Threaded plug and protective element for a plug

A protective element for a plug comprising a head, a body, and a flange inserted between the head and the body, the protective element comprising:

• a hollow containment body which extends along an axis and which is capable of containing the head of the plug, and
• a substantially ring-shaped base capable of overlying the flange of the plug,
• wherein the hollow containment body comprises, along the axis, a first portion joined to the base and having an inner lateral surface which includes a first profile configured to allow the head of the plug to pass and a second portion having an inner lateral surface closer to the axis relative to the inner lateral surface of the first portion and which includes a second profile which is not coincident with the first profile;
• wherein the first profile of the hollow containment body is substantially coincident with or circumscribes a first profile of an outer lateral surface of a first portion of the head and the second profile of the hollow containment body is substantially coincident with or circumscribes a second profile of an outer lateral surface of a second portion of the head.

A threaded plug, comprising:

• a structure which extends along an axis and includes:
• a head,
• a body including an outer thread, and
• a clamping flange inserted between the head and the body;
• wherein the head comprises, along the axis, a first portion having an outer lateral surface which includes a first profile and a second portion having an outer lateral surface which includes a second profile which is not coincident with the first profile;
• wherein the body is hollow and includes an end formed by the clamping flange, wherein the end includes at least one hole which passes through the clamping flange substantially in a direction of the axis, extending inside the first portion of the head.

A protective element for a plug comprising a head, a body, and a flange inserted between the head and the body, the protective element comprising:

• a hollow containment body which extends along an axis and which is capable of containing the head of the plug, and
• a substantially ring-shaped base capable of overlying the flange of the plug,
• wherein the hollow containment body comprises, along the axis, a first portion joined to the base and having an inner lateral surface which includes a first profile configured to allow the head of the plug to pass and a second portion having an inner lateral surface closer to the axis relative to the inner lateral surface of the first portion and which includes a second profile which is not coincident with the first profile;
• wherein the second profile of the inner lateral surface of the second portion of the hollow containment body is substantially circular;
• wherein the inner lateral surface of the second portion of the hollow containment body includes a plurality of recesses which develop in a direction of the axis of the hollow containment body and which are distributed along a circumference of the second profile.