Carbon steel embrittlement
Carbon steel embrittlement
(OP)
In Italy, last year the authorities applied a new law for embrittlement of steel due to low temperatures. In this law it is assumed that you must apply a safety system to avoid that the temperature in carbon steel equipment is lower than design temperature (i.e.: a temperature transmitter which controls a on/off valve).
In most cases, the design temperature for carbon steel is assumed -10°C (I think not mainly for real reasons, but as a "standard" value).
This would mean that if the gases coming from liquefation of criogenic liquids are passing trough these equipments after the vaporization during winter, the equipment would always be stoppped due to low temperatures.
What I'm asking is: what is approximately the minimum temperature I can reach with simple carbon steel, without having problems due to low temperatures?
Thank you
LB
In most cases, the design temperature for carbon steel is assumed -10°C (I think not mainly for real reasons, but as a "standard" value).
This would mean that if the gases coming from liquefation of criogenic liquids are passing trough these equipments after the vaporization during winter, the equipment would always be stoppped due to low temperatures.
What I'm asking is: what is approximately the minimum temperature I can reach with simple carbon steel, without having problems due to low temperatures?
Thank you
LB





RE: Carbon steel embrittlement
For plain carbon steel material, I have seen a typical value of 0 deg C, where you see a transition from ductile to brittle fracture behavior (50% flat fracture). This is a conservative value.
As the carbon content decreases and depending on the phosphorus and sulfur contents of the steel, the ductile to brittle transition temperature will shift to lower temperature with a more distinct transition behavior.
RE: Carbon steel embrittlement
RE: Carbon steel embrittlement
RE: Carbon steel embrittlement
RE: Carbon steel embrittlement
The EN Codes may be modestly different, but FIG. 323.2.2A of ASME B31.1 provides minimum design temperatures for variously manufactured carbon steels vs thickness where impact testing of the base material is not required. Similar curves are provided in ASME Section VIII, Div. 1.
Minimum design metal temperatures normally describe the minimum temperature of the steel at pressure and not the ambient atmospheric temperature.
RE: Carbon steel embrittlement
Have you any data for A312 type?
RE: Carbon steel embrittlement
RE: Carbon steel embrittlement
If they have these kind of laws around (or even the knowledge or technology) some years back, maybe Titanic wouldn't sink (lol).
RE: Carbon steel embrittlement