Gents, can anyone comment me on my above querry pls?

Vinod, You may get appropriate responses you provide some background to your questions and also, you seem to be using the term "legal requirement" regularly. I see that you are connected with the Middle East branch and assumme that your question pertains to a location in the Middle east/Gulf region. Most of the respondents to the forum are UK based and may assume that you are asking about UK legal requirements, which may not be the specific requirement outside UK. Having experience in chemical industry, all equipment has unique identification in the form of letters and numbers so that the same can be incorporated in Process & Instrumentation Diagrams (PID's) and Process Flow Diagrams (PFD's) etc. http://en.wikipedia.org/..._instrumentation_diagram

As Jay says you give little detail and this makes a response difficult. I doubt that there is any legal requirement directly. It is more a case of following the relevant code or good practice. I have replied on the assumption that you are talking about fuel storage facilities. This link takes you to the publications page from the Institute of Energy here in the UK. (The old Institute of Petroleum is now merged into this organisation.) They publish standards, good practice etc. You may find something of help within their publications that will guide you to current standards . http://www.energyinst.org/documents/518 p48

Thanks a lot indeed for your advise!