A securing part and an unscrewing safeguard system of a gradient coil plug for an MRT that can be fixed to a gradient coil bushing include a gradient coil plug, a gradient coil bushing, a cap nut with a keyed surface and, to secure the gradient coil plug to the gradient coil bushing, a multi-tooth ring fixed to the plug so that the ring cannot rotate, and a securing part with a multi-tooth ring engagement contour that can be brought into engagement with the multi-tooth ring, and with a keyed surface engagement contour that can be brought into mating with the keyed surface of the ring.