High-Temperature Video Inspection

A Proactive Approach to Heat-Treat Equipment Maintenance

September 12, 2012
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The cost of maintenance, generally speaking, increases dramatically as the operating temperatures increase. Your maintenance dollars can be spent (and wasted) if careful thought and clear understanding of the equipment design and the extent of the repairs are not taken into consideration. The largest hurdle managers have had to overcome is their inability to actually see the working interior that they are trying to maintain. Problems and repairs generally cost more because they’re dealt with after they fail or reveal themselves from the outside. It comes as no surprise that trying to avoid expensive cost and time overruns is a huge challenge when new problems are discovered while making repairs.

 

HTVR (High-Temperature Video Robot)

CASKOL developed the HTVR for our patented video inspection service to provide maintenance managers with an interior view of their continuous furnace, oven or kiln. To perform these inspections, we developed a robot with the ability to drive through hostile, confined spaces while providing sharp, clear video of the interior. The robot can pass through tunnels hundreds of feet long that may only be 9 inches high and 30 inches wide while driving over gaps that can be up to 24 inches across. We also designed the robot to tolerate temperatures of up to 1000˚F, enabling us to quickly set up and perform a video inspection without shutting down the heating zone.

 

Why inspect the interior of your heat-treating equipment?

The heating chamber is designed with many components that have to endure the damaging stresses of heat to maintain a high degree of temperature accuracy and uniformity as the material is heated. It’s always a good idea to have an inspection program for your heat-treating equipment. If spotted early, weaknesses or deterioration can usually be treated easily and affordably (Fig. 1). If ignored, it can deteriorate further and cause premature equipment shutdown or, worse, catastrophic failure, which bypasses the crucial planning phase of production.

    Maintenance is even more challenging with roller-hearth-type heat-treating chambers (Fig. 2). These hostile, confined spaces are normally inaccessible, forcing you to guess about the condition of the working interior. For instance, the large modern furnaces for the heat treatment of metal inside of controlled atmospheres contain a large number of radiant tubes. The operation of such furnaces is complex because each radiant tube is an independent heating device with burner and combustion chamber, the last being the most highly heated element in the furnace. It is, therefore, subjected to the greatest wear and requires constant servicing. Damage and deformation of one radiant tube disturbs the even balance of heat and increases the stress on the other radiant tubes in that zone. A breached radiant tube can contaminate the surface of the parts with soot or discoloration. Therefore, it is very important that a defective radiant tube be discovered in time and the defect subsequently remedied. With video from the robot you can view the condition of the radiant tubes (Fig. 2) while identifying and locating any possible:

•   Blisters or holes

•   Cracks

•   Warping

•   Sagging

•   Soot


A neglected but integral part of the heating chamber is the refractory lining. The refractory lining is not viewable during normal operation, if at all, and until now not viewable in its entirety without extreme measures. For the first time, our inspection videos allow you to look for signs of lining deterioration such as cracks, spalls, loose sections, eroded areas, etc. (Fig. 3). With annual inspections, you’ll have a video record to monitor the refractory’s condition as it ages. Now the refractory can be viewed easily and completely, allowing you to inspect and identify:

•   Expansion and control joints

•   Corner treatments

•   Areas around doors, site ports, nozzles, hangers, etc.

•   Anchors

•   Discoloration

•   Heaving

•   Depletions

•   Cracking

 

Many types of heat-treating processes control the rate of cooling with attached cooling zones. There are many types of cooling chambers with a variety of methods to achieve their job. These cooling zones are subjected to the stresses of heat along with other forms of deterioration (e.g., rust) that should be monitored. The fact is, cooling zones are rarely inspected at all until something goes wrong. These long, dark and neglected tunnels tend to be accumulation points for debris that at times damage or interfere with the flow of material. With our video service you will be able to locate and inspect:

•   Water jackets

•   Cooling fans

•   Baffles

•   Conveyor belts or rolls

•   Skid plates

•   Water leaks

•   Cracks

•   Debris


Inspecting Used Equipment

If you should buy or inherit used heat-treating equipment, thorough and accurate inspections are essential to the successful planning and budgeting of the installation and start-up. With video from CASKOL’s HTVR you can completely inspect the interior condition of the heating and/or cooling zone. Interior inspections are a sure way to evaluate used equipment and to circumvent any changes that were made to the internal structure or design that may not show up on the prints or in the manuals (Fig. 4).
 

Knowledge is Key

It’s an understatement to say that “time is money” when referring to operating and maintaining heat-treat equipment. Many companies strive to schedule production 24/7 to avoid the time and energy costs associated with shutdowns and start-ups. Until now, maintenance managers have been forced to react to equipment failures or deterioration as it is discovered from the outside, sometimes with catastrophic results.

One method to inspect the interior of heating zones that is still used today is to have a worker lie on a piece of plywood that is on the conveyor. With flashlight in hand they ride the conveyor into the heating chamber and take a look around before they’re reversed back out. This method, sidestepping the many safety concerns associated with it, will have some limited success but only where the ceiling is high enough and the chamber cool enough for human access.

Imagine what you could see if the heating-zone temperature was 1000˚F instead of 100˚F. The HTVR’s unique ability to tolerate high temperatures makes that possible. We can quickly perform a complete inspection of the heating and cooling zone without the time and expense of shutting down the heating zone. Our qualified technicians can set up and usually complete an inspection in less than one hour, freeing you to return to production.

Knowledge is the key to maintaining your production and operating schedules while staying within your budget constraints. For the first time, managers have exactly what they need to take a proactive approach to maintaining their furnaces, ovens or kilns. The HTVR opens a window to the working interior, allowing you to accurately predict your maintenance needs by locating and identifying the problem areas before they cause a breakdown.

Using video inspections as a regular part of your maintenance program can extend your uptime and control your costs, ensuring the vitality of your heat-treating equipment. The cost of a video inspection from CASKOL’s patented service is cheap insurance against the cost of equipment breakdowns and helps to keep you in control of your maintenance budget. IH

   

For more information:  Contact Kirby Kolek, president, CASKOL, LLC, 1035 4th Street, N.E., Massillon, Ohio 44646; tel: 330-837-9216; e-mail: sales@caskol.com; web: www.caskol.com

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