Piping System Design Software
Giulia Satmary
Simply defined, pipes are pathways through which fluids are contained and flow in a system. The fluids may be water, glycol solution, fuel oil and refrigerant liquid. A network of pipes, fittings, joints, valves and supports is defined as a pipe system.
Pipe system design is dependent on the requirements and design criteria that are specific of each discipline. The design of pipe systems is also governed by codes such as those published by ICC and standards and guidelines published by trade associations such as ASME, ASTM, NFPA, MSS, AWWA and ASHRAE.
An optimum pipe system design is critical to the operation and longevity of the overall infrastructure and requires a multipronged approach. With appropriate maintenance, piping is typically expected to last the age of the building, while other equipment is replaced at the end of its service life. As pipe systems span multiple disciplines with varying requirements, developing an all-encompassing design guideline would be a monumental task.
Pipes can be broadly classified as metallic type and nonmetallic type. Commonly used metallic pipes are carbon steel, copper and ductile iron. Metallic pipes and fittings have been used for ages and continue to be used extensively.
Steel pipes manufactured in accordance with ASTM A53 standard specification are typically used in the mechanical industry. ASTM A53 covers nominal pipe size from 1/8 inch through 26 inches. Based on the manufacturing process and size, steel pipe can be classified as Type S (seamless), Type F (furnace butt weld) or Type E (electric resistance weld). Type F is available in Grade A while Type E and Type S are available in Grade A and B. The two grades have slightly different chemical composition of steel such as maximum percentage of carbon. Grade B is widely used due to its higher tensile strength.
The wall thickness of steel pipe is identified by schedule or weight class. Depending on size, steel pipe is typically available from schedule 5 through schedule 160 and wall thickness increases with schedule number. For example, 8-inch steel pipe has an outside diameter of 8.625 inches. However, the wall thickness varies from 0.109 inch (schedule 5) to 0.906 inch (schedule 160).
The working pressure of steel pipe increases with its schedule. ASME B31 identifies the criteria for calculating the working pressure of steel pipe systems. Calculations should include allowance for mill tolerance on wall thickness, corrosion allowance and cutting allowance if using threaded or cut-grooved joints. The ASHRAE Fundamentals Handbook is an excellent reference and it provides working pressure of commonly used steel pipe schedules from nominal pipe size 1/4 inch to 20 inches.
For the mechanical industry, commonly used steel piping is schedule 40 and schedule 80 for sizes 10 inches and below. Schedule 40, STD (standard weight) and schedule 80 are commonly used for pipe sizes 12 inches and above.
Similar to steel piping, ASME B31 identifies the criteria for calculating the working pressure of copper tube systems. Copper tubes are available as hard-drawn (rigid) or annealed (bendable). Hard-drawn tubing has a higher working pressure compared to annealed tubing. Copper tubes are typically joined by using brazed, soldered, grooved-end or press-connect fittings. When brazing is used for joining hard-drawn copper tubing, the high temperatures associated with the joining process anneals copper at the joint and therefore the pressure ratings of annealed tubing are used.
Common nonmetallic pipe systems used in the mechanical industry are polyvinyl chloride, chlorinated polyvinyl chloride, cross-link polyethylene (PEX), high-density polyethylene, polypropylene, acrylonitrile butadiene styrene and others. Nonmetallic systems continue to gain popularity in the mechanical industry and proprietary plastic blends continue to be developed.
Nonmetallic pipes offer several advantages such as low cost, light weight, inherent corrosion protection, immunity from galvanic effects, chemical inertness, low thermal conductivity, low friction losses and ease of installation.
However, the application needs to consider the disadvantages, such as low baseline strength and severe degradation at elevated temperatures, high coefficient of expansion and limited ultraviolet resistance if installed outdoors. Nonmetallic pipes are typically joined by solvent, threaded and flanged connections.
The various pipe materials have inherent advantages and disadvantages. During design, it is critical that the attributes of pipe systems be reviewed in detail to ensure that the system that best satisfies the project requirements is selected.
Piping design, a critical component of engineering projects and process plants, is a crucial aspect of creating systems that transport liquids, gases, or solids from one place to another. It involves planning the layout, selecting materials, and determining the connections between pipes, valves, and other components.
In the industry, pipe design is the specialized engineering discipline focused on creating efficient and safe systems for transporting various substances. It plays a vital role in sectors such as oil and gas, power plants, and chemical processing, ensuring the seamless flow of materials while considering factors like safety, efficiency, and compliance with regulations.
In pipe design, understanding the hydraulic aspects is crucial. This involves analyzing the flow of fluids, determining velocities within the pipes, and assessing pressure drop to ensure an efficient and effective system.
To address energy efficiency, piping design involves considerations for insulation and thermal losses. This helps in maintaining desired temperatures within the system and minimizing unnecessary energy dissipation.
Creating detailed plans for the layout is a pivotal step. Utilizing both 2D and 3D models aids in visualizing the entire piping system, ensuring accurate routing, and facilitating effective communication in the design process.
Developing comprehensive lists detailing the various components and specifications within the piping system is essential. This serves as a reference for all involved parties and streamlines the execution of the design.
Adhering to industry standards such as ASME B31.1, ASME B31.3, or EN13480, mechanical design involves calculating the thickness of pipes. This ensures that the piping system can withstand the internal and external forces it may encounter during operation.
Providing clear and detailed isometric drawings is vital for construction teams. These drawings offer a three-dimensional representation of the piping system, aiding in accurate and efficient implementation.
Documenting the final state of the piping system, known as the As-Built design, ensures that the constructed system aligns with the original design intent. This documentation serves as a valuable reference for future maintenance and modifications.
A crucial element is conducting flexibility analysis in accordance with industry standards like ASME B31.1, B31.3, or EN 13480. This involves assessing how pipes respond to thermal expansion or contraction, ensuring that the system can accommodate these changes without causing stress-related issues.
Determining the type and position of supports is a key aspect of piping design. The proper selection and placement of supports are essential to maintain stability and prevent excessive movements or stresses in the piping system.
Consideration for pipes that are buried is vital in piping design. Understanding the impact of soil conditions and environmental factors on buried pipes ensures their integrity over time, preventing potential issues like corrosion or deformation.
Ensuring that the loads on equipment nozzles, such as those on pumps or static equipment, are within allowable limits is critical. This involves using standards like WRC-107 to assess and verify the structural integrity of these connections.
In advanced piping flexibility analysis, determining the Stress Intensification Factor (SIF) is crucial, especially for unique geometries not covered by standard codes like ASME B31.1/B31.3. This involves using methodologies outlined in B31J to assess and factor in stress intensification in non-conventional piping configurations.
Special transitions between rectangular and circular sections require careful consideration in advanced pipe design. Analyzing stress and deformation in these transition areas ensures smooth and reliable operation of the piping system.
Designing specialized supports is a key element in advanced piping flexibility analysis. This involves tailoring support structures to unique conditions, considering factors like load distribution and thermal expansion, to ensure the overall stability and integrity of the piping system.
Advanced flexibility analysis addresses the creep range, where materials deform over time under sustained loads. Designing for and operating within the creep range ensures the long-term durability and reliability of the piping system.
Considering cyclic loads and conducting fatigue analysis is crucial in advanced pipe design. This involves assessing how the piping system responds to repeated loading and unloading cycles, ensuring that it can withstand these dynamic conditions without experiencing fatigue-related failures over time.
ASME B31.3 sets guidelines for the design, construction, and inspection of process piping systems. It addresses aspects like materials, pressure design, flexibility analysis, and testing, ensuring the safety and reliability of piping systems in various industries.
API 570 focuses on in-service inspection, evaluation, and testing of piping systems used in the refining and chemical process industries. It outlines criteria for assessing the integrity of existing piping infrastructure, covering aspects such as corrosion, material degradation, and structural integrity.
ISO 14692 provides guidelines for the design and installation of glass-reinforced plastic piping systems in the petroleum and natural gas industries. It addresses considerations like material selection, design principles, and installation practices for GRP piping in challenging environments.
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