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Types, Uses, and Applications of Tanks & Vessels

Pressure tanks and vessels come in various shapes and sizes and are designed to hold gases, vapors, and liquids at high pressures, usually above 15 PSIG. Storage tanks hold various  liquids. Each type of tank has a unique set of properties and applications, but all play an important role in the safe and efficient operation of various businesses.

What’s the Difference Between Pressure Tanks & Storage Vessels?

Pressure tanks and storage vessels are pressurized containers that store gases and liquids. The main difference between these two types of tanks is the pressure at which they contain their media.

Pressure vessels store gases or liquids at a pressure above atmospheric pressure. Their Maximum Allowable Operating Pressure (MAOP) starts at 15 PSI but can reach up to 150,000 PSI. On the other hand, storage tanks have an MAOP of 15 PSI and only hold gases or liquids at atmospheric pressure. Also, pressure vessels are typically made from stronger materials such as steel or fiberglass, as they need to withstand higher pressures.

Different Types of Tanks & Vessels


There are three main types of pressure tanks:

  • Bladder: Bladder tanks have a rubber or synthetic rubber bladder that stores water. The principle behind a bladder tank is that as fluid fills the bladder it compresses the air in the tank. This air then puts pressure on the water in the tank, keeping the pressure constant.
  • Diaphragm: Diaphragm tanks work similarly, but instead of a bladder, they have a flexible diaphragm that divides the steel tank into two chambers. One chamber holds water, and the other chamber holds air. As water fills one chamber, the air applies force against the water chamber, maintaining constant pressure.
  • Air-over-water: Air-over-water tanks are traditional versions of pressure tanks with air filling the top part of the tank and fluid filling the bottom. The air puts pressure on the water, keeping the pressure constant until water is drawn out of the tank, decreasing the pressure. Air-over-water tanks are also commonly referred to as galvanized or stainless steel tanks.


Pressure vessels are designed to contain fluids or gases at high pressures and are used in various industries, from food and beverage processing to manufacturing.

  • Heat exchangers: Heat exchangers transfer heat between two liquids or between a liquid and a gas while preventing the two types of media from coming into direct contact with one another.
  • Process vessels: Process tanks carry out reactions or other production processes, such as distillation or filtration.
  • Storage vessels: Storage vessels store liquids or gases at high pressure, often for long periods.

How does a Pressure Vessel or Pressure Tank Fail?

There are several ways pressure vessel tanks can fail. The most common type of failure is material degradation, which happens when the material used to construct the vessel is not strong enough to withstand the pressure to which it is subjected. This can be due to an improper selection of material, incorrect design, or poor fabrication.

Another type of failure is structural discontinuity, which happens when there is a break or crack in the vessel’s structure. This can be caused by improper maintenance or a sudden increase in pressure. Finally, a reduction in the load-bearing capacity can also lead to failure. This happens when the vessel is not properly supported and begins to sag or collapse under its weight.

The safe operation of pressure vessels is essential for the welfare of workers and the general public. Unfortunately, pressure vessels can sometimes fail, leading to serious consequences. The most common types of failures are:

  • Brittle fracture
  • Stress rupture
  • Elastic deformation
  • Corrosion fatigue

Uses and Applications of Stainless Steel Tanks & Vessels

Highland Equipment Inc. specializes in designing and manufacturing high-quality stainless steel tanks and vessels for various industries. Below is an overview of the applications and uses of our sanitary tanks and vessels:

  • Pharmaceutical tanks store and transport sensitive materials for the pharmaceutical industry.
  • Food and beverage manufacturers use our tanks to store everything from wine and beer to milk and olive oil.
  • Dairy farms utilize our dairy tanks for the pasteurization of milk.
  • Breweries rely on our tanks for the fermentation and aging of beer.
  • We also create custom tanks and vessels for the cosmetics industry.

No matter the industry, Highland Equipment Inc. can provide the perfect solution for your storage needs.

Rely on Highland Equipment For High-Quality Pressure Tanks & Vessels

Tanks and vessels are an important part of many industries. Our process systems are vital to industrial food & beverage processing, pharmaceutical drug synthesis, dairy processing, alcohol production, cannabis extraction, and cosmetics processing.

If you need tanks or vessels for your company, request a quote from us. We can provide you with the best products for your needs, ensuring you get the most value for your money.

Positive Displacement Pumps vs. Centrifugal Pumps vs. High-Pressure Pumps

Many industries rely on pumps for their daily operations, including the dairy, brewing, food processing, beverage manufacturing, and personal care industries. Highland Equipment supplies various hygienic pumps for a wide range of applications. In this blog, we’ll take a detailed look at positive displacement, centrifugal, and high-pressure pumps, including their suitability for certain processing applications.

What Is a Positive Displacement Pump?

A positive displacement pump works by repeatedly taking a specific amount of fluid and mechanically moving it through the system. It uses cyclic pumping action driven by pistons, gears, rollers, screws, diaphragms, or vanes.

Positive displacement pump types include reciprocating and rotary pumps. The reciprocating pump relies on repeated back-and-forth strokes of a plunger or piston. These repeatable pumps are suitable for accurate dosing or metering applications.

Rotary positive displacement pumps use rotating gears to move fluids. The gears form a liquid seal with a pump casing, creating suction through the pump inlet.

What Is a Centrifugal Pump?

Centrifugal pumps use rotational energy from a motor to transfer fluid through a system. When the fluid passes through the pump, the rotating impeller adds velocity and pressure to the fluid as it is pushed toward a diffuser.

What Is a High-Pressure Pump?

High-pressure pumps have a conveying height of up to 1,200 meters. These pumps are common in high-rise buildings, which require sufficient pressure to supply the entire structure.

How Do These Pumps Compare?

Using a controlled amount of force, positive displacement and centrifugal pumps both transfer a set quantity of fluid from an inlet to an outlet. However, their mechanisms are different. Centrifugal pumps transfer kinetic energy from a motor to the liquid using an impeller, which rotates to pump fluid at a high velocity out of its discharge point. Positive displacement pumps displace fluid out of a cavity through suction.

These are some other ways in which centrifugal, positive displacement differ:

  • Performance: A centrifugal pump can vary the flow rate by changing its pressure. The flow rate is constant in a positive displacement pump, even during pressure changes.
  • Fluid viscosity: When dealing with highly viscous fluids, a centrifugal pump sees a decrease in flow rate due to frictional losses inside the pump’s cavity. A positive displacement pump’s internal clearance allows for viscous fluid handling and can increase flow rate as the viscosity increases.
  • Efficiency: A centrifugal pump’s efficiency peaks at a specific pressure, while the efficiency of a positive displacement pump varies according to the pressure.
  • Suction lift: Centrifugal pumps cannot create a suction lift, while a positive displacement pump creates a vacuum on its inlet to create a suction lift.
  • Shearing: The high-speed motor in a centrifugal pump can shear certain media. A positive displacement pump creates low shear, making it suitable for shear-sensitive fluids.

Which Pump Is Suitable for Your Sanitary Process?

The ideal pump for your sanitary process depends on the specific factors of your application. Centrifugal pumps are best for high-flow, low-viscosity applications, where you can take advantage of their high-volume capabilities. You can also customize them to move more gallons per minute than other types of pumps.

Positive displacement pumps generally run better in high-viscosity, low-flow applications. They allow you to control flow rate more flexibly, operate at lower speeds, and can prime themselves during “dry” periods where there is no liquid in the pump. Plus, positive displacement pumps can process suspended solids.

Consider the following specifications of your project to determine the best choice:

  • Desired flow rate
  • Pressure capability
  • Fluid characteristics, such as corrosiveness, temperature, and viscosity
  • Suction lift

Positive Displacement, Centrifugal, and High-Pressure Pumps From Highland Equipment

Depending on your specific application, you can choose between positive displacement, centrifugal, and high-pressure pumps. They each offer different capabilities and strengths under particular processing circumstances. Highland Equipment is your ideal partner for high-quality centrifugal, positive displacement, and high-pressure pumps for sanitary processes. Contact us today to select a pump best suited for your application.

A Guide to Stainless Steel Tank Fabrication

Highland Equipment has been building unmatched stainless steel tanks and equipment for various sanitary process applications since 1973. As the leading provider of sanitary process equipment, Highland Equipment has the tools and experience needed for various tank projects, from one-tank requirements, complex pressure vessels, skidded systems, and custom equipment to a host of customized tank projects. Our team of experts has the knowledge and professional background to provide custom solutions for all your equipment needs.

Overview of Stainless Steel Tanks

Sanitary stainless steel tanks are special containers used to store and transport a myriad of substances such as water, food and beverage, pharmaceuticals, personal care, cosmetics,  and other bulk materials. They feature superior flexibility and ease of use that make them ideal for various industries and applications. Stainless steel tanks are also known for their corrosion resistance and their ability to resist extreme temperatures. These attributes make stainless tanks the best equipment for storing sensitive materials. 

Stainless Steel Capabilities

Stainless steel tanks come with either a drum-like, rectangular, or cylindrical shape with thin walls made of stainless steel material. The stainless steel tanks offered by Highland Equipment are equipped with heat transfer capabilities to meet the needs of your specific applications. 

Depending on your objectives, our experienced engineering team and technicians can also equip the tanks with mixing components that come in various sizes. We also offer a range of atmospheric tanks that allow our clients to choose from different options, including dished tops and bottoms, flat tops and bottoms, and/or conical tops and bottoms. 

We can also custom-make your exact specifications for your stainless tank depending on several factors, including your specific application, the product to be stored, how often the tank must be cleaned, and other considerations.

Stainless Steel Mixing Tank Fabrication

Stainless steel comes in different grades designed to handle various substances and chemicals. These grades offer varying levels of corrosion resistance, strength, toughness, and high/low-temperature performance. During the fabrication of stainless steel, the following grades are widely utilized:

  • 304/304L: Stainless steel 304 comprises 18 to 20% chromium, 8 to 11% nickel, and 2% manganese. It offers adequate corrosion resistance for most applications. It is also less costly compared to other options.
  • 316/316L: 316/316L comprises 6 to 18% chromium, 10 to 14% nickel, 2 to 3% molybdenum, and 2% manganese. The addition of molybdenum adds an extra layer of corrosion resistance to make 316/316L more resistant to chemicals than stainless steel 304. 
  • Duplex: Duplex stainless steel is a blend of ferritic and austenitic metallurgical structures. It contains 20 to 28% chromium, 2 to 5% molybdenum, and 5 to 8% nickel. Austenitic stainless steel is superior to ferritic in terms of corrosion resistance and mechanical properties.

Highland Equipment provides end-to-end stainless steel tank fabrication solutions from equipment design and manufacturing to system integration, installation, and ongoing technical support. We practice comprehensive quality control throughout all phases of fabrication, and our team undertakes extensive weld inspections to guarantee flawless joints. We leverage our premier fabrication shop fitted with the latest technologies and tools to provide high-quality orbital welding services. 

Industries/Applications that Use Stainless Steel Mixing Tanks

Stainless Steel Mixing Tanks are a common sight dotting the landscape across the country. They are integral equipment among several industries that need dependable containers to store and transport substances. As mentioned earlier, stainless steel resists corrosion and extreme temperatures. It is also easy to clean and disinfect. These attributes make stainless steel ideal for a range of applications. Some of the industries that leverage stainless steel tanks to store valuable materials and substances include:

  • Dairy
  • Food and beverage
  • Pharmaceutical
  • Brewery 
  • Cosmetics manufacturing

At Highland Equipment, we apply a range of finishes to your stainless steel to guarantee optimal performance. Stainless steel is usually smooth and slightly reflective, but there are instances where its surfaces are brushed or bead blasted. The varying roughness calls for surface finishes to prevent moisture retention and material adhesion. Some of the stainless steel tank surface finishes that we apply include mill finish, mechanical finishes, electropolished, and more.

Highland Equipment Solutions

At Highland Equipment, we have the resources, capabilities, and tools to complete any of your stainless steel tank fabrication projects both in our workshop and in the field. As the industry leader in the design, fabrication, installation, and service of stainless steel process equipment, Highland Equipment is committed to providing exactly what you need, when you need it, and even where you need it. Contact us today to request a quote.

Considerations for the Custom Sales and Consultation Process

For nearly 50 years, Highland Equipment Inc. has provided stainless steel design and installation of sanitary process equipment for clients in a range of industries, including pharmaceutical, food and beverage, cannabis, cosmetics, brewing, and more. From complex pressure vessels to skidded systems and a variety of customized tanks and equipment, we approach each project with the personalized attention it requires and deserves. 

Every application is different, which is why they all require consideration of an array of factors when choosing your stainless steel grade, design, and more. When you request a quote for a custom solution, you should be specific about what you need. Here are the primary considerations:

An Overview of the Design Process

Our in-house engineering team collaborates with you on the stainless steel storage tank design that best suits your application. They work to meet ASME Section VIII Div. 1 Code and other industry standards while ensuring your design is both safe and cost-effective. In our years of experience, we’ve designed and constructed vessels of up to 18 feet in diameter and more than 65 feet in length.

The right design requires consideration not only of the size and shape you need, but how it fits in the space, how it can be accessed for maintenance and repair, and what environmental conditions it will face. You’ll need to choose a stainless steel grade based on machinability, corrosion resistance, and more. 

Grade Selection

Stainless steel is prized for its strength and durability, but different grades of steel offer different qualities. You’ll need to consider these factors:

  • Machinability: Stainless steel in general isn’t as machinable as some other metals, but grades Ugima 304 and Ugima 316 were developed to be more machinable without losing formability and corrosion resistance. 
  • Corrosion Resistance: Grades 303 and 416 offer enhanced machinability, but some corrosion resistance is lost. Grade 316 is a common choice for applications where corrosion resistance is of the utmost importance. 
  • Formability: Austenitic and ferritic stainless steels, like 304 or 430, are commonly chosen for their formability. Martensitic steels, on the other hand, are more brittle. 
  • Weldability: Stainless steel welders face challenges like intergranular corrosion, hot cracking, and stress corrosion cracking; austenitic grades 304L or 347 and ferritic grades 430 or 439 are typically the best options for successful welding. 

Corrosion Resistance

Stainless steel is an alloy of iron and at least 10.5% chromium. Its corrosion resistance comes from passivation: the metal is not responsive to oxidation because of the thin film of chromium oxides that forms at the surface. The passivation process includes exposing the stainless steel to the air, submerging it in a bath of nitric acid, removing contaminants, and neutralizing it in aqueous sodium hydroxide.

Different grades of stainless steel get their qualities from different amounts of chromium and additional materials, like nickel, manganese, or titanium. Molybdenum is often added for additional corrosion resistance, but that will make the stainless steel more brittle, requiring additional nickel to reduce that brittleness. 

Welding Considerations

Specific types of welds are used depending on the desired results. Orbital welding, for example, is an automated process that is highly precise and reliable. Fusion orbital welding, or automatic GTAW (Gas Tungsten Arc Welding), is an orbital welding process where the settings stay the same for the entire weld. Another option is wire feed orbital welding (or semi-automatic GTAW), commonly used for applications with thick wall pipes or materials that require fillers.

Some industries, such as food and beverage, dairy, brewing, medical, and others, require sanitary welding that meets stringent standards. These welds are inspected to ensure they are:

  • Smooth and impervious
  • Free of cracks and crevices
  • Nonporous and nonabsorbent
  • Non-contaminating
  • Inert
  • Corrosion-resistant
  • Durable and maintenance-free
  • Nontoxic
  • Cleanable

At Highland Equipment, we offer steel tank design and engineering, fabrication, installation, orbital welding, passivation, inspections, and more. With years of experience serving diverse industries, our team of professionals can help you with the many considerations required for your custom project. Contact us if you have any questions or request a quote today.

Aseptic Mixing Tanks: Applications & Considerations

Aseptic mixing tanks help keep contents consistently free from contaminants using either a nitrogen barrier or highly pressurized air to maintain a sterile environment. Highland Equipment provides aseptic tanks tailored to the specific needs of your application. In this blog post, we’ll review some of the primary industries that use aseptic tanks, as well as considerations for selecting an ideal solution.

Industries and Applications for Aseptic Mixing Tanks

Aseptic Mixing

A wide range of applications and industries use aseptic mixing tanks to keep contents sterile. The industries that regularly use these tanks include:

  • Pharmaceutical
  • Dairy
  • Food and beverage
  • Brewery
  • Cosmetics
  • Cannabis
  • Carton-based food products (broth, soup, alternative milks)

On a more specific note, aseptic mixing tanks are essential for mixing food-grade epoxy coatings and for blending vaccines.

What Is Aseptic Mixing?

Aseptic Mixing

Aseptic mixing entails blending disparate ingredients while protecting them from airborne pathogens, as well as the air itself. This process allows manufacturing companies in various verticals to remain compliant with any relevant standards and regulations while also increasing the shelf life of their products. Aseptic tanks facilitate sanitary mixing by closing contents off entirely from outside elements. Depending on the product, it’s also possible to install a tank with internal pressurization or vacuum capabilities to facilitate heating or cooling.

Aseptic tanks normally feature stainless steel construction and a vertical cylindrical shape. They also typically feature a conical or dished bottom and a cooling jacket fitting. With the right aseptic mixing tank installed, manufacturers can make sure their products remain safe to consume and resistant to the early spoilage caused by unexpected bacteria or contaminants.

Considerations for Aseptic Mixing

The versatility of aseptic tanks makes them quite versatile. In addition to safely storing certain products such as milk and other dairy products at proper temperature settings, aseptic tanks can also serve as surge tanks that work to neutralize pressure charges.

There are a couple of key benefits gained by implementing aseptic mixing tanks. These include:

Minimal Maintenance Requirements

Aseptic tanks require little effort when cleaning. Clean in Place (CIP) Steam in place (SIP) effectively cleans aseptic tanks, which helps ensure that workers don’t spend too much time on this task. The sterile nature of aseptic tanks further reduces the need to clean them. Mechanized and automated systems also minimize the need for general maintenance.

Easily Modified

Users can tailor aseptic tanks based on their changing needs. For instance, tank systems can easily connect with other tanks to create a single, larger aseptic tank system that accommodates business growth. Aseptic tanks are also available with various valves, toxicity measurement gauges, alarm systems, and ventilation systems, among other modifications. Installers may also fit tanks with bottom-mounted agitators for products that tend to separate when still.

Reliable Aseptic Tank Designs from Highland Equipment

If you’re in need of high-quality aseptic tanks, Highland Equipment can provide you with the right solution for your specific requirements. We offer end-to-end project management, including design and fabrication of your custom system, integration with your existing systems, installation, and ongoing support services. Our aseptic tanks feature an innovative mechanical sealed design and provide mixing, storing, and packing capabilities for a broad spectrum of industries and use cases.

To learn more about our stainless steel tanks, please visit our product page. For additional questions or concerns, please contact us today.

Electropolishing vs. Passivation of Stainless Steel

The aesthetics or physical properties of metal may often see improvement by the application of various finishing techniques. For example, in custom metal basket applications, applying an appropriate finish will impact the functionality of the basket as much as the base material does. 

Two of the most popular finishing methods used for stainless steel include electropolishing and passivation. At Highland Equipment, our customers often ask: Is electropolishing the same as passivation? While both finishing methods improve the material’s durability and resistances, there are distinct differences to consider when choosing between electropolishing vs. passivation.  


Electropolishing is a common finishing technique for the food and beverage, medical and dental, pharmaceutical, electrical, and semiconductor industries. The electropolishing process leaves a smooth, near-flawless finish. Manufacturers often use this method to impart non-stick qualities onto goods and components, making them easy to clean and ensuring process materials don’t stick to them during production.

The process uses a temperature-controlled chemical bath and an electric current to dissolve the metal’s outer surface layer. Electropolishing removes microscopic surface imperfections and eliminates discoloration from spot welds. It is a fast, cost-effective solution, even for parts with complex geometries.

Electropolishing is compatible with most stainless steels and a variety of other metals. Metal alloys that are good candidates for electropolishing include:

  • Stainless steel: 200-300 series, 400 series, precipitating hardening grade, and unusual
  • Nitinol
  • Titanium
  • Aluminum
  • Brass
  • Carbon steel
  • Copper
  • Nickel
  • Specialty alloys


Passivation is similar to electropolishing in that it uses a chemical bath to remove contaminants acquired during the manufacturing process. However, passivation uses an acidic solution that does not require an electrical current. Passivation won’t change the material’s aesthetic appearance, but it will improve the oxide layer that protects stainless steel. 

Passivation requires a thorough understanding of the type of alloy and how the chemical bath solution will interact with it. An inexperienced finisher using the wrong passivation solution could strip much more from the surface than intended and damage the workpiece beyond repair. 

The passivation process provides an excellent way to remove free iron and other contaminants from the surface of many stainless steel grades. Some stainless steel materials aren’t appropriate for this finishing method, however. When the steel has low chromium and nickel levels, or if the parts have been welded or brazed, passivation is typically not the appropriate finishing method.

Choosing the Right Finishing Process

Electropolishing vs Passivation

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When selecting stainless steel electropolishing vs. passivation, consider the following application-specific factors:


  • Offers an ideal solution for removing microscopic contaminants or imperfections
  • Strips the entire outer layer of metal
  • Will remove heat tinting and oxide scales
  • Suitable for parts with complex geometries


  • Does not require electrical current
  • Removes free iron and other surface contaminants
  • Won’t remove heat tinging or oxide scales but strengthens the oxide layer
  • Gentler than electropolishing

The choice comes down to the application for the stainless steel. For a flawless finish or to finish components with complex shapes and angles, electropolishing offers an ideal solution. Passivation is a less complicated and gentler technique used to remove surface contaminants and enhance corrosion resistance without peeling off the material’s outermost layer.

Working with Highland for Sanitary Stainless Steel Process Equipment

At Highland Equipment, we offer passivation as one of our many value-added services. Our staff can help you to determine if passivation is the right finishing method for your project. For more information about our passivation capabilities, please contact us today. 

Factory Acceptance Testing vs. Site Acceptance Testing

Both Factory Acceptance Testing (FAT) and Site Acceptance Testing (SAT) involve extensive testing of systems or system components to determine or verify compliance with the preapproved specifications. While there are similarities between the two, they are distinct processes. The following blog post outlines the key differences between FAT and SAT.

What Is a Factory Acceptance Test?

Passivation Methods to Preserve Stainless Steel Products

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Factory Acceptance Testing occurs at the vendor’s test facility before the completed equipment proceeds to the customer site. These tests verify whether the equipment meets all functionality and performance requirements as detailed by the User Requirements Specification (URS) document written by the manufacturer and executed by the customer or customer’s representative. They also provide vendors with an opportunity to identify issues and customers with an opportunity to make modification suggestions prior to shipment, both of which reduce the amount of time and money spent on resolutions and ensure the equipment is ready for use upon arrival. 

While FAT operations range from short and simple to comprehensive and complex, they are generally more rigorous than Site Acceptance Tests since vendors want to ensure the equipment fully complies with the terms of the contract. The tests conducted vary depending on equipment, customer, and vendor requirements. However, they generally cover the following: 

  • Inspection: Does the equipment conform to the final design and drawing specifications?
  • Contract Audit: Are all contractual obligations fulfilled?
  • Water Testing: Does the equipment operate as intended?

Some of the typical issues uncovered by factory acceptance testing include:

  • Quality or craftsmanship problems
  • Improper labeling and guarding
  • Insufficient throughput 
  • Lack of sanitary design 

What Is a Site Acceptance Test?

Site Acceptance Testing occurs at the customer’s test facility after the completed equipment is delivered to the customer site. These tests verify whether the equipment meets and/or exceeds the functionality and performance requirements written up by the customer themselves. They occur after all commissioning tasks for the equipment are completed but before installation. 

SAT operations typically involve running the equipment for one to two weeks to see if it performs as expected and if any major problems occur. If the equipment does not perform as expected or a problem arises, the vendor and customer must discuss how to resolve the situation. If the equipment does perform as expected and no problems follow, the customer can have peace of mind that the system does its job effectively and safely. 

Highland Equipment: Ensuring Equipment Quality With Comprehensive Testing/Inspection Procedures

At Highland Equipment, we do our part to assure our customers that our equipment does what it needs to do. Our team employs a variety of non-destructive testing (NDT) methods to carefully inspect our systems and verify they comply with the highest standards. To learn more about our testing and inspection capabilities, contact us today.


Passivation Methods to Preserve Stainless Steel Products

What is the Passivation of Stainless Steel?

Untreated stainless steel has a chemically reactive surface and can rust over time. However, the process of passivation — chemically washing the body of a stainless steel part — protects the surface and results in a longer-lasting item that better resists corrosion and rusting. Passivation removes free iron from stainless steel surfaces, which is highly advantageous for newly machined and manufactured parts. Some of the benefits of passivation include:

  • Resistance to the elements: The iron in stainless steel is the reactive component in the alloy. Chromium and nickel (the other metals in the alloy) are much less reactive to air, moisture, and water. Because the acid wash removes the surface iron, only the passive chromium and nickel oxide layer get exposed to air.
  • Reapplication: Stainless steel parts can undergo the passivation process multiple times without weakening or adverse reactions, allowing operators to deal with iron exposure from physical impact or damage. Regular passivation processes extend the lifespan of the item.
  • Reduced maintenance costs: Passivation reduces the risk of broken parts, contamination from rust, and unscheduled downtime.

The Passivation Process

Passivation is a three-step process that can happen immediately following fabrication and machining. 


  1. Technicians thoroughly clean the stainless steel part to remove grease, dirt, debris, and shavings. This step ensures that the acid wash reaches every inch of the surface to dissolve any unwanted free iron. It also reduces the risk of flash attacks—dark spots and deposits that stain the passivated surface.
  2. The parts are placed in a passivating bath of either nitric acid or citric acid. The components sit in the bath until all of the iron in the surface layers has dissolved.
  3. Testing verifies the removal of all iron from the surface, after which passivation is complete. Different grades of stainless steel may undergo slightly different testing methods. The most common test involves swabbing a test part with copper sulfate to see if plating copper develops.

Considerations for Tank Passivation

Passivation experts can carefully balance different factors to tailor the passivation process for each batch of stainless steel products. Some of the unique characteristics that can change between batches include:

  • The chemical composition of the passivation bath: The bath will use nitric or citric acid, depending on the stainless steel grade, the application specifications, and the environmental concerns of the company.
  • Submersion duration: Different parts need to be submerged in the acid for different lengths of time to ensure all iron gets dissolved.

These factors and others will play a role in the efficacy of the free iron removal process and the final surface quality, which affects the service life and aesthetic appeal of the final product. 

Choose Highland Equipment for High-Quality Stainless Steel Passivation

At Highland Equipment, we specialize in thorough passivation processes that result in high-quality, aesthetically pleasing stainless steel components. We offer a full suite of passivation surfaces to meet the finishing needs of numerous product types. Contact us or request a quote to see how our passivation services can support your project. 


Factors That Determine High Shear vs. Low Shear Mixing

Processing plants need rotating mixers that can handle different compositions and materials to meet a desired endpoint. When mixing impellers rotate in a batch, they generate shear, or stress, on the materials, to mix them together. The viscosity and other properties of liquids, as well as the presence of solids, determine the force needed to combine the materials. The amount of shear is dictated by the blade design and rotational speed. Mixers can use either high shear mixing or low shear mixing to incorporate the disparate materials into one mixture, depending on your needs.

High Shear Mixing

High Shear Mixing

Shear forces are caused by one force pushing part of a mixture while another force pushes a different part of the mixture in the opposite direction in a parallel field. The higher the shear force is, the better the materials can incorporate together, even mixtures with viscous liquids and solids. 

High shear mixers have a high-speed rotor that forces the mixture outward against a stator to generate shear. These mixers mix, rotate, and agitate the batch. One particular type of high shear mixing, called dispersion, uses high levels of horsepower to create even higher levels of shear. In addition to combining the mixture, high shear forces also ensure the materials are evenly distributed within the batch.

Low Shear Mixing

Low Shear Mixing

Low shear mixing is a gentler, less forceful mixing process. This process is ideal for miscible materials that don’t need a lot of energy or force to combine. It also can handle delicate materials—including adhesives, polymers, and structured food products—and materials with large particle sizes that shouldn’t be broken down during mixing. If the shear rate gets too high, the materials can start to suffer from shear degradation.

Low shear mixing processes feature a wide variety of different rotor blade designs, and they use the flow and turbulence in the tank to help incorporate the materials. 

Applications for High and Low Shear Mixing

Applications for High and Low Shear Mixing

High shear mixing and low shear mixing each meet the needs of different applications. High shear mixing equipment uses include:

  • Emulsifying and homogenizing liquid-liquid compounds
  • Dispersing powders into liquid compounds
  • Mixing liquid-liquid mixtures with materials that have different viscosity levels
  • Dispersing and suspending solids in liquids
  • Reducing particle sizes in mixtures

Low shear mixing processes are reserved for mixtures that need gentler handling or require less force to achieve the desired result. Popular applications include:

  • Combining miscible liquids and fluids
  • Flavoring
  • Increasing the efficiency of heating mixtures
  • Maintaining suspension of particles
  • Mixing liquid chemicals

Working With Highland: Leveraging Software to Optimize the Mix

The key to optimal low and high shear mixing isn’t just the hardware—it’s also the software. High-quality shear mixing software can model the different factors that impact sanitary mixing processes, including heat transfer, reactions, and turbulence.

Using this modeling, Fluent software can present a wide range of industrial functions, such as airflow over aircraft wings, semiconductor manufacturing, and more. New iterations of software are also user-friendly, in that they can easily be used by new and experienced operators. Users follow task-based workflow guides to speedily create simulation processes with accurate results based on different meshes, different blade radius and shape parameters, and more.

Fluent also uses a Mosaic meshing technology as part of its patent-pending high-speed system. This technology combines different boundary layer meshes to create a unique mesh. This ensures faster and more accurate flow resolution based on the models.

With this software, Highland can test different mixing scenarios and blade configurations to optimize the process and time requirements for every batch, design blades with the right radii and shapes to speed up mixing, create better consistency, and create customized equipment for each of our customers. 

Contact Us Today for High Shear and Low Shear Mixing Solutions

High shear and low shear mixing processes each play an important role in manufacturing. Different mixtures may need to be homogenized, while others need consistently suspended solids. High shear, or very forceful, mixing processes uses high-speed impellers, and low shear mixing processes use flow, turbulence, and rotational force to combined miscible goods. 

At Highland Equipment, we specialize in testing and designing high shear mixing and low shear mixing equipment. Every product is customized and thoroughly modeled to create the optimal shear mixing force for each of our customer’s needs. Request a quote today to get the customized mixing tools your facility needs.

How Do Companies Utilize Borescoping to QC Fabrications?

Borescopes are optical instruments that facilitate visual inspection of hard-to-reach spaces, such as the inside of narrow pipes or tubes. They consist of a lens or camera on one end, a flexible, semi-rigid, or rigid tube and/or fiber assembly, and a display on the other end. Industry professionals utilize them to inspect a wide range of industrial parts and products during manufacturing operations and maintenance and repair work. By detecting defects in components—e.g., cracks or leaks in welds—that need to be resolved, they help improve ROI and extend component life.

What Is a Borescope Inspection?

Borescopes are commonly used in non-destructive testing (NDT) operations involving components with hard-to-reach cavities. Some have lights on the lens end to enhance visibility within the component during inspection operations, while others (video borescopes) have a recording function that makes it easier to maintain comprehensive documentation of inspections. Regardless of the design and configuration, they serve the same function: helping technicians inspect component areas that are difficult or impossible to reach without damaging or dismantling the object. These instruments allow for fast and easy diagnosis of component issues, such as blockages, corrosion, cracking, erosion, or weak welds.

Borescope Inspection Procedure for Piping and Tubing

One of the most common applications for borescopes is the inspection of pipes/tubes and fittings. They are used to determine and/or verify the integrity of longitudinal weld joints in manufactured pipes and tubes and orbital weld joints in connected pipe and tube assemblies.

Common issues found in tube/pipe interiors include weld irregularities (which can lead to corrosion and buildup), gaps or light (which indicate an incomplete weld), and cracks or damage (which can cause malfunction). Catching these defects early on allows welders to rectify them before they cause more significant problems.

Once pipes and tubes are thoroughly inspected and approved for use, they are employed in a wide range of industrial applications and processes, including, but not limited to, the following:

  • Food Processing
  • Brewery and Beverage Systems
  • Aseptic Dairy Processes
  • Pharmaceutical Manufacturing
  • Any Piping System that is welded

Highland Equipment: How We Use Borescopes to Ensure Quality

At Highland Equipment, we are fully aware of the important role borescopes play in inspection operations. By utilizing these tools to inspect the hard-to-reach areas of our piping system fabrications, we ensure the quality of each weld and the integrity of the overall system. To learn more about how we use borescopes to ensure fabrication quality, contact us today.