Nuclear Engineering Plant Design

𝗗𝗲𝘀𝗶𝗴𝗻𝗶𝗻𝗴 𝗮 𝘃𝗲𝘀𝘀𝗲𝗹 𝗺𝗲𝗮𝗻𝘀 𝗮𝘀𝗸𝗶𝗻𝗴: Will it survive thermal cycling? Can it handle nozzle loads and wind stress? What happens during a vacuum collapse? If you only think in terms of diameter and thickness, you're missing the bigger picture. Let’s break it down 👇 As per ASME Section VIII, Div 1 & 2 ✅ Internal pressure: Hoop & longitudinal stresses via thin-wall or thick-wall formulas ✅External pressure: Requires stiffening rings, especially in tall columns or vacuum-rated vessels ✅Stress combinations: Consider dead load, wind/seismic (per ASCE 7), thermal gradients, and nozzle-induced stresses ✅Corrosion allowance: Typically 1.5–3 mm for carbon steel, adjusted based on process medium ✅Joint efficiency & weld inspection: Dictates allowable stress values based on radiography or UT compliance 📌 Design Inputs ✅Design pressure & temperature: Basis for material selection and wall thickness ✅Operating envelope: Define min/max conditions to address cold/hot cycling ✅L:D ratio: Short/fat vessels reduce wind loading but may raise material costs 📌Head type: ✅Hemispherical: High strength, high cost ✅2:1 Elliptical: Balance of stress distribution and fabrication ease ✅Torispherical: Economical for low-pressure designs ✅Internals like demister pads, trays, or baffles must be structurally supported and stress-checked. 📌Thermal Considerations: Expansion, Stresses, and Heat Transfer ✅Thermal gradients cause differential expansion → fatigue ✅Jacketed vessels need design for inner/outer shell pressure and flow distribution ✅Allow for expansion joints, support flexibility, and drainability ✅Evaluate material embrittlement temperatures (especially for low-temp services) ✅ PWHT: Post-weld heat treatment is mandatory for certain thickness/material combinations to relieve residual stress and meet notch toughness. 📌Support Design Impacts Stresses and Foundation Loads ✅Vertical vessels → skirt supports, possibly with gussets ✅Horizontal vessels → saddle supports with allowable spacing based on vessel weight and bending moments ✅Ensure baseplate design includes anchor bolt pull-out, moment resistance, and slotted holes for expansion ✅Wind and seismic design as per API 650, ASCE 7, or IS 875 ✅Lifting lugs, trunnions, and transportation saddles must be FEA-validated for static & dynamic loading 📌Material Selection: ✅Allowable stress at temp (ASME Sec II, Part D) ✅Corrosion resistance vs fluid compatibility ✅Fabricability (weldability, formability) ✅Impact toughness at low temps (per ASME UG-84, UCS-66) ✅For sour service (H₂S), NACE MR0103 compliance is critical. Use Austenitic SS, duplex steel, or Inconel depending on chemical exposure and design temp.

Fresh Air Requirement in HVAC (Ventilation Basics) Fresh air is essential to maintain indoor air quality (IAQ), comfort, and safety in buildings. --- 🔹 Why Fresh Air is Required • Removes CO₂ and pollutants • Controls odor and humidity • Improves occupant health --- 🔹 Fresh Air Standards (ASHRAE 62.1 / NBC) 👥 Person-Based Office • 8–10 L/s/person (17–21 CFM/person) Conference Room • 10–15 L/s/person (21–32 CFM/person) --- 📐 Area-Based Office Area • 0.3 – 0.6 CFM/ft² • 1.5 – 3 L/s·m² Conference Room • 0.5 – 1.0 CFM/ft² • 2.5 – 5 L/s·m² --- 🔹 📊 Example (Combined Calculation) For an office of 100 m² with 10 persons: • Person-based = 100 L/s (≈ 212 CFM) • Area-based = 200 L/s (≈ 424 CFM) 👉 Final Fresh Air = 200 L/s (≈ 424 CFM) (higher value considered) --- 🔹 Methods of Fresh Air Intake • Fresh Air Fan (FAF) • AHU with mixing box • DOAS • ERV / HRV --- 🔹 Key Point ✔ Use both person + area method ✔ Select higher value for design 👉 Proper ventilation = Healthy + Energy Efficient HVAC System --- #HVAC #FreshAir #Ventilation #IAQ #ASHRAE #MEP #HVACDesign #BuildingServices

We spend one third of our lives sleeping, and this time is crucial for our health, well-being, and cognitive performance the next day. Thanks to ASHRAE funding, we completed a research project (ASHRAE 1837-RP) that has provided new information on the importance of bedroom air quality and ventilation for sleep quality. A paper summarizing the numerous experiments we performed in two parts of the world (Europe and China) has just been published:https://lnkd.in/d6gSgsec. The most important finding is that existing ventilation practice in bedrooms must be changed, and that rectifying this will have consequences for design and residential ventilation standards in dwellings, student dormitories, and hotels. We recommend that bedroom ventilation should be at a level to keep the CO2 concentration emitted by bedroom occupants at 800 ppm or below. This will require much higher ventilation rates in dwellings (bedrooms) than are currently prescribed in the standards. Increased ventilation does not need to consume much more energy, but the actual challenge is how to retrofit billions of bedrooms that currently have no ventilation at all, except the possibility to open a window. We encourage more research and development in this area. To address this challenge, a research innovation network on sleep was recently initiated by @ISIAQ: https://lnkd.in/dVf2UmKV. Mizuho Akimoto Xiaojun Fan Li Lan Chandra Sekhar Shin-ichi Tanabe @David P. Wyon International Centre for Indoor Environment and Energy DTU Sustain

Buckling is a critical failure mode in pressure vessels under external pressure, causing sudden collapse due to compressive stresses. ASME Section VIII, Division 1 (UG-28, UG-29, UG-33) provides rules to calculate the maximum allowable external pressure (MAEP) for cylindrical shells and heads. Using geometric (L/Do, Do/t) and material factors (A and B from ASME II-D charts), the allowable pressure is determined with a safety factor of 3. For thin shells (Do/t ≥ 10), elastic or inelastic buckling formulas apply, ensuring stability against imperfections. ASME Section VIII, Division 2 (Part 5.4) offers a detailed design-by-analysis approach, using bifurcation or nonlinear collapse methods with factors like ΦB = 2/βcr or 1.5, respectively, often requiring FEA for complex cases. Division 1 is simpler and conservative, while Division 2 is precise but computationally intensive. Both address elastic and inelastic buckling, safeguarding fixed equipment integrity. #ASME #ASMESECVIII #API #Refinery #petrochemical #oil #gas #powerplant #gasoline #gasoil #crudeoil #pvelite #codecalc #engineering

In process & plant safety design, #pressure_vessel nozzles are not just functional—they are critical for #safe operation, #inspection, #control, and #emergency handling. Codes like #ASME Boiler and Pressure Vessel Code (Section VIII) and good engineering practices define what service nozzles should be included. Here’s a practical, safety-focused classification: 🔹 1. Process / Operating Nozzles These are mandatory for normal operation: Inlet nozzle – feed entry Outlet nozzle – product discharge Recirculation / bypass nozzle (if required) Drain nozzle – lowest point for complete draining Vent nozzle – highest point for gas removal. 👉 Safety note: Improper venting can lead to air pockets or vacuum issues. 🔹 2. Pressure Protection Nozzles (Critical for Safety) These are non-negotiable: Pressure Safety Valve (PSV) / Relief Valve nozzle Rupture disc nozzle (optional but common in hazardous service) 👉 Must comply with American Petroleum Institute standards like API 520/521. 🔹 3. Instrumentation Nozzles For monitoring and control: Pressure gauge / transmitter nozzle Temperature element nozzle (Thermowell) Level indicator nozzle (DP / sight glass / radar) Sampling nozzle 👉 Safety note: Redundancy (dual transmitters) is often used in critical vessels. 🔹 4. Utility & Maintenance Nozzles Ensure operability and long-term safety: Manhole / hand hole – for inspection & entry Cleaning (CIP) nozzle / flushing connection Nitrogen purging / inerting nozzle Steam-out connection (for hydrocarbons service) 🔹 5. Emergency & Special Service Nozzles Depending on service: Vacuum breaker nozzle (to prevent collapse) Emergency depressurizing / blowdown nozzle Fire water / spray nozzle (for fire protection in some designs) 🔹 6. Level & Safety Interlock Nozzles For automated safety: High-high level switch nozzle Low-low level switch nozzle 👉 Used in SIS (Safety Instrumented Systems). 🔹 Design Considerations (Very Important) Orientation matters: Vent → top Drain → bottom PSV → vapor space (top) Accessibility: Instruments and PSVs must be reachable Dead zones: Avoid nozzle placement that traps fluid Corrosion allowance: Especially for drain & sampling nozzles Minimum nozzle count vs safety: Don’t over-minimize at cost of safety ⚠️ Typical Minimum Safety Set (Industry Practice) For most pressure vessels, at least: Inlet + Outlet Vent + Drain PSV nozzle Pressure + Level measurement Manhole. #Knowledge #Engineering #Plant_Safety #Instrumentation

Dedicated Outdoor Air System (DOAS) Why humidity control? ASHRAE 170 sets minimum requirements for outdoor air delivery, overall supply airflow, and maximum relative humidity for many hospital spaces. The 60% upper limit of relative humidity is intended to prevent the uncontrolled growth of mold spores on surfaces and building materials and to potentially reduce the spread of infectious microorganisms. Occupants typically want indoor temperatures in the low- to mid-70s (Fahrenheit). That means maintaining an indoor dewpoint of about 55F for general patient spaces. In operating rooms and other specialty areas where lower space temperatures are the norm, indoor dewpoint may need to be as low as 46F. Whenever the outdoor dewpoint is above those temperatures, the introduction of outdoor air for ventilation brings unwanted moisture. Removing that moisture is one of the principal functions of a hospital HVAC system. Moisture removal can be a very large fraction of the total load that an HVAC system deals with - 75% or even more, depending on outdoor conditions.

💨 Minimum? Acceptable? Or just quietly outperforming expectations? There’s a certain school of thought that never tires of poking at ASHRAE Standard 62.1 by calling it “minimum,” “acceptable,” or “designed to barely get by.” You know the tone. If it sounds modest, it must be inadequate. And yet… when we evaluate actual health harm measured in DALYs (disability-adjusted life years lost), the picture changes. 📊 Using pollutant harm intensities from recent peer-reviewed studies by Morantes et al. (2024) and Jones et al. (2025), I compared how major IAQ standards perform at a population health level, not just in policy language (note: this is not an exhaustive list). • ASHRAE IAQP (2022): approximately 871 DALYs per 100,000/year • LEED v5 (EQc1 – Indoor Air Quality Performance - Option 2): approximately 719 DALYs per 100,000/year • WELL v2 (WELL v2 - Feature A01): approximately 1,093 DALYs per 100,000/year • RESET (Acceptable): approximately 2,113 DALYs per 100,000/year (excluding formaldehyde and ozone) which is roughly equivalent to typical residential exposure Why does this matter? Because ASHRAE 62.1 scope is clear: ....to minimize adverse health effects by keeping contaminant levels below harmful thresholds.... When implemented through the IAQP pathway, it performs exactly as intended, sometimes better than the more "premium" standards. So before dismissing “minimum standards” as merely “acceptable,” maybe it’s time we ask: 👉 Acceptable to whom and based on what evidence? 📚 References - Links in first comment. • Jones et al. 2025 – Harm budget from Indoor Air Contaminants • Morantes et al. 2024 – DALY Analysis in Residential Buildings • Sherman and Logue 2011 – Equivalence in Ventilation and IAQ • Logue et al. 2012 – Hazardous Air Pollutants in Homes • Zaatari et al. 2016 – using DALY-based modeling to develop optimized ventilation strategies. Max Sherman Benjamin Jones Giobertti Morantes William Bahnfleth #IndoorAirQuality #ASHRAE621 #IAQP #DALYs #HealthBasedDesign #VentilationStandards #LEEDv5 #WELLStandard #RESETStandard #EvidenceBased #HealthyBuildings #BuildingPerformance

🔧 Process Pressure Vessel Sizing: A Comprehensive Engineering Guide As process engineers, one of our critical tasks is properly sizing separation vessels for vapor-liquid and liquid-liquid systems. The following can be summarizing the key design criteria and methodologies. 📌 Key Topics Covered: 1️⃣ Selection Criteria - When to use vertical vs horizontal vessels • Vertical: Ideal for compressor KO drums, flash drums (smaller footprint, easy solids removal) • Horizontal: Better for reflux accumulators, flare KO drums (handles slugs, improved degassing) 2️⃣ Vertical Vessel Design - Critical dimensions and hold-up times • LLL positioning: 200mm above bottom TL • Hold-up times: 3-5 min (reflux) to 20-30 min (flare KO) • Kt values: 0.05 m/s without demister, 0.08 m/s with demister 3️⃣ Horizontal Vessel Methodology - Step-by-step sizing approach • Trial-and-error method with 60% liquid fill assumption • L/D ratio selection based on design pressure • HLL limited to 80% of diameter 4️⃣ Vessel Internals - Demisters and nozzle specifications • Wire mesh demisters: 100mm thickness, removes droplets >10 microns • Critical: Relief valve must be UPSTREAM of demister • Momentum criteria: ρv² ≤ 2500 kg/(m·s²) 5️⃣ Liquid/Liquid Separators - Two main configurations • Liquid-filled: For systems without vapor formation • With vapor compartment: Uses overflow/underflow baffles for interface control • Design based on Stokes Law for droplet settling velocity 💡 Pro Tips: ✓ Always check for foaming tendency (apply 0.7-0.8 derating factor) ✓ Consider degassing requirements for vertical vessels ✓ Use boots for L/L separation when flow ratio (heavy/light) < 0.2 ✓ Verify nozzle sizing with momentum and velocity criteria These design principles are applicable across oil & gas, petrochemical, and refining operations, ensuring safe and efficient separation performance. What's your experience with separator vessel design? Any additional considerations you always check? #ProcessEngineering #ChemicalEngineering #OilAndGas #VesselDesign #ProcessDesign #Petrochemical #EngineeringDesign #SeparationTechnology

𝗗𝗲𝘀𝗶𝗴𝗻 𝗣𝗿𝗲𝘀𝘀𝘂𝗿𝗲 𝗮𝗻𝗱 𝗧𝗲𝗺𝗽𝗲𝗿𝗮𝘁𝘂𝗿𝗲 - 𝗟𝗣𝗚 𝗩𝗲𝘀𝘀𝗲𝗹 (𝗔𝗣𝗜 𝟮𝟱𝟭𝟬) The design pressure of LPG pressure vessels shall not be less than the vapor pressure of the stored product at the maximum product design temperature. The additional pressure resulting from the partial pressure of non-condensable gases in the vapor space and the hydrostatic head of the product at maximum fill shall be considered. Ordinarily, the latter considerations and the performance specifications of the relief valve require a differential between design pressure and maximum product vapor pressure that is adequate to allow blowdown of the pressure relief valve (see API Standard 520). Both a minimum design temperature and a maximum design temperature shall be specified. In determining a maximum design temperature, consideration shall be given to factors such as ambient temperature, solar input, and product run down temperature. In determining a minimum design temperature, consideration shall be given to the factors noted in the preceding sentence as well as the auto-refrigeration temperature of the stored product when it flashes to atmospheric pressure. ASME BPVC Section VIII, Division 1 UCS-66(b) and Division 2, 3.11.2.5 provide adjustment curves that allow the impact test exemption temperatures to be reduced in increasing measure as pressures are reduced. Conservative application of those adjustment curves in conjunction with LPG vapor pressure curves allow the following auto-refrigeration conclusion. The reduced auto-refrigeration temperature will not mandate impact testing of the vessel material for LPG storage vessels that satisfy the requirements: ▪ Design pressure is 200 psig or greater. ▪ Service conditions will not involve more than 5 psi partial pressure of non-condensable gases such as nitrogen. ▪ Normalized or quenched and tempered materials or as rolled A516 including Gr 55, Gr 60, Gr 65 or Gr 70 are employed. ▪ The thickness of the vessel does not exceed 4 in. ▪ Satisfying the above criteria will ensure that the allowable minimum design metal temperature (MDMT) of the vessel material will be less than the adiabatic flash temperature of the LPG. When the vessel is repressurized, this must be done slowly to allow the temperature to increase as the pressure is increased. ... #BakrProcessSafety #SafeProcess #ProcessSafety #API2510 #ASMEVIII #PressureVessels #MechanicalIntegrity #SafeDesign #IndustrialSafety ... Join Our Safe Process Community 🌿 𝗢𝗻 𝗧𝗲𝗹𝗲𝗴𝗿𝗮𝗺 https://t.me/safeprocess 𝗢𝗻 𝗪𝗵𝗮𝘁𝘀𝗔𝗽𝗽 https://lnkd.in/eYDZp5_q 𝗢𝗻 𝗟𝗶𝗻𝗸𝗲𝗱𝗜𝗻 https://lnkd.in/enedbJjD

🏗️ Vertical Pressure Vessel Deflection — Often Checked Late, Felt Early Vertical pressure vessels don’t just carry pressure. They behave like tall cantilever structures, and their lateral deflection can quietly control the design. What drives deflection? 🔹 Wind load (usually governing) 🔹 Seismic forces in active regions 🔹 Thermal gradients and restrained expansion 🔹 Eccentric loads from platforms, piping, and internals Why it matters Excessive deflection can lead to: ❌ Nozzle overloads ❌ Piping stress failures ❌ Tray and internals misalignment ❌ Anchor bolt and foundation distress How it’s typically evaluated A vertical vessel is often idealized as a cantilever beam fixed at the base, with top deflection estimated from lateral loads (wind / seismic). While ASME Section VIII focuses on pressure integrity, deflection control is usually governed by: ✔ Structural checks ✔ Piping load limits ✔ Project-specific criteria Good engineering practice 📐 Common industry limits fall around H/200 – H/400, depending on: Vessel height & slenderness Nozzle sensitivity Connected piping flexibility Key takeaway Pressure design ensures the vessel doesn’t burst. Deflection control ensures everything connected to it survives. Designing both together is what separates a code-compliant vessel from a robust system. #PressureVessels #MechanicalEngineering #StaticEquipment #StructuralDesign #WindLoad #SeismicDesign #PipingEngineering #ASME #EngineeringBestPractice