The general operating principle is the same for all hydraulic tensioners & nuts models. High pressure hydraulic oil from a pump applies an accurate, axial load to the fastener. Once the system reaches a predetermined pressure, the operator uses a small bar to run the nut down by hand. This is easily accomplished because there is no load on the nut. After he seats the nut, he releases the hydraulic pressure, transferring the axial load to the fastener.
HTI offers three stud hydraulic tensioner models (Fixed, Variable and Subsea), hydraulic nut and hydraulic bolts. The following illustrations show the features and operation of HTI’s hydraulic stud tensioner models:
Fixed hydraulic tensioner models are compact, simple to use and the most economical. Each tool is designed for one thread size. The operator places the Bridge over the nut and threads the Load Cell on to the stud until it contacts the bridge. He then connects the hoses and follows the general operating steps noted above.
Variable hydraulic tensioner models allow the tensioning of several thread sizes or types of threads using one Hydraulic Load Cell. The variable hydraulic stud tensioner models also have side hydraulic ports, giving them the lowest installed height. The operator places the Bridge and Load Cell over the nut. Next he threads the separate Puller Bar onto the stud until it contacts the Load Cell. He then connects the hoses and follows the general operating steps noted previously.
The hydraulic nut replaces the nut normally used and stays with the stud. This is the most compact system and does not require additional stud length. The operator simply screws the hydraulic nut down tight and connects the hydraulic hoses. After reaching pressure, he either screws down a collar (style illustrated) or inserts shims designed for the application.
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