Wind Design Speeds and Pressure and Refinery

[lot]

Does anyone have a recommended wind speed and pressure ( psf ) for refinery piping and/or instrumentation? I have a large gas analyzer ( 300 lbs. ) that is going to be mounted on process pipes as high as 150 feet. It sits on a valve/flange and I'd like to verify the design using real numbers. Thanks.

 

[Ron]

The wind speed and the resulting pressure on the item are governed by:

1) Your location...obtain a reference such as ASCE 7 or other appropriate structural loading code having an isotach
2) The appropriate factors such as height of placement of the item and its shape
3) Load combinations that produce the most stringent requirements for the design case. These will include dead load, live load, wind load, snow load, and seismic load. Further, the wind load must be computed in several different directions and uplift could be important, though with your description of the part, it isn't likely that uplift is a big deal.

 

[lot]

Thanks for responding so quickly. I have all the desing data you stated I needed except the ASCE 7. Basically what I'm trying to find out is if there exists a Spec. or table, etc. that give guidlines for wind speed and pressures of equipment mounted on piping/at refineries to give me some idea of what the loads will be. The wind speed hasn't been so difficult to determine but the pressure ( psfg ) has.

 

[Ron]

In the tables in ASCE 7, the factors for round tanks, chimneys, etc. range from about 0.7 to 1.2. If you use 1.2 or even 1.25, you should be ok.

F/A=qCfGz, where q=basic wind pressure
Cf=shape coefficient, and Gz=gust response factor, depending on height. For anything over 100 feet, use 1.15.
A=projected area F=force....wind pressure=F/A

This is rough but conservative.

 

[Lina]

This is a sample step by step to calculate pressure on a glazed railing.

These calculations use American Society of Civil Engineers Standard 7-93, Minimum Design Loads for Other Structures to compute wind pressures on the railing for 160' heigh building located along the shoreline.
General Notes:
Category = 1 as per table 1 on page 2
Exposure = D as per section 4 on page 14
Use Table 4 with F=qz GZ Cf Af to calculate the force on the railing
qz is given in section 6.5 page 11
GZ is given in table 8
Cf is given in table 13 (The railing was assuned to be a solid sign)
Af projected area normar to wind (The area of glass Panel 39"x36" = 10SF)
Divide the force F calculated above by the area of the glass panel to obtain the designed pressure of the railing P(lb/sf)

Just follow these steps to design for the load on your analyzer.

 

Is there a spreadsheet calculator available to determine negative wind uplift pressure for roofing applications which conform to ACSE 7-93?

 

[Polecat]

TJMC:

Check out this site:

http://mecaconsulting.com.

They have several Excel spreadsheets driven by Visual Basic macros that really take the curse out of calculating those coefficients.

http://www.spiraleng.com

If you wish to visit my website, we can discuss these or other issues further.

 

[Tripp]

ASCE has a publication that deals with situations like this called "Wind Loads and Anchor Bolt Design for Petrochemical Facilities". It can be ordered online at:

http://www.asce.org/publications/booksdisplay.cfm?type=9704525

Tripp