National Stock Number: 5330-12-184-4706
Federal Supply Class: 5330
National Item Identification Number: 121844706
Description: BACK-UP RING,PREFOR
Detail: A CIRCULAR SHAPED ITEM WITH AN APERTURE MANUFACTURED TO PREDETERMINED DIMENSIONS, CONSTRUCTED WITH A RECTANGULAR CROSS SECTION THAT MAY BE SOLID, WITH JOINT, OR IN A HELICAL FORM THAT FACILITATES SPIRAL WRAP INSTALLATION. IT PREVENTS SEAL EXTRUSION UNDER PRESSURE AND IS DESIGNED TO FIT ON THE DOWN-PRESSURE SIDE OF A GLAND GROOVE WITH A PACKING, PREFORMED OR O-RING.
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