Whether or not to consider wind load and if so above which height ( sometimes size -height combination) , all these informations should be available to you through your project design specification for stress analysis.
Typically my experience tells me that below 8M height wind analysis is not considered for metal Pipes.However I have done wind analysis for FRP pipes travelling on low level racks as the rack was close to sea.
So you see that there cannot be any general guideline in this matter.You have to refer to your project design guide . That should be your bible in this matter.
I personally consider that for metal pipes wind analysis does not give realistic results if differential movements between pipe and connected structures ( may be a vessel or other pipe support structure )through structural sway is not considered.
A.Bhattacharya
Stress Analyst
Bechtel Corporation
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Anindya Bhattacharya