Smith-Blair 975 Restrained Dismantling Joint, Steel Body, AWWA Class D Flanges, 4-72 in

The Smith-Blair Style 975 is a restrained dismantling joint for valve, pump, meter and other flanged fitting installations, 4 to 72 in nominal. A flanged spool telescopes through a flanged coupling adapter sleeve to fit the gap between companion flanges, and restraint rods tie the two end flanges together to carry the thrust, so no other joint restraint is needed at the valve or pump.

It is the follower-flange design of the 971 with restraint rods added: the follower is cast ductile iron on 3-12 in and steel on 14 in and larger, with a Nitrile gasket sealing on the spool. Choose the nominal size, then alloy or 304 stainless bolts, nuts and tie rods.

Application: restraining and dismantling valve, pump, meter and other flanged fitting installations, including butterfly valves and pumps that come out of service for maintenance.

Key Features

• Working pressure up to 150 PSI
• Restraint rods tie the flanges together, making other joint restraints unnecessary
• Telescopes to fit varying face-to-face dimensions; no special tools required
• Flange gaskets install without prying apart mated flanges
• Meets applicable portions of AWWA C219; gasket certified to NSF/ANSI 61, and the Smith-Blair spec sheet certifies the joint to NSF/ANSI 61 and NSF/ANSI 372

Up to 150 PSI on every size. 4 to 72 in. For a particular installation the allowable pressure also depends on the piping system, service conditions and installation workmanship; Smith-Blair bases the restraint rod quantity on the system design working pressure and offers a higher-pressure design on request.

Materials subject to change by the manufacturer.

Flanged steel, ductile iron and cast iron pipe, and flanged valves, pumps, meters and fittings.

Choose the size and bolt material; the part number shows in the last option.

From the Smith-Blair 2025 price book; rod material follows the bolt choice (alloy or 304 stainless).

• Check that the companion flanges match the joint's flanges and are parallel and axially aligned, then clean the flange faces of scale, dirt and debris.
• Remove the restraint rods and loosen the follower bolts so the spool moves freely, set the joint between the companion flanges (note the flow orientation in the instructions) and bolt each end hand tight with the flange gaskets.
• Lubricate the spool and gasket with a soap-and-water solution that meets the water and pipe supplier's requirements, then slide the follower and gasket into place.
• Torque the end-flange nuts to the job specification, then insert the restraint rods and hand-tighten their nuts.
• Tighten the follower nuts evenly, alternating sides, to the torque in the instructions; re-torque after the line is pressurized.

From Smith-Blair Installation Instructions TI-033 (Rev 08/27/21), in the Data Sheet tab.