TEMA Guidelines Archives - Enerquip Thermal Solutions

Skip to Content

Tag Archive: TEMA Guidelines

Shell and Tube Heat Exchangers: A Guide to Industry Standards
August 21, 2024 6:01 am Leave a Comment
Shell and tube heat exchangers are critical components across various industries, from oil refining and pharmaceutical production to food safety and brewing. Despite the diversity of these industries, they all share a common challenge: selecting the right shell and tube heat exchanger for their specific operations.

Heat exchangers, when crafted with high-quality materials and meticulous standards, can have a long lifespan. However, when it’s time for a new purchase, making the right choice is essential. The configuration, codes, and industry standards your equipment meets are crucial factors that impact its performance and compliance. Adhering to these standards ensures that your products are not only of the highest quality but also meet all regulatory requirements.

Industry standards play a pivotal role in ensuring that shell and tube heat exchangers are built to perform effectively and safely. Selecting an exchanger that meets the necessary criteria is vital for avoiding operational issues and ensuring that your products are safe for distribution.

The following are key industry standards for shell and tube heat exchangers.

TEMA Standards

The Tubular Exchanger Manufacturers Association (TEMA) provides one of the most widely recognized industry standards. TEMA’s standards are categorized into three classes:
- Class B: For chemical processing applications
- Class C: For general commercial use
- Class R: Primarily for petroleum processing, but also suitable for large-scale operations
Each class addresses specific needs, such as the need for more robust construction in petroleum processing or the use of stainless steel in chemical applications. Understanding these distinctions helps in choosing the right heat exchanger for your industry.

ASME Standards

The American Society of Mechanical Engineers (ASME) sets standards that are crucial for the pressurized components of shell and tube heat exchangers, particularly those within the shell. The ASME VIII code is widely applied across various types of equipment, ensuring that the pressurized parts meet strict safety and performance criteria. Many heat exchangers are certified by both ASME and TEMA, as TEMA standards often complement ASME’s broader criteria.

ANSI Standards

The American National Standards Institute (ANSI) has been coordinating the U.S. voluntary standardization system for nearly a century. ANSI plays a key role in the development and improvement of industry standards, including those for shell and tube heat exchangers. Regular updates and calls for comments ensure that these standards evolve to meet industry needs.

PED Standards

Given the global use of heat exchangers, compliance with international standards is also essential. The Pressure Equipment Directive (PED) is a key standard in the European Union, covering everything from materials and harmonized standards to essential requirements and market surveillance. Adhering to PED ensures that your equipment is safe and legally compliant in the EU market.

CRN Standards

For operations in Canada, the Canadian Registration Number (CRN) is mandatory for all boilers, pressure vessels, and fittings. The CRN certifies that the equipment meets the specific safety standards of each province or territory. Understanding the CRN system, which includes province-specific codes, is crucial for ensuring compliance in Canadian markets.

3-A Sanitary Standards Inc.

Originating in the 1920s, 3-A Sanitary Standards were developed to ensure that equipment used in the dairy industry, and later food and pharmaceutical industries, could be easily cleaned and maintained. These standards, established by a collaboration of equipment fabricators, regulatory sanitarians, and processors, ensure that all equipment can be cleaned effectively, whether through a clean-in-place (CIP) system or manual cleaning.

When purchasing a shell and tube heat exchanger, getting the right certifications is crucial. Enerquip’s team of engineers will know what your industry requires and will work with you to meet your needs. We invite you to contact us or request a quote today.

More from the Enerquip Blog
Maximizing Heat Exchanger Efficiency with Impingement Devices
July 19, 2024 8:27 am Leave a Comment

Click to Expand

A shell and tube heat exchanger is a cornerstone of many production operations, designed to last for years under tough conditions. However, certain processes, especially those involving high fluid velocities, can lead to challenges like corrosion, erosion, and excessive vibrations. These issues not only impact the machine’s performance but can also reduce its lifespan, as vibration can cause tubes to pull out, leading to cross-contamination and damage to both the tubes and the shell.

To mitigate these risks, the Tubular Exchanger Manufacturers Association (TEMA) advises that when dynamic pressure (rho*v2) exceeds 1,500 in certain high-velocity situations, an impingement plate should be installed. These plates help reduce erosion and vibration by diffusing the high-energy fluid. However, they come with their own drawbacks, such as increasing the shell diameter or creating vibrations themselves. Therefore, careful consideration is needed before making modifications to the heat exchanger.

The Role of Impingement Devices in Steam Heating Systems

In steam heating applications, the use of impingement devices can significantly improve the efficiency and longevity of the heat exchanger. Steam heating systems are vital for various industrial processes, such as cleaning, sanitation, and product heating, and rely on maintaining precise temperature and pressure levels. Shell and tube heat exchangers are central to these systems, ensuring effective heat exchange between process liquids and steam.

Impingement devices help regulate the heat exchange process by increasing turbulence, reducing stagnation, and limiting corrosion. These devices keep the steam moving, particularly near the shell-side inlet, which enhances heat distribution and reduces the risk of vibration.

Exploring Virtual Testing and Other Solutions

Determining the best solution for high-velocity processes can be challenging. While impingement plates are effective, they may not always be the ideal solution. Using computer simulations, such as HTRI software, manufacturers can predict how different equipment will affect heat exchanger performance. These simulations use complex models to analyze fluid flow and allow engineers to explore other methods to reduce erosion and vibration risks.

Beyond impingement plates, other protective devices can be used to reduce vibration and prevent erosion. Options like annular distributors, impingement rods, and different baffle configurations (such as double-segmental) can save space and cost while addressing thermal expansion issues. In some cases, longer shells or U-tube designs offer further protection, preventing tube pullout or shell damage.

Types of Impingement Devices

At Enerquip, a variety of impingement devices are available to improve heat exchanger performance. The choice of device depends on factors such as fluid properties, velocity, and system pressure drops. Here are some common options:
- Baffles: These are installed perpendicular to fluid flow to increase turbulence and change the fluid’s direction, improving heat distribution.
- Annular Distributor (also called a steam bustle or vapor belt): This device ensures even fluid distribution over the tubes, preventing hot and cold spots.
- Twisted Tubes: Shaped like a corkscrew, these tubes disrupt fluid flow to ensure even heat distribution.
Maximize Efficiency with Enerquip

Choosing the right impingement device is essential for ensuring the longevity and efficiency of your heat exchanger, whether for industrial or sanitary applications. At Enerquip, we specialize in steam heating solutions and can help you determine the best methods to reduce erosion, vibration, and ensure efficient heat exchange. Contact us to learn more or request a quote to get started.

More from the Enerquip Blog
Designing a Shell and Tube Heat Exchanger
June 10, 2024 6:28 am Leave a Comment
Shell and tube heat exchangers are an integral part of many operations. The product flowing through the exchanger, such as dairy, food, or pharmaceuticals, will eventually be in the hands of customers who rely on consistent quality for their health and well-being. For this reason, it is crucial the exchanger is the best one for the job.

Manufacturers need to choose the right style of shell and tube heat exchanger. Different processes and industries have different requirements for their equipment. Because of this, customizing a shell and tube heat exchanger takes expertise from both the supplier and the buyer of the equipment. A lot that goes into fabricating a heat exchanger and taking all pertinent items into consideration is essential during the design phase.

The Shell

Perhaps the most recognizable part of the shell and tube heat exchanger is the shell itself. There are many different options for the shell design, including one-pass shells, two-pass shells, double split flows, divided flows and cross flows. These are all classified as different standards with the Tubular Exchanger Manufacturers Association. There are also several streams within the shell that need to be taken into consideration when designing it.

There are many different materials that shells can be made from. The materials should be resistant to corrosion and sturdy enough to encase the tubes and the high-pressure processes that will occur within. Carbon steel is a common material used for shells, as is stainless steel. Stainless steel is highly resistant to many forms of corrosion, making it a preferred material for many manufacturers.

It’s important to understand what liquid will be flowing through the shell side. Knowing the liquid that will be used will help to determine the material, as the metal chosen should not react with the fluid used. Viscous fluids can be used either on the tube side or the shell side. However, many exchangers that use viscous liquids on the shell side experience vibrations, which puts the equipment at risk of damage and maldistribution.

Tubes and Tube Sheets

There are three types of tube sheet designs. A fixed tube sheet has tubes that run from one end of the shell to the other and is welded to the shell. A U-tube heat exchanger only requires one tube sheet because the tubes leaving the tube sheet are bent at the end of the exchanger and returned to the same sheet. The third type is the floating head. This requires two tube sheets; one, which is fixed to the shell, and a second, which is located at the other end but is not fixed, allowing for tube expansion.

There are many factors to consider when choosing between these three. One of them is cost. The u-tube tube sheet is likely the least expensive as only one tube sheet and channel is required. The fixed tube sheet is more expensive but gives you more options for more viscous fluids. Finally, the floating head tube sheet is the costliest, as it has the most complex design.

However, while cost plays an important part in the decision-making process, it cannot be the only factor. It is crucial that the tubes and tube sheets be cleaned and maintained to prevent breaks, leaks and fouling. The fixed tube sheet’s tubes can be accessed for cleaning (with cleaning rods or pressurized water), but the tube bundle cannot be removed from the shell, making cleaning difficult. On the other hand, the U-tube and floating head designs allow for the bundle to be removed, so cleaning is easier.

Learn more about maintaining your shell and tube heat exchanger.

More from the Enerquip Blog
Choosing an Exchanger Channel Style
December 2, 2015 5:36 pm Leave a Comment
Editor’s Note: This content was last updated 3/11/24.

Shell and tube heat exchangers offer a myriad of configurations to suit various needs. The crucial initial step in selecting the right exchanger for your business involves choosing the optimal combination of styles. Fabricators collaborate closely with manufacturers to pinpoint the specific requirements the exchanger must fulfill.

A pivotal decision that fabricators and manufacturers must make pertains to the type of channel, or bonnet, to employ in the shell and tube heat exchanger. This entails considering both the front channel, through which fluid enters the tubes, and the rear channel, where the fluid either exits the exchanger or undergoes another cycle.

Each type of channel—front or rear—is denoted by a designation set by the Tubular Exchanger Manufacturers Association (TEMA).

Varieties of Shell and Tube Heat Exchangers

When designing a shell and tube heat exchanger, the customer and fabricator will select the front channel, the shell type, and the rear head types. Each has its own merits and drawbacks, but aligning with the specifics of the application will guide the choice. Understanding the intended use of the exchanger is crucial for determining which qualities to prioritize.

For example, if the exchanger will handle toxic chemicals, particularly if hazardous materials will flow through both the tube side and the shell side, the N-type bonnet might be optimal. In this construction, the tubes, tube sheet, and shell are all welded together, reducing the risk of leaks. However, if welding everything together is unnecessary, there’s little advantage over other types. The N-type bonnet is challenging to clean and maintain, and replacing parts is more cumbersome compared to some alternatives.

If ease of cleaning and maintenance are top priorities, an A- or B-type designation would be advantageous. Both facilitate easy cleaning, as accessing the tube sheet is straightforward. These are the most common channel options, suitable for most exchanger applications. When choosing between the two, considerations should include the fluid pressure in the exchanger, the importance of tube cleaning, solution cleanliness, and cost.

The A-type is the easiest to clean because the tubes can be reached without disconnecting piping or removing the bonnet. Many manufacturers prefer A-type channels because they simplify cleaning the tube side, allowing the use of contaminated tube side fluids. However, this bonnet style has two gasketed seals, increasing the risk of leaks in high-pressure processes.

The B-type exchanger lacks the second seal, reducing the risk of leakage, making it more suitable for high-pressure processes. However, cleaning is more challenging because the bonnet needs removal to access the tubing. Manufacturers handling clean tube side fluids but dirty shell side solutions often choose this option, which is also more economical.

Lastly, the C-type provides access to the tubes without removing the piping, although it’s challenging to clean and maintain. It’s suitable for high-pressure applications and for handling hazardous substances on the tube side.

There are also D-type channels, primarily used for extremely high-pressure applications. Like the C-type, repairs are difficult because the tube bundle is attached to the bonnet. However, cleaning is not problematic as the tubes can be accessed without moving the pipes. It’s the most expensive option for the front channel.

Choosing the right bonnet is a critical decision in planning the fabrication of a shell and tube heat exchanger. While many exchangers perform well with an A-type or B-type channel box, there are instances where an N-type, C-type, or D-type may be preferable. Manufacturers should carefully discuss the options with their fabricator and understand the expected uses of their machine before making a final decision.

Machined vs. Fabricated Channels

Depending on the application, you’ll also need to decide if a machined channel or a fabricated channel is a better option.

Machined designs involve creating parts from solid stainless steel plate or forging through milling and drilling, ensuring cleanability and easy draining. On the other hand, fabricated designs are built from raw materials, offering larger volume for product hold-up and removable covers for tube cleaning, making them ideal for more viscous product applications. Depending on the specific requirements of your application, one may be more suitable than the other.

Enerquip provides various designs for both machined and fabricated channels, each offering unique benefits. Here, we compare the two.

Enerquip Simplifies the Decision-Making Process

If you’re in the market for a shell and tube heat exchanger but uncertain about the best style for your application, consult the experts at Enerquip. With experience in designing and fabricating shell and tube heat exchangers since 1985, we’ve likely worked with your exact process conditions. Contact us today or request a quote.

More from the Enerquip Blog