Fabricated Jacketed Valves

There are four basic categories of fabricated jacketed valves. Within each category, however, numerous options are available, such as types and locations of heating medium connections, bonnet jackets or additional heat coverage for specific areas, and materials of construction. To the best of our knowledge there are currently no industrial fabrication standards that specifically address jacketed valves. Unless instructed otherwise by the customer, CSI designs, fabricates and tests jackets for valves in accordance with the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1. Valves sent to our shops for jacketing are pressure and leak tested before and after jacketing.

Before specifying fabricated jacketed valves, designers should carefully consider the thermal requirements of the process along with sizes of flanges and types of valves to be used. Most large, full-port ball valves, for example, are available only in two-piece or three-piece configurations. Fabricating full jackets on these types of valves is very difficult (and expensive). Metal-seated ball and plug valves are also difficult to jacket without compromising leak-rate standards. In these instances designers may be better served to consider bolt-on heating jackets.

The four basic categories of CSI Fabricated Jacketed Valves are as follows:

Type A, Partial Jacket (Core-Size Flanges). The jacket terminates a short distance from the backs of the flanges. The body of the valve remains unmodified. These types of jacketed valves are used with Swaged Jacketed Pipe or similar piping with core-size flanges. Temperature profiles of the system generally are fairly wide.	Type A, Partial Jacket A = Takeout same as valve of line (core) size. B = Flange size same as nominal valve size.
Type B, Full Standard Jacket (Jacket-Size Flanges). The jacket covers the body of the valve and extends flange to flange. Before jacketing, the valve body is modified by lengthening the body and adding oversize flanges. The new face-to-face dimension is the same as a standard valve having the same size as the new flanges. Example: A 3" x 4" jacketed plug valve, Type B, has the face-to-face dimension as a 4-inch plug valve. These types of jacketed valves are used with Standard Jacketed Pipe.	Type B, Full Standard Jacket A = Takeout same as valve of jacket size. B = Flange size one size larger than core pipe.
Type C, Full Jacket (Core-Size Flanges). The jacket covers the body of the valve and extends flange to flange. The jacket terminates on the periphery of the flanges. The flange bolt holes are modified with tapped inserts. The valves must be installed by inserting and threading studs from the adjacent mating flanges. The tapped inserts are double-seal welded on front and back to contain the heating fluid. These types of jacketed valves are used with Swaged Jacketed Pipe or similar pipe with core size flanges.	Type C, Full Jacket, Core-Size Flanges A = Takeout same as valve of line (core) size. B = Flange size same as nominal valve size.
Type D, Full Jacket (Jacket-Size Flanges, Short Body). The jacket covers the body of the flange and extends flange to flange. The body is modified by adding oversize flanges. The face-to-face of the jacketed valve is the same as the body size of the valve. Example: a 3" x 4" jacketed globe-type control valve, Type D, has the face-to-face dimension of a 3-inch globe-type control valve. These types of jacketed valves are used with Standard Jacketed Pipe, usually in very dense piping systems where space is very limited, and to replace jacketed valves with special takeouts.	Type D, Full Jacket, Short Body A = Takeout same as valve of line (core) size B = Flange size one size larger than core pipe.