Chemicals, corrosives, oil, and other potentially dangerous materials—These are some of the common materials stored and transported via storage tanks. And, like any sort of tank that's designed to store and transport materials or waste, it needs to be routinely cleaned out to ensure the health of the tank itself as well as the surrounding environment. Tank cleaning has the potential to be very dangerous. The nature of tank cleaning involves working in confined spaces combined with the contaminants that remain inside the tank that can increase the risk of fire, explosion, chemical exposure, and more.

In this post, we'll dig into why it's important to clean storage tanks and how workers can stay safe while doing so. Here's a closer look at what you need to know about tank cleaning procedures. But first, an overview of tanks and what they're used for:

What are Tanks Used for?

Simply put, storage tanks are used to store and haul hazardous waste. With capacity ranging from 2,000 gallons to 30,000 gallons, it's not uncommon to see these tanks being pulled by trucks on highways throughout America as they travel to their final destination. While it can be routine to see these tanker trucks on the roads, what's inside the tanks is anything but routine. When storage tanks are used routinely to store and transport waste, they must be cleaned regularly to ensure they remain in good enough condition to continue safely carrying hazardous materials and chemicals.

Why do Tanks Need to be Cleaned?

Tanks need to be routinely cleaned out to avoid wear and tear of the tank itself. Like any kind of tank or container, sludge has the potential to build up on the bottom of the tank over time, causing corrosion and the potential for leakage. It can also lead to oxidation, which can limit the overall storage capacity of the tank itself. The bottom line is that an unkempt tank can lead to safety risks for not just the environment, but for your workers too.

When do Tanks Need to be Cleaned?

This is a difficult question to answer based on the various situations that may require tank cleaning. For instance, tanks should always be cleaned before any material changeovers take place to ensure that any previous materials that are being stored don't contaminate any new materials being stored. Another point to consider is if a tank was previously carrying a highly reactive or corrosive material, it should be cleaned before new materials are added to avoid a possible reaction between the differing substances (explosion, toxic gas release, fire, etc.).

Additionally, to maintain productivity and efficiency, plant managers often carry out tank cleanings during planned shutdowns or schedule routine maintenance repair periods to perform such work. The size of the tank and what material the tank was holding will dictate how long it takes to thoroughly and safely clean.

How Storage Tanks are Typically Cleaned

Tanks are typically cleaned using pressure washers. The pressurized nature of the water helps remove any contaminant buildup from the tank walls to make the tank is as clean as possible.

Safety Hazards and Tank Cleaning

Why are storage tanks so dangerous to clean? Aside from their role in holding hazardous waste and materials, a danger in and of itself, there are a few other reasons why there's risk when carrying out this task.

For starters, there's usually only one point of entry to storage tanks - and workers need to enter the tank itself in order to properly clean it. This also leads to poor ventilation—without proper ventilation or an oxygen supply, gases in a confined spaces are not “diluted” by oxygen or released from the tank, meaning there are higher concentrations of these contaminants in the air. When you couple these limited openings with the fact that storage tanks are not designed for human occupancy, it's easy to understand why tanks are considered a "confined space." Any worker that has an issue working in tight spaces or is claustrophobic may not be the best person to carry out this type of work.

Then, there's the hazardous waste and other materials that these tanks are designed to store and transport, which can produce toxic vapors and gas releases and have the potential to cause explosions, lead to radiation exposure, and present other physical threats.

The bottom line is that only trained professionals should attempt to clean a storage tank used to hold hazardous waste. Professionals need to be properly certified and follow OSHA tank cleaning procedures for locking out and tagging out the tanks each day. There are also various other procedures and best practices that they need to follow, which the untrained and uncertified worker may not be aware of. Additionally, workers need to be aware of how to properly dispose of any waste and contaminants following tank cleaning to not harm the environment and stay in line with any regulations regarding hazardous waste disposal.

In the next section, we'll get into why wearing the right PPE is also essential for keeping workers safe.

Minimize Tank Cleaning Hazards with the Right PPE

Ensuring workers are properly trained and certified to perform tank cleaning is one thing. Keeping them protected with the right PPE is just as important. Here's a look at the recommended OSHA tank cleaning PPE:

  • Hardhat: This is used to keep workers safe from any overhead hazards.
  • Eye protection: OSHA suggests that workers wear both eye protection and side shields to properly protect their eyes from any potential hazards.
  • Gloves: Heavy-duty leather gloves are recommended, as workers may come into contact with objects or debris featuring sharp edges. Workers may also come into contact with chemicals.
  • Boots: Any footwear should be ANSI-approved to ensure proper protection.
  • Respiratory protection: Like we noted in the above section, a few of the factors that make tanks so hazardous to clean are their confined space nature and the risk of contaminants in higher concentrations. And these contaminants aren't to be inhaled. That's why respiratory protection is so important. Depending on the contaminants inside, N, R or P95 filters should be inserted into respirators. It's also important that any respirators that are worn fit the worker properly by undergoing respirator fit testing.
  • Harness and retrieval lines: When cleaning certain tanks, workers must be harnessed with retrieval lines attached to them to ensure that they're properly accounted for and can make a swift exit in the event that something goes wrong.
  • Full body suits: If there's a risk of contaminant exposure to the skin, full body suits might be considered within the tank environment. These disposable body suits cover the skin and the entire worker's body, thereby preventing it from coming into contact with any potential contaminants such as chemicals or biohazards.

It's important to note that the aforementioned PPE includes just the basics. Depending on the material that the storage tank was holding, additional PPE or procedures may be required to mitigate risk and further protect workers. For example, tanks don't exactly have overhead lighting inside of them to make it easy to see and carry out cleaning. Movement may also be restricted, and it may even be difficult to communicate within the tank if everyone is wearing a respirator. For these reasons, additional PPE and safety measures, such as checking hazardous gas concentration levels before entering the tank, may be required.

General Safety Tips for Tank Cleaning

PPE is important for keeping workers safe while tank cleaning, but there are various other best practices to follow as well. Here's a closer look at other measures to take to minimize risk when performing tank cleaning:

  • Safety first: Before any tank cleaning takes place, a plan should be created and reviewed by all participating personnel. This plan should include more than just tank cleaning procedures, but it should also assess any potential risks. For instance, it should account for any valves that need to be turned off. This plan should also include all and any necessary permits required to carry out tank cleaning. Planning and coordination are key to a successful outcome.
  • Prepare for the worst: It's never fun to think of the worst-case scenario, but it's better to prepare for the worst than to be caught off-guard and have a crisis on your hands. A confined space rescue team should be on standby, and workers should know where to go to retrieve emergency medical kits in the case of the unthinkable happening.
  • Ensure only trained professionals are performing tank cleaning: It's worth reiterating - only trained professionals should be carrying out tank cleaning. These professionals need to be properly certified and know how to carry out work in confined spaces. Tank cleaning isn't a job that just anyone can do - it takes the right person to do it.

As you can see, there's considerable risk involved in tank cleaning - even for a trained professional. That's why it's crucial to eliminate as much risk as possible. Outfitting your professionals with the right PPE and can help prevent both short- and long-term illnesses, or worse.

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