A-321 First Officer reported a cockpit fire extinguisher damaged and leaking halon during cruise flight. The crew coordinated with the cabin crew and secured the faulty cockpit fire extinguisher in a Thermal Containment Bag; TCB; and the flight continued to destination.

Narrative

While cruising at FL330; pilots heard a hissing noise coming from behind the FO's seat. The crew found the flight deck fire extinguisher was discharging uncontrollably. The crew donned 100% O2 while the Line Check Pilot (LCP); seated in the jump seat; removed the fire extinguisher from the bracket. The valve was found to be damaged near the pressure gauge and the crew could not stop the discharge (The safety pin was still installed). The CA remained PF and the FO coordinated with the FAs to set up the galley cart to open the flight deck door. The fire extinguisher was placed in the TCB and removed from the flight deck by the second jump seater. The fire extinguisher was then sealed in the larger cabin TCB to minimize Halon discharge in the cabin and subsequently secured in the aft lavatory. Crew opened all flight deck vents and remained on O2 until the fumes dissipated. Flight continued uneventfully to ZZZ and landed safely.