Importance of Vents and Drains in Piping System

Written by Anup Kumar Dey in Piping Design Basics

Vents and Drains are required in piping systems to meet the Process, Construction, Testing, and Commissioning requirements. These are basically small tapping connections from the main pipes having a total length limited to 300 mm. These connections are with an isolation valve or without. Even though vents and drains are small connections in the piping system and are very often missed or neglected, they are very important and must be provided. Installing vents and drains after the pipe has been installed results in additional costs and an extended schedule. In this article, we will learn about Vents and Drains in detail.

What is a Vent and Drain Connection?

A vent is a piping connection taken from the top of the main pipe whereas a drain is the tapping connection taken from the bottom of the main pipe. In a piping configuration, vents are usually taken from the high point and that is why they are known as high point vents. Similarly, drains are considered in the low points and are popularly known as low point drains.

Types of Vents and Drains

Depending on the purpose of the vent or drain connection, vents and drains are classified into two groups.

Hydrostatic test vents and drains, and
Process vents and drains

Hydrostatic Test Vents and Drains

Hydrotest vent and drain connections are provided for use during hydrostatic leak testing. Hydrostatic vents and drains shall be provided only for the piping system subjected to the hydro test. Vent connections are located at high points and drain connections are located at low points of piping systems based on the physical piping configuration.

The main purpose of hydrostatic vents is to expel the air present in the pipe while filling the pipe with water for hydro-testing. If the air does not get a passage to be removed, it will be compressed inside the piping system, will cause an air bubble, and a pressure drop will occur. Also, water venting from high point vents will ensure the complete filling of water for starting the test. Once this is ensured, these vents are closed and pressurization starts.

The hydro testing drain connections are used to drain the water from the pipe after hydro testing is completed. During draining the vent connection is also kept open.

If the piping system is subjected only to pneumatic tests (e.g. instrument air, nitrogen system, etc.), then hydro-test vents and drains need not be provided. Fig. 2 below provides some typical hydro test vent and drain assembly details:

**Fig. 2: Hydrotest Vent and Drain Assembly Examples**

Hydrostatic test vent and drain features:

Hydrostatic test vent and drain connections are not usually shown in the P&ID drawings but are shown in the detailed construction piping drawings.
Hydrostatic drains are provided with an isolation valve but Hydrostatic vents are normally provided without valves. However, if valves are provided they shall be shown in the P&IDs.
When Hydrostatic vents and drains are marked on the P&IDs, they are tagged as ‘HV’ & ‘HD’ respectively to differentiate from the process vent & drains. Access is normally not provided for hydrostatic test drains and vents.
Hydrostatic vents shall be provided for line sizes 1½” and above Since line sizes 1” and below are considered to be self-venting. However, Hydrostatic drains shall be provided for all line sizes (including small bore piping).
The hydrostatic vent & drain sizes and arrangement shall be as indicated in the piping standard drawing or stated in the project specifications.
Hydrostatic vents not provided with valves, but with threaded plugs or end caps shall be seal welded after testing.

Process Vents and Drains

Process vent and drain connections are provided in piping systems for use during operation (start-up, shut down) or maintenance. These are provided for specific process requirements. These drain and vent connections are shown on the P&IDs and related detailed piping drawings. Process vents and drains are always provided with valves and are located such that they are easily accessible by operations or maintenance personnel. Once the venting or draining operation is complete, these valves are closed to continue the normal operation.

Process vents and drains are closed with suitable closure devices like plugs, caps, and blinds are sometimes connected to the vent/drain systems. On the pump discharge piping a drain connection shall be provided between the check valve and block valve to permit the draining of the line downstream of the check valve. This drain connection shall be indicated in the P&ID. Fig. 3 below shows some typical process vent and drain assembly details.

**Fig. 3: Process Vent and Drain Assembly examples**

Characteristics of Vents and Drains

A Hydrotest drain shall not be provided if a line already has a process drain at the lowest point of the piping system. The process drain itself shall act as a hydro test drain in such cases.

A Hydrotest vent shall not be provided if a line already has an instrument connection (e.g. pressure/ temperature instrument) at the high point of the piping system. This connection itself shall act as the hydro test vent.

Adequate gussets/ bracings shall be provided to support the vents and drain in case of lines are subjected to vibrations.

Vents shall be avoided in control valve assemblies at elevated locations by using flat-side top reducers. The same is applicable to the outlet of relief valve lines with flat-side top reducers. During testing, the hydro tester shall provide a temporary spool with a vent connection in lieu of the control valve.

Depending on process requirements, hydro test drains may have to be connected to the drain system.
If there are service-specific drain systems like hot oil, hot water, etc., care shall be taken to connect the drains to the appropriate drain system.

Separate vents and drains shall be provided on the lines in a system if the piping specification or pressure class changes. With pressure break or class break, separate hydro-test packs are prepared, and hence separate vent and drain for the hydro test must be provided.

There are some cases where a hydrostatic vent may be required in the case of a vertical pocket or vertical pocket with a manual valve. Similarly, These are some cases where a hydrostatic drain may be required

What is Friction Welding? Principle and Types of Friction Welding

Written by Anup Kumar Dey in Engineering Materials,Mechanical

What is meant by Friction Welding?

Friction welding is a solid-state welding technique for joining workpieces by producing heat through mechanical friction. They do not use an external heat source to melt or convert the metal into a plastic state. Instead, the welding is formed by the application of external pressure. In friction welding, one part of the pieces to be joined rotates relative to the other. Because of this movement, friction is generated that heats up the materials at the contact surfaces. Till the completion of the welding cycle, a high-pressure force is applied.

What metal joints are used in friction welding?

The major benefit of friction welding is that it can be used to join dissimilar metals. Friction welding is widely used with metals like steel, aluminum, copper, titanium, nickel alloy, and thermoplastics in a wide variety of aviation and automotive applications. An eco-friendly process, friction welding is also used to manufacture subassemblies for industrial printers, material handling equipment, marine, and oil applications. The components that are usually manufactured using the friction welding process are gears, axle tubes, hydraulic piston rods, drivelines, valves, truck roller bushes, connection rods, pump shafts, drill bits, etc.

Working Principle of Friction Welding

Friction welding uses the principle of heat generation by friction between two members. During the friction welding process, two surfaces to be welded are made to rub against each other at a very high speed. The developed friction between the rotating and non-rotating surface produces enough heat at the weld interface. Once the required welding temperature is generated, a uniformly increasing external pressure is applied till both the workpieces form a permanent joint. This is the basic principle of all types of friction welding processes, even though the exact process may vary slightly depending on the type.

What are the steps in Friction Welding?

All the friction welding processes mostly follow the following steps:

Step 1: One part to be welded is placed in a rotor-driven chuck and the other part is held stationary. Now the rotor is switched on to rotate at a very high speed along with the workpiece.
Step 2: The rubbing of welding surfaces creates sufficient heat (of the order of 900-1300⁰ C for steel). Now a high pressure is applied through the stationary part.
Step 3: Once the temperature of the welding surfaces reaches the required temperature, the rotor is stopped.
Step 4: Now, the pressure is increased continuously till both parts weld to each other.

Refer to Fig. 1 below that explains the Friction welding process steps clearly.

**Fig. 1: Friction Welding Working principle**

What are the Types of Friction Welding?

There are 6 types of friction welding processes that are widely used. They are:

Inertia Friction Welding
Direct Drive Friction Welding
Linear Friction Welding
Orbital Friction Welding
Friction Stir Welding (FSW), and
Friction Stir Spot welding

Inertia Friction Welding:

In the inertia friction welding process, different-sized flywheels are attached to the chuck and spindle shaft. The part is rotated by a motor that is connected to the spindle shaft. During the start of friction welding, the motor connected to the spindle shaft rotates the part to the required rotational speed. When the necessary speed is achieved, the motor is disengaged from the spindle shaft. Depending on the weight of the part, chuck, spindle shaft, and flywheels, rotational inertia is created by the free-spinning components. At this point, the frictional welded process started with the application of pressure. As the heat is generated by utilizing the rotational inertia when the parts are brought together, this method is known as Inertia Friction Welding.

Direct Drive Friction Welding:

In the direct drive friction welding process, the spindle shaft is permanently connected to the motor. Frictional heat between the wending surfaces is produced when the two pieces are brought together and the motor drives the rotating part. The process is usually controlled by the CNC program. It continuously slows down the spindle while the friction welding process takes place and then stopped at a pre-decided point. This type of friction welding is advantageous when a specific orientation of the workpieces is required.

Linear Friction Welding:

In the linear friction welding process, the moving chuck doesn’t spin. On the contrary, it oscillates in a lateral motion (linear). Throughout the entire friction welding process, the workpieces are held under pressure. The main benefit of this method is that by using linear friction welding, parts of any shape having high shear strength can be joined.

Orbital Friction Welding:

In orbital friction welding, both of the parts to be welded are rotated in the same direction and at the same speed, keeping an offset by up to 1/8” between their axes. When the weld cycle is completed, the rotation is slowed and the parts are returned to the same axis. However, the forging pressure is maintained while the materials re-solidify.

Friction Stir Welding (FSW):

Friction Stir Welding or FSW is a type of friction welding process that uses a special non-consumable tool with a cylindrical shoulder and a profiled pin for joining the two surfaces of the workpieces. Heat is generated between the rotating tool and the workpiece which softened the interface region. When the tool is traversed along the joint line, it mechanically intermixes the softened material of the two pieces of metal and forges the weld interface through mechanical pressure applied by the tool. Friction Stir Welding is used in trains, modern shipbuilding, and aerospace applications. Friction Stir Welding was invented in 1991 by Wayne Thomas.

Friction Stir Spot Welding:

Friction Stir Spot welding is a variant of the FSW mentioned above. It works by rotating, plunging, and retracting a non-consumable tool into two workpieces in a lap-joint configuration to make a “spot” weld. During the friction stir spot welding process, there is no traversing of the tool through the workpieces.

Other Types of Friction Welding Processes

Friction Stud Welding: It involves a rotating stud that is forced on the plate surface under controlled conditions. Friction stud welding has a very short weld time and high-quality welding.
Friction Taper Plug Welding: Widely used for repairing cracks in steel pipe or plates, friction taper plug welding is accomplished by drilling a tapered hole. Then friction welded into the hole is performed using a tapered plug with a similar included angle. The complete conical surface of the tapered plug is welded to the matching surface of the hole.

Benefits of Friction Welding

Friction welding provides various advantages with respect to conventional welding processes. Some of the advantages of using friction welding are:

Joining Dissimilar Materials: Friction welding allows to join of aluminum with steel or copper to aluminum. Similarly, various bi-metallic friction welded joints can be produced.
No external heat source or flux application
Fast and efficient process
Need very less surface preparation
As the welding process is CNC controlled, the friction welding process produces consistent quality products.
Reduced Material wastage
Environment-friendly process
As solid-state welding, friction welding avoids defects associated with fusion welding.

Online Courses on Friction Welding

To learn more about the basics and mechanisms of friction welding, the following two online courses will help you:

Fundamentals of Friction Stir Welding
Advance Study in Friction Stir Welding

Top Piping Design Software Packages for 2024 | 2D & 3D Modelling Software Packages | Piping Design CAD Tools

Written by Anup Kumar Dey in E3D,PDMS,PDMS-E3D,Piping Design Basics,SP3D

Piping design software is an inevitable part of piping engineering in recent times. Using these piping software packages a piping engineer/designer prepares 3D and 2D models of the exact plant. The exact piping arrangements are produced with exact dimensions, coordinates, and sizes similar to the real plant which helps in actual space estimate, clash checking, pipe routing, and supporting. In the market there are various piping design software packages are available. So, choosing piping software for a specific application is really difficult as so many choices are available. In this article, We will list down the top piping design software packages which are widely used in the piping and pipeline design industry.

Types of Piping Design Software Programs

Depending on the software application capabilities, piping design software packages can be categorized into two groups. They are

3D software packages and
2D software packages

Top 3D Piping Design Software Programs

3D piping design software packages are widely popular as they depict the complete plant layout in a 3-dimensional environment. 3D plant models are very easy to understand as it is exactly similar to the real plant. Widely used common 3D piping design software packages are:

SP3D by Hexagon
E3D/PDMS by AVEVA
AutoPLANT 3D by Bentley
AutoCAD Plant 3D by AutoDESK
CADWorx Plant Professional by Hexagon

Piping Design Software Package: Smart Plant 3D or SP3D

Smartplant 3D or SP3D is one of the best plant design solution programs developed by Intergraph (Hexagon). This is a next-generation, data-centric, rule-driven piping design software package that is specifically designed to take care of all the critical elements of plant design. This truly iterative engineering design solution is capable of designing the plant, marine, and material handling facilities with ease in a highly developed 3D environment providing a competitive edge to all piping specialists. With its high-end graphics, SP3D by Hexagon PPM provides the ease of creating, analyzing, modifying, and optimizing a plant design model. Smartplant 3D as piping design software helps to effectively manage the schedule and cost for fast-track projects. The main features of this piping design software program are:

Global Engineering and Data Reuse capability, Concurrent engineering.
Multi-discipline design helps in better decisions.
Design reuse for getting a competitive edge.
Ease of use that increases productivity.
More effective design reviews and communication.
Design accuracy and consistency.
Task-based modeling

Piping Design Software Program: E3D/PDMS

PDMS or Plant Design Management System is also one of the highly popular 3D CAD piping design software programs developed by AVEVA. This is one of the oldest (Started in 1976) high-end software packages in use. However, AVEVA has decided to phase out this software from the market by 2024 and will replace PDMS with their latest, most advanced 3D software E3D Design.

AVEVA E3D is more powerful, advanced, and efficient as compared to the earlier PDMS. E3D as a piping design software solution saves more time as less time is required for administrative tasks. With E3D organizations can improve the working speed, quality, and profitability altogether. The main features of the E3D software are:

Highly efficient and fast
Great flexibility and agility
Remote working feasibility
Widely secure
Easy to adapt
State-of-the-art user interface
Automatic and accurate generation of drawings from 3D models.

AVEVA E3D provides clash-free multi-discipline 3D plant systems for process, power, and marine plants for both greenfield and brownfield projects. AVEVA E3D Design users also have the capability to interact with laser scan data and data from traditional static scanners and mobile, airborne and hand-held devices from a wide choice. If you are looking for an online E3D course, then the following two online AVEVA E3D courses will be highly beneficial:

AutoPLANT 3D as Piping Design Software Package

AutoPLANT 3D is an intelligent, spec-driven, sophisticated 3D plant design and modeling software application developed by Bentley, USA. By creating intelligent piping layout drawings, equipment, raceways, and isometrics in a single application, the AutoPLANT 3D modeler saves time and cost. The software uses an AutoCAD-based application for design work which is quite easy to use, customize, and administer.

AutoPLANT also provides a tightly integrated set of tools for interactive routing and placement in a 3D multi-discipline environment. Some benefits of AutoPLANT 3D as a piping design software program are:

A single streamlined application,
Easy integration with other Bentley products.
High information mobility,
Lower risk due to industry-proven mature software
Scalability,
Easy design review and clash detection.

Piping Design Software Program: AutoCAD Plant 3D

AutoCAD Plant 3D is a modern plant design solution developed by Autodesk. Built on the AutoCAD platform, this pipe design software package adds modern 3D models of piping, equipment, and support structures. It has the ability to generate isometrics very quickly. Integrated into AutoCAD P&ID, the program is quite easy to model and edit which increases productivity and lowers cost. More details about AutoCAD Plant 3D can be found here. To help you master your learning journey about the AutoCAD Plant 3D software, the following two online AutoCAD plant 3D courses will serve as a boon:

Piping Design Software Package: CADWorx Plant Professional

CADWorx Plant Professional is also a next-generation plant design and automation package to create intelligent and realistic 3D models. Developed by Intergraph (Hexagon), CADworx has the complete DWG file-based range of tools providing unparalleled flexibility and collaboration. The software works on AutoCAD or BricsCAD platform and is very easy to create complex 3D plant models. The main features of CADWorx Plant Professional as piping design software are:

Specification-driven design tools
HVAC ducting and cable tray routines
Model/P&ID synchronization
Detects clashes/collisions
Isogen auto-isometrics
Detailed bill of materials
Real-time design status
Equipment modeling
Piping specifications in metric and imperial formats
Auto-routing to create quick 3D piping models

Top 2D Piping Design Software Packages

Even though most companies prefer 3D software packages for their plants, still the use of 2D piping design software programs is continuing. The most common 2D piping software packages that are widely used are:

AutoCAD
Microstation
PROCAD
AVICAD
IronCAD
Lucidchart

Other Piping Design Software Programs

There are many other piping design software packages with limited uses like

PDS (rarely used in recent times)
CADISON
M4 Plant
G4 Plant
CADMATIC
EPLANT-Piping
Pipe Designer 3D
OpenPlant
Rhinopiping
Smap3D
Autodesk Inventor
Autodesk Revit
Solidworks, etc

Which is the Best Piping Software?

From the above list of piping software packages, the following two programs have unparalleled advantages and so rule the piping design software market for big complex plants. Both of these two software programs have quite good features:

E3D by AVEVA and
SP3D by Hexagon

Selection of Piping Design Software Program

The selection of an appropriate piping design software package is not easy. The selection process depends on various factors which must be studied beforehand. The important parameters for selecting the best piping design software are:
2D/3D Capability: Depending on the project requirements, the software environment 3D or 2D must be decided before selecting the piping design software.

Price: The economy plays an important role in all business decisions. Hence, the piping design software cost with respect to the value must be studied.
Technical support: Technical and customer support is one of the main criteria for choosing any software program. It is always preferable to choose the software which provides 24X7 live support.
Ease of Use: Easy software packages are always preferable.
Software Compatibility: User-friendly, compatible software programs should be selected which provide easy sharing options using common business tools like MS Office, PDF, etc.
Templates and Symbols Library: Piping design software programs having inbuilt templates and exhaustive symbols libraries are always preferred.

Click here to know about the best piping stress analysis software programs for piping industries.

Top Pipe Stress Analysis Software Packages for 2024

Written by Anup Kumar Dey in Caesar II,Piping Design Basics,Piping Stress Analysis,Piping Stress Basics,Start-Prof

The piping engineering would not have been developed so much in absence of piping software packages. Today, almost all the piping design activities are performed using various piping software packages. This software package not only helps in proper visualization but also helps in clash checking, accurate analysis, and production of piping isometric and other drawings in a shorter period of time. In recent times, the piping design and analysis are so much dependent on various piping design and stress analysis software packages that one can not just think of doing manual engineering. The engineering time and cost have both have reduced to a great extent because of this piping software. Using these advanced piping software packages, piping designers and engineers create complex plants complying with the governing codes and standards in very little time. For designing and analyzing piping and pipeline systems from Oil and Gas, Power, Chemical, Refinery, Petrochemical, Pharmaceutical, and Process industries, various piping software packages have proven themselves over the years and now stand strong in the industry. In this article, I will provide a list of top pipe stress analysis software packages that are highly popular and used widely in industries.

Best Piping Stress Analysis Software List

Piping stress analysis is a major part of piping engineering. This is considered the most critical job in piping design activity. To ensure that the pipe routing by piping designers will work without failure for its design life, all critical lines are analyzed using various piping stress analysis software. Such piping stress analysis software is designed to determine stress, load, and displacement values which are then compared with governing codes and standards to check compliance. Various static and dynamic modules of these stress analysis software packages confirm the structural and operational integrity of the piping and pipeline system. The most widely used piping stress analysis software packages are:

CAESAR II
AutoPIPE
Start-Prof
Rohr2
Caepipe

Piping Stress Analysis Software- CAESAR II

The most popular piping stress analysis software package in the piping industry is CAESAR II by Hexagon. Developed in the mid-1980s, the CAESAR II by COADE as piping stress analysis software completely revolutionized the world of piping stress analysis. The manual, time-consuming, error-prone, tough stress analysis endeavors by piping engineers got converted into a fast, easy, accurate process which in turn saved a lot of time and money for organizations. Now the latest versions of the CAESAR II software have the capability of analyzing complex systems in a very short period. The software has inbuilt databases from various international codes, standards, and different manufacturers to help the user in all respects of pipe stress analysis. It has compatibility with various piping design and process design software which saves time in modeling and analysis. Its color-coded 3-D model and output results easily help the piping stress engineers understand the area of concern in the piping system. CAESAR II as piping stress analysis software has both static and dynamic analysis capabilities. This software can handle both aboveground and underground piping stress analysis with various international codes altogether. The major benefits of CAESAR II software are

Easy and Quick modeling.
3-D Graphics to understand the concern areas.
Recommended and User-defined static load case editor to simulate and analyze any type of process condition.
Interfacing with various 3rd party piping, process, and FEA software.

Most of the big organizations use CAESAR II as their preferred pipe stress analysis software. Each year, the developers of the CAESAR II update the software and release new versions to meet the latest code requirements. Recently they have released Caesar II Version 14 which is the latest version of the software. It included the Hydrogen Piping and Pipeline Code in their database.

However, It has a few drawbacks as well.

The main drawback is the CAESAR II software is very costly compared with other piping stress analysis software available in the market.
The plastic pipe stress analysis (HDPE, PE, etc) module has not been added yet.

Pipe Stress Analysis Software- AutoPIPE

AutoPIPE is the pipe stress analysis software from Bentley Systems, USA. Their cost-effective solution for piping stress analysis for process, power, and nuclear units are efficient and popular. Possessing, both static and dynamic analysis capabilities the software is fast and provides results meeting the code requirements. AutoPIPE software has more popularity in the USA and Canada. It is believed that the dynamic capabilities of AutoPIPE are better as compared to CAESAR II. Also, the analysis of plastic piping systems like HDPE, PE, etc. is possible using AutoPIPE. This software is cheaper as compared to CAESAR II software. Click here to know more details about AutoPIPE vs CAESAR II

If you are a beginner and your organization uses the AutoPipe Stress analysis program then the following online course will surely clear your basics of Pipe Stress Analysis using Bentley AutoPIPE:

Learn Piping: Pipe Stress Analysis using Bentley AutoPIPE

Start-Prof as Piping Stress Analysis Software

Introduced in the year 1965, PASS/START-PROF is the oldest pipe stress analysis software. Possessing both static and dynamic capabilities, this piping and pipeline stress analysis software has a highly efficient solver including a user-friendly 3D graphical view. Developed by industry experts from Russia, START-PROF has all the capabilities where CAESAR II lags. Also, the software costs less than half the cost of CAESAR II software. It has an inbuilt feature to use the ASME B31J SIF calculation module. Similar to CAESAR II, it is not required to run a separate module for B31J. Earlier the software was used only in Russia but in recent times, the use of START-PROF as an efficient pipe stress analysis software is growing worldwide at a faster pace. It can import files from various 3rd party software like CADWorx, SmartPlant 3D, Autodesk REVIT, Bentley Autopipe, AVEVA PDMS, AVEVA E3D, HEXAGON CAESAR II, OpenPlant, Auto plant, Smart 3D, etc.

The best part of START-PROF software is that the developers update the software to incorporate all major changes in new codes on a regular basis (Faster than CAESAR II developers)

With much of positives, the START-PROF software has already been successfully used in the UK, Mexico, Brazil, China, Australia, Egypt, Turkey, Singapore, Thailand, Japan, Italy, Czech, Latvia, Serbia, Bulgaria, Germany, Finland, South Korea, USA, India, South Africa, Pakistan, Mongolia, France, Indonesia, Ukraine, Belarus, Kazakhstan, Uzbekistan, and Russia. The software has included all the major codes and standards in its database and is highly capable of stress analysis of Above-ground Piping, Buried Pipelines, Vacuum Piping, PUR Insulation Stress Check, Cryogenic Low-Temperature Piping, Jacketed Piping, High-Pressure Piping, Plastic Piping, High-Temperature Piping with Creep and Stress Relaxation Effects, FRP, GRP Piping, and Nonferrous Material Piping. Click here to know the comparison between CAESAR II and Start-Prof Software.

Piping Stress Analysis Software: ROHR2

ROHR2 as pipe stress analysis software is widely used in Europe. Developed by SIGMA Ingenieurgesellschaft mbH Germany, ROHR2 can efficiently perform static and dynamic analysis of complex piping systems and associated steel structures. For more than the last 40 years, the ROHR2 pipe stress analysis software is serving various clients in Europe. It covers the majority of the international and European codes for Piping and pipeline stress analysis line ASME Codes, EN codes, CODETI, STOOMWEZEN, FDBR, KRV, ISO, DIN, etc. It provides various nozzle analysis modules like API 610 / API 617 / API 661 / DIN ISO 9905 / NEMA SM23 / Nozzle Spec / EN ISO 5199 / DIN EN ISO 10437 / DIN EN ISO 10440 / DIN EN ISO 13709, etc. It is believed that the dynamic capabilities of ROHR2 software are better than CAESAR II.

Pipe Stress Analysis Software: CAEPIPE

CAEPIPE is the pipe stress analysis software program by SST Systems Inc, USA. Mostly used in the USA and Europe, this software has the capability to perform linear and non-linear, static, and dynamic piping stress calculations with unmatched speed. This is one of the cost-effective and productive pipe stress analysis software solutions with the best in class capabilities. The CAEPIPE software package is already successfully used in various industries like Power, Nuclear, Refinery, Fertilizer, Sugar, Aircraft, Defense, Water, Ship Building, Chemical, Oil & Gas, Paper, Building Services, and Petrochemical industries.

Other Pipe Stress Analysis Software Packages

The above 5 are the most widely used and popular pipe stress analysis software. There are some other piping stress analysis software packages in the market that are used by a small number of piping engineers. Those software packages are:

Simflex-IV Pipe Stress Analysis Software by the Equity Engineering Group
Triflex Pipe Stress Analysis Software by PipingSolutions Inc
PEPS by DST Engineering
WinPIPE by WinPIPE, LLC
AnSYS
Pipepak by ALGOR Inc.
CloudCalc PipeStress
PIPESYS

Selecting the Piping Stress Analysis Software

The selection of a piping stress analysis software package will depend on various factors like

Client Requirement: This is the main criterion for the selection of a specific pipe stress analysis software. As the clients are the drivers of the EPC projects in the piping design consultancies. So, whatever software the client suggests is agreed upon by the design consultancies. To date the software, CAESAR II has wide popularity. It roughly controls more than 70% of the piping stress analysis market share worldwide. The majority of the clients prefer the piping stress analysis solution using Caesar II. This is the reason that even though START-PROF, AutoPIPE, CAEPIPE, and ROHR2 have wide capabilities as compared to CAESAR II, design consultancies are forced to choose Caesar II for their software.

Cost: The economy is the second important criterion for the selection of software packages. Among the above-mentioned top five pipe stress analysis software, Caesar II is the costliest software. All other software packages cost less than half of the Caesar II software. This is the reason that the use of other Pipe stress analysis software packages, specifically START-PROF and AutoPIPE is growing significantly in recent times. Also, the developers of those software packages have successfully proved the acceptability of the output results in comparison to CAESAR II.

Ease of Learning, Software Support, and Training: This is the third criterion for the selection of a piping stress analysis software package. All the top five pipe stress analysis software companies provide very good engineering support and training. However, when it comes to providing local support, CAESAR II wins because there are so many experienced professionals in every organization who develops their juniors for the same software. However, as slowly, other pipe stress analysis software packages are considered in design consultancies, the skills for other software packages are also increasing.

Remarks

Due to the slowdown in the Oil and Gas Market because of Low Crude Prices and COVID, most of the design organizations are not getting good projects. So, the cost of pipe stress analysis software packages has become significant in those respect. So, it is time to think about reducing the software cost. So, in this respect, a licensing cost that will charge only when the software is used will be very beneficial. Bentley AutoPIPE has a similar concept. They charge for the software only for the days it is used. A similar concept will be highly beneficial.

Also, as all software packages are compatible with one another, organizations can think of purchasing different software packages. For example, if a project requires 3 CAESAR II licenses. They can easily buy one CAESAR II, one START-PROF, and one AutoPIPE license which will save the high cost of 3 CAESAR II licenses. Piping engineers will learn all three software packages and model and analyze the systems in their respective software packages. Now if the client wants reports in Caesar II format, all files can easily be opened in the CAESAR II software, and the final run can be made in CAESAR II along with report preparation. However, this is my personal thought. Don’t know if there will some major difficulty. Kindly provide your views on this in the comments section.

I had set up a poll request for Linkedin users about which pipe stress analysis software they use. 1076 users had voted and the result was 81% uses CAESAR II, 13% uses AutoPIPE, 3% uses START-PROF, and 3% uses ROHR2.

Click here to learn Top piping design software packages.

What are Hub Connectors? | Its Design, Benefits, and Applications

Written by Anup Kumar Dey in Mechanical,Piping Design Basics

Hub connectors or hub and clamp joints are an alternate method of joining pipes as compared to traditional ASME B16.5 pipe flanged joints. Pipes and equipment can easily be joined using clamp and hub connectors as this metal-to-metal sealed connector is highly reliable and easy to assemble. The clamp and hub connector joint consists of the following components:

Two hubs
Two clamps
One seal ring
Eight nuts
Four studs

Refer to Fig. 1 below that shows the elements of a typical clamp and hub connector.

**Fig. 1: Elements of a Hub Connectors**

Design of Hub and clamp Connectors

Hubs are designed following ASME Sec VIII Div. 1-Appendix 24 to sustain internal pressure and clamps are designed as per ASME Sec VIII Div. 2 Part 4 to resist external loads. For the design and selection of clamp and hub connectors, the following information is required:

Connecting pipe size (OD and ID) and thickness.
Design pressure and temperature of the piping system where the hub connectors will be installed.
Materials for the clamp, hub, seal ring, and bolting (as per the piping class).
Any specific service requirements, etc.

The codes and standards used for design calculations of clamp and hub connectors are

ASME VIII div.2,
API 6A/17D,
API 17 TR8,
ISO 13628-7,
EN-13445-3
and DNV OS-F101 & F201.

For sub-sea applications, clamp connectors are usually made from duplex materials, and designed following DNV-RP-F112 to meet the required HISC resistance.

Welding of Components

The hubs are rigidly welded to the pipe with a seal installed. Clamps are tightened using bolts. This arrangement provides superior strength as compared to conventional flange joints and prevents leaks.

Placement of Bolts & Seal Ring

To prevent direct pressure and avoid bending, the bolts are installed in a perpendicular direction with respect to the pipe axis. The seal ring, resembling, the shape of a ‘T’ in cross-section is used to seal the connector. The design of the connector helps to:

Withstand higher tensile loads
Provide higher strength with lower seal size and weight
Allow proper seating of the seal
Reduce bolting torque

Benefits of Using Hub & Clamp Connectors

As compared to the conventional flange joints, the clamp and hub connection joint provides the following advantages:

Simple Connection requiring only four bolts.
Lightweight & Smaller in size; Compact Design: Hub and clamp connectors usually have around 80% less weight, 10% less outside diameter, and 50% less overall length than the standard ASME B16.5 flanges. Hence, they use significantly less space.
Reduce Downtime as can be assembled or dismantled quickly with fewer bolts.
Economical Solution: A hub and clamp connector provide an economical solution for piping joints by reducing the total cost of installation.
Leak-Free: Clamp and hub connectors can withstand higher temperature and load variations and ensures leak-free operation when installed correctly.
360° orientation around the pipe is possible.
Lower Bolt torque.

Applications of Hub & Clamp Connectors

The hub and clamp connector joints are used in piping systems requiring high-integrity seals. They are suitable for applications involving corrosive, erosive, high-pressure-temperature, and cyclic conditions. This is the reason that clamp and hub connectors are used in the following industries:

Oil and Gas Production
Chemical and Petrochemical processing
Petroleum refining
Food processing
Industrial gas manufacturing
Fossil and nuclear power generation
Coal gasification and liquefaction
Synthetic fuel processing
Research and Development
Aerospace manufacturing, etc

Hub connectors can also be used in pumps, compressors, manifolds, pipeline pig closures, and valves. Specially designed hub and clamp connectors are also suitable for pressure vessel nozzles.

Materials for Hub and Clamp Connectors

The following table provides some typical materials used in hub and clamp connector piping joints.

	Hub Material	Seal Ring Material	Material of Clamp	Bolting Material
Carbon Steel	A105N/A694 F60/F65/F70/F75	AISI 4130 / 4140 + PTFE coated	Forged AISI 4130/4140	A193 B7/A194 2H for non-sour service and A193 B7M/A194 2HM for sour service.
Low Temp Carbon Steel	A 350 LF2	AISI 4130 / 4140 + PTFE coated	Forged AISI 41430/4140	A320 L7/A194 7 for non-sour service and A320 L7M/A194 7M for sour service.
Stainless Steel	A182 F316/F316L	A 182 F316 + PTFE coated	SS316/SS316L	A193 B8M/A194 8M
Duplex Stainless Steel	A182 F51/ A182 F53/A182 F55	A182 F51/ A182 F53/A182 F55 + PTFE coated	SS316/SS316L	A 276 UNS S32760
Nickel Alloy UNS N06625	B564 UNS N06625 or CS with Inconel625 weld overlay	Alloy 718 + PTFE coated	Forged AISI 4130/4140	A193 B7/A194 2H for non-sour service/ A193 B7M/A194 2HM for sour service.

Table 1: Materials for Clamp and Hub Connectors

Flange vs Hub Connector

The main differences between a flange connection and a hub and clamp connection are provided below:

Flanges	Hub and Clamp Connector
Flanges are the weakest links in a piping installation and may develop leakage problems.	Clamp and hub connectors provide better tightness and withstand more loads and stresses as compared to flanges.
Gaskets must be replaced during the maintenance of flanged joints.	Self-energized metallic seal rings are reused.
Bolt holes must be aligned during installation	No bolt holes to align in hub connectors
Multiple bolts depending on the pressure class rating and size	Only 4 bolts for tightening.
Larger diameter and length.	Shorter overall length and a smaller diameter.
Installation takes a longer time.	Quick assembly or disassembly.
Multiple sizes and a wide variety of manufacturers and hence the range of choices. Standardized items.	Limited manufacturers and non-standard items.

Table 2: Flange vs hub Connector

What is a Breather Valve? | Breather Valve for Tanks

Written by Anup Kumar Dey in Instrumentation,Mechanical,Piping Interface,Process

A breather valve is a special type of pressure and vacuum relief valve used to protect atmospheric and low-pressure tanks & vessels in which fluids are filled and drawn at a high flow rate. Proper installation of breather valves can prevent tank explosions due to overpressure and collapse due to vacuum conditions. The breather valve does not release the vapor until the tank pre-set pressure is reached. So, it can be used to reduce evaporation loss. It balances the fluctuations in pressure & vacuum by eliminating excessive pressure or vacuum and provides increased fire protection and safety.

Using weighted pallets or springs in the breather valves, the pressure and vacuum protection levels can be controlled. It is normal practice to combine both pallet and spring systems in one unit to provide the required Pressure/Vacuum settings. In a breather valve, the pressure settings require a spring section, whilst the vacuum settings use the pallet method.

Working of a Breather Valve

A breathing valve consists of an in-breathing valve and an out-breathing valve. They are arranged side by side or overlapped. When the tank pressure becomes equal to atmospheric pressure, the disc and seat of the pressure valve and the vacuum valve work together making the seat tight without leakage. When the pressure or vacuum increases, the disc of the breather valves opens and retains a good seal because of the “adsorption” effect on the side of the seat.

When the tank pressure increases and reaches its design values, the pressure valve opens discharging the gas in the tank into the outside atmosphere through the side of the vent valve known as the pressure valve. At this time, the vacuum valve is closed due to the positive pressure in the tank. On the other hand, during the out-breathing process due to tank loading and evaporation of liquid due to higher atmosphere temperature, the vacuum valve opens due to the positive pressure of atmospheric pressure. The external gas enters the tank through the suction valve known as the vacuum valve. At this point, the pressure valve closes. Both the pressure valve and the vacuum valve do not simultaneously open at any time. The inhaling and exhaling process stops when the pressure or vacuum in the tank drops to normal and the pressure and vacuum valves close.

Types of Breather Valves

Breather valves can be categorized into the following groups:

Pressure and vacuum relief valve: To prevent overpressure or vacuum conditions, the composite pressure and vacuum relief valve are used. Two independent units one to control pressure and the other to control vacuum can also be manufactured and procured as necessary.
Pilot-operated relief valve: To protect from low-pressure or vacuum situations, the pilot-operated relief valves provide safe, accurate, and dependable protection.
Air-operated relief valve: To reduce evaporation loss, highly efficient air-operated valves are used.
Emergency vent valves: For fire or emergency temperature conditions, the emergency vent valve maintains the positive pressure in the tank within allowable design parameters.
Gauge Hatch: Similar to emergency vent valves to carry out manual measurement of tank level with a metallic tape where conventional float and tape type-level instrument is out of action.
Tank Blanketing Valve: To maintain the constant pressure in the vapor space of the storage tank when the tank is under unloading mode or vapor under condensation due to low ambient temperature, Tank blanketing valves are used.

Functions of a Breather Valve

The main functions of a breather valve is:

reducing the vapor loss from the storage tank
preventing the vacuum and pressure from exceeding the tank design limits.
preventing flammable conditions.
protecting the tank contents from moisture intrusion.

Common Standards for Breather Valve

Common standards that govern the design and selection of breather valves are

DIN EN 14595: Tank for the transport of dangerous goods-service equipment for tanks-pressure and vacuum breather vent.
API 2000: Venting of Atmospheric and Low-Pressure Storage Tanks.
API 2521: Use of Pressure-Vacuum Vent Valves for Atmospheric Loss
API 2513: Evaporation loss in the Petroleum Industry-Causes and Control

Advantages of Breather Valve

The main advantages that the application of breather valves serves are

Content protection
Fire hazard prevention
Explosion prevention.
Reduction of corrosion and emission.
Low maintenance.
Safe Pump operation.

Installing Breather Valves

The breather valve must be mounted at the highest point on the top of the tank to reduce evaporation losses and other exhausts. Also, it will ensure the most direct and maximum access to the breather valve. Usually, the Breather Valve is mounted on a nozzle opening of a fixed roof atmospheric storage tank. As the fixed roof atmospheric storage tanks do not contain any controlled openings, there are high chances of rupture under increasing pressure caused by pumping liquid into the tank or as a result of vapor pressure changes caused by severe thermal changes. On the contrary, the tank can implode during the pumping out procedure or thermal changes. When the liquid level lowers, the vapor space pressure is decreased to below atmospheric pressure. This vacuum condition is alleviated using the breather valve.

Parameters Affecting breather valve performance

The proper working of a breather valve depends on the following five factors:

Pressure and Vacuum Settings
Temperature Variations
Temperature vs Humidity
Number of Airlifts, and
Amount of Desiccant

Selection of Breather Valves

The selected breather valve must be able to reduce moisture intrusion in the tank. These valves must protect the tank from a vacuum and excessive pressure. Hence, the breather valve needs to be sealed except during the airlift and in extreme temperature conditions. Certain tank parameters must be known for the proper selection of a breather valve. These are

The maximum pressure and vacuum condition that the tank is able to withstand.
Tank volume.
How quickly the pressure change can take place.
The temperature variation during the storage.
Relative humidity and temperature of the storage area.

Materials for Breather Valves

Breather valves are usually manufactured of the following materials:

Carbon Steel
Aluminum
Stainless Steel
Cast Iron

However, breather valves can be manufactured of any material that is required based on service conditions.

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