Aggressive CO2 corrosion of weld HAZ was shown to affect the fatigue properties of pipeline girth welds in a strain-based design which allowed tensile stresses on cool down. Two types of accelerated growth mechanisms were present based on crack tip dissolution and what appeared to be an unknown local embrittlement. Testing showed
chemical inhibition could control the first propagation mechanism.
Keywords: pipeline, wet natural gas, corrosion fatigue, CO2 corrosion, girth weld, fatigue crack propagation