Effect of Microstructure on Hydrogen Diffusion in Weld and API X52 Pipeline Steel Base Metals under Cathodic Protection

Table 5

OCP, current density at 50 mV and 100 mV above the OCP.

Test condition	Solution	pH	OCP (ECS)	E; 50 mV; above OCP; (mV)	i; 50 mV above OCP (A/cm^2)	E; 100 mV above OCP; (mV)	i; 100 mV above OCP; (A/cm^2)
BM	NS4	8.4	−0.716	−0.666		−0.616
	NS4 + thiosulfate	8.6	−0.766	−0.716		−0.667
WM	NS4	8.1	−0.695	−0.645		−0.595
	NS4 + thiosulfate	8.8	−0.758	−0.708		−0.658
QBM	NS4 + thiosulfate	7.9	−0.743	−0.692		−0.642
ABM	NS4 + thiosulfate	8.3	−0.766	−0.717		−0.667