7 replies to this topic

[Anshi harry]

Hello friends i m new user here. Could anyone told me which chemicals are capable of removing rust, without
leaving any film or residue.

[Bobby Strain]

Search Google for "carbon steel piping pickling"

[kirang11]

dry HCl

[Pilesar]

I use the electrolytic method of rust removal when possible. As long as the rusty piece can be submerged, the result is very satisfactory. No chemicals required except for a small amount needed for the electrolyte.

[latexman]

Dry HCl?  Anhydrous HCl can be stored in carbon steel.  It's when water is added it gets corrosive.

[Anshi harry]

dry HCl

Okk but How we use dry HCL?? could you please elaborate the process?? 

[kirang11]

In our unit we have done acidizing using dry HCL. I assume you want to remove rust in some reactor circuit section. I will explain what we have done in our case. first we have circulated naptha free of water less than 10 wt ppm in the section where rust is to be removed. during this procedure the flow of naptha is ensured through bypass of controllers, standby pumps etc. H2 is introduced into naptha and normal operating conditions are maintained. Note the reactor now is without catalyst, drain all low points in the section being acidized to find any free water. changeover of pumps is also being taken during this procedure. Now I assume downstream to your reactor is stabilizer/stripper for which reboiling is started and its overhead gases being sent to scrubber. put fresh caustic (20% strength) into scrubber. Now check for water content in naptha that is being circulated is now showing moisture content less than 10wt ppm using some moisture analyzer.once moisture < 10ppm wt. now arrange anhydrous HCL cylinders chain them in upright position, use proper PPE. put the anhydrous HCL cylinder on a weighing scale (0-100Kg) and tie this cylinder with chain to some pillar. now a connecting line from cylinder to the reactor circuit is already arranged. slowly open the globe valve of the cylinder and observe the weight dropping to 95. close the valve.wait 1 hour then inject another 5kg by opening valve. do this continously on hourly basis. if the HCL weight doesnt decrease in cylinder throw Low pressure steam raise its pressure above the system pressure. whenever cylinder is being emptied fresh HCL cylinder is placed. during this procedure mositure probe is taken out of service. mositure readings are taken on daily basis. during this process whenever low point drain like control valve bypass LPD is opened a huge amount of water is found which is an indication that rust is being removed. draining is to be done at regular intervals.This procedure is repeated until no water is found. It may take 2-3 days. the HCl that is introduced in the section is being neutralized by fresh caustic in the scrubber, so it is also necessary to change the caustic whenever its strength is going down.Also during this procedure proper reboiling in stabilizer/stripper downstream to the reactor section is maintained. reading of HCL should show 1000ppm on stabilizer offgas going to scrubber and no HCL reading at stabilizer bottoms when measured with dragger tubes.  Rust is being removed when we dont find any water in the naptha that is being circulated in the section.I hope i explained in simplest way.

[asad.humam]

Hello, I am new user here.,

 

Can anyone know about "pickling of nitrogen (N2) line application" ?? is there any standard/code for this ??, is this mandatory or not ??

 

Regards