What Is an Internal Inspection?

Internal inspection refers to an examination of the interior of an asset. 

Internal inspection is part of an inspector's work, along with external inspection, in order to ensure that the entirety of an asset is inspected.

An internal inspection may also be called an interior inspection or an inner inspection.

These inspections are used to determine the condition of the inside of the asset and to identify any defects that may require further testing or maintenance.

Historically, internal visual inspections have been conducted in person, by having an inspector enter the confined space inside an asset like a boiler or tank. But over the last several years sophisticated robotics solutions like Flyability’s indoor drones have allowed inspectors to stay safely outside the asset, instead sending the robot into it to collect visual inspection data.


Inspectors typically do an internal visual inspection to help keep assets in good working order.

They may also use other non-destructive testing (NDT) methods to collect data during interior inspections, depending on the specific requirements of the inspection they're conducting.

[Internal inspections are just one area in which inspectors use non-destructive (NDT) testing methods. Learn more about NDT and the other scenarios in which it is performed in this guide.] 

Ways To Conduct An Interior Inspection

Interior inspections are typically conducted by using:

  • Using scaffolding

  • Rope access

  • Remote Visual Inspection (RVI) tools

For all three of these approaches, the goal is for the inspector to get the data they need to determine the condition of the asset. It’s important to note that each of these approaches has its own value and use, and that they may be combined to help inspectors collect all the data they need.

With scaffolding and rope access, inspectors will be collecting that data in person. 

 If they’re conducting a visual inspection, they’ll visually review the interior of the asset they’re inspecting by standing on scaffolding or working on ropes. 

On the other hand, if they’re collecting visual data remotely using a drone or some other robotics solution, the inspector will usually be standing outside the asset.


Scaffolding is built as a temporary structure for inspectors to climb onto and conduct internal inspections. 


This approach to internal inspections is by far the most costly way to perform an internal inspection. Building scaffolding and taking it back down while an asset is out of commission is incredibly time consuming, and that time translates into prolonged downtimes, which are one of the most expensive aspects of most inspections.

Traditionally, scaffolding has been the go-to method used by inspectors for internal inspections. However, given the high costs associated with scaffolding, companies have been turning to other methods to conduct internal visual inspections.

Learn more about scaffolding and all its uses in our in-depth guide.

Internal Rope Access 

Internal rope access is a method used for at-height inspections and for inspections in confined, hard-to-reach places.


Certified rope access technicians will use a system of safety hardware and ropes to conduct internal inspections inside large industrial assets like pressure vessels, boilers, and stacks.

Internal rope access allows inspectors to get an up close look at defects and also enables them to conduct light maintenance work on ropes.

This internal inspection method is less expensive than using scaffolding, but it’s imperative to use experienced rope access technicians who are certified.

Learn more about rope access in our in-depth guide.

Remote Visual Inspection Tools

Using remote visual inspection (RVI) tools, like drones, can save companies money and is fast becoming a preferred method for confined space entry.

internal-inspection-flyability-5The Elios 3 performing an inspection at a water department

Drones like Flyability’s Elios 3 and other RVI robots can also be sent into confined spaces—which pose serious risks for human-entry—to collect data. 

Because RVI tools eliminate the need to build and take down scaffolding, days or even weeks of  downtime can be saved, resulting in significant savings for companies. Another benefit to using a drone or robot for remote visual data collection is that they can reduce insurance premiums, since companies can avoid sending people into dangerous confined spaces.

Learn more about inspection tools in our in-depth guide.

Three Questions Inspectors Must Answer When Conducting Internal Inspections

Inspectors use common NDT methods to answer the following three questions when conducting internal inspections:

1. Are there any defect(s) in the asset?

An inspector will first perform an internal inspection of an asset to determine if there are any defects in the asset. Inspectors will document these defects and to keep a detailed historical record of the condition of the asset.

2. Where are the defect(s) located?

Without the right equipment, this question can often be the hardest to answer when using RVI tools for an internal inspection. Because advanced indoor positioning systems, like GPS, don’t function in densely situated indoor spaces, like mines and sewers, it can be hard for inspectors to identify the location of a defect seen in footage collected remotely.

Furthermore, defects found inside assets that have uniform surfaces, like chimneys or tanks, are difficult for inspectors to locate because there are no reference points for inspectors to use to pinpoint the location of a defect. 

In order to locate defects in their visual data, inspectors sometimes use the following data points:

  • Barometric measurements

  • Blueprints

  • Calculating the speed of an RVI

  • Maps

  • Reference points from the video footage

Inspectors are also using new software to help them pinpoint the location of defects. Flyability’s Inspector 3.0 software—software made just for use with Flyability’s drones—provides inspectors with a sparse point cloud that shows them exactly where defects are located. This information can then be shared with other stakeholders in the inspection process, like maintenance managers or site administrators.

3. What are the dimensions of the defect(s)?

Locating defects is important, but knowing the dimensions of a defect will inform maintenance crews on next steps, helping them decide whether the defect should be inspected further, monitored, or fixed.

Industries & Assets That Require Internal Inspections

Internal inspections are crucial for industrial assets, since even small defects can eventually lead to catastrophic events that threaten employees’ safety if they go undetected and unaddressed.

Here are the industries in which inspectors conduct internal inspections:

  • Aerospace

  • Agriculture

  • Chemicals

  • Construction

  • Manufacturing

  • Maritime

  • Mining

  • Oil & Gas

  • Pipeline

  • Power & Utilities

  • Public Safety

And here are the most common types of assets that require internal inspections:

  • Boilers

  • Cokes

  • Grain bins

  • Mines

  • Pressure vessels

  • Pipelines

  • Sewers

  • Stacks

  • Tanks

  • Wind turbines

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