99 Diseases of Pressure Equipment: 885 Embrittlement

This is the name given to a form of embrittlement that occurs in 400 series of stainless steels, duplex SS's and less commonly in some 300 series stainless steels containing a metallurgical phase called ferrite. The embrittlement occurs from 600 F to 1000 F, but most readily at a temperature of 885 F, hence the name. Like graphitization above, 885 embrittlement is not something that can be easily detected or reported before failure. The embrittlement is usually not much of a problem at higher operating temperatures, but can result in cracking and failure of embrittled equipment during shut downs and start ups. As with graphitization, if 885 embrittlement is a possibility, then it usually can only be confirmed by physical testing involving bending or impact tests. Hardness tests may also give some indication of 885 embrittlement. Fortunately, this is a rather uncommon type of failure as it is well known by most materials folks and is avoided by the right type of materials selection for pressure equipment. However, some types of trays and other non- pressure containing hardware may be constructed of susceptible alloys and end up cracking during repair or maintenance activities. Do you have equipment operating with susceptible alloys in the susceptible 885 embrittlement temperature range?