Replacing Radiant Heat Tubes?

Investing in replacement radiant tubes requires careful consideration. Maintenance managers are looking for consistent heat transfer, maximum efficiency and longevity.  Purchasing managers should be mindful of these needs while also considering the up-front investment.

But quite often, cost is not as black and white as it seems. There are many factors that affect efficiency and lifespan.  Radiant tubes can last anywhere from one to five years depending on the furnace and how it’s used.  When your company starts planning for radiant tube replacement, it’s smart to work together to identify what’s most important to your operation so you can make a smart purchase. 

Here are several items you should consider when replacing radiant tubes for your gas-fired heat-treating furnaces.

Consider why your radiant tubes fail

Although it’s difficult to inspect and monitor them once they are installed, there are a handful of issues that typically cause premature failure.

(1) Improper joint fusion: Joints in both cast and fabricated tubes can be improperly prepared resulting in premature failure of the tube.

(2) Constant thermal cycling: Continually cycling your furnace on and off is very destructive to the life of the tube. It’s best to turn your furnace on and leave it on as long as you can.

(3) Improper burner alignment and calibration: Proper burner installation and tuning is imperative to the longevity of your radiant tubes.

We have a full article on why radiant tubes fail prematurely that’s worth your time if you’re continually experiencing failures. You might need the input from a trusted vendor to understand why your radiant tubes are failing.

Don’t make the mistake of accepting your current lifespan without exploring these failure points. Also be aware that this discussion will likely lead to a conversation about design.

Consider how a re-design might extend the lifespan

If you pursue a re-design, you’ll be exploring several key elements. The biggest one is cast versus fabricated radiant tubes.

In a cast design, you are dealing with a specific metal type, poured into a cast mold which limits the ability to address failure points. Castings are inherently more brittle than fabricated tubes, so they are prone to breakages. Cast tubes are known to have a heavier wall, which results in less heat transfer during your manufacturing process.

Alternatively, you can opt for fabricated radiant tubes. They are lighter and have thinner walls which results in better heat transfer. They are also more ductile, so they are less likely to fracture at the joints. You can also target particular failure points based on your specific needs since different materials (alloys) and tube styles can be incorporated.

We have a full article comparing cast versus fabricated that goes into more detail that’s worth reading as well.

What about cost?

Remember that you get what you pay for. If you’ve been re-ordering the same style of radiant tube for years and accepted it’s lifespan, you might be throwing away your money.

Cast tubes might have a slight cost advantage, but the higher weight coupled with longer lead times makes cast tubes less appropriate in most applications.

Here are a few statistics you should know as you evaluate the up-front investment:

• Your historic replacement costs
• The typical lifespan of your radiant tubes
• The costs associated with furnace downtime

Alloy Engineering fabricates radiant tubes in any configuration and wall thickness and supports all furnace OEM tube designs. To learn more, contact us here or call us at 440.243.6800.