Sealing arrangement for internal tubesheet for tubular heat exchangers

A sealing arrangement for an internal tubesheet of a tubular heat exchanger, the tubular heat exchanger having a channel and a shoulder in which a ledge of the tubesheet is fitted, comprising:

• a gasket fitted between the shoulder and the tubesheet, the gasket being made of spiral wound construction but without any metallic rings on the gasket, and both the shoulder and tubesheet being without a locating groove;
• a channel box on an outer side of the tubesheet, the channel box being provided with an inner face resting on the ledge of the tubesheet and an outer face of the channel box being reduced in diameter and arranged to align with a centerline of push bolts, the outer face of the channel box attached to an annular ring, and the push bolts being provided in threaded holes;
• the push bolts when tightened load the annular ring and in turn load the gasket through the channel box and the tubesheet, the reaction to this load in an outward direction being taken by a split shear ring essentially by the action of shear stress;
• and
• a gusset provided between the inner face of the channel box and the annular ring such that the load on the annular ring from the tightening of the push bolts is transmitted to the channel box through the gussets and ultimately to the tubesheet to load the gasket;
• wherein the channel is provided with an end portion with an inner diameter that is gradually reduced towards the shoulder to achieve a close running fit with tubesheet.