Guy cables

HORIZONTAL BRIDGING TERMINUS POINT SEGURED BY TEMP. GUY CABLES... 

When using pultruded parts in long or tall structures, such as monopole towers, an excess amount of material or cross bracing must be used to compensate for the property reductions compared to filament wound composite parts. A low-cost structural composite tubing product is required with significantly improved stiffness and reduced maintenance costs, thus enabling the use of efficient structural system with guyed cables. 

GUY CABLES, REMEDIATION DEVICES, AND SUPPORT OF FLARE STACKS... 

Guy cables can be remediation devices to stabilize a dynamic unstable stack or process column, or as a built-in design support mechanism for a tail and narrow diameter stack. A flare stack is more involved than other types of stacks because there are thermal gradients to complicate matters. 

Determining the pre-tension required for guy cables on flare stacks is necessary for proper support. The method discussed here has been used in practice and is therefore tried and proven. 

Flare stacks supported by guy cables are ubiquitous in use and seem quite innocuous to the untrained eye. However, their failure during the flaring of a stack could have dire consequences. This section is based on actual pretensioning cases that have proven to be successful. 

This section concerns the static problem of guy wires. Experience has shown that if guy cables are properly tensioned, flow-induced vibration (FIV), induced by vortex shedding, is of minimal concern. The reason is that the natural frequency of the stack is well above the resonant range. One reason for pre-tensioning the cables is to avoid FTV. 

A guy cable is 1935.07 inches long and weighs 0.154lb ,/in. At operating flare conditions, the guy cable connection on the upper part of the stack (guy cable support ring) is 700°F and at grade the temperature is 500°F. The elevation of the guy cable connection is 114.042 feet. The ambient air temperature is 104°F (40°C). The material of construction of the flare stack is A333 Gr 3. 

The average temperature of the stack from the guy cable support ring connection to grade is calculated as... 

With total sag of 5.648 inches, the required tension in the guy cable is,... 

The consideration of wind loads in a plant or operating facility normally happens when a section of a tower is to be stress-relieved by post weld heat treatment and an entire shell portion of the vessel is to be heated to the stress-relieving temperature. In this application, you must be cognizant of the imposing wind loads on the vessel. Another application would be the installation of guy cables, as discussed in Chapter 3, and the loads on these cables. These simations are routine in plants, hi the case of relieving stress on a process column, only the wind shear and bending moments at the location under consideration are of interest. 

There is also a discussion about the application of gny cable supports for stacks in regards to dynamic response and wind loads. Of particular interest is a discussion about flare header stacks and how to design guy cables for these tall and slender structures. 

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