hallo friends
In hydrocracker we want to open high pressure separator vessel for inspection. as the vessel contain a lot of muck which consist pyrophoric material and H2S. what are the standard practices of cleaning the vessel and dislodging the muck before opening, so that vessel manentry can be safey?

Be 100% sure that vessel is isolated, steamed-out and washed by appropriate cleaning solvent (or at least not dry). Guidance on pyrophoric iron hazards and mitigations you can find in ChE website:

http://www.cheresources.com/ironfires.pdf
http://www.cheresources.com/search_results...phoric+iron#946

Dear sunil hello & Good morning,
As a general precaution,

the material suspected to contain pyrophoric iron has to be kept moistened with water

and should not be allowed to come in contact with atmospheric air/oxygen(immidiate storage in air tight polyethylene bag or other handy portable containers till underground burial is helpful) .

Additionaly any combustibles or flammable materials pocketted within the 'muck in question' could prove fire hazard.
Controlled oxidation with dilute Potassium permanganate aquous solution internal flushing or with other such safer material can be really helpful,but solution must not be concentrated.
Hope this helps
Qalander