| 摘要 |
A retaining apparatus, in particular an internal tree cap, for use in a wellhead is disclosed, the wellhead having a central bore and first and second retaining means, such as a shoulder and a groove, within the bore of the wellhead. The retaining apparatus has housing for location within the bore of the wellhead. A first engagement assembly is provided for engaging with the first retaining means in the bore of the wellhead to thereby retain the housing within the bore of the wellhead. A second engagement assembly for engaging with the second retaining means in the bore of the wellhead is also provided. The apparatus further comprises a preload assembly operable when the housing is located within the bore of the wellhead to apply a preload to the housing between the first and second retaining means. A method for retaining an assembly within a wellhead bore, in which a preload is applied between the first and second retaining means, is also disclosed.
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