Since they hold inside them crucial elements of an industrial facility (ie. raw materials and products), storage tanks are industrial assets that are desired to be operational 24/7/365. However, as is the case for any piece of equipment, storage tanks will suffer wear and tear during usage. Depending on the product for which it is used and general operating conditions, the stress applied on a storage tank in operation may be moderate or high. To ensure their healthy and continuous operation of storage tanks, Maintenance Best Practices for Storage Tanks are always worth knowing.

Avoiding operational failure in storage tanks is especially important due to the risk in case of failure being great. If a tank failure occurs, tank contents may leak into the environment, causing severe environmental pollution. In addition to that, since most tanks are used for holding volatile and/or toxic compounds there are high OHS risks in case of a leakage. Lastly, a tank failure means tank will be decommissioned for a significant amount of time, meaning lost profits.

Luckily, inspection and maintenance techniques have come a long way; thus, the possibility of a catastrophic tank failure is minimized. However, maintenance itself continues to incur risks and costs on asset owners. Tanks are huge pieces of equipment with very large interiors. If maintenance is needed in the interior, the massive amount of product inside should be moved elsewhere.

Traditional inspection methods do not provide an opportunity to gauge whether or not tank maintenance is necessary, without taking the tank out-of-service. On the other hand, AIS Field’s current portfolio helps asset owners to know precisely whether or not and where maintenance is necessary. In addition, thanks to the developments in computational methods, we are able to help the customers in performing predictive maintenance. That way, asset owners can plan ahead their maintenance, without wasting their precious time and resources with unnecessary out-of-service inspections and maintenance.

The Importance of Regular Inspections

Inspections have a close relationship with maintenance. For storage tanks, NDT inspections are used to determine if, when and where maintenance is required. Without scanning of the structure via NDT, it would be almost impossible to properly and efficiently carry out inspections in such vast structures.

Regular inspections ensure long-term safe operation for industrial assets. NDT has no detrimental effect on structural integrity, it is rapid, low-cost and reliable. For storage tanks, inspections such as ultrasonic thickness and weld inspections are performed routinely, and are mandatory for asset owners, as per API 653. In-service UT inspections of tank walls are possible in some cases; on the other hand, tank floor inspection with traditional methods is not possible due to the impossibility of human operators to collect data under such conditions.

This means, conventional methods dictate that tank is taken out-of-service if bottom is to be inspected. This creates the problem of impossibility of separating inspection schedules from maintenance schedules and avoiding unnecessary downtimes.

AIS Field’s RUVI Oildiver solves this problem. In addition, AIS Field’s RUVI Wallker can climb interior or exterior tank walls for thorough UT inspection. This not only brings reduction of OHS risks but also brings significant cost reduction since with this method it is now possible to inspect tank walls without scaffolding. 

What is the Ideal Regular Cleaning and Maintenance Schedule?

As is explained thus far, ideal interval for cleaning and maintenance for an asset owner is actually to never do cleaning and maintenance, since these incur great costs. This desire clashes with the difficulty of making sure of asset integrity. For storage tanks, since traditional methods cannot ensure integrity of tank bottom without emptying tanks for inspection, maintenance schedules are the same as inspection schedules, since once the tank is opened, it makes sense to do maintenance as well. As a rule of thumb, Inspection-maintenance interval is around 10 years; however, it can also be altered due to various factors. However, if reliable in-service inspection is possible, the ideal time of maintenance is exactly when a structural defect is detected and no sooner. 

It is not yet possible to perform in-service maintenance on a tank interior. However, if presence or lack of structural defects can be detected in-service, the need for maintenance can be shown to be non-existent. In other words, best case scenario is to do in-service inspections and postpone maintenance if the structure is found in a good condition and only start in-service repairs when it is not.

AIS Field’s solution, RUVI Oildiver, is precisely aimed at doing just that. Since our robotic inspection makes possible in-service scanning of tank bottom floor, asset owners can ensure safety and compliance without putting their tanks out-of-service.

Tips for Optimal Storage Tank Maintenance

Since typically there is limited time allocated for tank maintenance, rendering the maintenance as efficient as possible is paramount. The key concept in efficiency is resource allocation. Thus, the resources necessary for maintenance (manpower, equipment etc.) should be allocated to where they are the most needed. To do that, prior planning is essential.

However, for a successful planning procedure, quality data is a must. Quality data on the other hand can only be obtained via quality inspection. If abundant and accurate inspection data is available, the planner will be able to allocate available maintenance resources to where they are the most needed. Without quality data, maintenance procedure may run into problems, can be more costly or take more time. Examples of the lack of quality data can be given as too few data points, low repeatability, low accuracy, lack of data from critical areas etc.

How AIS Field can Help You?

To reach maintenance best practices, Ais Field can help you with obtaining quality data. Main aim of AIS Field’s robotic solutions are to provide our customers with quality inspection data.

First of all, AIS Field robots reach hard-to-reach or dangerous places without any OHS risks, thus we are able to provide data from everywhere.

Secondly, AIS Field robots are able to carry out full mapping of your asset with tens of thousands of data points, a feat simply impossible for human operators.

Thirdly, robotic inspection has a much higher repeatability compared to human operators.

All things considered, not only does AIS Field robotic solutions help you in reaching regularity in inspections with minimal cost and health hazards, they also provide high quality data to make maintenance planning mush more efficient.