Procedure 5-5 Hub Rings used for Bed Supports

The traditional way of supporting beds inside vessels has been to use straight beams. An alternative approach to the conventional straight beam design is to utilize a circular beam, commonly referred to as a hub ring , supported by equally spaced radial beams. The radial beams are like the spokes of a wheel. 

As design loadings have increased, the spacing of beams has decreased. The height, width and thus weight of beams has increased, as well as the cost. This in turn has led to increasing the manway size to accommodate deeper beams while the access between the beams has become smaller and smaller. The hub ring can provide an innovative solution to this problem. 

In the hub ring design the radial beams are typically one quarter of the vessel diameter in length. Since the moment formula for a simply supported, uniformly loaded beam is wl /8, the beams are proportional, not to 

For vessels larger than about 10 feet in diameter, a cross beam, or multiple cross beams, may be required inside the hub ring to support tray decks or grating panels. Once again, these cross beams can be spaced such that more than adequate space is allowed for personnel access. 

The design is based on N number of equally spaced, radial loads. The upper ring is in compression. The lower ring is in tension. 

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