC). Composite Materials: Materials such as fiberglass and carbon fiber composites may also be used in some applications to prevent hydrogen permeation while offering lightweight solutions. 2. Wall Thickness Design The wall thickness of hydrogen pipelines is crucial in managing internal pressures, stresses, and the effects of hydrogen embrittlement. According to the ASME B31.12 code, the pressure design thickness must account for both the internal pressure and the material’s susceptibility to hydrogen. In particular, the following considerations are essential: Internal Pressure: Hydrogen pipelines often operate under high pressure (up to 1500 bar in some cases), which necessitates thick walls to withstand the mechanical stresses. The design must ensure that the material selected can resist these pressures without failure. Hydrogen Effects: Hydrogen-induced stress must be factored into the thickness calculation, as it can significantly affect material properties. The Mf factor is applied to adjust for the ductility reduction in metals due to hydrogen exposure, effectively increasing the required thickness. 3. Stress Analysis for Hydrogen Pipelines Piping Stress analysis is essential to ensure that the pipeline can withstand both mechanical and thermal stresses while maintaining safety. The unique properties of hydrogen introduce specific factors that must be considered in the stress analysis: Thermal Stress: Hydrogen pipelines can experience significant temperature fluctuations depending on the phase (gas or liquid) and transport conditions. Thermal expansion and contraction in pipelines can induce stress at joints and bends, which needs to be carefully calculated. Dynamic Loading: Hydrogen pipelines design can also experience dynamic loads due to flow fluctuations, temperature variations, or external forces such as seismic activity or thermal cycling. The stress analysis must factor in these dynamic loads to ensure the system remains intact over time. Fatigue and Fracture Mechanics: Hydrogen embrittlement is a particular concern when performing fatigue analysis. Materials that are exposed to hydrogen may fail earlier than expected under cyclic loading. The ASME B31.12 code provides guidelines to account for this and helps identify potential fracture points in the system. MECS Engineering utilizes advanced stress analysis software to model these factors and also applying finite element analysis (FEA) to simulate the pipeline’s behavior under various conditions. This enables precise calculations for stresses at different locations and provides valuable insight into potential weak points in the design. 4. Leak Detection and Prevention Given hydrogen’s flammability and small molecular size, leak detection and prevention are critical aspects of the Hydrogen piping design process. The following design features are incorporated to minimize the risk of hydrogen leaks: Leak-Free Joints: Piping joints must be carefully designed to ensure leak-tightness. Welding is typically the preferred method for creating joints in hydrogen pipelines, as it provides superior sealing properties compared to mechanical joints. Sealing Technologies: Advanced sealing materials such as elastomers and fluoropolymers are often used in hydrogen pipeline systems to prevent leaks. These materials are chosen for their resistance to permeation and ability to maintain flexibility in extreme conditions. 5. Design for Seismic and External Loads Hydrogen pipelines, especially those that span large distances or are located in seismic zones, need to be designed to withstand external loads, including seismic activity, soil movements, and other environmental factors. The following considerations are essential: Seismic Analysis: In regions prone to
Top 5 Reasons for Piping Failures and the Importance of Stress Analysis for prevention
Top 5 Reasons for Piping Failures and the Importance of Stress Analysis for prevention </h6 > Home / Learning Piping systems are critical to various industries, including power, oil and gas, water treatment, chemical processing, HVAC, and other process industries. Despite their importance, these systems have been associated with numerous reliability and safety incidents. Ensuring their reliability, integrity, and safety demands rigorous analysis. A variety of factors contribute to pipe failures, ranging from material degradation to design flaws. Such failures can result in significant costs, including expensive repairs, unplanned production downtime, and, in severe cases, serious safety hazards. Understanding the causes of pipe failures and the role of stress analysis is vital in preventing these issues and maintaining system reliability. Below is a comprehensive look at the common causes of pipe failures and the critical role of stress analysis in mitigating these risks. Causes of Pipe Failures 1. Lack of Stress Analysis for Various Loads: Insufficient stress analysis and inadequate piping flexibility can lead to excessive loads on the system, ultimately causing failure. Piping systems are subjected to various types of loads, including primary loads like hoop stress, secondary loads such as thermal load or displacement, sustained loads, occasional loads, and reaction or impact forces. Each of these loads affects the system’s performance, and if not properly analyzed and managed, they can lead to system failure. Below are the common loads that occur in piping systems and can cause failure if not adequately analyzed and maintained. 1.1 Principal Piping Stresses: Fluid pressure within a pipe creates three primary types of stress: Longitudinal (Axial) Stress (δa): This stress acts along the length of the pipe. In the case of a pipe sealed with caps at both ends, the longitudinal stress is exerted toward the fittings, potentially causing the fittings to detach or push the pipe ends outward. Circumferential (Hoop) Stress (δh): This stress acts outward, around the pipe’s circumference. It is the most significant stress and can cause the pipe to split along its length, especially under high pressure. Radial Stress (δr): Radial stress is exerted away from the pipe’s central axis, extending outward toward the pipe wall. It is the least significant of the three types of stress. Among these three types of stresses, hoop stress has the largest effect followed by axial stress and radial stress being the smallest. Principal or primary stresses are typically force-driven, meaning they are caused by external forces such as gravity, internal pressure, spring load, pressure safety valve operation, and water hammering. These forces can exert significant stress on piping systems, making it crucial to account for them during the design and analysis phases to ensure the system’s integrity and avoid potential failure. 1.2 Principal Piping Stresses: Sustained loads are caused by internal pressure and the weight of the piping components, including valves, flanges, and fluid, as well as additional factors like thermal insulation or snow in colder climates. These loads primarily create longitudinal or axial stress (δa) from fluid pressure. If not properly managed with adequate pipe supports, sustained loads can lead to piping failure or collapse. 1.3 Sustained Load: Sustained loads are caused by internal pressure and the weight of the piping components, including valves, flanges, and fluid, as well as additional factors like thermal insulation or snow in colder climates. These loads primarily create longitudinal or axial stress (δa) from fluid pressure. If not properly managed with adequate pipe supports, sustained loads can lead to piping failure or collapse. Earthquake and Blast Load: Forces generated by seismic events or explosions. Wind Load: Caused by sudden air movement. If not accounted for in the design, it can lead to piping failure or damage to facilities. 1.4 Displacement Stress: Displacement stress is a secondary load, like thermal stress, that fluctuates between hot and cold conditions. As the temperature changes, the allowable stress (Sc and Sh) also changes. This can cause failure if the material is exposed to a single excessive hot load or repeated cycles that exceed the allowable stress range (SA). Thermal expansion is a type of displacement stress that usually occurs with temperature fluctuations in the piping system and if the system is not flexible enough to handle these changes then it causes a leakage or pipe failure. 1.5 Piping Reaction Forces: Reaction forces in piping can result from pressure safety valves, slug flow, and water hammering. These forces, classified as dynamic loads by ASME B31.3, can cause vibration and potential damage to the piping system. Pressure Safety/Relief Valve Reaction Force: When the safety valve opens, it generates reaction forces due to back-pressure and sudden impulses, particularly in gas services with high velocity and pressure. Proper pipe support is essential to manage these forces. Slug Flow Reaction Force: Slug flow, a mixture of gas and liquid, causes vibration and load fluctuations, negatively affecting the piping system and potentially shutting down the process. Water Hammering Load: Water hammering occurs from rapid changes in flow rate, such as valve operation or pump cycling, creating pressure surges that can damage the piping. 2. Corrosion: Corrosion is a chemical reaction where metals return to their natural state, often leading to material degradation and pipe fragility. The main types of corrosion affecting piping systems include: Uniform Corrosion: Caused by exposure to moisture and oxygen, resulting in rust. Galvanic Corrosion: Occurs when dissimilar metals interact, accelerating corrosion at the joint. Pitting and Crevice Corrosion: Common in environments with acidic or chloride-containing fluids, leading to localized, deep pits. Corrosion can weaken pipes, making them prone to breakage. To mitigate corrosion risks, material selection, coatings, and cathodic protection are essential preventative measures. 3. Water Hammering: High velocity or pressure in piping systems can lead to water hammer, a phenomenon where abrupt changes in flow generate pressure waves that strike valves and pipe walls, causing loud rattling sounds and potentially damaging pipe supports, valves, and the pipes themselves. This occurs when fast-moving fluid is suddenly stopped, creating stress on the pipe walls. When a valve closes quickly, it interrupts the flow,
What is Piping stress analysis – In simple words and why is it important
What is Piping stress analysis – In simple words and why is it important Home / Learning An introduction to stress analysis and its importance Introduction to pipe stress analysis: Pipe stress analysis is the study of stresses in a piping system. It is a term applied to calculations, which addresses the static and dynamic loads such as deadweight (self-weight of the pipe including fluid, fittings and its associated components), internal and external pressure, thermal loads (due to change in temperature), seismic loads, wind loads, vibration, water hammer, steam hammer, slug force, PSV reaction force, etc. Not all the type of loads are applicable in every system e.g. if the system temperature is expected to stay at ambient conditions, thermal loads will not apply. The applicable loads derive from the design basis. We will cover separately an article on the “Design Basis†(both for nuclear and non-nuclear applications). The objective of the stress analysis is to calculate these loads and strategically design the layout which allows required flexibility (e.g. expansion loops or change in the direction of pipe) and provide the constraints (directional and rotational) using piping supports, anchors, and hangers. The type of supports can be rigid, spring, snubbers, etc based on the stresses and forces in the piping system. Why Stress Analysis is so important: We have practically seen many failures where the stress analysis is not performed properly and/or the required supporting system is not installed in the field as per the design. Some of our personal experiences are: 1. Steam Pipe header: Complete block of the foundation shifted. You can imagine the amount of forces generated in the pipe header due to thermal expansion which shifted the complete concrete block. In this case, the importance of stress analysis was completely ignored. 2. All loads from the design basis not considered during the analysis. 3. Earthquake anchor movement for Seismic loads response spectrum not properly analyzed. 4. Cold pull suggested by design based on the analysis not properly implemented. (Note: sometimes the cold pull of pipe is needed due to higher expansion expected because of high temperature and a long run of pipe. In those situations a cold pull is recommended to accommodate the full expansion when the pipe is heated and expands). 5. The travel stop pin from the spring hanger is not taken out. 6. Missing nuts and bolts in the hangers. A very common problem in a running station and ignored. 7. Allowable forces at the equipment nozzle exceed the allowable provided by the manufacturer of equipment such as Pumps, compressors, heat exchangers, vessels. This is a very common situation for a stress engineer when it is not practically possible to limit the forces at the equipment nozzle provided by the equipment manufacturer. A solution to this is to work together with the equipment manufacturer engineer as they generally have more margins than defined in their standard specifications. I have faced and resolved this type of issue on many occasions. Objectives of Piping Stress Analysis: The main purpose and objective of piping stress analysis is to ensure structural integrity and to maintain system operability. It can be elaborated as below: • To ensure adequate flexibility in the piping system for absorbing the thermal expansion of the pipe. • To ensure that the stresses in the piping components are within the allowable limits with respect to applicable codes and standards. • To keep the piping connected equipment nozzle loads within specified allowable limits with respect to relevant standards (e.g. NEMA SM 23, API 610, API 661, API 667, ASME sec III, etc.) and Vendor allowable. • To select the correct type of pipe support based on piping stress calculation. • To check and ensure pipe displacements at maximum and minimum temperatures for clash-free routing. • To calculate and ensure loads and moments on the supporting structures are in the acceptable range with respect to civil requirements. • To solve dynamic problems in piping, such as those due to seismic loads, mechanical vibration, acoustic vibration, fluid hammer, pulsation, transient flow, relief valve discharge. • To ensure leakage proof flange joints. • To find out unintentional disengagement of pipe from support. One of the prerequisites for satisfactorily performing piping stress analysis is to become familiar with the principles of strength of materials. Below is a brief understanding of pipe material behavior under stresses in a piping system. Stress-strain behavior of material: Typical stress-strain behavior of a ductile material under tensile loading is shown in the famous stress-strain curve below, taking A 53 Gr B – a commonly used CS material. The various terms associated with the stress-strain curve of material is briefly discussed below and same is shown at different stages of the curve: • Stress: – The resistance developed in the material per unit area against the applied force is the stress in the material. It can be simply specified as force per unit area of the material. Stress (s) = Force / Cross-sectional area • Strain: – A component subjected to load undergoes deformation. The deformation is quantified by strain defined as the change in length per unit length of the material. Strain (e) = dl / L (Lateral strain) • Modulus of elasticity (E): – Up to a certain limit of loading known as the proportional limit, the strain developed in the material is in direct proportion to the stress. This law is called Hooke’s law and the constant of proportionality, E, is the modulus of elasticity or Young’s modulus, which is a definite property of the material. Mathematically: E = s / e> • Yield strength: The point at which the specimen or material under tension or compression generates a large deformation without the addition of any load is called the yield point. The corresponding stress is called the yield stress, or yield strength, Sy. The yield point is easy to recognize for materials with a stress-strain curve similar to that shown in the above figure. • Ultimate Tensile Strength: The maximum
Key Considerations for Optimal Steam Piping Design
Key Considerations for Optimal Steam Piping Design Home / Learning Steam piping design is a paramount consideration engineers and designers working in industries such as Power, Oil and Gas, Petrochemicals, refineries, and other process industry. Steam piping serves as the vital system that transports steam from steam generators, commonly known as boilers, to different points of usage.Depending on the specific application, the steam can be either saturated or superheated, operating under extremely high temperatures and pressures. To ensure both the safety and efficiency of steam piping systems, strict adherence to industry codes and standards is imperative. In this comprehensive article, we will explore the key aspects of steam piping design, including code requirements. Code Requirements for Steam Piping Design The two most common codes for the design and construction of steam piping systems are ASME B31.1 – Power Piping and ASME B31.3 – Process Piping. B31.1 applies to steam piping systems in power plants, while B31.3 covers piping in chemical, petroleum, pharmaceutical, and other process industries. These codes outline the minimum requirements for material selection, design, fabrication, inspection, and testing to ensure safety and reliability. Selecting the Right Piping Materials Choosing the appropriate materials for steam piping is crucial due to the extreme conditions that steam systems operate under. The most common materials used are carbon steel, stainless steel, and alloy steel. These materials offer excellent resistance to high temperatures and pressure. For higher-temperature applications, consider materials such as chrome-molybdenum alloys. Factors Influencing Material Selection: Temperature and Pressure: Steam piping systems can operate at varying temperatures and pressures. Material selection should consider the maximum and minimum temperatures the system will experience, as well as the pressure levels it will handle. Strength and Toughness: The material must possess sufficient mechanical strength to handle the stresses generated by high pressures and temperature differentials. Toughness is important to prevent brittle fractures under sudden temperature changes.Thermal Expansion: Steam piping materials should have compatible thermal expansion properties to prevent issues related to differential expansion and contraction.Also Read: A comprehensive guide to pressure vessel design: Ensuring Safety and Reliability Common Piping Materials for Steam Piping Design Carbon Steel (ASTM A106/A53): Carbon steel is widely used in steam piping due to its affordability, high strength, and thermal conductivity. It’s suitable for lower temperature and pressure applications. However, it’s susceptible to corrosion in the presence of moisture and aggressive substances in the steam.Stainless Steel (ASTM A312/A358): Stainless steel offers excellent corrosion resistance and strength, making it suitable for a wide range of steam applications. Types 304 and 316 are commonly used in steam piping systems.Alloy Steel (ASTM A335): Alloy steels, such as chrome-molybdenum alloys (e.g., P11, P22), offer enhanced resistance to high-temperature and high-pressure conditions. They are commonly used in superheated steam applications.Duplex and Super Duplex Stainless Steel: These materials combine high corrosion resistance with strength, making them suitable for aggressive environments or applications with both high pressure and temperature.Nickel Alloys: Nickel-based alloys, like Inconel and Monel, are used in extreme conditions involving high temperatures and aggressive media. They’re suitable for specialized applications in industries like petrochemicals. Applicable Codes for Material Selection: When selecting piping materials, it’s important to consult industry codes and standards that provide guidance on material specifications, properties, and limitations. For instance:ASME B31.1 and ASME B31.3 codes provide guidelines for material selection based on factors like temperature and pressure ratings and ASTM standards provide detailed specifications for various piping materials, helping engineers choose suitable materials based on the application’s requirements. Sizing and Layout of Steam Piping Design Sizing and layout are critical aspects of steam piping design that directly impact the efficiency, performance, and safety of the entire system. Properly sizing the pipes and arranging them in an optimal layout ensures efficient steam distribution, minimizes pressure drop, and reduces the risk of operational issues such as water hammer, condensate accumulation, excessive pressure drop, steam trapping, steam quality, and leakage of steam. The optimum design also helps in the following important points related to sizing and layout: Sizing of Steam Piping: Steam Flow Rate: Determining the steam flow rate is the first step in sizing steam pipes. This involves understanding the amount of steam required for the process and accounting for any potential variations. Pressure Requirements: Consider the desired pressure at the point of use. Pipe sizing should accommodate the pressure drop due to friction and elevation changes, ensuring that the required pressure is maintained.Velocity: Steam velocity within the pipes should be maintained within acceptable limits. Very high velocities can lead to erosion, while low velocities may cause condensation and reduced efficiency.Pipe Diameter: The calculated steam flow rate and pressure drop help determine the appropriate pipe diameter. Smaller pipes can result in excessive pressure drop, while oversized pipes lead to condensation and reduced efficiency.Sizing Standards: Industry codes and standards, such as ASME B31.1 and B31.3, provide guidelines for pipe sizing based on factors like flow rate, pressure, and material. The layout of Steam Piping design: Routing and Accessibility: The layout should allow for easy access for maintenance and repairs. Proper routing prevents obstruction and minimizes the need for complex maneuvers around the piping. Pressure Drop Minimization: Arrange pipes to minimize pressure drop, especially in long runs. Consider gradual inclines and declines to prevent pockets where condensate can accumulate. Expansion and Flexibility: Account for thermal expansion and contraction. Properly placed expansion joints and loops accommodate these movements without stressing the piping or causing misalignments. Drainage: Incorporate proper drainage points to allow condensate to be efficiently removed from the system. Improper drainage can lead to reduced heat transfer and potential water hammer issues. Branching and Manifolds: Design branching and manifold systems that ensure uniform steam distribution to different points of use. Avoid abrupt changes in pipe diameter that can cause turbulence. Supports and Hangers: Install supports and hangers at appropriate intervals to prevent excessive stress on the pipes. This maintains the integrity of the system and prevents sagging. Isolation and Valves: Include isolation valves for maintenance purposes, allowing sections of the system to be shut off without
6 Most Popular Piping Stress Analysis Software Packages Used In The Industry
6 Most Popular Piping Stress Analysis Software Packages Used In The Industry Home / Learning Introduction: Piping stress analysis constitutes a major portion of engineering work in most of the industries e.g. Power, Oil and Gas, Petrochemicals, Refineries, pulp and paper, chemicals, and process industry. The current trend in the EPC and owner sector is integrated systems of management, design, manufacturing, and construction. There are various software for stress analysis, some of them developed and used by big corporations for their own use particularly in the Nuclear industry. In this article, we will cover the 6 most commonly used piping stress analysis software. Piping Stress Analysis Software Tools: 1. CAESAR II, by Hexagon 2. Autopipe, by Bentley 3. CAEPIPE, by SST USA 4. Rohr2, by Sigma, Germany 5. PEPS, by DST Engineering 6. PASS/STRAT-PROF Now let’s take a brief look on all this software one by one, 1. CAESAR II, by Hexagon: Caesar II by Hexagon (Previously Intergraph) is arguably the most popular 3D tool for piping stress analysis. It enjoys the largest market share as a pipe stress package. Caesar II works on beam element method. It is used in the piping industry to understand and evaluate working piping models. Caesar II works on a color-coded system in the output report, which helps to understand the areas of concern in the piping system. The software can be easily integrated with other Hexagon 3D model software. CII is user-friendly and has a large database consisting of over 35 international and local codes (such as ASME B31.3, B31.4, B31.1, B31.8, European codes, and many more) making it much easier for the user to analyze a piping model in question. Benefits and features of Caesar II(source: Hexagon PPM site_Caesar II features PDF): Time required for modeling gets reduced as the software has a large database of all types of standard models. Most of these works with a single click. The graphics involved in the modeling is highly optimized which helps to keep bigger models also smooth. It has an advanced analysis and stress reporting system. The use of recommended load cases option is very handy to import all the important cases in one click. Caesar II gives the user access of 3rd party Finite element analysis tool for FEA related checks. Advanced analysis features such as the use of ASME B31J. Interfacing with most of the CAD-based software is robust. 2. Autopipe, by Bentley AutoPIPE is one of the most popular piping stress package in the EPC industry. The software is developed by Bentley Systems, a US based organization. Autopipe’s cost-effective solution to design any plant piping including nuclear units makes it highly efficient and popular. It increases productivity and improves quality with special piping stress features such as both static and dynamic analysis, wave loading, fluid transients available. The software can be easily integrated with all other Bentley and 3rd party applications such as Smart Plant, Aveva E3D, Autodesk Plant 3D, PDS, CAESAR II etc. (Source: Few of the points taken from Bentley.com_Autopipe section) For Nuclear applications, the software has AutoPIPE Nuclear. AutoPIPE Nuclear(Source: Bentley.com_Autopipe section): The software allows to analyze critical nuclear systems adhering to ASME Class 1, 2, or 3 standards. It gives the productive graphical CAD interface as well as a graphical view of results. AutoPIPE Nuclear conforms with ASME NQA-1, ISO 9001, CSA N286.7-99, ASME N45.2, and 10CFR50 standards backed by several independent audits by the Nuclear Regulatory Commission (NRC) customers and the Nuclear Procurement Issues Committee (NUPIC). Benefits and features of Autopipe (Source: Points taken from Bentley.com_Autopipe feature section): Unique graphical user interface. All major international and local codes (total 25) are included in the stress package. Quality assurance as per 10CFR Part 50 Appendix B, 10CFR Part 21, and ASME NQA-1. Advanced analysis features including the latest ASME B31J requirements, Stress intensification factors, fluid transient analysis 3. CAEPIPE, by SST Systems: Caepipe is developed by SST Systems USA. It performs both linear and non-linear, static and dynamic piping stress calculations. It is used in EPC and client-based industries for e.g., oil and gas, power, nuclear, fertilizers, petrochemicals etc. Benefits and feature of Caepipe (Source: points taken from sstusa.com_caepipe section): Multiple windows of the model can be opened for the visual and textual detailing of the system. System updates in a single-window gets updated in all the windows giving a dynamic real-time effect. Advanced analysis features including the latest ASME B31J requirements. Advanced Microsoft windows installation for better operation. 4. Rohr2, by SIGMA Ingenieurgesellschaft mbH Rohr2 is a leading piping stress software mainly used in Europe. This package is developed by SIGMA Ingenieurgesellschaft mbH The main tasks of ROHR2 are component analysis, construction, and structural analysis of complex piping systems and associated steel structures. ROHR2win is the pre- and postprocessor of ROHR2. All inputs can be made using ROHR2win. A wide range of control functions enables the user to check the input data easily. The software can be integrated with 3rd party applications such as Smart Plant, Aveva PDMS/ E3D, CAESAR II, Caepipe etc. Benefits and features of Rohr2 (Source: Points taken from rohr2.com basics and feature section): ROHR2 includes optional modules as ROHR2fesu (used for detail FEA analysis of branch connections, Trunnions, Junction stress checks, etc.) and ROHR2flange (Used for flange check evaluation). ROHR2 consists of a good database of all international and European codes and standards such as, ASME B31.1, B31.3, B31.4, B31.8, CODETI, EN codes etc. It offers transfer data with all major CAD and CAE systems. Both dynamic and static analysis can be performed in Rohr2. 5. PEPS, by DST Computers PEPS is developed by DST engineering of Switzerland. The software package contains PIPESTRESS, the stress analysis package and Editpipe, it’s pre and post processor. The package is claimed being used by more than 400 engineering organizations used in 30 countries. The PEPS program is used for stress analysis of piping systems falling under nuclear Class 1, 2 & 3 and non-nuclear codes. It is being used as the main piping
