What corrosion mechanisms affect pulp mill piping?
Chloride attack from process chemicals. Erosion from fiber slurries. Acid corrosion in digesters. Caustic stress corrosion cracking. Microbiologically influenced corrosion.
How are pipes protected in bleach plant service?
Specialty alloys like duplex stainless steels. Rubber linings for abrasive services. Increased wall thickness for erosion allowance. Proper slope and velocity control. Regular corrosion monitoring programs.
What design features handle fiber slurry flows?
Large radius bends minimize wear points. Removable wear backs at critical areas. Proper velocity control prevents settling. Accessibility for regular inspections. Reinforced branches at direction changes.
How are recovery boiler pipes welded?
Special procedures for high-temperature alloys. Post-weld heat treatment requirements. Full penetration welds for all connections. Extensive NDE including radiography. Hardness testing of heat-affected zones.
What maintenance practices prevent pulp pipe failures?
Regular thickness surveys in erosion zones. Deposit removal during shutdowns. Lining inspections and repairs. Valve and fitting maintenance programs. Comprehensive record-keeping of all inspections.
