Flexible pipes are used extensively for production and transport of oil and gas in the offshore industry. About 60% of the Norwegian production of hydrocarbons are based on transportation through such pipes. Several incidents of critical corrosion of the armor wires confined in the annulus between the inner liner and the outer sheath have been reported over the last 10-20 years. Some of the corrosion incidents are related to exposure to oxygen and CO2 when the outer sheath has been breached. However, there are also numerous incidents when brittle fracture and rupture typically associated with hydrogen embrittlement and H2S corrosion/cracking have been observed. With increased souring of many reservoirs even in the North Sea, there is a growing concern for environmental cracking of the armour wires. It is, therefore, necessary to establish a comprehensive understanding of the mechanical and chemical behaviors of annulus and its effect on hydrogen uptake and environmental fracture of the armour wires.