In the correct sequence for installing plasma cutting consumables, which item is installed last?

• A. Retaining cup
• B. Shield
• C. Nozzle
• D. O-ring

Answer: (B)

In plasma cutting, the order of assembling the consumables is arranged to establish the correct arc gap, seal against gas leaks, and protect the tip. The inner pieces—nozzle, o-ring, and retaining cup—are installed first so they seat precisely and create the proper spacing and seal. The shield is the outer piece that surrounds the nozzle and directs the gas flow and arc length, and it also protects the tip from slag and heat. Because the shield defines the final working distance and should not be stressed during the placement of the inner parts, it is installed last.