Your spreader$-$bar is a standard, hollow structural shape HSS $44\frac{1}{8}.$ The AISC Steel Construction Manual lists the geometric properties of this section in the document "AISC Table $1-12$ Tubes" on D$2$L$.$ You may use a modulus of elasticity for structural steel of $29,000$ksi.

Typical design factor of safety for structural steel design $($like a building$)$ is $1\mathrm{.}5-2.$ For cranes$/$lifting$/$rigging$,$ OSHA states the following:

$1926\mathrm{.}753($e$)(2)$

Components of the multiple lift rigging assembly shall be specifically designed and assembled with a maximum capacity for total assembly and for each individual attachiment point. This capacity, certified by the manufacturer or a qualified rigger, shall be based on the manufacturer's specifications with a $5$ to $1$ safety factor for all components.

You will be calculating the allowable compressive load of the spreader bar. State what factor of safety you will use in your calculation, and why. Please determine the allowable compression load $($rating$)$ in the spreader bar for our application.

From your statics in Application Exploration #I based on the $10-$ft long slings, determine the maximum weight of the wall $($i$.$e$.$ maximum load$)$ that can safely be lifted by the system. And what should the corresponding safe rating for the set of $10-$ft slings be$?$

You desire a safe compression rating of $8$ kips in your spreader bar, and instead of the square structural shape wish to use a pipe section $($property table given in the document "AISC Table $1-14$ Pipes" on D$2$L$).$ Assuming cost is directly proportional to weight, select the most economical pipe size for the job with the condition of a maximum outside diameter of $4\mathrm{.}5in.$