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.

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