Almost every piece of equipment and machinery in the Oil and Gas industry requires the use of bolted joints due to numerous advantages that they offer regarding productivity and maintenance however these advantages vanish by inadequate materials selection and installation procedures. Most anti-corrosion coatings applied to bolts do not offer a consistent tightening and they are affected by torqueing during assembly; the nut factor relates the bolt’s installation torque to the tension required to tighten the bolt maintaining a consistent nut factor would solve problems such as over-torquing and corrosion resulting from the coatings peeling-off which may lead to leaking from the joint and even to joint failure. Organic coatings have historically suffered from flaking and peeling when torqued hence metallic coatings such as Ni-Co electroplating may offer a more reliable performance.In order to obtain experimental data comparing the behavior of coatings used in bolted joints simulating service conditions cyclic torquing (up to 5 cycles) was applied to fasteners with different coatings and the nut factor and corrosion resistance was evaluated. The tested samples were B7M ASTM A193/A193M bolts and 2HM ASTM A194/A194M nuts with the following coating conditions: 1) No coating 2) Ni-Co Electroplating 3) zinc undercoat with PTFE topcoat and 4) TSA / PTFE. All samples were tested with dry runs (no lubricant) and two different commercial lubricants. A Skidmore-Wilhelm load cell was used to apply the cyclic torquing and to calculate the nut factor on each cycle. Corrosion tests were performed before and after torquing following ASTM G59 standard and environmental exposure following ASTM B368 standard to evaluate the materials corrosion resistance without torque. Ni-Co electroplating showed a better performance compared to the other tested coatings it offered the highest nut factor consistency and the lowest corrosion rate after the cyclic torqueing and after environmental exposure.The main impact of this work is providing consistent and reliable test data about nut factor and corrosion resistance of coatings; this data can be used to compare available coated fasteners for selection of the best solution for bolting in oilfield and industrial application. Ni-Co electroplating is featured as a coating that provides corrosion resistance and nut factor consistency regardless the number of assembly/disassembly cycles it is proposed as a solution to avoid joint leaking and likely catastrophic failures.

Corrosion of carbon steel materials in brine solutions.  Model results will be compared with literature data and lab experiments. Conditions will be limited to near neutral pH (5-9), temperature  from 22oC to 55oC, and O2 atmospheres up to 101.325 kPa.