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Who is a Piping Design Engineer or Piping Designer or Piping Layout Engineer?

Written by Anup Kumar Dey in Mechanical,Piping Design Basics,Piping Interface

Piping Design Engineers, Piping Layout Engineers, or Piping Designers are piping professionals who design the piping network of the complete plant. Piping Designing means deciding the overall plant layout, the equipment location, the Plot Plan, the pipe routing, the development of the 2D or 3D CAD models, and finally the piping isometrics. Broadly Piping Design Engineers or Piping Designers perform a maximum of the piping design work scope. A smaller part is performed by Piping Materials Engineers and Piping Stress Engineers in a different manner.

Piping design is a very critical activity. It requires knowledge of various aspects. As the maximum part of any plant is covered by piping and equipment and structures are connected to piping, it is very important that piping design must be proper. Failure to do any single part can cause serious damage to the plant. So piping engineers and designers should follow their duty with utmost care. In the following paragraphs, I will present a list of the most basic points that a good piping designer or piping design engineer should know.

Pipes, Pipe Fittings, Piping Components

All piping designers /piping design engineers should be aware of the broad spectrum of piping and piping-related items. This translates to

Codes, Standards, Specifications, Guidelines

All piping design engineers/ designers should be aware of important design points from relevant Codes (ASME B31.3, ASME B 31.1, etc. as applicable), Standards (API or ASME standards), Specifications (Company Material Class and other specifications), and Guidelines (Local Company guidelines like Shell DEP rules, Norsok standards, etc). The more conversant with such documents the piping engineer/designer is, the less time he will be taking for designing activity.

Interaction with other Engineering groups

All piping designers/ piping layout engineers need to understand the activities and roles of all the other engineering and design groups on the project. He should be aware of the complete workflow process. These include Process, Static Equipment, Rotary Equipment, Civil, Structural, Electrical, and Instruments/Control Systems. All these groups contribute to a large extent to Piping’s success and vice versa.

Piping Design Execution

The success of Piping Design activities is closely linked to P&IDs, equipment GA drawings, instrument drawings, stress analysis, and structural support design. So a good piping design engineer/piping designer must be able to identify the areas where the piping design is being held up.

Software Tool Knowledge

In recent times all piping design activities are performed in various commercial software like PDS, PDMS, SP3D, E3D, AutoCAD, etc. So the design engineer should be knowledgeable in operating the required software for the project. He must also be aware of other software like Navisworks, SPR, MS-office, etc.

Sample 3D piping design model
Fig. 1: Sample 3D piping design model

Working knowledge of Process Documents

All piping designers and engineers need to be able to read and understand one of the most basic process documents called P&ID (Piping and Instrument Diagram) or PEFS (Process Engineering Flow Scheme). Piping Design Engineer should know how to extract data from P&ID and use those in Piping Design. Throughout the complete detailed design phase, P&ID will be the master navigator of piping design.

Basic Process Variables

The design engineer/designer must be well aware of a few basic process variables like pressure, temperature, flow, and level. Also, the instrumentation used to regulate and/or measure these variables are a very important parameter for piping designer/layout engineer.

Drawing Content

All piping engineers and designers must know to present their designs following company standard templates. Drawing content and standard dimensioning practices must be pre-decided in order to clearly communicate the designs to construction and fabrication personnel.

Preliminary knowledge of Process Equipment

Knowing and understanding different types of process equipment (Vessels, Pumps, Heat exchangers, Reactors, Fired Heaters, Compressors, Flares, Storage Tanks, etc) is an added advantage for all piping designers/engineers. They should be aware of the piping-related issues for each type of equipment and piping design rules governed by the equipment. The piping engineer/ designer should know that a few types of equipment have nozzles fixed by the manufacturer and for others, the piping designer should locate the nozzles. Preliminary knowledge of the operational, maintenance, and installation/construction issues for each piece of equipment is very important.

Piping from Equipment

All the piping design engineers and piping designers should know the piping rules to be followed for different kinds of equipment along with maintenance/operational space requirements.

Allowable pipe spans for pipe supporting

All designers should know the use of piping support spans and guide spans for preliminary pipe support. Piping with different materials and pipe schedules has different spans. Also, these spans may change based on temperature and fluid being transported.

Typical model by a piping designer
Fig. 2: Typical model by a piping designer

Preliminary Knowledge of Piping expansion

It’s always advantageous to have preliminary knowledge of the thermal expansion of different piping materials for different temperatures. In recent times various software like Pipe Data Pro easily provides these data. However, knowing how to use that data efficiently is very important. The thermal growth or thermal movement with an increase or decrease in temperature must be allowed for and incorporated into the overall design. Care should be taken that one line is not hitting the other line and sufficient spacing should be provided. Additionally, these expansion data will be used for expansion loop design and shoe/support length design.

Designing and Locating Piping Expansion loops

All piping design engineers and piping designers should know the use of simple rules and methods for sizing expansion loops for the most common sizes, schedules, and materials.

Basic knowledge of flexibility while pipe routing

All piping engineers/ designers must understand the concept of adding flexibility. Normally critical lines are checked by Piping Stress Engineers to have the required flexibility. But non-critical lines are routed by piping design engineers or piping designers. Hence, he must be aware of providing flexibility while pipe routing.

Impact of Piping Insulation Requirement

The piping engineer should know the impact of insulation on piping, mainly on supporting and support loading.

Heat Tracing

All piping designers/engineers should be aware of the purpose of process heat tracing, know the different methods (Jacketing, Tracer Tubing, or Electric), Tracer commodity (Steam, Oil, Hot Water, etc.), and Tracer system requirements and be able to design heat tracing circuitry.

Piping Deliverables

All piping professionals should know the purposes of each of the piping deliverables, like plot plans, key plans, piping plans and sections, GA Drawings, and isometrics.

Impact of Weight and loads

The effects of weight and loading should be known to every piping design engineer/piping designer. They need to have access to basic weight tables for all the standard pipe schedules, pipe fittings, flanges, and valves for steel pipe.

Specific Pipe Routing Rules like Rack Piping, Vessel piping, Exchanger Piping, etc.

All piping engineers or designers should know specific considerations for equipment piping, their support, impact on nozzle loading, etc.

Fabrication and Construction methods

Understanding shop spool fabrication, modularization, and field erection construction methods are important for a good piping engineer or piping designer.

Plant Economics

Last but not the least, Optimized and Economic pipe routing is very important to reduce project costs and increase profitability. Hence, piping design activities must be performed to be aware of the economic aspects.

Professionals, who possess such knowledge and applies this knowledge in project work constantly is undoubtedly very good piping design engineer or piping designer, or piping layout engineer.

Piping Engineer: Types, Roles, Career, Skills, Jobs

Written by Ahmad Anas in Mechanical,Piping Design Basics,Piping Interface,Piping Stress Analysis

In the engineering world, piping engineers play a vital role in the design, construction, and maintenance of piping systems. Whether in oil and gas, chemical processing, water treatment, or power generation, these professionals ensure that fluids and gases are transported safely and efficiently.

1. What is a Piping Engineer?

A piping engineer is responsible for the design, analysis, and maintenance of piping systems that transport various substances, including liquids, gases, and slurries. Their work is critical in industries like oil and gas, petrochemicals, water treatment, and power generation, where the integrity and efficiency of piping systems directly impact safety, productivity, and environmental compliance.

2. Piping Engineer Types

Piping Engineer is one of the famous engineering groups in the Oil & Gas, Petrochemical, Refinery, Chemical, Power, Steel, Water, and Pharmaceutical sectors. They are responsible for designing the piping systems that carry water, steam, gas, oil, two-phase mixture, waste, or other fluid. They are involved in the design, erection, troubleshooting, and all other aspects of the creation of these piping systems. Depending on the job profile they perform, there are various types of piping engineers. Let’s start to explore Piping Engineer types through this article.

Broadly, Piping Engineers can be grouped into the following classes:

  1. Piping Design Engineer or Piping Layout Engineer
  2. Piping Materials Engineer
  3. Piping Stress Engineer
  4. Piping Field Engineer/ Piping Commissioning Engineer

2.1 What is a Piping Design or Layout Engineer?

Piping Design Engineers deal with the piping routing design of the entire plant. They utilize various design software such as SP3D, PDMS, CADWORX, SOLIDWORKS, AutoCAD, PDS, Microstation, E3D, etc. They use their knowledge to define the most suitable economic pipe routing, type of fittings, space requirement, and various parameters in the design. A major part of their job involves coordination with other departments and the resolution of conflicts as and when they occur.

Examples of 3D model by piping design engineers
Fig. 1: Examples of a 3-D model by piping design engineers

2.1.1 Roles of a Piping Design Engineer

In addition to the above, they are responsible for the following jobs:

  1. Preparing Work Instruction for Designers.
  2. Discussing and Analyzing problems that arise during Design.
  3. Preparing Piping MTO
  4. Providing technical support to the team.
  5. Planning and Scheduling work activities for the piping team.
  6. Reviewing Vendor drawings, Interdisciplinary item checking.
  7. Click here to know more about the major qualities that are required to be a good piping design engineer.

2.2 What is a Piping Material Engineer?

A Piping Material Engineer prepares project piping class and material specifications. They prepare MTO, and review valves and special items. Click here to know the complete roles and responsibilities of a Piping Material Engineer.

2.3 What is a Piping Stress Engineer?

A piping Stress Engineer is a Piping professional who provides technical expertise in piping design. They develop Static and Dynamic piping models and analyze system stresses using pipe stress analysis software like Caesar II, CAEPIPE, AUTOPIPE, & PASS/START-PROF, Rohr-2, etc. He is the final barrier to whether the piping design is good to proceed with fabrication/construction or not. He verifies the piping layout and supports and ensures sufficient flexibility of the piping system. Click here to know the complete roles and responsibilities of a Piping Stress Engineer.

Example of Pipe Stress analysis.
Fig. 2: Example of Pipe Stress Analysis.

2.4 Field Piping Engineer / Piping Commissioning Engineer

There are also piping engineers who specialize in field jobs. Their task is to ensure all the piping that has been installed is based on the design. They will solve any problems on-site and communicate to the design engineering department in case there are any changes required. They will work from the installation of the piping until the commissioning. Sometimes, the piping design engineers are deputed to the site to perform the field piping engineering job.

In Subsea structures or small-scale projects, all the above tasks (all jobs of design engineer, materials engineer, stress engineer, and field engineer) are done by a single piping engineer.

3. Is Piping Engineering a Good Career?

Yes, piping engineering can be a great career choice for those interested in a stable and rewarding profession. With strong demand across industries like oil and gas, chemical processing, and power generation, piping engineers enjoy competitive salaries and ample opportunities for advancement. The role also allows for a variety of work environments, from design offices to on-site project management, and offers the chance to make a significant impact on safety and environmental compliance.

Piping engineering was one of the best career options earlier. However, from the last few years (2014 to 2020), due to lower crude oil prices, the Corona effect, and the advancement of electric vehicles, the oil market suffered a huge loss. So the number of new piping projects was declined, which reduced the requirement for qualified piping engineers. However, from early 2021 onwards, the crude oil price increased and now stabilized at higher prices, which created a good demand for piping engineers in various sectors. The demand for piping engineers in the oil and gas industry is believed to be increasing throughout recent times.

At the same time, many piping engineering institutions around the world are producing a large number of piping engineers each year. So competition is increasing each day which directly impacted the Piping Engineer’s Salary and remuneration.

Also, in recent times, there has been a sudden surge of many experienced freelancers. So many companies are providing jobs to them without the need for preparing the required infrastructure to build a design team.

4. Skills Required for a Piping Engineer

As Piping Engineering is almost 95 % technical job, to become a successful piping engineer, one needs to have good imagination, knowledge, and willingness to learn. The following skills are required for a good piping engineer:

  • Observational Skills
  • Analytical Skills
  • Project Management Skills
  • Written and Verbal Communication Skills
  • Drafting Skills

Normally, Mechanical and Chemical Engineers opt for the piping engineering profession.

4.1 What is the basic knowledge required for a piping engineer?

A piping engineer should have a solid understanding of fluid mechanics to analyze the behavior of fluids within piping systems. Familiarity with industry codes and standards, such as ASME and API, is essential for ensuring compliance in design and installation. Knowledge of material properties, including metals and polymers, is crucial for selecting appropriate piping materials. Additionally, skills in stress analysis are necessary to assess how piping systems will withstand operational loads. Proficiency in design software like AutoCAD, E3D, SP3D, and CAESAR II is important for creating accurate models, while an understanding of thermodynamics helps in managing temperature variations. Strong communication skills are also vital for collaborating with multidisciplinary teams, along with basic project management and troubleshooting abilities to effectively oversee and resolve issues within piping systems.

5. Piping Engineer Jobs

There are various companies that offer jobs for piping engineers. Some of the most reputed companies are:

6. Industry Applications of Piping Engineers

Piping engineers are employed in a variety of industries, each presenting unique challenges and requirements.

6.1 Oil and Gas

In the oil and gas sector, piping engineers design systems for transporting crude oil, natural gas, and refined products. This includes offshore platforms, refineries, and gas processing plants. They must account for high pressures, extreme temperatures, and potentially corrosive environments.

6.2 Chemical and Petro-chemical Processing

Piping systems in chemical plants transport a wide range of hazardous and non-hazardous materials. Piping engineers in this field focus on safety, regulatory compliance, and process optimization, often employing advanced materials and corrosion-resistant coatings.

6.3 Power Generation

In power plants, piping systems transport steam, water, and gases critical for energy production. Piping engineers must ensure that systems are designed for maximum efficiency while maintaining safety and environmental standards.

6.4 Water Treatment

Piping engineers in the water treatment industry design systems for the transportation and treatment of drinking water and wastewater. This role often involves working with environmental regulations and ensuring that systems are sustainable and efficient.

6.5 Other Industries

The above-mentioned industries are the core industries for piping engineers. Additionally, the following industries recruit piping engineers at various levels:

  • Mineral Industry
  • Mining Industry
  • Offshore Industry
  • Steel Industry
  • Food Processing Industry
  • Pharmaceutical Industry, etc

7. How Much Does A Piping Engineer Make?

The salary of a piping engineer can vary significantly based on factors such as experience, location, and the specific industry they work in. On average, piping engineers in the United States can expect to earn between $70,000 and $120,000 annually, with entry-level positions starting around $60,000. Experienced engineers, especially those in managerial or specialized roles, can make upwards of $150,000 or more.

In addition to base salaries, many piping engineers receive benefits such as bonuses, health insurance, and retirement plans, which can enhance overall compensation. Regions with a high demand for engineering talent, such as areas with active oil and gas sectors, often offer higher salaries to attract skilled professionals.

7.1 Salary of a Piping Engineer in India

The salary of a piping engineer in India can vary widely based on factors such as experience, location, and the specific industry. Generally, here’s a rough breakdown:

  • Entry-Level (0-2 years): ₹3,00,000 to ₹5,00,000 per year
  • Mid-Level (3-7 years): ₹5,00,000 to ₹10,00,000 per year
  • Senior-Level (8+ years): ₹10,00,000 to ₹20,00,000 or more per year, especially in managerial roles or specialized positions.

In metropolitan areas and sectors like oil and gas or chemicals, salaries may be on the higher end of these ranges. Additionally, benefits and bonuses can further enhance overall compensation.

8. Differences between Piping Engineer and Design Engineer

A piping engineer focuses on planning and designing piping systems within various structures, ensuring compliance with safety and efficiency standards. They work closely with other professionals to tackle technical challenges and ensure the systems function properly.

On the other hand, a design engineer has a wider scope, managing the overall design of project elements beyond just piping. They are tasked with conceptualizing and detailing components, systems, or structures, taking into account functionality, aesthetics, and safety considerations.

While both positions involve engineering principles and design processes, they cater to different facets of projects. Their major differences are listed below:

AspectPiping EngineerDesign Engineer
Primary FocusDesign and maintenance of piping systems for fluid transportGeneral design of products or systems across various domains
Industry ApplicationPrimarily in oil and gas, chemical, and power generationBroad applications including consumer products, machinery, and electronics
Key ResponsibilitiesPiping layout, material selection, stress analysisConceptualization, prototyping, and overall system design
Software ToolsCAESAR II, PDMS, AutoCADSolidWorks, AutoCAD, CATIA, or other design software
Code ComplianceEnsures adherence to piping codes (e.g., ASME, API)Ensures design meets industry standards and regulations
CollaborationWorks closely with process and mechanical engineersCollaborates with various engineering disciplines as needed
Problem-Solving FocusResolving issues related to fluid dynamics and pressureAddressing design challenges related to functionality and aesthetics
Piping Engineer vs Design Engineer

This table highlights the key distinctions, illustrating how each role contributes uniquely to the engineering landscape.

9. Piping Engineer Certification

Piping engineer certification is a credential that validates a professional’s expertise and knowledge in the field of piping design and engineering. These certifications demonstrate proficiency in industry standards, best practices, and technical skills essential for effective piping system design and maintenance. Obtaining certification in piping engineering can be a valuable investment in one’s career, demonstrating commitment to the profession and enhancing professional standing.

Here are some recommended piping engineering certification courses that can help enhance your skills and credentials:

  • Certified Piping Designer by Piping Designers and Engineers Associations
  • ASME B31.3 Process Piping Certification by ASME.
  • API 570 Piping Inspection Certification by API.
  • CAD Software Training (e.g., AutoCAD, CAESAR II, AutoPipe, E3D, SP3D, Rohr II, etc) by various training providers
  • Piping Engineering and Designing Courses by SPED.

10. What is a Piping Engineer: Video Tutorial

Roles and Responsibilities of Piping Engineers

The role of a piping engineer is crucial in various industries, ensuring the safe and efficient transport of fluids and gases. With a combination of technical skills, industry knowledge, and innovative thinking, piping engineers face unique challenges and opportunities.

This comprehensive understanding of the piping engineer’s role highlights not just their technical expertise, but also their contribution to the safety and sustainability of modern infrastructure. Whether you are a student considering this career path or an experienced engineer looking to broaden your horizons, the world of piping engineering offers a wealth of opportunities and challenges that are essential for our increasingly interconnected world.

Differences Between ASME B31.3 and B31.1: B31.3 vs B31.1

Written by Anup Kumar Dey in Mechanical,Piping Design Basics,Piping Stress Analysis,Piping Stress Basics

When it comes to piping design and construction in industrial settings, the American Society of Mechanical Engineers (ASME) plays a crucial role in establishing safety and performance standards. Two of the most referenced codes within the ASME B31 series are ASME B31.3 and ASME B31.1. While both codes govern piping systems, they cater to different industries and applications. In this article, we’ll delve into the key differences between ASME B31.3 and ASME B31.1

What is the ASME B31.3, or Process Piping Code?

ASME B31.3, or Process Piping Code, provides rules for piping design for petroleum refineries; onshore and offshore petroleum and natural gas production facilities; chemical, pharmaceutical, textile, paper, ore processing, semiconductor, and cryogenic plants; food and beverage processing facilities; and related processing plants and terminals. This code is known as the Bible for Process Piping Professionals. So this code dictates the design considerations of process plants.

ASME B31.3 covers a wide range of fluid services, including liquids, gases, and vapors that are often transported at high pressures and temperatures.

What is ASME B31.1, or Power Piping Code?

ASME B31.1, or Power Piping Code, provides rules for piping typically found in electric power generating stations, industrial and institutional plants, geothermal heating systems, and central and district heating and cooling systems. This code is very important for power piping professionals, as this code governs the design rules for power generation plants.

ASME B31.1 is tailored for piping systems that are used in power generation and industrial plants, particularly those involving steam and other high-energy fluids.

Difference Between ASME B31.3 and ASME B31.1 (B31.1 vs B31.3)

During piping stress analysis of a piping system, it sometimes seems that there is no major difference between ASME B31.3 and ASME B31.1. Simply changing the codes in the input spreadsheet is sufficient for analysis. But if we take a closer look at both B31.3 and B31.1, we can understand that there are some major differences in the rules, applications, and guideline considerations between ASME B31.1 and ASME B31.3. In this article, we have listed 18 major differences between the process piping (B31.3) and the power piping (B31.1) code.

From the above discussions, it is clear that both ASME B31.3 and ASME B31.1 codes, i.e., Process Piping Code and Power Piping Code, are different. Both are related to piping design aspects but vary widely in design considerations. The following table lists the major differences between ASME B31.3 and ASME B31.1.

Sr. NoParameterASME B31.3-Process PipingASME B31.1-Power Piping
1Scope (B31.3 vs B31.1)ASME B31.3 provides rules for Process or Chemical Plant piping.ASME B 31.1 provides rules for Power Plant piping.
2Basic Allowable Material StressAs per ASME B31.3, the basic allowable material stress value is higher (For example the allowable stress value for A 106 B material at 250 Deg C is 132117.328 Kpa as per ASME B 31.3) than the same as per B31.1.The basic allowable material stress value as per ASME B31.1 is lower  (For example the allowable stress value for A 106 B material at 250 Deg C is 117900.344 Kpa as per ASME B 31.1) than that of ASME B31.3.
3Allowable Sagging (Sustained)ASME B31.3 code does not specifically say about any limit of allowable sagging. An allowable sagging of up to 15 mm is acceptable in general. B31.3 does not provide a suggested support span.ASME B31.1 clearly specifies the allowable sagging value as 2.5 mm. Table 121.5-1 of ASME B 31.1 provides a suggested support span.
4SIF on ReducersProcess Piping Code ASME B31.3 does not use SIF (SIF=1.0) for reducer stress calculationPower Piping code ASME B31.1 uses a maximum SIF of 2.0 for reducers while pipe stress calculation.
5Factor of SafetyASME B31.3 uses a factor of safety of 3; relatively lower than ASME B31.1.ASME B31.1 uses a safety factor of 4 to have higher reliability as compared to Process plants
6SIF for Butt Welded JointsB31.3 uses a SIF of 1.0 for butt-welded jointsB31.1 uses a SIF of up to 1.9 max in stress calculation.
7Approach towards SIFASME B31.3 uses a complex in-plane, out-of-plane SIF approach.ASME B31.1 uses a simplified single SIF Approach.
8Maximum values of Sc and ShAs per the Process Piping code ASME B31.3, the maximum value of Sc and Sh are limited to 138 Mpa or 20 ksi.For the Power piping code (ASME B31.1), the maximum value of Sc and Sh are 138 Mpa only if the minimum tensile strength of the material is 70 ksi (480 Mpa) otherwise it is dependent on the values provided in the mandatory Appendix A as per temperature.
9Allowable Stress for Occasional StressesThe allowable value of occasional stress as per ASME B31.3 is 1.33 times ShAs per ASME B31.1, the allowable value of occasional stress is 1.15 to 1.20  times Sh
10Equation for Pipe Wall Thickness CalculationThe equation for pipe wall thickness calculation in B31.3 is valid for t<D/6.There is no such limitation in the Power Piping (ASME B31.1) wall thickness calculation. However, they add a limitation on maximum design pressure.
11Section Modulus, Z for Sustained and Occasional StressesWhile Sustained and Occasional stress calculation, the Process Piping code ASME B31.3 reduces the thickness by corrosion and other allowances.ASME B31.1 calculates the section modulus using nominal thickness. Thickness is not reduced by corrosion and other allowances.
12Rules for material usage below -29 Deg. CB31.3 provides extensive rules for the use of materials below -29 °CThe power piping code, B31.1, does not provide any such rules for pipe materials below -29 deg C.
13Maximum Value of Cyclic Stress Range FactorThe maximum value of cyclic stress range factor, f as per B31.3 is 1.2.As per ASME B31.1, the maximum value of f is 1.0
14Allowance for Pressure Temperature VariationAs per clause 302.2.4 of ASME B31.3, occasional pressure-temperature variation can exceed the allowable by (a) 33% for no more than 10 hours at any one time and no more than 100 hours/year or (b) 20% for no more than 50 hours at any one time and no more than 500 hours/year.As per clause 102.2.4 of ASME B31.1, occasional pressure-temperature variation can exceed the allowable by (a) 15% if the event duration occurs for no more than 8 hours at any one time and not more than 800 hours/year, or (b) 20% if the event duration occurs for not more than 1 hour at any one time and not more than 80 hours/year
15Design LifeProcess Piping following ASME B31.3 is normally designed for 20 to 30 years of service life.Power Piping using ASME B31.1 is generally designed for 40 years or more of service life.
16PSV reaction forceB31.3 code does not provide specific equations for PSV reaction force calculation.ASME B31.1 provides specific equations for PSV reaction force calculation.
17Hydrostatic Test PressureAs per ASME B31.3, the hydrostatic test for the piping system needs to be performed at 1.5 times the design pressure corrected for temperature, which means the design pressure must be multiplied by ST/S in the case of process piping. Here, ST=pipe material allowable stress at test temperature, and S=pipe material allowable stress at component design temperature. (Clause 345.4.2)The hydrostatic test pressure following ASME B31.1 is 1.5 times the piping design pressure. (Clause 137.4.5)
18Pneumatic Test PressureThe pneumatic test pressure as per ASME B31.3 is (1.1 to 1.33) times the design pressure of the piping system. (Clause 345.5.4)B31.1 instructs to use a pneumatic test pressure between (1.2 to 1.5) times the design pressure for the piping system. (Clause 137.5.5)
Differences between process piping and power piping codes:(ASME B31.1 vs ASME B31.3)

Other differences between ASME B31.1 and ASME B31.3:

The other differences between ASME B31.3 and ASME B31.1 are

  • There is a difference in bending and forming requirements in both codes.
  • The welder and brazer qualifications are not identical.
  • The limitations for the use of cast irons are different in both codes.
  • The criteria for using soldered, brazed, and threaded joints are different in both codes.

The following image (Fig. 1 ) shows a rough estimate of different stress values of the same system with code change in Caesar II-2018 software:

Stress values for the same system with code change
Fig. 1: Stress values for the same system with code change

Understanding the differences between ASME B31.3 and ASME B31.1 is crucial for engineers and professionals involved in the design and maintenance of piping systems. Each code serves a distinct purpose and addresses the specific needs of its respective industry, ensuring that piping systems operate safely and efficiently under their unique conditions.

Some other useful differences for you.

Differences between ASME B 31.4 and ASME B 31.8
13 major differences between Seamless and Welded Pipe
10 Differences between Pressure and Stress
Difference between Tee and Barred Tee
Difference between Stub-in and Stub-on Piping Connection
Difference between Centrifugal and Reciprocating Compressor
Difference between PDMS and PDS
Difference between Piping and Pipeline
Difference between Pipe and Tube
Difference between Primary load and Secondary load
Difference between Caesar II and Start-Prof
Difference between API and ANSI Pump

Pipe Thickness Calculation of Straight Pipe under External Pressure/ Vacuum Pressure Condition

Written by Anup Kumar Dey in Engineering Materials,Pipeline,Piping Design Basics,Piping Interface,Piping Stress Basics

Piping systems under vacuum conditions, Jacketed Piping, Offshore pipelines, piping inside equipment, etc. are subjected to both internal as well as external pressure. Contrary to the internal pressure, external pressure compresses the material, and Failure of piping under squeezing action can occur at lower pressure. This is due to elastic buckling. The pipe geometry is weaker in compression than in tension and failure can occur well below the yield point under the influence of external pressure. So, the piping system must be designed to withstand external pressure.  

External pressure pipe wall thickness calculation must be performed for all lines having the possibility of external pressure or vacuum pressure. By preliminary understanding, it may seem that as the internal design pressure is usually more than the external design pressure, so designing for internal pressure will take care of the external pressure design thickness as well. But this is not the case. As the piping system behaves differently under vacuum or external pressure conditions. Due to the buckling consideration all design philosophy changes for external pressure design thickness calculation.

For straight pipe under external pressure, two checks are performed:

  • First is the membrane stress check in accordance with pipe thickness calculation based on internal pressure Eq. (3a) [or (3b)] of ASME B31.3 (Clause 304.1.2).
  • The second check is a buckling check (As specified in Clause 304.1.3 of ASME B31.3) in accordance with the external pressure design rules outlined in ASME BPVC, Section VIII, Division 1, UG-28 through UG-30. The design length, L, the running centerline length between any two sections stiffened in accordance with UG-29 means the length between flanges, heads, stiffeners, etc.

In this article, we will explore the external pressure pipe thickness calculation steps with an example problem.

External Pressure Pipe Wall Thickness Methodology

In external pressure design pipe thickness calculation, initially, a pipe thickness is calculated based on internal pressure conditions. Please click here to explore the steps required for pipe wall thickness calculation for internal pressure using ASME B 31.3.

Once the pipe thickness is selected based on internal pressure, that pipe thickness is checked with respect to buckling following ASME BPVC UG-28 rules to find if that thickness is sufficient for external pressure conditions. So, this is basically verification of the selected pipe thickness as per ASME B 31.3, clause 304.1.3, and ASME BPV Code, Section VIII, Division 1, UG 28.

ASME BPV code provides two separate procedures for calculating the minimum required thickness, for Do/t >= 10 and Do/t <10. Here Do=Outside Diameter of the Pipe and t=Minimum required thickness.

Buckling pressure calculations in ASME BPVC, Section VIII, Division 1 require the calculation of two parameters; A and B.

  • Parameter A is a function of geometry and
  • Parameter B depends on A and the material property curve. The charts that provide parameter B account for plasticity between the proportional limit of the stress-strain curve and the 0.2% offset yield stress.

Example Problem for External Pressure Design Pipe Thickness Calculation

We will consider a 32″ Carbon Steel Pipe with 31.75 mm thickness with the following parameters for external pressure design thickness calculation.

  • P : External Pressure = 15 psi Section
  • Do: Outside Diameter of pipe = 813 mm for 32″ pipe (as per ASME B36.10M)
  • L: Assumed unstiffened length of pipe = 12000 mm (472.4 inches), (based on the piping layout for calculation purposes).
  • T: Selected Pipe wall thickness based on internal pressure = 31.75 mm;
  • t: Selected Thickness less mill tolerance of 0.3 mm and corrosion allowance of 3 mm = 28.45 mm (1.12 inch)
  • T: Design temperature = 149 Deg. C
  • Y: SMYS of the material = 35000 psi
  • E: modulus of elasticity of the material at design temperature = 294000000 psi

External Pressure Design Pipe Thickness Verification Steps

Step-1: Calculation of Do/t

Calculate Do/t; Here Do=32″ and t=1.12 “. So Do/t=32/1.12=28.57 which is greater than 10.

So we will follow the first method of ASME Sec VIII Div 1.

Step-2: Finding L/Do

Find L/Do;

Here, L=472.4″ and Do=32″; Hence L/Do=14.76- approximately 15

Step-3: Finding Factor A

Finding Factor A from  Fig. G of ASME Sec II, Subpart 3, Part D,

For finding factor A, Enter ASME BPVC Section II, Part D, Subpart 3, Figure G at the value of L/Do and Do/t determined in Steps 1 and 2. The figure is reproduced below in Fig. 1 for sample reference purposes.

ASME BPVC Curve for Determination of Factor A
Fig. 1: Geometric Chart for Components Under External Pressure Loading

From Fig.1; The factor A=0.00135.

Step-4: Finding Factor B

Determining the value of Factor B

Using the values of A calculated in step 3 (A=0.00135 for our case), enter the applicable material chart in subpart 3 of Section II, Part D.

As our material is CS with SMYS=35000 psi, we have to refer to Fig. CS-2. (Reproduced in Fig. 2 for reference)

ASME BPVC Curve for Determination of Factor B
Fig. 2: ASME BPVC Curve for Determination of Factor B

From the curve value of Factor B=13200.

In cases where the value of A falls to the right of the end of the material/temperature line, assume an intersection with the horizontal projection of the upper end of the material/temperature line. If tabular values are used, the last (maximum) tabulated value shall be used.

Step-5: Calculating Maximum Allowable External Working Pressure, Pa

Calculation of Maximum Allowable External Working Pressure Pa

Now, Using this value of B (as calculated in Step-4), calculate the value of the maximum allowable external working pressure Pa using the following equation (Fig. 3):

Maximum Allowable External Working Pressure Calculation Formula
Fig. 3: Maximum Allowable External Working Pressure Calculation Formula

Since Pa (606.89 psi) > P (15 psi), the selected pipe wall thickness can withstand full vacuum. So our pipe is safe for a full vacuum condition.

Few more useful Resources for you.

Pipeline wall thickness calculation with example
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Piping Layout and Design Basics

AVEVA E3D Tutorial: Equipment Modeling with Practical Example

Written by Pravin Govindraj in E3D,PDMS-E3D,Piping Design Basics

In this AVEVA E3D Tutorial, we will explain the steps for creating a vertical column (Tag: C-1101). The E3D Equipment modeling steps are shown using two different methods. Let’s dive into the article.

E3D Equipment modeling Steps

Go to the Discipline tab of the software to select different sectors like Piping, Structures, and Civil as per requirements. For our case, Select Equipment Tab as shown in Fig. 1A.

Fig. 1: Opening the job for E3D Equipment Modeling

In E3D, we should first create a Site, Zone, etc. similar to AVEVA-PDMS. For the “Site” creation go to Create click on Site In the General tab (Refer to Fig. 1B) and provide a name as you want. Here, I am giving the name Aveva E3D. Don’t provide space between words. Click on Ok.

For Zone creation click on the Zone Tab under Create, give a suitable name for the Equipment (Refer to Fig. 2A) and click OK. Next, Go to the Equipment Tab, and in create tab click on Equipment. Give name as C-1101 as per equipment datasheet and hit Enter. In the Position tab, Keep East, North, and Up as 0 mm for the time being. We will fill in these values later. Refer to Fig. 2B. Now, Under attributes, Give a Description name as Cracking Tower. You can fill in the remaining details if you have them, otherwise, you can keep it blank and press OK to continue further.

Zone Creation in E3D
Fig. 2: Zone Creation in E3D

Method 1: Creating Equipment by Primitives

In Method 1, we will be creating the equipment by Primitives (Not Standard Equipment). So, Select Cylinder shape from the Create tab. Refer to Fig. 3A.
Here you can see the drawing, same as AutoCAD the cursor will be displayed (Fig. 3B). Now give the value for East : 0 mm and hit the Tab button on the keyboard it will lock the position, you can see the red lock symbol in each Easting, Northing, Up, tab after Hit Enter.

Now it’s time to specify the diameter and height of the column. Enter 1413 mm as diameter and 14076 mm as height as shown in Fig. 3C.

Creating Vertical Column using Primitives in AVEVA-E3D
Fig. 3: Creating Vertical Column using Primitives in AVEVA-E3D

You can now see the vertical cylinder on the window.

Method 2: Creating the Equipment by using Commands

Go to the Tools tab and click on Command for the command window.
Give the command PIN1 at CE and Enter.
You can see PIN1 at the center of the window.
Now write New cylinder height 14076, and diameter 1413, and Press Enter.
This is the shortcut command for creating a cylinder in E3D keeping the view in Elevation.
The origin of the cylinder is in the center. But as per the drawing, the cylinder base should be at the bottom, not the center. So, Give command as
By u 7038 (half the height of the cylinder) and hit Enter.
U means up. Now the cylinder is placed above as you can see in Fig. 4.

Creating Vertical Column using Commands in AVEVA-E3D
Fig. 4: Creating Vertical Column using Commands in AVEVA-E3D

Now before proceeding to the next section, Let’s learn a few settings.
For wireframe view press the F11 key on the keyboard.
Or else go to the View tab and click on the Current view in the settings tab.
The view settings window will open.
Under the effects section, uncheck shaded then apply and cancel. Refer to Fig. 5.

Settings for E3D
Fig. 5: Settings for E3D

Next, go to Project tab -> click Options -> View -> Selection & Snaps
Click Advanced under Snap Settings and Under the Object tab uncheck P-point and press OK. Refer to Fig. 6

P-Point Settings for E3D
Fig. 6: P-Point Settings for E3D

Modeling the Cone Ends of the Column

Now for the Cone
Click on Cone from the create tab.
After clicking on Cone (Refer to Fig. 7A) move the cursor to the top of the Center of the cylinder, you can see the top P-point Of the cylinder with a square shape.
Click here on top of the cylinder.
Now give the diameter as 1413 mm and press enter.
By moving the cursor upside of the cylinder, Give height as 280 mm and hit enter.
Now give the next diameter as 1067 mm and click enter
Now the cone is ready.

For the next steps of the cylinder, Select the Cylinder shape from Create tab.
Go to the cone, again click on the top P-point of the cone
Now give Diameter as 1067 hit Enter and Height as 7849 Hit Enter as per the datasheet.
Refer to Fig. 7B and 7C

Modeling the cone part of column in E3D
Fig. 7: Modeling the cone part of the column in E3D

Modeling the Dish End in E3D

For the Dish-end (Refer to Fig. 8), Go to the Equipment tab and click the Down arrow in the create tab. Then click on the Dish shape. After clicking on Dish, move the cursor to the Center of the cylinder’s top P-point. Click here on top of the cylinder

Now give diameter as 1067mm enter. After that, E3D will ask for the height of the dish. Now press the down arrow on the keyboard you will be able to see in the window two boxes which are knuckle radius & back.
Click on the knuckle radius and give the value as 20 mm and press Enter.
After the knuckle radius, provide the height of the dish as 200mm and Hit Enter.

Now the cylinder is ready as you can see in Fig. 8.

Modeling the dish of column in E3D
Fig. 8: Modeling the dish of the column in E3D

Modeling the base plate of the column in E3D

For modeling, the base plate click on the box shape as shown in Fig. 9
Give the value as follow:
East: -1050 mm press the tab button, North: -1050 mm again tab button Up: 0 mm and hit enter.
East: 2100 mm press the tab button, North: 2100mm again tab button Up: 0mm and hit enter.
Now specify the Z-length (width of base plate)
D: 25mm enter as per the datasheet.

Modeling the base plate
Fig. 9: Modeling the base plate

Column C-1101 is ready.

Video Tutorial for E3D Column Modeling

I am sure still, you have many doubts about the above steps. Hence, the video tutorial for the above-mentioned column is attached herewith for a clear understanding. Please like and subscribe to the channel (Bounce Back) for more updates. You can download the column datasheet from the links provided in the you-tube video description.

E3D Column Modeling Video Tutorial

AVEVA E3D Online full training courses

If you are looking for an online complete step-by-step E3D training course then the following course will help to fulfill your hunger. Kindly click on the below-mentioned subject, review the details of the course and then enroll to proceed:

AVEVA E3D Training Course From Beginner to Advanced 2021

Few more useful articles for you.

Tutorial on Pipe Modeling using AVEVA E3D software
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PDMS Video Tutorial/Lessons for Beginners
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Variable Spring Support Design without the aid of Caesar II Hanger Auxiliary

Written by Shaily Buch in Piping Stress Analysis,Piping Stress Basics

Variable Spring Hanger Supports are widely used in critical pipe systems for their load-bearing capability allowing thermal movements. In Caesar II, We can easily design a variable spring hanger support by double-clicking the checkbox for the hanger auxiliary. The software follows the below-mentioned steps to select its spring.

  • CAESAR II puts rigid support at the hanger location and does a weight analysis to find out the weight that the support should carry. This load is used as the Hot Load (HL).
  • CAESAR II applies a force equal to that Hot Load (but not stiffness (k)) at the hanger location and then runs an operating analysis. This tells CAESAR II how much that location wants to move vertically (y) under the operating loads. So this becomes the “theoretical” hanger movement. Now, the “theoretical” cold load is calculated as Cold Load (CL) = HL + ky.
  • CAESAR II adds the CL as a force and the spring stiffness as a restraint stiffness to all load cases of the model and then runs all the normal load cases.

In this article, We will design a variable spring hanger support by following the above Caesar II Algorithm. The steps for manual spring hanger design are explained below with an example.

Manual Spring Hanger Design Procedure

The example problem is shown in Fig. 1.

Variable Spring Hanger Design without Caesar II Hanger Auxiliary
Fig. 1: Variable Spring Hanger Design without Caesar II Hanger Auxiliary

Let’s assume that we will design a variable spring hanger support at node 15 as shown in Fig. 1A. At node 20, the pipe is Resting.

To design the spring support, A weight run is to be taken with a Rigid double-acting Y restraint at node 15 (without friction). Assume the load computed to be 3540 N.

Now apply that force (3450 N) at node 15 in an upward direction and run an operating case. Note the lift-off at 20 as shown in Fig. 1C. Observe the travel at 15 let us assume it here as 5.785 mm.

In case, there is no lift-off in the nearby supports (Node 20) then the above-computed values will be the final Hot Load and Spring Travel.

But as the support at node 20 is lifted off, Remove the support at node 20 and Run a weight case with a rigid double-acting Y restraint at node 15 (without friction). Refer to Fig 2A. Assume, the load experienced at node 15 is now 3651 N.

Manual Spring Hanger Support Design Example
Fig. 2: Manual Spring Hanger Support Design Example

Now, an operating case runs are to be taken with 3651 concentrated loads (Fig. 2B) in an upward direction at 15. Suppose this time the travel is 5.829 mm.

Hence, for the above system
Computed Hot load = 3651 N.
Computed theoretical travel from cold to hot =5.829 mm.

On the basis of the computed hot load and the thermal travel one can estimate the maximum permissible spring rate as depicted below:

 kmax =(Var X HL)/ |yth |——————– (a)

Where Var is the maximum permissible variation.

Now the computed hot load can be located in the columns of the spring support catalog table from the vendor. For that spring size select the spring series with a spring rate less than or equal to that calculated by (a).

The cold load can be calculated by

Cold Load= H.L + ky

The cold load calculated above is then located in the table under the same spring size.
If the cold load does not fall under the column of the selected size then a different spring series or spring of an adjacent size is to be selected.

Note that when specifying hanger’s hot and cold loads, It is important to add the anticipated hardware weights to these values especially if it is significant like trapeze assembly or large clamps, etc. The prime requirement being the necessity of the hanger to support hardware as well in order to avoid imbalance in the system by the weight of hardware.

Few more spring support related articles for you.

Spring Hanger Pipe Support Selection Procedure for Piping Stress Analysis
Technical and General requirements for Spring Hangers while purchasing.
TBE of vendor Spring hangers: Main points to consider before placing an order
Spring hangers: Common Interview Questions with Answers
Spring hanger selection and design guidelines for a Piping engineer using Caesar II
Basics of Pipe Stress Analysis