Fwd: [MW:9707] drain line failure

---------- Forwarded message ----------
From: Yogesh kumar <yogeshandpini@gmail.com>
Date: Thu, Feb 3, 2011 at 3:57 PM
Subject: Fwd: [MW:9704] drain line failure
To: materials-welding@googlegroups.com

dear experts

 

we are facing similar problem in one of our catalyst drain line which is intermittent in service since commisioning.

the line operates at the time of decantation only,frequency once a week .it's being observed that a localized paper thinning of firstly CS then SS304 has taken place in a short span of 1 month of their commisiong(decanation cycle 2).

 

the thinning to big hole has taken place to downstream/ of valve in CS/SS both and upstream of Valve in the pipe portion while the line metallurgy was CS.

 

No remarkable thickness loss in vessel bottom portion.

 

only the red lined portions have problem.

 

the flow direction is shown in sketch.

 

op. conditions are;

 

 Temp;55-70degC,90 Max

press; 0.1kg/cm2

 

process fluid; residues of TiCl4+MgCl2+hexane

we inject Live steam(MP) from other nozzle to strip out the hexane in the drain,and neautralize the vessel by dosing caustic 20% just before beginning of decanation.

 

we are expecting erosion/corrosion due to flow +HCL  but,the root cause is not clear.

 

Kindly give probable reason and remedy for the same.

 

 

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.