ABSTRACT

Remote visual testing (RVT) of large surface areas ( > 1 sq. meter) associated with vessel inspection requires a unique hardware approach compared to that of commercially-available borescopes, fiberscopes and videoborescopes. Faced with stricter OSHA regulations and the increased global competitiveness of today's market place, process facilities have looked toward a technical solution, including man-less entry into vessels, pressure vessels and tanks for their internal inspections. A unitized pan, tilt, light, color, zoom video inspection system was developed for use in confined-space, and hazardous-area locations associated with these components.

INTRODUCTION

Since the early 1970's commercially-available borescopes, fiberscopes and videoborescopes have been successfully applied to a very wide range of industrial inspection tasks including aircraft engines, nuclear steam generators, pharmaceutical tubing and border crossing contraband detection. As a virtual spin-off of the medical instrument market place, industrial RVT has adopted and modified medical probe technology for suitability in the fast growing commercial sector. However, in the technical transfer of medical hardware to the larger scale applications of petro-chemical process units such as pressure vessels, mixers, tanks and steam drums, it became apparent that a scaled-up approach was necessary. Additionally over the past several years, VT/RVT has been professionalized as an official NDT discipline by way of ASNT's TCIA Level-III testing and certification process and many industrial facilities are dramatically increasing the use of RVT.

BACKGROUND

Heavy industry including power generation, refineries, chemical and process plants have historically sent personnel into large pipes, tanks, pressure vessels and mixing vats whenever routine or emergency inspections were needed. With the recent addition of U.S. Department of Labor's OSHA regulation CFR 1910.119 Process Safety Management, inspection methodology, frequency and history must be documented by trained personnel. Figure 1 shows a typical Teflon-lined, pharmaceutical-grade vessel which is 8' dia. x 12' high with a 24" dia. man-way. Typical inspection includes verifying the integrity of plastic, stainless steel, refractory or glass linings, inspecting welded supports or assessing the condition of mixing blades, vanes and seals.

Figure 1: Typical Pharmaceutical-grade Teflon-lined Vessel

Numerous injuries and deaths have been documented over the years due to the hazards of heat, lack of oxygen, presence of toxic fumes and even failure of electro-mechanical systems such as gate valves. Additional OSHA regulations (CFR 1910.146) have made it illegal to send workers into confined spaces without significant safety systems in place including:

*
• SIGNS, WORK PERMIT, & WRITTEN PROCEDURE *
• SIGN-IN, SIGN-OUT BOOKS AT THE ENTRANCE *
• FIRST AID, CPR, CONFINED SPACE, RESCUE AND RESPIRATORY TRAINING *
• SAFETY WATCH *
• GFI POWER *
• RETRIEVAL RESCUE HARDWARE *
• AIR SAMPLING APPARATUS *
• CLEANING & PURGING OF THE VESSEL *
• BLANK OFF, LOCK-OUT, TAG-OUT OF THE VESSEL

Driven mainly by costs, many industrial facilities, through their safety departments, are following this letter-of-the-law and using human entry into confined space as a last resort for inspection work and especially those intermediate range applications (12" - 24" dia.) where human access is impractical. Unfortunately, early attempts to employ medical-offshoot technology for large area inspections were largely unsuccessful due to fundamental limitations associated with lighting, lensing and resolution in these small instruments.

By the late 1980's consumer preferences for smaller, lighter, higher-quality and lower-cost camcorders created a market demand that was filled by electronic giants such as SONY, MATSUSHITA, TOSHIBA and PHILLIPS. This multibillion dollar business drove the development of higher resolution CCD imagers, miniature lensing and a host of electronic image processing and storage techniques which became readily available at reasonable cost to the industrial NDT markets. The huge R&D investments justifiable in a consumer electronics market, which could never have been made in the industrial inspection sector, became a technical windfall. What was left to be done was packaging. The elements of a suitable industrial RVT device include:

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• ELECTRONIC IMAGER, such as a charge-coupled device (CCD) *
• LENSING, preferably variable focal length (Zoom) *
• LIGHTING, directional, focused white light *
• PACKAGING, waterproof, small size, light weight, corrosion resistant *
• MANIPULATION/POSITIONING - mounts, poles and remote control of viewing direction *
• CONTROL CABLE - power, control & video signals *
• USER INTERFACE - joystick operated, easy to use, video monitor *
• DATA STORAGE - video tape of PC-based frame grabber

The Figure 2 block diagram illustrates the design of a small (( 5.5") pan, tilt, light, color zoom CCTV inspection system which is scaled to inspect 8" - 30' dia. vessels.

zoom Figure 2 : Inspection System

Figure 3 is a 3-D rendering of the 5.5" dia. pan, tilt, zoom (PTZ) head showing the framing angles available which allow detailed, close-up inspection of a component although the camera is 10-15' away. The remote "PAN" feature allows the inspector to sweep left and right; "TILT" permits looking up and down.

24 : 1 ZOOM	12 : 1 ZOOM
zoom	zoom
FIGURE 3: 5.5" dia. PTZ Head

FIELD DEPLOYMENT

After several field deployments to test the camera's suitability in terms of sufficient resolution, magnification and lighting, it was determined that a proper positioning pole was needed to affix the camera's position at various locations in the vessel. Figure 4 shows a swivel-base tripod with 1" dia. carbon-reinforced plastic (CRP) support poles. The poles allow the PTZ camera head to be cantilevered into a vessel using a flange mount to secure the system.

zoom FIGURE 4: Vessel Deployment Tool

CONCLUSION

The 5.5" dia. pan, tilt, light, color, zoom video inspection camera system has been successfully used to inspect several hundred vessels to date. Users report savings between U.S. $5,000 - $50,000 per deployment by not having to shut down or send personnel into these vessels. Additionally, a faster, safer more thorough and documented inspection is achieved. The video images have been digitized and transmitted over the INTERNET to corporate engineering headquarters for analysis, archiving and trending. Further development work is being done so that the camera head can be deployed into CLASS I, DIVISION 1 hazardous locations as defined by the National Electric Code (NEC) and the National Fire Protection Association (NFPA).