Questions regarding the design formulas in GB50341-2014
Thread Content
In accordance with clause 6.3.2 of standard GB50341-2014, when the fixed design point method is used to calculate the thickness of tank walls (see the equations below), td = 4.9D(H – 0.3)ρ/[σ]d∅ (6.3.2-1) and tt = 4.9D(H – 0.3)ρ/[σ]t∅ (6.3.2-2). Clause 6.3.3 states that the nominal thickness of the tank wall panels shall not be less than the larger of the calculated thickness under test conditions or design conditions, plus the respective thickness allowances (i.e., C = C1 + C2). But in some calculation formulas, such as those in the \"Training Manual for Pressure Vessel Design Engineers\" on page P511 (A8.4.2): td=4.9D(H-0.3)ρ/［σ］d∅+C1+C2; tt=4.9D(H-0.3)ρ/［σ］t∅+C1. Why is there no C2 value in this formula? (Although the td value is greater than the tt value during calculations, the larger of the two values is taken.)
The image shows API650. In practice, this is how it’s generally handled: no corrosion margin is taken into account when calculating water pressure; the new tank isn’t subject to corrosion under such pressure. If the thickness of large storage tanks is increased, it’s a waste!