Stainless stove pipe discolored

[kingfisher]

my outside pipe is discolored up near the cap and it kind of looks like rainbow colors. Is this normal, I have only been burning for about 3 weeks.

 

[crazy_dan]

mine does that too every year mine has not stayed that way but it does get the rainbow effect every year.

 

[oilstinks]

my stainless cap is discolored also.

 

[theheatelement]

that is just the heat discolloring the steel... perfectly normal. Your cap should be 304 which is non magnetic.. if it's not it's most likely inferior SS... just take a magnet and check it, doesn't matter how big the magnet is you'll be able to tell..

 

[727sunset]

I just finished a new installation and noticed the same discoloration near the top of my chimney after the first use, although it was NOT overfired. After checking the chimney outside wall temp with an IR temp reader it was not hot at all. Windex took of the discolouration with ease. Hope this helps.

 

[727sunset]

Well I've had a few fires since cleaning the chimney exterior and the bluish (heat) discolouration has not returned. Right now I'm left wondering if the cause was some manufacturing residue either in the chimney or stove that was burnt during the initail firing.

 

[Corey]

I don't think the blue discoloration near the top of the flue is heat...at least it shouldn't be - flue shouldn't be that hot up there. More likely it's a very thin film of smoke / organic material - possibly even oil from the manufacturing process - giving an 'iridescent' look - like a soap bubble film or a drop of oil in a water puddle. The fact you mentioned it cleaned off with windex further supports this. Actual 'tempering' colors are a change in the surface of the steel - only removable by sanding or otherwise mechanically removing the discolored steel and blue/purple color won't kick in until ~ 550-600ºF

Your IR gun readings are only valid if you are up on the roof with the probe near the pipe and you properly correct for the emissivity of the polished stainless pipe vs flat black paint which is what most guns are calibrated to.

 

[Fsappo]

Normal for stainless from my experience.