Investigating Material and Component Failure - TCR Engineering ...

PULP AND PAPER INDUSTRY CORROSION
Corrosion issues in the paper industry are normally most significant in the wet
process equipment. Various manufacturing steps have there specific corrosion
problems. Temperature, chemical constituents, concentration, size and quality of
the wood fibers, and metals used in components are some of the factors affecting
corrosion in equipment. Paper recycling and environmental concerns regarding
chemical releases have required the pulp and paper industry to change their
processes.
There is an understandable development of decreasing the total quantity of
process water used, by recycling and reusing the water in closed-loop systems.
Closure has resulted in increasing concentration of dissolved organic and
inorganic solids, a decrease in pH and an increase in operating temperatures.
This results in a more significant corrosion environment for the equipment.
Some of the major steps in the pulp and paper industry are listed below:
• Pulp production
• Pulp processing and chemical recovery
• Pulp bleaching
• Stock preparation
• Paper manufacturing
Paper mills have been historically constructed of a mixture of carbon steel and
stainless steels components. There has been a trend to use more stainless steel
in paper equipment. Stainless steels have there own corrosion concerns. Proper
selection of stainless steels and associated welding processes for these new
environments are significant issues to the pulp and paper industry.
Some of the corrosion concerns in the pulp and paper industry are listed below:
• Pitting
• Crevice corrosion
• Stress corrosion cracking
• Microbiological attack
• Corrosion of welds
• Corrosion fatigue
Failure and Root Cause Analysis White Paper by TCR Engineering, India 18