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Complete Pipe Stress Analysis using Caesar II Online Course (30+ Hours)

Written by Anup Kumar Dey in Caesar II

Piping systems are the veins of industrial plants, carrying fluids and gases critical for various processes. Ensuring the reliability and safety of these piping systems is paramount, and this is where Advanced Pipe Stress Analysis comes into play. Advanced Pipe Stress Analysis goes beyond basic analysis, offering a comprehensive understanding of how pipes behave under various conditions.

Pipe Stress Analysis is a critical aspect of piping design that evaluates the effects of loads, pressures, and thermal gradients on a piping system. Basic Pipe Stress Analysis typically considers factors like pressure, temperature, and weight to ensure the system’s integrity. However, as systems become more complex and industries demand higher efficiency, Advanced Pipe Stress Analysis becomes essential.

Various sophisticated software tools are essential for Advanced Pipe Stress Analysis. One such powerhouse in the field is Caesar II. Developed by Hexagon PPM, Caesar II is a widely used software application that plays a pivotal role in ensuring the integrity and reliability of piping systems. Caesar II allows engineers and designers to model, analyze, and optimize piping systems. Known for its robust capabilities, the software enables a comprehensive evaluation of various factors influencing pipe behavior, providing a detailed understanding of stress, deformation, and stability under different operating conditions. Throughout the course, the explanations and case studies are provided using Caesar II software.

The complete online pipe stress analysis course is divided into several modules. Each module will explain some aspects of Pipe Stress Analysis that are required for every pipe stress engineer. New modules will be added as and when prepared. You can enroll in the module that you require.

Module 1: Basics of Pipe Stress Analysis (Duration: 5 hours)

  • Click here to join the course. You will learn the following:
    • How to Use Caesar II Software
    • Creating a 3D model of the piping system adding piping, components, fittings, supports, etc
    • Modeling equipment connection in Caesar II
    • Basics Theory of Pipe Stress Analysis
    • Load Case Preparation
    • Analyzing the system and reviewing the Results

Module 2: Pipe Support Engineering (Duration: 2 hours)

  • Join the module by clicking here. The support engineering module will cover the following details:
    • Role of Pipe Supports in Piping Design
    • Types of Pipe Supports
    • Pipe Support Spacing or Span
    • How to Support a Pipe
    • Pipe Support Optimization Rules
    • Pipe Support Standard and Special Pipe Support
    • Pipe Support Engineering Considerations

Module 3: ASME B31.3 Basics for Pipe Stress Engineer (Duration: 1.5 hrs)

  • To enroll in this module click here. You will learn the following:
    • Learn the basics from ASME B31.3 required for a pipe stress engineer
    • Learn Code equations that stress analysis software use
    • Learn the allowable values for different types of code stresses
    • Learn Material allowable stresses
    • Learn to calculate pipe thickness as per ASME B31.3

Module 4: Stress Analysis of PSV/PRV Piping System in Caesar II (Duration: 1 hr)

  • Enroll in this module by clicking here. This module covers
    • Brief about Pressure Safety Valve Systems
    • PSV Reaction Force Calculation
    • Application of PRV Reaction Force in Stress System
    • Case Study of Stress Analysis of PSV System using Caesar II Software
    • Best Practices for PSV Piping Stress Analysis

Module 5: Flange Leakage Analysis in Caesar II (Duration: 1 hr)

  • Click here to enroll in this module. It covers
    • Reasons for Flange Leakage
    • Basics of Flange Leakage Analysis
    • Types of Flange Leakage Analysis
    • Case Study of Flange Leakage Analysis using Caesar II (Case Studies of Pressure Equivalent Method, NC 3658.3 method, ASME Sec VIII method)

Module 6: Spring Hanger Design and Selection (Duration: 1.5 hours)

  • Here is your module for registering. Spring hanger module covers:
    • What is a Spring Hanger?
    • Types of Spring Hangers
    • Differences between Variable and Constant Spring Hangers
    • Design and Selection of Spring Hangers
    • Case Study of Spring Hanger Design and Selection Using Caesar II

Module 7: WRC 537/WRC 297 Calculation in Caesar II (Duration: 1 hr)

  • To join the module click here. It will cover the following:
    • What is WRC 537 and WRC 297
    • When to Perform WRC Calculation
    • Steps for WRC Calculation
    • Practical Case Study of WRC Calculation

Module 8: Buried Pipe Stress Analysis (Duration: 1.5 hr)

  • Click here to enroll for this course. It covers
    • Learn how to model buried piping and pipeline systems in Caesar II software
    • Additional Inputs required for buried pipe stress analysis
    • Create load cases based on ASME B31.3/B31.4/B31.8 codes
    • Perform the underground/buried pipe stress analysis
    • Review the results calculated by the software and understand their meanings

Module 9: Pump Piping Stress Analysis Using Caesar II (Duration: 2.5 hrs)

  • To enroll in this course proceed by clicking here. The course briefly covers
    • Learn the basics of pump piping stress analysis.
    • Learn to create load cases for pump piping analysis in Caesar II software.
    • Learn to read data from pump GA to model and analyze using Caesar II.
    • Practical Case Study of a Pump Piping Stress Analysis

Module 10: Static and Dynamic Analysis of Slug Flow in Caesar II (Duration: 1.5 hrs)

  • To learn from this course click here. It covers
    • Basics of Slug Flow Analysis
    • Calculation of Slug Forces
    • Application of Slug Forces
    • Static Analysis of Slug Flow
    • Dynamic Analysis of Slug Flow

Module 11: FRP-GRP-GRE Piping/Pipeline Stress Analysis Using Caesar II (Duration: 1.5 hrs)

  • Proceed here to enroll in this module of the course. It briefly explains
    • Basics of FRP/GRE/GRP Piping
    • Inputs to ask from the vendor for FRP/GRP/GRE Pipe Stress Analysis
    • Modeling and Analyzing GRP/FRP/GRE Piping system in Caesar II
    • Flange Leakage Checking for FRP Piping Systems
    • FRP Pipe Supporting Guidelines

Module 12: Pipeline Stress Analysis using Caesar II (Duration: 1.5 hrs)

  • Click here for enrolling in this module. This module covers
    • Liquid and Gas Pipeline Stress Analysis using ASME B31.4 and ASME B31.8
    • Difference between Piping and Pipeline
    • Differences between ASME B314 and ASME B31.8
    • Use Caesar II software for pipeline stress analysis with a practical case study

Module 13: Dynamic Analysis of Piping Systems in Caesar II Software (Duration: 1.5 hrs)

  • Join this module by clicking here. This module covers
    • Dynamic Analysis Basics
    • Static Analysis vs Dynamic Analysis
    • Types of Dynamic Analysis
    • Modal Analysis Case Study
    • Response Spectrum Analysis Case Study

Module 14: Guide to Reviewing a Pipe Stress Analysis Report (Duration: 1 hr)

  • Click here for joining this module. It covers
    • Learn How to Review a Pipe Stress Analysis Report
    • Requirements of Pipe Stress Analysis Report
    • What to Review in a Pipe Stress Analysis Report
    • Practical Sample Review Process
    • Steps for Reviewing Pipe Stress Analysis Report

Module 15: Flow-Induced Vibration Analysis of Piping System (Duration: 1 hr)

  • Enroll in the FIV analysis module by clicking here. It covers:
    • Common causes of piping vibration and their effects.
    • Definition of Flow-Induced Vibration.
    • Reasons for FIV in a piping system.
    • FIV Study/Analysis Steps Based on Energy Institute Guidelines
    • Mitigation Options of FIV Study Results.

Module 16: Acoustic Induced Vibration Basics for Piping Systems (Duration: 45 Mins)

  • Click here to enroll in this module. This module covers:
    • What is Acoustic-Induced Vibration or AIV?
    • Causes and Effects Of Piping Vibration
    • Acoustic-Induced Vibration Analysis Steps
    • Mitigation of AIV

Module 17: Storage Tank Piping Stress Analysis (Duration: 1 hr)

  • Click here to enroll in this module. Storage tank piping stress analysis module covers the following
    • Differences between a storage tank and a pressure vessel?
    • Types of storage tanks used in oil and gas industries
    • Why is storage tank piping critical?
    • What is Tank settlement?
    • What is Tank bulging?
    • Storage Tank Nozzle Load Qualification
    • Practical case study of storage tank piping analysis

Module 18: Stress Analysis of Tower/Vertical Column Piping System (Duration: 1.5 hrs)

  • To join Module 18, Click here. This module Covers:
    • Application of Vertical Columns/Towers
    • Inputs Required for Column Piping Stress Analysis
    • Creating temperature profiles for Column/Tower Piping systems
    • Modeling of the Equipment
    • Clip/Cleat Support Modeling from Towers
    • Skirt Temperature Calculation
    • Nozzle Load Qualification
    • Practical Case Study

Module 19: Stress Analysis of Heat Exchanger Piping System (Duration: 1.5 hrs)

Module 20: A Roadmap to Pursue a Career in Pipeline Engineering (Duration: 1 hr)

  • Join the course by clicking here. It covers:
    • What is a Pipeline?
    • What is Pipeline Engineering?
    • Types of Pipeline Engineers, Their Roles and Responsibilities
    • Opportunities for Pipeline Engineers
    • Piping vs Pipeline; What are the Differences?
    • Piping or Pipeline- Which Career Option is Better?
    • How to become a Pipeline Engineer

Module 21: Steps for Pipeline Wall Thickness Calculation & Case Study (Duration: 1 hour)

  • Click here to enroll in this module. This module covers:
    • Need for Pipeline Thickness Calculation
    • Pipeline Thickness Calculation Steps for Restrained and Unrestrained Pipelines
    • Example of Pipeline Thickness Calculation for Aboveground Pipelines
    • Buried Pipeline Thickness Calculation Case Study
    • Additional Checks to satisfy pipeline thickness calculations

As mentioned earlier, new modules will be added frequently. So, keep visiting this post. Also, you can request any specific module by mentioning it in the comment section.

Is Pipe Stress Analysis Required for Cold Water Piping Systems from Pump Stations?

Written by Anup Kumar Dey in Piping Stress Basics

Is Pipe Stress Analysis Required for Cold Water Piping Systems from Pump Stations? This is perhaps one of the most frequently asked questions in the water piping industry. Engineers often argue over this question which results in a dual answer. Some engineers say stress analysis is not required and others say it is required. In this article, we will explore the answer to the above question.

The answer to the above question is not straightforward. In general, as for water piping systems with pump stations, the difference between the maximum working temperature and installed temperature (generally 10 to 20 Degrees) is less, hence it is believed that pipe stress analysis of such water piping systems is not required. This could be valid up to a certain point if good engineering judgments are followed and the piping system is provided with sufficient flexibility.

But before we can conclude, a high level of assessment must be conducted to understand if pipe stress analysis is required. The parameters that substantiate the need for pipe stress analysis are:

How an increase in pipe temperature affects the system:

Even though it is believed that the water piping system will be near to installed temperature. Still, there could be variation due to the following reasons:

  • Seasonal variation of temperature from winter to summer.
  • Empty pipe exposed to sunlight.
  • Full pipe exposed to sunlight.
  • Temperature variation between day and night.

How external forces and displacements affect the water piping and Pump system:

Forces and displacements due to seismic, wind, and structural settlements may impose unacceptable levels of stress on the system. These stresses can not be estimated without proper pipe stress analysis.

Limitation of Pump Nozzle Loadings:

It’s difficult to estimate the nozzle loads without performing pipe stress analysis.

Support optimization:

Cold water piping systems usually have very large sizes along with large valves that result in huge structural loading. Without proper stress analysis, those loads can be overestimated and support optimization may not be possible.

Design of Expansion Bellows or Expansion Joints:

The use of rubber bellows or steel expansion joints at pump stations for water piping systems is quite common. In general pump stations are routed quite straight without much flexibility. So, these expansion joints are used to absorb thermal expansion which in turn reduces pump nozzle loads.

However, there is a concern as the subject of expansion joints is one of the most misunderstood components in the piping industry. In the usual case, simple untied bellows are used which is simply a flexible element between two flanges. It is true that they easily absorb the thermal expansion by compressing the bellow elements in all axial, lateral, angular, and torsional directions. However, a pressure thrust force is generated in untied expansion joints which must be calculated and considered in pipe stress analysis to get the actual effect. This pressure thrust force will be transferred to the pumps. In some situations, the pressure thrust force, itself, will be more than the allowable pump nozzle loads.

Another option is to use a tied expansion bellows. However, even though the tie rods will take care of the pressure thrust load, they will not compress to absorb axial movement and the thermal effect will be transferred to the nozzles. So, their position has to be such that the thermal movement is lateral.

A common misconception is to use tied bellows to a pump line with a gap in the tie nut and believe that the tie rods will take care of the pressure thrust force and the gap between the tie rod nuts will help in absorbing the thermal force by compressing. But as soon as any thermal expansion occurs, the tension in the tie-rods reduces and the pressure thrust load is transferred to the nozzle. So, this has to be carefully considered.

Typical Example of a Pump Station Cold Water Piping System

Fig. 1 below shows a typical example of a water piping system pump station.

Cold Water Piping from Pump Station
Fig. 1: Cold Water Piping from Pump Station

From the image, you can easily understand that the configuration does not have sufficient flexibility, and nozzle loads may increase the allowable.

From the above discussion, we can understand that pipe stress analysis for cold water lines from pump stations needs to be performed

  • To compute nozzle loads.
  • To study the effect of seismic and other displacements
  • To design the pipe expansion joints.
  • To optimize the supports.
  • To study the thermal effects.
  • To assure owners that the design is properly engineered.

References and further Studies

More details about the subject can be found here.

What is a Golden Joint? Meaning, Application, and Code Requirements

Written by Anup Kumar Dey in Construction

We all know that a hydrostatic test is performed in all piping systems to ensure the integrity of all the joints. It is a code requirement before the commissioning of the piping/pipeline system. However, in certain situations, hydrostatic testing may not be technically feasible or may be hugely cost-intensive. For example, When a new piping component is connected to an already existing pipe. The situation may not always be favorable for hydro tests. In such a situation, the golden joint comes as a savior to construction professionals. The joint is called “golden” because of its highly critical nature and the importance of its quality. In this article, we will learn the meaning and applications of golden joints in piping.

What is a Golden Joint?

Golden Joint is a pipe/pipeline joining procedure where hydro testing is not performed after the joining. Extensive NDT methods like radiographic test/ultrasonic testing methods are used to ensure that the joint is defect-free, design is in line with codes and standards, and fit for intended service. A golden joint is also known as a golden weld or closure weld.

Examples of Golden Joints

Some typical examples of golden joints are:

  1. Golden joints in tie-ins from existing pipe parts.
  2. During Hot tapping from running/working/operating pipelines.
  3. When only a little repair work is performed on the system at one or two locations, and hydro-testing of the complete system is difficult, costly, and time-intensive.

Golden Joint Procedure

The requirements of golden weld joints are identified by the construction contractor. Then they mark up the isometric/alignment drawings and get permission from the client. Next following a proper golden joint fabrication method statement, the welding is performed. Next NDE and final inspection clearance is taken and the golden joint is approved. The golded weld or closure weld must be performed by a highly skilled welder.

NDE requirements for Golden Joints

Non-destructive examination or NDE is performed after the PWHT if required by the piping class, thickness, and service limitation. In general, the following NDT tests are performed for golden piping joints.

  • Radiographic Testing: Radiographic testing can be performed as per the guidelines provided in Article 2 of ASME BPVC Code section V.
  • Ultrasonic Testing: Ultrasonic testing can be performed as per the guidelines provided in Article 5 of ASME BPVC Code section V.
  • Magnetic Particle Testing: Magnetic Particle Testing is performed as per the guidelines provided in Article 7 of ASME BPVC Code section V.
  • Dye Penetration Test: Dye Penetrant testing is performed as per the guidelines provided in Article 6 of ASME BPVC Code section V.

Code requirements for Golden Joints

ASME B31.3 Requirements for Golden Joint

As per clause 345.2.3 (c) of ASME B31.3, The final weld connecting piping systems or components need not be leak tested (golden weld) provided the weld is examined and passes with 100% radiographic examination or 100% ultrasonic examination.

ASME B31.4 and ASME B31.8 codes also permit the use of golden pipeline welds for tie-in joints.

Golden Weld Joint ASME B31.4:

Clause 437.1.4-b of ASME B31.4 provides requirements for golden welds. It states:

Testing Tie-Ins. Because it is sometimes necessary to divide a pipeline into test sections and install test heads, connecting piping, and other necessary appurtenances for testing, or to install a pretested replacement section, it is not required that tie-in welds be tested; however, tie-in welds and girth welds joining lengths of pretested pipe shall be inspected by radiographic or other accepted nondestructive methods in accordance with para. 434.8.5(b) if the system is not pressure tested after tie-in. After such inspection, the joint shall be coated and inspected in accordance with para. 461.1.2 before backfilling.

ASME B31.8 requirements for Golden Joints

Clause 841.3.1-a of ASME B31.8 specifies the requirements for golden welds. As per this code:

The circumferential welds associated with connecting pretested assemblies, pretested repair pipe lengths or sections, and welded tie-in connections are not pressure tested after construction in accordance with para. 841.3.2 or para. 841.3.3 or leak tested after construction in accordance with para. 841.3.4 or para. 841.3.5 shall be examined by radiography, ultrasonics, magnetic particle, or other comparable and accepted non-destructive methods in accordance with paras. 826.3 (c) and 826.3(d).

API 570 Requirements for Golden Weld Joints of Piping

As per API 570, when performing a pressure test of a final closure weld that joins a new or replacement section of piping to an existing system is not practical, all of the following four requirements need to be satisfied.

  • a) The new or replacement piping section is pressure tested and examined by the applicable code governing the design of the piping system, or if not practical, welds are examined with appropriate NDE, as specified by the authorized piping inspector.
  • b) The closure weld is a weld between any pipe or standard piping component of equal diameter and thickness, axially aligned (not miter cut), and of equivalent materials.
  • c) Any final closure butt weld shall be of 100 % RT; or angle beam ultrasonic flaw detection may be used, provided the appropriate acceptance criteria have been established.
  • d) MT or PT shall be performed on the root pass and the completed weld for butt welds and on the completed weld for fillet welds.

The owner/user shall specify industry-qualified UT angle beam examiners for closure welds that have not been pressure tested and for weld repairs identified by the piping engineer or authorized piping inspector.

API RP 14-E Requirements for Golden Joint

API RP 14E recommends that when hydrostatic or pneumatic tests create any adverse effect on the piping or operating fluid, a golden joint can be used.

Applications of Golden Joints

As explained above, Golden Joints are commonly encountered in the following situations:

  • Pipeline/Piping Tie-Ins: When connecting new sections of pipeline or piping to existing systems.
  • Facility Modifications: During the integration of new equipment or piping into an operational system, such as through Hot Tapping.
  • Closed-Loop Systems: In scenarios where internal pressure testing is impractical.
  • Final Welds in Inaccessible Locations: Where the completion of the last welds is in areas that are difficult to access.

Features of Golden Joints

Common features of Golden Joints include:

  • Mandatory Non-Destructive Examination (NDE): Since pressure testing is not used, thorough NDE methods like Ultrasonic Testing (UT) and Radiographic Testing (RT) are required to check the weld for any flaws.
  • Strict Welder Qualification: Only highly qualified and certified welders are allowed to perform Golden Joints.
  • 100% NDE Coverage: Every layer of the weld must be carefully inspected using NDE techniques.
  • Detailed Documentation: Comprehensive records of the welding procedure, welder qualifications, and NDE results are required for future reference and traceability.

Piping Materials vs Pipeline Materials: Major Differences

Written by Anup Kumar Dey in Engineering Materials

Both pipelines and piping systems play a pivotal role in the transportation of fluids, gases, and other materials across various industries. Even though the terms “piping” and “pipeline” are often used interchangeably, there are significant differences between the two. The major differences between piping and pipeline are already discussed here. Note that, there are distinctions between the materials used in piping and pipelines. In this article, we’ll learn some of the differences between piping and pipeline materials while exploring their characteristics, applications, and considerations.

What are Piping Materials?

Piping refers to a system of pipes used to convey fluids within a facility or plant. Piping materials are carefully selected based on factors such as the type of fluid being transported, temperature and pressure requirements, corrosion resistance, and cost considerations. Some of the materials used in Piping are:

Metals:

Common metals used in piping systems are:

  • Carbon steel,
  • LTCS (low-temperature carbon steel)
  • Stainless steel,
  • Copper, aluminum, and various other alloys.

Carbon steel is a popular choice for its strength and affordability, while stainless steel is preferred for its corrosion resistance, making it suitable for corrosive environments.

Plastics:

Plastic materials are chosen for their corrosion resistance, flexibility, and ease of installation. Common plastic materials in piping are:

  • Polyvinyl chloride (PVC),
  • Polyethylene (PE)/HDPE, and
  • Polypropylene (PP)

Composite Materials:

Fiberglass-reinforced plastic (FRP) and reinforced thermosetting resin (RTR) are composite materials increasingly utilized in piping. These materials offer a balance of strength, corrosion resistance, and lightweight characteristics.

Piping vs Pipeline Materials
Piping vs Pipeline Materials

What are Pipeline Materials?

Pipelines are long-distance transportation systems designed to carry large volumes of fluids or gases over extended distances. Pipeline materials must withstand the challenges posed by external environmental factors, such as soil conditions, temperature variations, and potential ground movement. Common materials used in pipelines are:

  • Carbon Steel: Carbon steel remains a predominant material for pipelines, especially in the oil and gas industry. It provides a balance of strength, durability, and cost-effectiveness. Pipeline materials use API 5L code for the pipes and API 6D code for the valves.
  • High-Strength Alloys: In high-pressure and extreme temperature applications, pipelines may incorporate high-strength alloys such as X65 or X70 to ensure structural integrity.
  • Corrosion-Resistant Alloys: For corrosive environments, corrosion-resistant alloys like duplex stainless steel or nickel alloys are employed to prevent degradation over time.
  • Non-metallic pipelines: Pipelines can also use PE/HDPE/PP materials or FRP/GRP/RTR/GRE materials for fluid transportation.

Differences between Piping Material and Pipeline Materials

The major differences between Piping and Pipeline Materials can be discussed considering various parameters as mentioned below:

Material Selection Criteria

Piping materials are decided considering the following parameters:

  • The type of fluid that will be transported through the pipes
  • The design and operating temperatures and pressures of the pipes
  • The flow medium characteristics, such as viscosity, density, corrosiveness, abrasiveness, etc.
  • The fracture tendencies of the pipes, such as fatigue, creep, thermal expansion, etc.
  • The corrosion and erosion of the pipes, such as galvanic, pitting, stress corrosion cracking, etc.
  • The environment where the pipes will be working, such as indoor, outdoor, underground, underwater, etc.

On the other hand, pipeline materials are selected considering the following factors:

  • The fluid transportation efficiency (the ability of the pipeline to deliver the fluid with minimal losses, such as friction, leakage, etc.)
  • Safety and reliability (the ability of the pipeline to prevent or withstand failures, such as rupture, explosion, fire, etc.)
  • The environmental impact (the effect of the pipeline on the surrounding environment, such as soil, water, air, wildlife, etc.)

Temperature Resistance

Piping materials have the capability of carrying fluids at very high temperatures and pressures. While the temperature capability of Pipelines is limited to 232 degrees C as per ASME B31.8 (120 degrees C as per ASME B31.4).

Design Allowable Stresses

Piping materials are limited by the design’s allowable stresses which is governed by the term Sc and Sh which are much lower than the material yield strength. On the other hand, the pipeline material’s design allowable stress is governed by SMYS (Specified minimum yield strength). So, pipeline materials have a very low safety factor than piping materials.

Material Thickness

For the same pressure rating, pipeline materials usually have less material thickness as compared to piping materials. Hence, the weight of the piping materials is more than that of pipeline materials for the same pressure classes.

Hydrotest Pressure

Piping materials are usually hydrostatically tested at 1.5 times the design pressure whereas pipeline materials are hydrotested at 1.25 times the design pressure.

Corrosion Resistance

In most cases, the piping materials have to resist the corrosion generated by the fluid it carries means internal corrosion. While pipeline materials need to withstand external corrosion from soil and environmental factors.

Temperature and Pressure Ratings

Piping materials must meet specific temperature and pressure requirements based on the application, while pipeline materials need to account for the varying conditions along their extensive routes.

Cost Considerations

Piping materials are often selected based on factors such as installation costs and ease of maintenance within a confined space. Pipeline materials, on the other hand, must balance upfront costs with the long-term durability required for extended transportation routes.

Environmental Factors

Pipelines traverse diverse landscapes, and materials must be chosen considering factors like soil conditions, seismic activity, and temperature fluctuations.

Here’s a comparative table that outlines the major differences between piping materials and pipeline materials:

FeaturePiping MaterialsPipeline Materials
ScopeUsed for smaller, often individual sections or componentsUsed for larger, continuous segments of transportation systems
Size RangeTypically smaller diameter, up to a few inches in diameterGenerally larger diameter, from several inches to several feet
Common Materials– Carbon Steel
– Stainless Steel
– PVC
– Copper
– PEX		– Carbon Steel
– Stainless Steel
– Ductile Iron
– HDPE
– Concrete
ApplicationUsed in residential, commercial, and various industrial applicationsPrimarily used in industrial and utility applications, including oil, gas, and water transportation
Pressure RatingsGenerally designed for various pressure ratings depending on applicationDesigned to handle high pressure and high flow rates over long distances
FlexibilityOften more flexible and easier to handle and install in smaller sectionsLess flexible, typically requires heavy equipment and precise installation
Jointing Methods– Threaded
– Welded
– Flanged
– Compression
– Solvent Weld		– Welded
– Flanged
– Bolted
– Mechanical Couplings
CostGenerally less expensive due to smaller size and simpler applicationsTypically more expensive due to size, material requirements, and installation complexity
DurabilitySuitable for a range of applications with varying durability needsDesigned for long-term durability and resistance to harsh conditions
Corrosion ResistanceVaries by material; options for corrosion-resistant materials like stainless steel or PVCOften designed with materials or coatings that resist corrosion in challenging environments
InstallationEasier to install in small sections; often done manuallyRequires heavy machinery and specialized techniques for installation
MaintenanceGenerally easier and less costly to maintain and replaceMaintenance can be more complex and costly due to the scale and potential for more significant issues
Standards and CodesSubject to various industry and local standards for residential and commercial useGoverned by stringent industry standards and codes for large-scale infrastructure, such as API, ASME, and ASTM
Temperature RangeVaries by material; some designed for high temperatures, others for coldDesigned to handle extreme temperatures and environmental conditions. However very high design temperatures are usually not expected.
Table 1: Piping Materials vs Pipeline Materials

In a nutshell, Piping materials are often constructed with a wide range of materials and components, such as cast iron, carbon steel, low-temperature carbon steel, alloy steel, stainless steel, duplex stainless steel, nickel alloys, aluminum, titanium, etc. Piping materials also use different codes and standards for the pipes, fittings, and valves, such as ASTM, BS, API 5L, ASME B31, ANSI, DIN, ISO, etc. Pipeline materials have to mainly consider fluid transportation efficiency, safety and reliability, and environmental impact. Pipeline materials are typically constructed with a single type of material, such as steel, plastic, or composite. Pipeline materials use API 5L code for the pipes and API 6D code for the valves.

Pressure Vessels vs Storage Tanks: Major Differences

Written by Anup Kumar Dey in Mechanical

Pressure vessels and storage tanks are both types of containers that are used to store fluids. However, they have different characteristics, functions, and applications. In this article, we will explore the major differences between pressure vessels and storage tanks.

What is a Pressure Vessel?

A pressure vessel is a mechanically designed container that holds gases, vapors, liquids, or two-phase fluids at pressures different from the ambient pressure. Usually, they are equipped with provisions for the introduction or removal of heat from the container. To avoid the risk of bursting, the pressure vessels are designed, fabricated, installed, and maintained following industry codes, standards, and procedures. Pressure vessels have various parts including shell, head, nozzle, saddles, skirts, etc.

The ASME BPVC is used for rules and guidelines for the design, construction, inspection, testing, and certification of pressure vessels. It ensures the safe operation of vessels under various pressure and temperature conditions. Pressure vessel manufacturers, operators, and regulators worldwide use the ASME BPVC code to ensure the integrity and safety of pressure vessels used in various industries.

What is a Storage Tank?

A storage tank can be defined as a container designed to store liquids or gases at atmospheric or low pressures. Storage tanks are usually made from thin-walled materials so they don’t hold as much pressure as pressure vessels. They’re often found to hold fuel for cars, which has less than 10 psi but is still high enough to create problems if not properly contained. Storage tanks consist of some of the important parts like shell, roof, bottom, nozzle, manhole, etc.

The API 650 and API 620 standards provide rules and guidelines for the design, construction, inspection, testing, and certification of storage tanks to ensure their safe operation under various pressure and temperature conditions. These standards are widely recognized and followed by manufacturers, operators, and regulators worldwide to ensure the integrity and safety of storage tanks used in various industries.

Pressure Vessel vs Storage Tank
Storage Tank vs Pressure Vessel

Differences between a Tank and a Pressure Vessel

Pressure vessels and storage tanks differ in several aspects, such as shape, purpose, construction, orientation, mounting, material, size, cost, and heating method. Here are some of the key differences between them:

Shape:

Pressure vessels can have various shapes, such as cylindrical, spherical, rectangular, or conical, depending on the design requirements and the type of fluid stored. Cylindrical pressure vessels are one of the most common types. They have a cylindrical shape with flat or dished ends, offering a simple and effective design for containing fluids under pressure. These vessels are used in applications such as storage tanks, air receivers, and hydraulic accumulators.

Spherical pressure vessels have a spherical shape, offering the best design for containing fluids under high pressure. These vessels are used in applications such as gas storage, liquefied natural gas (LNG) carriers, and nuclear reactors.

Rectangular pressure vessels have a rectangular shape, offering a compact design for containing fluids under low to moderate pressure. These vessels are used in applications such as water heaters, boilers, and autoclaves.

Conical pressure vessels have a conical shape, offering a tapered design for containing fluids under varying pressure. These vessels are used in applications such as rocket engines, nozzles, and diffusers.

Storage tanks, on the other hand, are usually cylindrical in shape, with flat or conical roofs and bottoms, offering a simple and economical design for storing fluids under low to moderate pressure. These tanks are used in applications such as fuel storage, water storage, and oil storage. Spherical tanks and cylindrical bullet tanks are also found for low-pressure storage applications.

Purpose:

Pressure vessels and storage tanks have different purposes, depending on the type of fluid stored and the process involved. Pressure vessels are primarily used for processing, separating, or transporting fluids under pressure. They often serve as reactors, heat exchangers, distillation towers, separators, reboilers, knock-out drums, scrubbers, dryers, coalescers, etc for various industries, including chemical, petrochemical, oil and gas, power, pharmaceutical, and food and beverage.

Storage tanks are primarily used for storing liquids or gases at a specified pressure. Storage tanks often serve as reservoirs for various industries, including petrochemicals, pharmaceuticals, and water treatment plants.

Construction:

Pressure vessels and storage tanks have different construction methods, depending on the design requirements and the type of fluid stored. Pressure vessels are usually made of thick-walled materials, such as carbon steel, stainless steel, alloy steel, or composite materials, to withstand high pressure and temperature. They are also welded, bolted, or riveted together, depending on the size and shape of the vessel. Pressure vessels are also equipped with various accessories, such as valves, gauges, safety devices, insulation, etc, to control and monitor the pressure and temperature of the fluid inside.

Storage tanks are usually made of thin-walled materials, such as carbon steel, stainless steel, aluminum, or plastic, to store low to moderate-pressure fluids. They are also fabricated, erected, or assembled on-site, depending on the size and shape of the tank. Storage tanks are also equipped with various accessories, such as vents, overflows, drains, ladders, platforms, etc, to facilitate the filling and emptying of the fluid inside.

Orientation:

Pressure vessels and storage tanks have different orientations, depending on the design requirements and the type of fluid stored. Pressure vessels can be horizontal, vertical, or inclined, depending on the space available and the flow direction of the fluid. Horizontal pressure vessels are used when the fluid has a low-density difference or a high viscosity, such as oil, water, or air. Vertical pressure vessels are used when the fluid has a high-density difference or a low viscosity, such as gas, steam, or liquid. Inclined pressure vessels are used when the fluid has a moderate density difference or a moderate viscosity, such as two-phase fluids, slurries, or mixtures.

Storage tanks are usually vertical, with flat or conical roofs and bottoms, depending on the type of fluid stored and the environmental conditions. Vertical storage tanks are used when the fluid has a low vapor pressure or a high specific gravity, such as water, oil, or diesel. Flat-roofed storage tanks are used when the fluid has a moderate vapor pressure or a moderate specific gravity, such as gasoline, kerosene, or ethanol. Conical-roofed storage tanks are used when the fluid has a high vapor pressure or low specific gravity, such as propane, butane, or ammonia.

Mounting:

Pressure vessels and storage tanks have different mounting methods, depending on the design requirements and the type of fluid stored. Pressure vessels can be supported by legs, skirts, saddles, lugs, or brackets, depending on the size, shape, and weight of the vessel. Legs are vertical supports that are attached to the bottom of the vessel, providing simple and stable support. Skirts are cylindrical or conical supports that are attached to the bottom of the vessel, providing a rigid and uniform support. Saddles are curved supports that are attached to the sides of the vessel, providing flexible and adjustable support. Lugs are protruding supports that are attached to the sides of the vessel, providing convenient and portable support. Brackets are angular supports that are attached to the sides of the vessel, providing compact and lightweight support.

Storage tanks can be supported by foundations, piers, columns, or piles, depending on the size, shape, and weight of the tank. Foundations are concrete or steel structures that are built on the ground, providing solid and durable support. Piers are vertical supports that are built on the ground, providing simple and economical support. Columns are vertical supports that are built above the ground, providing flexible and adjustable support. Piles are vertical supports that are driven into the ground, providing strong and stable support.

Size:

Pressure vessels are generally smaller in size than storage tanks, as they have to contain higher pressure and temperature. Storage tanks are larger in size than pressure vessels, as they have to store larger volumes of fluid at lower pressure and temperature.

Cost:

Pressure vessels are more expensive than storage tanks, as they require more material, labor, and quality control to ensure their safety and performance. Storage tanks are less expensive than pressure vessels, as they require less material, labor, and quality control to ensure their functionality and durability.

Below is a tabular format outlining the main differences between a pressure vessel and a storage tank:

Pressure VesselStorage Tank
Pressure vessels contain gases or liquids at high pressure.Storage tanks hold liquids or gases at atmospheric pressure or low pressure.
Operating under high pressure (above atmospheric pressure) is the main characteristic of every type of pressure vessel.Storage Tanks operate at or near atmospheric pressure or low pressure.
Pressure vessels are engineered and designed to withstand significant internal pressure.The design of storage tanks focuses on storing and retaining fluids with minimal pressure resistance.
Pressure vessels are utilized in various industries like chemical, petrochemical, power generation, mineral, food, pharmaceutical, etc.Storage tanks are commonly used in storage applications to store fuel, water, crude oil, etc.
The design of pressure vessels requires rigorous stress analysis and design calculationsStorage tank generally has less complex stress analysis and design requirements
Pressure vessel usually has thicker walls to handle high pressure.In most situations, storage tanks have thinner walls due to lower pressure requirements.
Safety relegation of pressure vessels is subjected to strict requirements and codesThe storage tank follows safety regulations but usually has fewer requirements
Most pressure vessels require pressure relief devices to prevent overpressure.Storage tanks are usually equipped with vents for pressure equalization.
Pressure vessels can be mobile or stationary depending on the application.Typically the storage tanks are stationary and not designed for mobility.
Table 1: Storage Tanks vs Pressure Vessels

Note that pressure vessels and storage tanks have distinct differences in design, purpose, and applications. However, there may be some overlap in their usage based on specific industry requirements and operating conditions.

Pressure vessels are integral components in a wide range of industries, ensuring the safe storage, transportation, and processing of fluids under pressure. Understanding the different types of pressure vessels and their specific applications is vital for engineers, designers, and professionals working with these critical components. Whether it’s cylindrical, spherical, storage, heat exchangers, or reactors, each type serves a distinct purpose and plays a significant role in various industrial processes, contributing to the advancement and safety of modern technology and infrastructure.

What is Pressure Vessel Fabrication?

Written by Anup Kumar Dey in Mechanical

Pressure vessel fabrication refers to the process of manufacturing containers designed to hold fluids or gases at varying pressures, often under high or elevated pressure conditions. These vessels are found in a wide range of industries, including petrochemical, pharmaceutical, aerospace, nuclear, food, and more. The process of pressure vessel fabrication involves planning, studying pressure vessel general arrangement and fabrication drawings, selecting appropriate materials, assembling, welding, testing, and inspecting these vessels to ensure they meet specific safety and performance standards.

Pressure vessels are crucial components in various industrial processes where the containment of substances under pressure is essential for the successful operation of various applications. Pressure vessel fabrication must adhere to strict engineering and quality control standards to ensure the vessels’ integrity and safety in their intended use at different pressures and temperature conditions. It is a complex and highly specialized field that requires precision, skill, and adherence to strict quality standards. In this blog post, we will explore the process and key considerations of pressure vessel fabrication. Fig. 1 below shows an example of typical pressure vessel fabrication.

Pressure Vessel Fabrication
Fig. 1: Pressure Vessel Fabrication

Key Considerations in Pressure Vessel Fabrication Process

Pressure vessels often work under a range of varying pressure and temperature. So, its fabrication must be proper so that the equipment performs the intended operation for its design life without failure. The fabrication of a pressure vessel is a complex process and it involves several critical considerations.

Pressure Vessel Fabrication Drawing

Pressure vessel fabrication drawings are detailed technical drawings that provide a visual representation of the design, dimensions, and specifications of a pressure vessel. These drawings serve as a crucial reference for the designers, inspectors, and fabricators during the manufacturing and quality assurance process. Pressure vessel fabrication drawings are typically created by experienced engineers and designers using Computer-Aided Design (CAD) software to ensure precision and adherence to design codes and standards.

The fabrication drawing shows all details required for equipment fabrication such as dimensions, part detailing, weld details, nozzle schedules, bill of material, design data, equipment plan view, elevation view, sectional views, etc. Here’s what is typically found in a pressure vessel fabrication drawing:

  • Pressure Vessel Design Code
  • Vessel Geometry that includes detailed illustrations of the vessel’s shape, dimensions, cross-sections, and overall geometry. The fabrication drawings provide the vessel’s diameter, height, and specific features like nozzles, manholes, or flanges.
  • Material Specifications to inform the pressure vessel fabricator about the material, grade, and thickness to be used in the fabrication process.
  • Welding Details like the type of welds, welding locations where welding is required, weld joint details, and weld size requirements are typically included.
  • Information related to Pressure Vessel Nozzles and Openings like nozzle positions, sizes, and types of nozzles and openings, including details like flange ratings and orientations.
  • Pressure and Temperature Ratings for the vessel’s design
  • Reinforcement and Supporting details
  • Instrumentation and Accessories such as pressure gauges, safety valves, sight glasses, and level indicators that may be attached to the vessel.

Once the pressure vessel fabrication drawing is generated, the fabricators produce the pressure vessel following the below-mentioned steps:

1. Material Preparation:

Material preparation is a crucial first step in pressure vessel fabrication. It involves the following activities:

  • Material Selection: The material requirement of each component is mentioned in the vessel fabrication drawing. The selection of appropriate materials is done by the material engineers based on factors such as the type of substance to be stored, operating temperature, and pressure conditions. Some of the common pressure vessel materials are carbon steel, stainless steel, LTCS, alloy steel, and exotic alloys.
  • Cutting and Shaping: Selected materials are then cut, shaped, and prepared for assembly according to the vessel’s design specifications. This includes cutting sheets or plates into the required shapes and sizes.
  • Edge Preparation: The edges of the material pieces are often prepared to ensure proper fit-up and weld quality. This may involve beveling or chamfering the edges.

2. Welding:

Welding is a critical process in pressure vessel fabrication. Skilled welders are responsible for joining the prepared material pieces to create the vessel’s shell and heads. The welding process includes:

  • Welding Techniques: The use of appropriate welding techniques such as shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), or submerged arc welding (SAW), depending on the materials and design.
  • Weld Joint Preparation: Preparing the joints for welding, which may involve bevelling or chamfering, and ensuring proper alignment.
  • Quality Control: Continuous monitoring of the welding process to ensure high-quality and defect-free welds.

3. Heat Treatment:

Heat treatment is often applied to pressure vessel components after welding to relieve residual stresses and enhance material properties. The heat treatment process usually involve:

  • Stress Relieving: Controlled heating and cooling to reduce stresses induced during welding, which can help prevent cracking and improve material properties.
  • Normalizing: A heat treatment process that refines the grain structure and improves material uniformity.

4. Testing:

Testing is a critical aspect of pressure vessel fabrication to ensure the vessel’s integrity and safety. Common tests include:

  • Non-Destructive Testing (NDT): Some of the common NDT methods are radiography, ultrasonic testing, magnetic particle testing, and dye penetrant testing. They detect defects and ensure the welds are sound.
  • Hydrostatic Testing: Filling the vessel with a liquid, usually water, and pressurizing it to verify its performance and to check for leaks or deformations.

5. Surface Finishing:

After testing, the pressure vessel undergoes surface finishing, which includes:

  • Cleaning: Removing any contaminants, oils, or residues from the vessel’s surface to prepare it for surface treatments.
  • Painting or Coating: Applying paint or protective coatings to the vessel’s exterior to prevent corrosion and enhance its appearance.

6. Final Inspection and Documentation:

Before the vessel is ready for delivery, it undergoes a final inspection to ensure compliance with design specifications and industry standards. This step includes:

  • Visual Inspection: A thorough visual examination of the vessel’s components and welds.
  • Documentation: Preparing comprehensive documentation that includes material certificates, welder qualifications, NDT reports, and other quality-related documents.

7. Delivery and Installation:

Once the pressure vessel has passed all quality control checks and inspections, it is prepared for delivery to the client’s site. This involves:

  • Transportation: Safely moving the vessel to the installation site, which may require specialized equipment and transportation methods.
  • Installation: Installing the pressure vessel at the intended location, often involving the connection of piping, instrumentation, and safety mechanisms for it to be fully operational.

To ensure the successful fabrication and safe operation of pressure vessels, each of these steps plays a crucial role, especially when industries prioritize safety and performance. Adherence to design specifications and industry standards is essential throughout the entire fabrication process.

Video Tutorial on Fabrication of Pressure Vessel

Refer to the following video, that explains the process of a typical vessel fabrication process clearly.

Pressure Vessel Fabrication Video Tutorial