Krish Choosing a better metallurgy from erosion-corrosion of the spray nozzle is one option. Before that, it is advisable to consider possible mal-distribution of fluid cum vapor flow in the distributor to have severe erosion. Possibly you may have to examine if there is increase in velocity of fluid flow (both mixed vapor cum fluid flow) in the distributor and the design velocity distribution for incoming and outgoing pipes to know if by chance the distributor design is having problem. Or is there a possibility of mixed vapor-liquid stream in the system? You can examine from this angle. If fluid flow is as per suggested design parameters of velocity control, then you can examine to consider a deflector type arrangement (if such arrangement is possible to be fitted) to reduce direct impact of fluid velocity flow. Usually a diverter or deflector arrangement for fluid flow helps in such systems (if there is space in the FCCU). A deflector prevents direct entrainment of high velocity fluid or vapor stream in the distributor pipe. After examining these carefully, then only you can think of better metallurgy which can take higher erosion-corrosion for the same design flow patterns in the distributor. Hope this helps C.V.Srinivasan Nishi Engineers pvt ltd India Dec 09, 2007 E-mail: nishi@vsnl.com >We have faced severe erosion in the FCCU feed optimix >distributor(spray type)nozzle pipe made up of Alloy-6(Co >alloy).Is there any better metallurgy is available to avoid >erosion?What are the possible way to prevent erosion in the >distributor. > >regards,

with regards to Mr. srinivasan, alloy 6 is a proven MOC w.r.t. erosion resistant provided it meets the essential chemistry and properties. The following can be done on opportunity basis or from DCS if there exists any check line 1. To check steam and oil port nozzle ejection fouling or any change in orifice for differential atomisation distribution 2. Whether the erosion in final outlet distributor alloy 6 nozz pipe is general or local or linear or areal. This can give up an idea about erosion background tarcking. 3. Pl. track back whether if there was any past history of any local repair/ buid-up case in the same . 4. To check for any fouling / plugging / choking of the final steam/oil atomisation spary orifice. 5. Also to check any significant solid contaminations with feed oil from VGO or LSWR (if used). 6. Also to check surface chemistry afeter light buffing if possible of ur used pipe by PMI to check design compliance. 6. Alloy 6B can be an upgradation but ur MOC is a good one. may be of some help. regards