Spiral Grooving In order to avoid differential pressure sticking in the hole. Stress Relief Groove & Bore Back Box Stress relief grooves improve bending strength of pin and box connections and, therefore, durability. Stress relief grooves for box and pin are defined by API. Bore back box is nothing but gradual reduction of internal diameter by gradually increasing material cross sectional area at critical section. This will ultimately reduce drastically stress concentration during Static / Dynamic loading and prevents box connections from failure Hardbanding We provide several hardbanding materials for Customerâs choice: Arnco-100XT, Arnco-300XT, TCS-8000; Slip and Elevator Recess Slip and elevator recesses improve downhole handling efficiency and safety. Slip and elevator recesses are machined in accordance with API 7-1.