Hydrogen embrittlement has long been one of the most troublesome phenomena related to materials’ failures in the widespread Oil and Gas industry and yet it is the cause of recent failures and subject of new studies and analyses. Hydrogen embrittlement a form of environmentally assisted cracking (EAC) occurs when a material’s mechanical strength is weakened by the penetration of atomic hydrogen inside the material; the hydrogen sources are diverse and they all intervene in this phenomenon. In plated bolts the coating’s application may induce the penetration of hydrogen into the base-material cathodic protection by sacrificial coatings or impressed current may also have similar effect. The purpose of the present work is addressing the influence of different metallic coatings on the amount of hydrogen present in the steel bolting substrate in service conditions and relate it to the extent of hydrogen embrittlement; by co-relating environment stress and materials properties this investigation attempts to present safe alternatives to prevent hydrogen embrittlement failures.The tested samples were B7M ASTM A193/A193M bolts and 2HM ASTM A194/A194M nuts with the following coating conditions: 1) No coating 2) Zn plating 3) Zinc-Nickel plating and 4) Ni-Co ASTM B994 SC 18 Class 1 electroplating. Potentiodynamic tests in simulated sea-water solution evaluated the kinetics for hydrogen production on the different materials. Determination of hydrogen permeation into the substrate across the coatings was carried out in a Devanathan–Stachurski cell. Cathodic protection of -1.1 V vs Ag/AgCl in simulated seawater solution was applied to tensile samples varying the environmental pressure and the exposure time before breakdown in air. The results showed an outstanding performance of the Nickel-Cobalt coating compared to the sacrificial coatings; sacrificial coatings produced large currents by the cathodic reaction and allowed hydrogen penetration to the base-material Nickel-Cobalt produced less current and the permeation was much lower. The mechanical tests showed that Nickel-Cobalt is not affected by the cathodic charging while the tested sacrificial coatings reduce their mechanical resistance in a 50%.The results from this effort have an outstanding relevance in offshore and subsea deep-water drilling and production equipment that depends on high strength carbon and low allow steels. Nickel-Cobalt alloy ASTM B994 is proposed as the emerging technology for carbon and high strength steel bolts to be used in marine environment and subsea where failure is not an option.

The effect of the combined uncertainties on the performance of bolts in drilling and production systems using a Bayesian probabilistic approach.  Also - managing the performance of bolts.