Hagani 786 TP 316 L will have good resistance at 100% concentration of hot chlorine at your temperature of 200 deg cent. If temperature drops or concentration gets lower (due to process condition variable changes), TP 316 L will be affected by pitting and SCC also . The fact that you are getting chlorine pH @ 1.5 indicates that some possibility of entry of moisture and hot vapor cholorine getting diluted to HCL exists ( i.e, hot chlorine either gets condensed and becomes dil HCL or with lower concentration of hot cholorine RP 316 L starts pitting). TP 316 L will pit and fail if temp drops or concentration of hot chlorine gets lower below 80% at your operating temperature or even at a lower operating temperature of around 80-100 deg cent. You may try to analyze the flaks and greenish color deposita also. Please check if the tube supplied is only TP 316 L or with additions of Cu etc as special grade materials. Trust this helps you to investtigate further C.V.Srinivasan Nishi Engineers Pvt Ltd India April 19, 2007 E-mail: nishi@vsnl.com >We have recycle gas cooler whose tubes are of A249-Tp316L >through which process gases flowes mostly of hot chlorine >vapour arround 200 deg centi and shell side cooling water to >cool the hot vapours of chlorine. The life period was >usually about 3 years but this time it failed within 18 >months. On inspection found water in green colour indicating >presence of chlorine with ph of 1.5 and also found some >flakes which were being done for xrd analysis. Please sugget >is it chlorine attack on the tubes which caused the failure >as liquid chlorine in lower concentration is more harmfull >than hot vapour chlorine or concentrated chloine? the tube >damage was found on inlet side (hot). Do I need to do any >further analyis? Please suggest.