What is tank inspection: Everything you need to know

oil and gas storage tanks

Storing large quantities of anything is no easy task. Especially when what you are storing is toxic, explosive, or hazardous in any other way. Luckily, that’s what we have storage tanks for.

However, tanks need to be properly cared for and frequently inspected to ensure they do their job correctly.

We’ve created this article to help you take care of your containers and business. So, without further ado, let’s look at everything you need to know about tanks and tank inspections.

What is a storage tank?

Many companies use storage tanks for holding large quantities of goods and resources. Typically, they use them for various organic and non-organic liquids and vapors, which are not fit for open-air storage. As mentioned above, this can be because the goods or resources can be toxic, flammable, combustible, etc.

For example, some of the industries that use tanks are:

  • chemical
  • petrochemical
  • cosmetic
  • plastic
  • steel
  • refineries
  • power and energy
  • graphic and paper
  • food and beverage

There are many different kinds of storage tanks — each with unique build characteristics, intended uses, and necessary inspection requirements. Depending on their specifics, we can divide these storage vessels into different groups based on various factors.

The two common divisions are:

1. Altitude/Location-based

Depending on where we place a storage tank, it can be either above ground or underground. The main differences between the two are security and accessibility.
Underground tanks are safer from vandals but are harder to access, making underground tank inspections an issue. Meanwhile, above-ground tanks are the exact opposite — less secure but easier to access and inspect.

2. Atmospheric

Depending on their design and build, tanks can be atmospheric or pressurized. The difference is how much pressure they can withstand, which dictates what resources they can contain.
Atmospheric tanks can withstand 2.5 psi and are typically used for various oils (crude, heavy, gas, furnace), naphtha, gasoline, water, and certain gasses. Meanwhile, even low-pressure tanks can withstand up to 15 psi and are used for water, light crude oil, pentane, volatile chemicals, liquid oxygen, hydrogen, etc.
Specific examples of tanks:

  • fixed-roof tanks
  • external floating roof tanks
  • domed external roof tanks
  • internal floating roof tanks
  • horizontal tanks
  • variable vapor space tanks
  • LNG (liquefied natural gas tanks)
  • low-pressure tanks
  • medium pressure tanks
  • high-pressure tanks

Risks associated with storage tanks

Damaged or failing tanks can cause considerable damage. Leaks can pollute the surrounding environment, cause a fire or result in an explosion.

As a consequence, not only will your company suffer immense financial losses, but you could also be indirectly responsible for considerable environmental damages or loss of human life.

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Inspect your storage tanks with digital checklist

Download a free Preventive Maintenance template to inspect the condition of your storage tanks

The need for maintenance and inspections is clear. But before we explore those, we should discuss how tank leaks happen.

What causes storage tank leaks?

There are several things that can threaten the integrity of your storage tanks. However, according to USA’s Environment Protection Agency (EPA), corrosion is the most common cause of leaks and tank failures.

Corrosion happens over time, which makes it particularly dangerous for older tanks. Typically, it takes several years to cause real damage, but it could only take a few months, depending on the conditions.

The speed at which your tanks corrode depends on local weather and exposure to the elements, tank condition, and maintenance.

If too much metal rusts away, your tank can become unstable and shift or burst under pressure, resulting in a dangerous leak. This also applies to pipes and all other associated equipment, not just the storage unit itself.

The same thing can happen if you overfill your containers. Liquids change their volume in different temperatures, so if you don’t leave room for the necessary expansion, you could end up with a catastrophe.

How to prevent tank leaks

There are 3 steps to effective storage tank prevention. First, you should get your containers from reputable sources, which construct and assemble them in accordance with the necessary legal requirements.

For example, atmospheric tanks are subject to the American Petroleum Institute Storage Tank Division (abbr., API STD) 650 and its European equivalents. Meanwhile, low-pressure tanks are subject to API STD 620.

storage tank inspections explanation

Second, you need to create an inspection and testing plan (ITP). We’ll discuss the possible inspection approaches in the next section. Finally, you need to carry out regular maintenance and address any potential hazards as soon as you discover them.

The 3 approaches to storage tank inspections

Maintaining storage tanks requires a lot of effort. There are many aspects of the containers that can get damaged and cause issues. To find them and address them in time, you’ll need to create a complex ITP.

Meaning just one kind of inspection won’t be enough to guarantee your facility’s complete safety. The 3 types of inspections you should consider for your storage tanks are:

1. Risk-based Inspections (RBI)

Sometimes also known as a risk and reliability assessment. It prioritizes examining pipes, pressure vessels, and other high-risk parts of the storage tank system.

The process starts with risk analysis, where you assess the history of failures and defects of your storage tanks. You can do this, for example, even with an equipment maintenance checklist.

Based on that knowledge, you can create an inspection schedule to regularly check up on the components that malfunction most often.

2. Time-based Inspections (TBI)

TBI is the industry standard and legal requirement for most companies using storage tanks worldwide.

Instead of prioritizing the highest-risk components, with TBI, you try to find the right interval for inspecting your entire facility.

However, just as with RBI, you need to consider a variety of aspects to find the correct solution.

These include susceptibility to corrosion, exposure to chemicals, exposure to elements, the likelihood of accumulation of dust or dirt, risk of harmful vibration, etc.

3. Non-destructive Testing (NDT)

NDT is the only way to inspect the immediate state of storage tanks without draining their contents and disassembling them. It’s typically not required by law, but offers many benefits, like accident prevention and improving your storage’s reliability and quality.

NDT relies on a variety of high-tech techniques. These include Ultrasonic Thickness Testing, Phased Array Flaw Detection, Eddy Current Tube Testing, etc.

How to digitize tank inspections

As you can see, there is a lot to keep track of when it comes to creating an efficient ITP. Thankfully, there’s no need to do it all by hand anymore. Instead of wasting precious resources, including your time, staff, and finances writing everything down and creating towering stacks of paper, you can take your inspections digital.

In doing so, you can improve your operation’s safety and efficiency, save yourself the trouble of a potentially catastrophic malfunction, and spare Earth’s natural resources.

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Preventative Maintenance Checklist

Download a free Preventive Maintenance template to inspect the state of the equipment or machinery

On top of that, digital also offers numerous benefits beyond ecology. It’ll allow you to view all necessary information regarding your tank inspections in one place, give you access to real-time data and reports, etc.

With resco.Inspections, you can create new inspection forms, checklists, and reports on the fly and digitize old ones. Our form Designer not only gives you access to 100+ features, saves your time and money, but also saves the environment.

Learn how to improve the quality of your facility, your environment, and your own life by going paperless. Request a trial for resco.Inspections today!