Reed why do you not hear much about the use of stainless steel in boiler systems. Is it the cost or some other reason?

Dan

I should add:  All that 'stainless' means is that the alloy contains better than about 11% chromium.  'Stainless' covers a lot of ground.

You can go out  to the superalloys (that are used in the nuclear power industry-pressure vessels, heat exchangers) (Inconel,Hastelloy) but these are probably more properly considered nickel alloys, rather than just stainless. They stand in relation to stainless in about the same way that stainless does to carbon steel.

BobH

 SS is used extensively in the nuclear side of boilers. Every aspect of the primary coolant system is either 100% SS, or is clad with SS. But like Bob said, it is very expensive when compared to carbon steel. SO expensive, it is cheaper to run the carbon steel to failure and replace with a new one than to buy SS.

Dirk

Hey if this gives you any more help with your question besides the cost upfront you should also look at the life/ cycle cost where a cast iron will give you thirty years and  a stainless will give you ten years.

                                       steve 

I suppose I should try to jump on here now and then and answer some of these too.  

Stainless steel is just like Bob says, and subject to chloride corrosion and stress issues.   Typical simple stainless as everyone thinks of when it's mentioned is anything but simple.   There's many alloys out there and they have their strenghths and weakness. 

I have experience with 308/316/409 series, although there's many other types of it out there.  In the outdoor wood boiler manufacturing people started making them from mild steel, then stainless.  the 308 types had/have stress and cracking issues on the seams/welds as well as corrosion issues. 

The 316 is food grade and costs like it sounds.  409 type is made with titanium and is more ductile/durable as far as stress cracking and has some good corrosion resistance properties too.  If you look at the companies out there that are making their outdoor boilers and furnaces from stainless, most are using this 409 alloy. 

Welding stainless steel gives off some very nasty toxic gas, and must be well ventilated.