Could anyone explain me about the wind directions philosophy which we show in our piping drawings (like GAD, Plot…

One of the reasons you would like to know the prevailing wind direction, when laying out a site is to help you position items such as cooling towers.

Having wind information will help you to position, for example, cooling towers.

Take a look at the training section that deals with Equipment location:
Section - II A: General Guidelines for Equipment and Piping Location, Spacing, Distances and Clearances http://pipingdesigners.com/wp//Training%20- ... n%202a.htm

Locate cooling towers downwind of buildings and equipment to keep spray from falling on them. Orient the short side of the tower into the prevailing summer wind for maximum efficiency. This means that the air flow (wind) will travel up the long sides and be drawn in to both sides of the cooling tower equally. When the wind is allowed to blow directly into one long side it tends to blow straight through and results in lower efficiency.

As a general rule you won’t indicate wind direction on Piping Plans. However in certain instances it would be “nice” too know! I’ve seen where the prevailing winds took exhausted steam to the near by turbine air intake (in arctic conditions) and iced it up. I myself have indicated prevailing winds at H2S scrubber sites to indirectly explain why that equipment is located at down wind edge of the facility.
This is one of those pieces of information that “needs” to be indicated WHEN it is a consideration of your design.

I feel it is always good to have prevailing wind direction shown on the layout drawings.

Facilities such as offices, store rooms, admin buildings, change room, canteen, workshops etc. are preferably to locate upwind or (at least) cross-wind of the prevailing wind direction.

The Wind Rose (wind direction indicator) should be mandatory on all Overall facility Plot Plans. During the development of the overall plot plan is when you consider and fix the location of all major items that would be affected by wind.

Items such as:
- Cooling Towers
- Flares
- Open flame sources (Fired Heaters, Fired Boilers, etc)
- Unplanned Vapor leak sources
- Occupied buildings
- Tank Farms

In most places wind does not always blow in the same direction all the time. I worked on a project once where 50% of the year the wind blew East to West and the other 50% of the year it blew West to East. I had to locate a large 10 cell Cooling Tower some place. I lined up the long axis of the tower on the East/West line of the prevailing wind. Now during the summer and winter season the wind traveled down both of the long sides of the cooling tower and was sucked in the cells equally all year. The other equipment was located a few hundred feet to the North of the cooling tower and out of the over spray zone.

Once the Overall Plot Plan is approved and the individual Unit Plot Plans have been created using the (wind) information from the Overall Plot Plan you would not normally need to repeat the Wind Rose on any other documents.

Thanks for the valuable post Jop!
Also, another important point to know is the way the cooling towers need to be located ideally to have better efficientcy from the cooling towers.

I am working on a project where there are 3 prevailing wind directions (unfortuntely)

March – April NW
May – June SW
Remainder SE

But depending on the above information South-East is the direction seems to be predominant for me where most of the times in the year wind flow direction is (SE). I will consider this as the governing thing while deciding the location of wind flow affected pieces of equipments.

Correct me if somebody thinks otherwise!!

Flares should be located in an open area considering minimum sterile area preferably upwind from process units & preferably downwind from administrative buildings to minimize odours.