Failure of Carbon steel pipes at high temperature

[sadanand091]

What type of failure occurs when the temperature of fluid though a carbon steel pipe goes up?
Say above 800 F or 400 C?

 

[rconner]

I have noticed the graph at

http://www.engineeringtoolbox.com/temperature-allowable-stresses-pipes-d_1338.html

- others could perhaps provide background/source etc (in partial answer to your question, failure of e.g. a boiler with steam at 800 deg C would certainly not be pretty and that is probably stretching the limits - all study to avoid that with regard to materials should be done!)

 

[MJCronin]

"Say above 400 F or 800 C?" ???????

What exactly is your question ?

Plain carbon steel piping can provide many. many years of service at 400F and very short service, ending with catastrophic failure at 800 C.

Most piping codes limit carbon steel usage to a maximum continuous service temperature of about 775F (~412C)

At 800C (1472F) a phenom known as graphitization quickly occurs.

This has been discussed many times on this forum in the past.....

http://www.structint.com/what-we-do...-services/engineering-services/graphitization

Some sage advice and cautions suggested here:

http://www.eng-tips.com/viewthread.cfm?qid=62030

MJCronin
Sr. Process Engineer

 

[Wascator]

Also be careful with engine exhaust through carbon steel pipe; if it gets too hot (i.e. someone comes along and insulates it) it can fail rapidly. Use stainless.

 

[sadanand091]

I am extremely sorry,
I messed up the units. Actually I meant 400 C (~800F).
@MJCronin,
Can you please explain why do "most piping codes limit carbon steel usage to a maximum continuous service temperature of about 775F (~412C)"?
What type of failure is observed at temperature higher than this?

 

[TGS4]

The failure mode for continuous service at that temperature is spherodization/graphitization. In essence, the carbon comes out of solution with the iron and forms graphite flakes or spheres. This greatly weakens the steel and will lead to rapid, catastrophic failure without much warning.