304 Stainless Steel vs. Nichrome Heating Coils

[ultrasound34]

Hi,

I am looking for a pros and cons for choosing one material over another in an electric resistance heating coil application.

The two choices are: 304 Stainless Steel or Nichrome.

The client is looking at stainless steel because of perceived corrosion resistance. However, all of our experience is in using nichrome elements. They've worked well for decades and decades, and the chromium oxide provides corrosion resistance.

The Nichrome elements are less expensive, but the client has directed us to evaluate stainless steel heating coils as well. What other pros and cons should we consider?

Thank you!

 

[Compositepro]

The key question is how hot the coils will get. If red-hot then 304 can't compare to Nichrome. At a few hundred degrees 304 could work, but I don't know if there is any advantage.

 

[EdStainless]

If they are at steady temp then 304 will do OK.
If they cycle then the oxide will spall and Nichrome will be much better.

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Plymouth Tube

 

[metengr]

Nichrome is the far better selection for this type of application.

 

[ultrasound34]

Thank you for your replies.

Yes, the coils will be cycling. As a matter of fact, they could reach temperatures of 300-600° (multiple stages), then be exposed to 60° air.

We always use Nichrome, and do not have any experience with stainless heating coils. So thanks for the info!

 

[arunmrao]

Have you considered using Kanthal material (Fe Cr Al alloy). This will be cheaper option to Nichrome ,disadvantage is that it becomes brttle upon heating. It has no resale value as scrap,while Nichrome fetches good value based on Ni price.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[ultrasound34]

Uh, no, becoming brittle upon heating seems like a major disadvantage for a heating coil. Thanks!

 

[mcguire]

330 could be a reasonable candidate. That's its main use.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[arunmrao]

ultrasound,the elements last long and are economical. However,if the coil gets cut in use,it is difficult to repair. Also,you may need to look at the power density of the heating element.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[ultrasound34]

SO it sounds like Nichrome is the best choice? Especially since the heating element will be heated up to 600°F then subsequently exposed to cool (60°F) air?

Thank you everyone.

 

[EdStainless]

If the coils never actually get above 600F then a Fe-Cr alloy would work fine, no need for Ni in it.
At this temp Kanthal and similar grades would not get brittle.
And they cost a heck of a lot less.

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Plymouth Tube