Pass - Heater / Heat Exchanger / Boiler

A continuous flow circuit consisting of one or more tubes in series.

Pilot

A smaller burner that provides ignition energy to light the main burner, each connected by return bends or other fittings.

Plug header

A cast return bend provided with one or more openings for the purpose of inspection, mechanical tube cleaning, or draining.

Plenum

A chamber surrounding the burners that is used to distribute air to the burners or reduce combustion noise.

Pigtail

Small diameter piping that connects steam/methane reformer tubes to the inlet and outlet headers.

Protective coating

A corrosion-resistant material applied to a metal surface; for example, on casing plates behind porous refractory materials to protect against sulfur in the flue gases.