Introduction
Industrial tank cleaning has long been a challenging and hazardous task. Using traditional methods based on manned confined space entry or CSE*, workers face numerous risks, from exposure to toxic chemicals to flammable and oxygen deficient atmospheres. However, with the advent of robotic tank cleaning, recently the oil industry has witnessed a significant improvement in risk mitigation and consequent safety performance. This innovative technology not only reduces the human element in hazardous environments but also enhances efficiency and precision of the cleaning process. In this article, we will explore the safety, health & environmental benefits of robotic tank cleaning.
Robots
In the context of cleaning the internals of atmospheric storage tanks, robots are available today that comply with the most rigorous ATEX Zone 0, Class1 Div1 electrical safety standards. These allow usage in storage tanks containing a wide range of raw materials and products. They are designed to effectively remove even viscous materials such as heavy fuel oil. They benefit from rapid set-up on site and require no modification to either tank wall or roof to provide entry points, utlilising standard 24”, 600mm manways. They can be fully submerged in oil, with cameras and lights on arms which rise above the liquid level where necessary. Controlled from a portable control room located outside the tank, the robots, or more accurately remotely operated vehicles (ROVs) are propelled via a variety of different designs of tracks, powered via hydraulic systems. Different track designs allow lined tank floors to be accommodated. The robots utilise low voltage cameras and lights to allow precise positioning within the tank, by the remote operator. They suck liquids and sludges via one of a range of suction heads connected via a 4” or 6” hose to a suction tanker outside the tank. Stubborn sludges are removed with the addition of gas oil cutting fluids, high pressure water which is separated from the original tank contents once they have been removed from the tank.
However, robots, like any piece of machinery can fail. It would be wrong to pretend that this can’t happen. When subject to arduous duties, components will wear and problems can develop. Whilst routine maintenance is designed to avoid this happening, the reality is that it can and does. This is frustrating, but all that happens is that the robot just stops working. The operator has time to evaluate the situation, fault find and recover the robot. In comparison, when a problem develops during a CSE, rescue from a poorly lit, large storage tank, 1m deep in sludge when the injured party is 30m from a 600mm exit hatch and can’t potentially help themselves to escape, is a whole different story. The consequences of a problem are worlds apart.
Minimising human exposure – A step change in risk reduction for an operating organisation
One of the most immediate advantages of employing robotic tank cleaning systems is the significant reduction in human exposure to hazardous environments. Traditional tank cleaning methods often require workers to enter confined spaces, exposing them to potentially harmful chemicals, fumes and oxygen-deficient atmospheres. Robotic systems, on the other hand, can navigate such environments with ease, ensuring that human workers remain at a safe distance, isolated from the hazard. Adopting a manless tank cleaning philosophy, can represent a step change in risk reduction for an operating organisation.
Eliminating Confined Space Entry Risks
Confined space entry involves working in spaces with limited access and egress and these spaces are often poorly ventilated and contain harmful substances. Robotic tank cleaning removes much of the need for workers to physically enter these spaces, thus mitigating the associated risks of accidents, injuries, and exposure to toxic substances.
Conventional confined space entry, if it is to be carried out safely, relies heavily on the use of personal protective equipment (PPE). Operators of high hazard plants are all too aware of the difficulties of ensuring full compliance with PPE requirements – PPE may not be worn as the manufacturer intended, it may be of the wrong specification or it may have become defective during use. Breathing apparatus is hot and uncomfortable and rapidly leads to fatigue. Its safe usage requires constant and vigilant monitoring by trained personnel.
Operating procedures are also a cornerstone of traditional approaches to CSE tank cleaning. Ensuring that all the working parts of a complex procedure come together in a timely manner is a challenging task. Such procedures often consist of 50-60 pages of close-written corporate memory regarding ways to avoid incidents that have happened previously on that site, in that company or within the industry. They rely on the effective coordination of the inputs of multiple different personnel from both the operating and contracting companies, together with thorough training and effective communication. Operators regularly learn that their Permit to Work procedures can and do fail in myriad different ways, across the full range of tasks routinely carried out in refineries and terminals. During a confined space entry, sadly, such failures of Permit Procedures rarely have minor consequences. Robotic technology obviates the need for such processes as part of the removal of sludge from tanks.
Process Safety
Incidents occurring during confined space entries may be classified as ‘Process Safety’ events, characterised as they are by the fact that the hazards are present largely because of the nature of solids and fluids being handled and importantly, by their low frequency, high consequence nature. Because such events, thankfully, only occur infrequently, it can be difficult for operating companies to assess how effectively their systems mitigate such risks. As a result, it can be a surprise to management when an incident occurs, as patterns in the company statistics or KPIs regarding CSE incidents may not have been detected.
It may be that instead of managers asking, “Do we see incidents related to CSE entries?”, to which the answer may well be “Not in the recent past”, instead companies should be asking, “Do we see problems with either PPE compliance or permit procedures?” For most operating sites, the answer to the latter would be will be, “Yes”. They might then go on to ask, “If that is the case and such relatively frequent problems were to arise in the context of a CSE, would the results be considerably more hazardous?” To that question, the answer would also likely be, “Yes”. Such a discussion might prompt an evaluation of the viability of the traditional approach.
The conclusion might be that a site with an operating history without any confined space incidents for 10 years could well be working on ‘borrowed time’ and not be aware of it.
Reducing Occupational Hazards
Traditional tank cleaning methods often involve physical exertion and repetitive activities, leading to potential musculoskeletal injuries. Robotic systems eliminate this occupational hazard, as they are designed to carry out tasks with precision and consistency, without the risk of physical strain or fatigue.
Robots aren’t susceptible to the weaknesses of pre-existing medical conditions, ill-health, twisted joints, pulled muscles or fatigue. Health monitoring regimes can be reduced as exposure of workers to toxic materials is decreased and longer term liabilities of employers are therefore also reduced. A typical 50m, 165’ dia. crude oil tank might involve up to 5,000 man hours of exposure to CSE hazards when carried out in the traditional fashion. This can be avoided by use of robotic technology.
Minimising Environmental Impact
Robotic tank cleaning systems are also designed to minimise environmental impact. They utilize less water and cutter stock than other processes, such as water jetting or the employment of water cannons, thereby reducing the burden on waste treatment systems. This both facilitates compliance with environmental regulations and leads to reduced waste declarations and hence improved sustainability performance. This not only contributes to a safer work environment but also supports achievement of sustainability targets.
Enhancing Precision and Efficiency
Robotic tank cleaning systems are equipped with advanced sensors and imaging technologies that allow them to precisely navigate and clean tanks. Modern robotic technology utilizes a range of different suction heads, designed to reach under, over and round internal heating coils, roof drains, and other internal tank furniture. This facilitates access to challenging areas and ensures a thorough cleaning process. This level of precision not only results in a higher quality of cleaning but also reduces the likelihood of contaminants being left behind, which could lead to potential safety hazards in the future.
Conclusion
Robotic tank cleaning has emerged as a game-changer in industrial cleaning processes, revolutionizing safety standards in hazardous environments. By reducing human exposure to risks, reducing the need for confined space entry, and enhancing cleaning precision and efficiency, this technology not only protects workers but also improves the quality and sustainability of industrial operations. As industries continue to adopt and advance these technologies, we can expect even greater strides in safety and efficiency in the years to come.