ReplacementFigure 7-8 shows a typical O-ring installation.When such an installation shows signs of internalor external leakage, the component must bedisassembled and the seals replaced. Sometimescomponents must be resealed because of the agelimitations of the seals. The O-ring should alsobe replaced whenever a gland that has been inservice is disassembled and reassembled.Often a poor O-ring installation begins whenan old seal is removed. O-ring removal involvesworking with parts that have critical surfacefinishes. If hardened-steel, pointed, or sharp-edged tools are used for removal of O-rings orbackup rings, scratches, abrasions, dents, andother deformities on critical sealing surfaces canresult in seal failure which, in turn, can result inFigure 7-7.—Critical dimensions of an O-ring.might scratch or mar component surfaces ordamage the O-ring. An O-ring tool kit isavailable in the supply system for O-ring in-stallation or removal. If these tools are not onhand, special tools can be made for this purpose.A few examples of tools used in the removaland installation of O-rings are illustrated infunctional failure ofWhen removingnot use pointed orthe equipment.or installing O-rings, dosharp-edged tools whichFigure 7-8.–Typical O-ring instalation.7-9
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