By: Ron Kessler, Business Development RDVI North America
As seen in the July-August 2014 issue of Tank Storage Magazine.
Internal floating roofs (IFR) are utilized to control emissions of regulated material and require routine inspections as mandated by the Code of Federal Regulations 40 CFR 65.43. Tank owner/operators are to perform visual inspections for IFR Type A failures annually. These inspections are conducted from the manways and do not require tank entry. IFR Type A failures include:
Additionally, more intrusive inspections are required for IFR Type B failures at a minimum once every 10 years (and any time the vessel is emptied). IFR Type B failures include:
Historically, inspections for IFR Type B failures required a manned entry into the vessel. A confined space entry of this nature requires extensive planning and must be supported with product transfer, supplied air and an extensive lockout/tagout (LOTO) effort. However, a new solution utilizing remote digital video inspection (RDVI) techniques is now available for single seal tanks to alleviate the challenges associated with IFR Type B inspections.
RDVI (also referred to as remote visual inspection or
RVI) enables visual inspection of nearly every plant system and component
without confined space entry or costly disassembly. This inspection method utilizes
highly skilled and experienced technicians, deploying a wide array of video
borescopes, remote operated cameras, robotic crawlers, and specialized tooling
to deliver clear, concise visual data. All inspection activities are supported
with comprehensive detailed reports that include pertinent data points and
images to document asset health. The benefits of this inspection method are
threefold. Remote inspection of the seal minimizes operational and safety risks,
provides substantial cost savings and maximizes condition assessment/documentation.
Image 1: Illustration of an RDVI Camera Insertion into a Floating Roof Tank
Inspection of the seal for Type B failures has traditionally imposed a confined space entry which requires extensive planning and preparation. A manned entry of this type involves an inspector with supplied air, supported with a safety team for emergency egress to climb down onto the surface of the floating roof. Hazards from the inspection activity include slip/trip and falls, affixation and heat exhaustion. Tank preparation may include product transfer, tank isolation and an expansive LOTO procedure. RDVI can effectively eliminate the need for confined space entry for this inspection activity.
Of course, safety precautions must also be observed when utilizing RDVI technology. An experienced and knowledgeable inspection team working in aggregate with the asset owner will need to evaluate, control and monitor the inspection environment to safely mitigate hazards. Each inspection begins with a static tank and the strategic deployment of air movers to aerate the annulus space between the floating roof and fixed roof. A four gas meter is then deployed and used to continuously monitor the atmosphere for the duration of the inspection. Camera systems must be grounded, purged and pressurized with an inert gas before deployment. An additional four gas meter is attached to the camera system. Additional safety precautions such as disabling lights and limiting the insertion into the tank may also be utilized depending on the product, product level and site-specific safety procedures. The continuous monitoring of the camera’s internal pressure, flow of gas to the camera (if utilized) and tank atmospheric conditions allow for the safe execution of the inspection activities. In summary, while safety measures must be followed in any inspection setting, RDVI greatly reduces the safety and operational risk involved with this examination.
While costs vary with location, product, tank size and plant specifics, a comprehensive cost analysis often reveals that a manned entry into the vessel exceeds a half million dollars. Contributing factors include disruption to plant operations and efficiency, as well as labor associated with LOTO efforts and emergency rescue teams. Deploying remote operated cameras alleviates many of these costs.
RDVI technology is deployed with minimum impact to plant operations. While the tank should be idled for a proper inspection, product is not required to be transferred. The LOTO efforts are minimized as the inspection has moved from a confined space entry to a remote operated camera entry. Additionally, no emergency rescue teams are required to support the examination.
Condition assessment and documentation has always been subject to the individual inspector entering the tank and the limited tools at their disposal. Written reports often lack transcending and meaningful content, constrained by the nature of the medium. Utilizing remote operated cameras to examine floating roof tanks gives inspectors the ability to pause the inspection, increase/decrease light to better define the inspection surface, and zoom in to carefully analyze the seal from several angles.
RDVI technology also enables the entire inspection to be recorded via digital video and still images. Each image contains the time and date, as well as the pan and tilt degrees of the camera. Written reports contain and/or reference images and video enabling a more comprehensive record of the examination. The record can then be reviewed allowing for detailed training, project preparation and sharing with other sites or seal fabricators. This detailed documentation also enables inspection comparisons and inspection repeatability. Inspections become more consistent and more comprehensive as the process and procedure become more uniform to the application. In short, remote examination enables the inspector to record, review and repeat.
Image 2: IFR Inspection Image
High quality images are a critical component of remote visual inspection. Several key factors may contribute to achieving optimum results. Two general categories are discussed below:
1. Camera selection & qualification. Camera selection is based on the camera tip to target distance, physical attributes of the inspection surface, accept and reject criteria, and obstacles that may impede quality inspection results. Once the camera tip to target distance or range of distances is determined, a camera qualification should be conducted to verify the resolution capability of the camera at these distances. The goal of this exercise is to determine if the camera system and monitor are capable of revealing the minimum flaw size necessary for the examination. Once the camera parameters have been qualified, the field of view (FOV) should be noted to determine the surface area of the seal that one image will satisfactorily capture. While video will be taken throughout the inspection, images are often used to share specific examples of seal condition assessment.
2. Inspector/equipment operator. The conveniences of modern camera technology often mask the skill necessary to deliver a quality inspection. While auto focusing, point-and-shoot style cameras are the perfect addition to any smart phone, the same technology will often deliver less than stellar inspection performance. The inspection parameters previously discussed and the ever present environmental variables such as weather, lighting and inspection obstructions require advanced camera features such as manual focus, long exposure, IR filter and image stabilization. Experienced RDVI practitioners understand these variables and deploy every camera feature appropriately and proportionately to deliver quality inspection results.
RDVI enables visual inspection of nearly every plant system and component and is supported with comprehensive detailed reports that include pertinent data points and images to document asset health. The immense benefits of RDVI include reducing operational and safety risks, a substantial cost savings and improved condition assessment/documentation.
Working in tandem with industry personnel, Quest Integrity Group delivers a robust solution for the examination of IFR Type B failures utilizing its own RDVI™ technology. This minimally invasive visual inspection technique is safely deployed on single seal tanks, is cost effective and capable of providing enhanced inspection deliverables while avoiding confined space entry. Used in conjunction with other non-destructive testing methodologies to sustain reliability based inspection and/or maintenance programs, RDVI supports safe and efficient plant operations and increased uptime.