Tube Turns® Double Bolt Yoke style closure/manway is compact in size and functional in design. A typical unit consists of a forged hub, a hinged blanking head, split-yoke clamps, operating bolts, and a self-energizing O-ring gasket. Materials of construction are in accord with ASME specifications, and manufacture complies with applicable rules of the applicable ASME code for Pressure Piping and with the ASME Boiler and Pressure Vessel Code.
Operation is smooth and direct, and even the largest unit can be opened or closed in a matter of minutes. Turning of the actuating bolts - accomplished by one operator using only standard hand tools - spreads the yoke halves until they are fully separated, allowing the head to be swung open on its hinge. There is no need to tug or hammer at dangerous or heavy flanges or metal doors or to struggle with bulky lugs and threads.
Contact surfaces of the clamping yokes, head and hub are tapered (at less than the friction angle) of dry carbon steel. When the head is closed and the yoke bolts are tightened, the head and hub are wedged together, compressing the O-ring and effecting a leak proof seal. After the pipeline or vessel has been pressurized, the end load on the closure head intensifies frictional resistance at the tapered surfaces, thereby developing an inherent holding action that tends to overcome the relatively small component of force seeking to separate the holding elements. This design pre-supposes non-lubricated contact surfaces.
Code stamping of Tube Turns® Hinged Closures is available on request at a nominal extra cost. This includes (1) the furnishing of a Partial Data Sheet verifying shop inspection of the unit by a commissioned inspector of the National Boiler and Pressure Vessel Inspectors, and (2) the affixing of the ASME stamp on the closure.
In the event that shop inspection and stamping in accordance with Section VIII of the ASME Boiler and Pressure Vessel Code is not required, Tube Turns® can furnish a Manufacturer's Statement of Code Compliance. This document affirms that the Hinged Closure is manufactured in accordance with the applicable requirements of the code.
The Chain and Sprocket Drive option is by far the most economical opening assist device we offer for the Tube Turns® Double-Bolt Yoke-style Closure. This is a manually operated aid which assists in the opening and closing of the yoke. These units not only make the process faster, they also prevent uneven movement of the yokes which may cause binding. On larger closures, ratio reduction is available to further reduce the force required to operate the unit. Hand wheels can also be furnished which provide faster operation and eliminate the need for additional tools.
The basic pattern of the Tube Turns® Chain and Sprocket Drive follows the principle of the familiar bicycle chain and sprocket arrangement. Same size sprockets are attached to longer than standard yoke bolts. Positioned around the sprockets is a linked belt of chain. For safety precautions, a chain and sprocket guard is furnished. A lever or crank is fitted to one of the sprockets which when turned rotates both yoke bolts simultaneously. This device can be modified by changing the ratio of the sprockets to increase speed and ease of opening the yoke bolts.