Answer:
525°C is the maximum safe operating temperature the engineer should recommend for this reaction.
Explanation:
Volume of the cylindrical container = V = 
Height of the vessel = h =60.0 cm
Diameter of the vessel = d = 50.0 cm
Radius of the vessel = r = 0.5d = 25.0 cm


1 mL = 0.001 L
117,809.72 mL = 117,80972 L ≈ 118 L
Pressure of the gas in vessel = P = 7.40 MPa = 

1 atm = 101325 Pa

Mass sulfur hexafluoride gas = 19.2 kg = 19200 g
1 kg = 1000 g
Moles of sulfur hexafluoirde = 
Temperature of the gas in vessel = T
Using an ideal gas equation :


T = 797.8 ≈ K 798 K
T = 798 - 273°C = 525°C
525°C is the maximum safe operating temperature the engineer should recommend for this reaction.