Interpretations of certain provisions in the GB50341 Code for Design of Vertical Cylindrical Welded Steel Oil Tanks
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1. For the formula 5.1.3 Lm=215tb/(Hwρ)^0.5, does tb refer to the value in Table 5.1.2 or a value determined by the designer? From the formula, it can be seen that once tb is determined, the larger Hw is, the smaller Lm needs to be (of course, both values must be greater than 600). Why do I feel that the higher Hw is, the more dangerous the device becomes? Why does Lm become smaller instead? Could someone analyze this for me theoretically? 2. Formula 7.1.6: A is less than or equal to mtg/(1415·tgθ), where mt is the total mass of the tank wall and the components supported by the tank wall and the tank top (excluding the tank top plate). What exactly do the components supported by the tank wall and tank roof refer to? Could you give an example? Thank you first.
The geometric nonlinearity between the tank wall and the tank bottom leads to deformation coordination. Therefore, with a constant thickness of the bottom edge plate, the higher the liquid level, the greater the hydraulic pressure on the bottom edge plate, and the shorter the distance over which the effect of coordinated deformation is felt. Such as the reinforcement rings on the tank walls, the edge-binding angle steel, and the supporting structures at the top (beams and rafters, etc.); if pillars are added in the middle of the roof, those constitute partial supporting structures (beams and rafters, etc.). It’s just my personal understanding; I hope it can be of some help to you
1) tb refers to the value in Table 5.1.2. 2) In fact, Hw came first, followed by tb. The larger Hw is, the larger tb is as well. Determine Lm after Hw and tb are determined
The components supported by the tank walls and tank roof refer to ladders, platforms, handrails, pipe racks, etc.
Thank you very much, I roughly understand now.
tb should represent the effective thickness of the edge plate (the selected thickness minus the corrosion allowance and any negative deviations). The thickness of tb should be in line with the thickness and stress levels of the bottom ring wall plates; refer to API 650 and EN 14015. Last edited by Half-baked on 2009-3-19 at 10:08.]