I am reasonably sure that you won't find a website with a drawing that shows individual valves.

What exactly is the purpose of your question? How will you use such detailed information obtained from a generic drawing in a particular situation? Maybe we can help you better in a different way.

I have a enquiry for valves for hydrotreater unit. I need to find out the location of valves to understand why some of them are critical!!

Are you located at a refinery?

A hydrotreater is a fairly large unit.  Some areas include high pressure hydrogen.  You would need the complete set of P&ID's for the specific unit  --  and the definition of critical.

All process block valves are expected to isolate various equipment areas to permit maintenance etc.  What valves are considered critical; and which are not critical?

The valves which I am looking for are:
1. Stripper reboiler pump spillback
2. Stripper bottoms to stripper reboiler pass
3. Stripper reboiler pump discharge
4. Stripper receiver sour water
5. Stripper bottoms bypassing feed stripper bottoms     exchanger
6. Separator bottoms to effluent separator liquid exchanger
7. Separator sour water to coker Naphtha unionfining unit

Would this help?

Haven't you just answered your own question by identifying the location of the valves? I would highly doubt that you are going to get someone to share their P & ID's with you as it would most likely breach the confidentiality agreements that we have with our clients.

The common thread sounds like hydrogen sulfide.  These sound like NACE applications.  See MR0103-2005 or read about sulfide stress cracking.

consideritsolved:

I hate to be this blunt but the very fact that you asked such a question on an online forum discloses that you know very, very little about oil refineries.

(1) It would be rare for a hydrotreater in a specific refinery to have exactly the same P&ID as any other refinery P&ID.

(2) It would even more rare for the hydrotreater in one refinery to have exactly the same heater exchange scheme, the same type of reboiler, the same piping arrangement and the same valves as any other refinery hydrotreater.

(2) As you have already been told by the earlier responses above, you have no chance at all of anyone giving you a P&ID of their particular hydrotreater ... and you certainly won't find one on the Internet.

(3) What one refinery considers to be "critical" valves most probably differs greatly from what another refinery considers to be "critical". Even if someone gave you a P&ID, I have never seen a P&ID that labeled valves as being "critical" or "non-critical".

(4) Your best recourse (in fact, your only sensible recourse) is to go back to whomever sent you that enquiry and ask them for a detailed list to the valves they seek ... a list that includes the valve types, sizes, materials of construction, pressure and temperature classifications, etc.

Milton Beychok
(Visit me at www.air-dispersion.com)
.

All
I did some research and found that
1. CHPS, HHPS, Sour water letdown valves are critical. Also the pump spill back valves are critical.
2. Check this website for a process flow diagram for gas oil hydrotreating http://www.dresser.com/internet/pages/documentwarehouse/index.cfm?r=49&numPageID=153
select technical data. You can find an article.
3. This shows the location of valves. It is close to a P&I.
4. It is only a forum for us to exchange our views, a doctorate in refining is not the basic requirement to join this forum.

No, a doctorate in refining is not required, but the formation of an intelligent question is useful. As stated above one refinery's definition of critical is not the same as anothers. I have had clients whom have "safety critical" as well as "business critical".

consideritsolved:

I don't have a doctorate myself ... but I do have experience. During my career of 30-40 years as a process design engineer for one of the major refinery engineering and construction companies, I did the complete process design of about 6-8 hydrotreaters. When I tell you that a process flow diagram you found on the Internet is a long, long way from a P&ID and does not represent all of the multitude of possible hydrotreater P&IDs, you can take that as the gospel truth.

I repeat: Your best recourse (in fact, your only sensible recourse) is to go back to whomever sent you that enquiry and ask them for a detailed list to the valves they seek ... a list that includes the valve types, sizes, materials of construction, pressure and temperature classifications, etc.

Milton Beychok
(Visit me at www.air-dispersion.com)
.