подскажите, пожалуйста, как перевести "cock cap"

контекст (речь идет о safety valves) - Install new liner seal and apply a light coat of lubricant to cap bolt threads. When installing
the cap, make sure it is seated squarely into body. Install cap bolts hand tight, then tighten
an additional 1/4 to 1/2 turn uniformly so as not to “cock cap”.

Заранее благодарю