Tells how much water the valve can pass when it is fully open with pressure drop 1 bar accross it
Unit is m3/hr
Kv= Cv * 0.865
Tells how much water the valve can pass when it is fully open with pressure drop 1 psi accross it
The unit is gallon/minute
Thermal relief valve should be set to pressure less than design pressure and higher than operating pressure because its design is small in size, so it will not discharge high flow
Calculating the wall thickness of a pipe is essential for ensuring the structural integrity and safety of piping systems, especially under internal pressure. The following steps outline how to calculate the pipe wall thickness based on ASME standards, particularly ASME B31.3 for process piping.
Steps for Pipe Wall Thickness Calculations Based on ASME
1. Determine Design Parameters
- Internal Design Pressure (P): The maximum internal pressure the pipe will experience (measured in psi or Pa).
- External Pressure (Pe): If applicable, the external pressure impacting the pipe (measured in psi or Pa).
- Design Temperature (T): The maximum temperature the pipe will operate at (°C or °F).
- Pipe Diameter (D): The nominal outside diameter of the pipe (in inches or mm).
2. Identify Material Properties
- Allowable Stress (S): Obtain the allowable stress of the material at the design temperature, which can be found in ASME Section II, Material Specifications, or the material’s datasheet (measured in psi or Pa).
- Thickness Corrosion Allowance: Account for any additional thickness required for corrosion or erosion, usually expressed as a fixed value (in inches or mm).
3. Select the appropriate ASME formula
For an internally pressurized pipe, the minimum required thickness can be calculated using the following formula from ASME B31.3:
Note: For specified thickness definitions within ASME, you may also include a term for the minimum wall thickness. This can be specifically stated in different ASME sections.
4. Account for External Pressure (if applicable)
If the pipe is subject to external pressure, you must also consider the external pressure when calculating the wall thickness. Use the formula:
5. Determine the Design Thickness
Combine thicknesses computed for internal and external pressures:
This equation helps in determining the final design thickness, accounting for both internal and external pressures.
6. Check Against Standard Pipe Schedules
Check if the calculated wall thickness meets or exceeds available standard pipe sizes and schedules (such as Schedule 40, 80). Pipe thicknesses defined by ASME pipe schedule can be found in ASME B36.10 and ASME B36.19.
7. Consider Additional Design Factors
Include any additional factors such as:
- Fatigue considerations for cyclic loading.
- Impact considerations for low-temperature applications.
Adjust the thickness accordingly if required by safety factors or specific application standards.
8. Final Review and Compliance Verification
Ensure the final design meets all relevant codes and standards (such as ASME B31.3, B31.1, etc.) and industry best practices. Perform peer reviews or checks per organizational procedures.
Summary
Calculating pipe wall thickness using ASME standards requires a comprehensive understanding of the operational conditions, material properties, and appropriate mathematical formulas. Consider the internal and external pressures, allowable stress, and corrosion allowances to ensure safety and compliance. This process is critical for the design, material selection, fabrication, and maintenance planning of piping systems. Always refer to the latest ASME codes and standards for the most accurate and safe design practices.
Calculating pressure drop in piping systems is a crucial aspect of engineering design. It helps in understanding the hydraulic performance of a pipeline and ensuring the system operates efficiently. The following steps outline the method to calculate pressure drop in a piping system based on ASME standards.
Steps for Piping Pressure Drop Calculations
1. Define Parameters of the System
2. Determine Flow Rate
3. Calculate Flow Velocity
Using the flow rate, calculate the fluid velocity in the pipe:
4. Calculate Reynolds Number
Note:
5. Determine the Friction Factor
Where:
6. Calculate Pressure Drop in the Pipe
7. Include Additional Losses (if applicable)
Consider fittings, bends, valves, and other components in the piping system that contribute to pressure drop:
8. Calculate Total Pressure Drop
Add up the pressure drop from the straight pipe and all additional components to find the total pressure drop across the entire system.
Summary
The calculation of pressure drop in piping based on ASME standards involves understanding fluid properties, determining the flow regime, calculating friction factors, and applying the Darcy-Weisbach equation. Additional losses due to fittings and other components should also be considered. Always refer to relevant reference materials and standards for specific guidelines. This method will provide the necessary calculations to ensure efficient system design and operability.
Hot tapping is a technique used to create a connection to an existing pressurized pipe system without having to drain the system. Calculating the requirements for a hot tap involves several steps, including determining the size of the hot tap, assessing the pipe’s operating conditions, ensuring safety, and calculating any necessary factors like pressure and flow. Below is a systematic approach to hot tap calculations:
Steps for Hot Tap Calculations
1. Determine the Specifications of the Existing Piping System
- Pipe Size: Measure the nominal diameter of the pipe (e.g., inches or mm).
- Pipe Material: Identify the material of the pipe (e.g., carbon steel, stainless steel).
- Operating Pressure: Determine the internal pressure of the pipe when the hot tap will be performed.
- Operating Temperature: Measure the temperature during operation as it affects material strength.
2. Assess the Appurtenance
- Hot Tap Size: Decide on the size of the hot tap. This is usually based on the flow requirements for the new piping or branch connection.
3. Calculate Required Wall Thickness for the Effective Area
Using the ASME Boiler and Pressure Vessel Code, the wall thickness can be calculated based on the pipe diameter, material, and pressure parameters. Use formulas such as:
4. Select the Hot Tap Fitting
- Ensure the hot tap fitting is designed for the same service conditions (pressure, temperature) as the existing pipe.
5. Determine the Safe Working Conditions
- Review safety factors using established standards (like ASME, API).
- Calculate the Stress Intensity Factor (SIF) if applicable to ensure the existing pipe can tolerate the additional stresses from the hot tap without failures.
6. Calculate Flow Factors (if needed)
If there will be a flow through the new branch connection, perform calculations to ensure the desired flow rate is achieved. Use equations:
7. Safety Precautions and Verification
- Verify all calculations with industry standards.
- Conduct a risk assessment to ensure the operation will be safe.
- Ensure that the integrity of the existing system is maintained by performing strength evaluations.
8. Performing the Hot Tap Action
- Ensure proper equipment and personnel are ready.
- Implement procedures to execute the hot tap:
- Secure the worksite.
- Use the appropriate cutting equipment.
- Monitor pressure and flow during the operation.
9. Inspection and Testing Post-Hot Tap
- After the hot tap has been made, conduct inspections to confirm no leaks occur.
- Perform pressure testing if required to ensure the integrity of the new connection.
Summary
Hot tap calculations involve understanding the specifications of the pipe, calculating the required wall thickness, selecting the appropriate fittings, and ensuring safety considerations are met. The calculations help guarantee that the hot tap process is safe and effective, maintaining the integrity of the existing pipeline while allowing for new connections. Always refer to relevant codes and engineering practices for more specific guidelines tailored to your operation.
Conducting a complex piping design analysis involves multiple steps that encompass planning, modeling, analysis, and optimization. Below is a comprehensive guide on how to perform such an analysis:
Step-by-Step Process for Complex Piping Design Analysis
1. Define System Requirements
- Gather Data: Collect all relevant information including:
- Piping and instrumentation diagrams (P&IDs).
- Process flow diagrams (PFDs).
- Design and material specifications.
- Operating conditions (pressure, temperature, flow rates).
- Fluid properties (density, viscosity, corrosiveness).
- Identify Constraints: Take note of physical limitations (space constraints) and regulations (codes and standards).
2. Piping Layout and Routing
- Create a Preliminary Design:
- Use CAD software to develop a preliminary layout.
- Ensure the layout minimizes bends and fittings, optimizing for straight runs where possible.
- Consider Valves and Fittings:
- Select appropriate fittings and valves based on the service.
- Position them for ease of operation and maintenance.
3. Modeling the System
- Use Advanced Software:
- Create a 3D model using software such as CAESAR II, AutoPIPE, or PDMS.
- Incorporate All Components:
- Include pipes, valves, fittings, supports, and equipment connections in the model.
- Define Material Properties:
- Input mechanical properties (yield strength, Young’s modulus) and material grades.
4. Perform Stress Analysis
- Identify Load Conditions:
- Determine types of loads acting on the piping system:
- Sustained Loads: Weight of the piping, fluid, and insulation.
- Thermal Loads: Expansion or contraction due to temperature changes.
- Dynamic Loads: Vibration, water hammer, and seismic forces.
- Run Calculations:
- Use the software to calculate stresses and displacements under defined load conditions.
- Ensure that calculated stresses remain below allowable limits specified in relevant standards (e.g., ASME B31.3, B31.1).
5. Flexibility Analysis
- Assess Thermal Expansion:
- Evaluate how the piping system accommodates temperature variations.
- Implement expansion loops, bends, or joints where necessary to prevent overstress.
- Dynamic Analysis:
- Perform dynamic simulations to assess response to transient events such as start-up or shutdown conditions.
6. Support and Anchor Design
- Select Supports: Determine the type and location of supports (e.g., hangers, anchors, guides).
- Ensure Adequate Spacing: Follow industry guidelines for support spacing to reduce sagging and maintain pipe alignment.
7. Validate with Field Data
- Site Inspections: Conduct field inspections to confirm installation and support placement matches the design.
- Physical Measurements: Verify that actual conditions align with your design assumptions.
8. Optimize Design
- Analyze Results: Review stress, displacement, and load data to identify critical areas.
- Make Adjustments:
- Re-route piping if necessary.
- Adjust support placement or types.
- Change material thicknesses or grades based on stress results.
9. Documentation and Reporting
- Compile Reports: Document all findings from modeling and analyses.
- Ensure Compliance: Verify adherence to applicable codes and standards throughout the design.
10. Collaboration and Review
- Peer Review: Get feedback from colleagues or external experts to identify potential oversights.
- Stakeholder Input: Work with clients or project stakeholders to ensure the design meets all functional and regulatory requirements.
Key Considerations
- Software Proficiency: Familiarize yourself with advanced piping analysis software that provides detailed and accurate models.
- Interdisciplinary Coordination: Collaborate with other engineering disciplines (e.g., mechanical, civil) to ensure a well-integrated design.
- Safety Factors: Always apply appropriate safety factors as dictated by design codes.
Summary
By following these steps, you can achieve an accurate and thorough complex piping design analysis, ensuring that the system is safe, efficient, and compliant with industry standards.
A simple piping design analysis involves several key steps to ensure the safety and efficiency of the system . Here’s a breakdown of how to perform one:
1. Define the System :
- Gather necessary information, including piping layout drawings (P&IDs and isometrics) .
- Determine material specifications .
- Identify operating conditions (temperature, pressure) .
- Note support locations and types .
- Document equipment connections and locations .
2. Determine Pipe Size and Schedule:
- Calculate the required flow rate and velocity based on the fluid properties and system requirements .
- Select an appropriate pipe size that can handle the flow rate without excessive pressure drop or erosion .
- Determine the pipe schedule (wall thickness) based on the operating pressure and temperature, considering safety factors and code requirements .
3. Calculate Pressure Drop:
- Calculate the pressure drop through straight pipes, fittings (elbows, tees), valves, and equipment using appropriate equations and charts .
- Consider both friction losses and minor losses due to fittings and valves .
- Ensure that the total pressure drop does not exceed the available pressure head .
4. Layout and Routing :
- Route the piping in a simple, neat, and economical layout .
- Ensure adequate flexibility to accommodate thermal expansion and contraction .
5. Model the System:
- Create a 3D model of the piping system using stress analysis software such as CAESAR II, AutoPIPE, or Rohr2 .
- Include all piping, bends, elbows, tees, flanges, and supports .
- Input piping geometry, material properties, and operating conditions .
6. Support Design:
- Select appropriate supports (hangers, guides, anchors) based on pipe size, weight, and thermal movement .
- Position supports at suitable intervals to prevent excessive stress and deflection .
7. Stress Analysis :
- Input the loads the piping system will experience, including:
* Internal pressure and temperature
* Weight of pipe and fluid
* External loads (wind, seismic, thermal expansion)
* Dynamic loads (fluid flow-induced vibrations, transient events) - The software will calculate stresses, forces, and displacements in the system based on the input conditions .
- It will compare the results against allowable stress limits set by design codes .
8. Flexibility Analysis:
- Assess the piping system’s ability to absorb thermal expansion and contraction without overstressing the components or equipment connections .
- Incorporate expansion loops, expansion joints, or flexible connectors as needed .
9. Evaluate the Results:
- After running the analysis, the results must be carefully evaluated . Key metrics to review include:
* Stresses in each pipe segment (compared to allowable stresses)
* Forces and moments on supports and equipment
* Displacements at critical locations (e.g., at equipment nozzles)
* Support loads and reactions
10. Optimize the Design:
* If the analysis reveals areas of concern, adjustments should be made to the design . Common solutions include:
* Adding or repositioning supports
* Incorporating expansion loops or joints
* Modifying the layout to reduce stresses
* Changing the material or wall thickness of the pipe
11. Verify Compliance:
* Ensure that the final design meets all relevant codes and standards .
Weight of water in pipes filled with water can be calculated as
ww = 0.3405 di 2 (3)
where
ww = weight of steel pipe filled with water (Pounds per Foot Pipe)
di = inside diameter (inches)
Weight of Empty Steel Pipes
Weight of empty steel pipes can be calculated in imperial units as
wp = 10.6802 t (do – t) (2)
where
wp =weight of steel pipe (Pounds per Foot Pipe)
t = pipe wall thickness (Inches)
do = outside diameter (inches)
Or. alternatively in metric units
wp = 0.02464 t (do – t) (2b)
where
wp =weight of steel pipe (kg/m)
t = pipe wall thickness (mm)
do = outside diameter (mm)
Cross Sectional Area
Cross-sectional Area of a Steel Pipe can be calculated as
A = 0.785 di 2 (1)
where
A = cross-sectional area of pipe (Square Inches)
di = inside diameter (inches)