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Pulp & Paper Solutions

Corrosion-resistant flanges for bleach, caustic, and recovery boiler service.

Overview

Pulp and paper mills operate continuously with exposure to bleach sequences (chlorine dioxide, hypochlorite), caustic (sodium hydroxide), and recovery boiler flue gas. Corrosion rates in these environments exceed most industries. 24/7 operation means zero tolerance for planned maintenance; flanges must deliver multi-year service life.

Applications

Bleach plant manifolds and piping

Caustic circulation systems

Kraft recovery boiler inlet/outlet

Black liquor pipeline connections

Condensate and cooling water lines

Digester nozzle flanges

Chemical storage tank connections

Relevant Standards

  • ASME B16.5 (base specification)
  • TAPPI TIP 0304-24 (pulp/paper industry guide)
  • NACE SP0403 (caustic service)

Material Grades

ASTM A182 F304L

non-magnetic austenitic

ASTM A182 F316L

molybdenum for chlorides

ASTM A182 F321

titanium-stabilized

Duplex 2205

chloride service temperature limit ~250F; verify chloride concentration in recovery boiler service

Hastelloy G-30

recovery boiler flue gas

Common Pressure Classes

Class

150

Class

300

Class

600

Typical Service Specifications

Pulp mill flanges operate at 150-600 PSI with temperatures from 80°F to 600°F (recovery boiler). Chloride/sulfide stress corrosion cracking (CSCC) and pitting dominate failure modes. Material selection, gasket compatibility, and bolt pre-tension all affect corrosion performance.

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