I. Towers and vertical vessels
Plumbness shall be checked by viewing from two directions. Check of plumbness of very tall equipment will be done early in the morning or on a cloudy day. Out-of-plumb of the equipment installed shall not exceed 1.0mm per 1m of height or a total of 20mm for the entire height whichever is smaller, unless otherwise specified by the equipment supplier. Where the measurement of the center line of the equipment may be impracticable due to other structures or the like, two flange faces adjacent perpendicularly on the equipment body will be measured, and the mean value shall be adopted. Tolerance of position and elevation shall not exceed ±3mm.