Juniper Industries Knife Edge Inspection

THE INTEGRITY OF EVERY WATERTIGHT CLOSURE DEPENDS ON A GOOD KNIFE EDGE AND GASKET SEAL. KNIFE EDGES ARE SUBJECT TO WEAR AND TEAR. THEY ALSO MAY BE DAMAGED BY MISALIGNMENT WHEN CLOSURES, THEIR FRAMES OR THE SURROUNDING STRUCTURES ARE BENT OR STRESSED. IN ADDITION TO BASIC VISUAL INSPECTION TO MAKE SURE GASKETS ARE CLEAN AND FREE OF PAINT AND THAT BOTH KNIFE EDGES AND GASKETS ARE SOUND, THERE ARE A FEW SIMPLE TESTS THAT REVEAL ANY PROBLEMS WITH GASKET INTEGRITY. ONE COMMON TEST IS THE CHALK TEST, WHICH IS COVERED ON ITS OWN PAGE. IN ADDITION, THE FOLLOWING BASIC TESTS SHOULD BE PART OF GASKET AND KNIFE EDGE INSPECTION PROCEDURES.

FIVE STEP BASIC STRAIGHTNESS TEST

OPEN THE FITTING. CLEAN THE KNIFE EDGE AND GASKET TO REMOVE PAINT, DIRT, RUST AND NICKS. USE #320 GRIT ALUMINUM OXIDE ABRASIVE CLOTH TO CLEAN THE KNIFE EDGE. BE SURE TO REMOVE ANY GRIT WITH A CLEAN RAG.
PLACE A STRAIGHTEDGE 30" - 36" LONG AGAINST THE KNIFE EDGE. THE KNIFE EDGE SHOULD NOT VARY IN STRAIGHTNESS BY MORE THAN ± 1/16". IF A STRAIGHTEDGE IS NOT AVAILABLE, A TAUGHT PIECE OF STRING WILL ALSO REVEAL DEVIATION FROM STRAIGHTNESS. IF THE KNIFE EDGE IS OUT OF TOLERANCE DUE TO A SMALL VISIBLE BEND, RESTORE IT TO STRAIGHTNESS BY BENDING OR HAMMERING. IF THE BEND CANNOT BE EASILY REPAIRED THIS WAY, CONSIDER REPLACING THE CLOSURE.
CHECK THE HEIGHT OF THE KNIFE EDGE, WHICH SHOULD BE 1-7/16" ± 1/8". A KNIFE EDGE THAT IS TOO HIGH DAMAGES THE GASKET. GRIND IT DOWN TO THE REQUIRED HEIGHT. A KNIFE EDGE THAT IS TOO LOW DAMAGES HINGES. BUILD IT UP WITH CRES STAINLESS STEEL ELECTRODE AND AFTERWARDS FILE IT TO MAKE IT STRAIGHT AND SMOOTH. FOR STEEL CLOSURES USE TYPE 309 ELECTRODE, FOR STAINLESS CLOSURES USE TYPE 316 ELECTRODE AND FOR ALUMINUM CLOSURES USE TYPE 5356 ELECTRODE.
CHECK THE FRAME AND KNIFE EDGE FOR TWISTING BY PUTTING STRINGS AT RIGHT ANGLES (FOR ROUND CLOSURES) OR DIAGONALS (FOR RECTANGULAR CLOSURES) ACROSS THE CLOSURE. THEY SHOULD JUST TOUCH WHERE THEY CROSS. IF THEY ARE MORE THAN 1/8" APART AT THEIR INTERSECTION OR IF THEY PRESS ON EACH OTHER SO MUCH THAT ONE STRING VISIBLY DISTORTS THE OTHER, THE TWIST OF THE KNIFE EDGE OR FRAME IS EXCESSIVE AND THE CLOSURE WILL PROBABLY HAVE TO BE REPLACED.
CHECK THE FRAME AND KNIFE EDGE FOR WARPAGE BY PUTTING STRINGS AT RIGHT ANGLES ACROSS THE CLOSURE. IF THE CLOSURE IS A RECTANGULAR, THE STRINGS SHOULD CONNECT THE CENTERS OF OPPOSITE SIDES. THEY SHOULD JUST TOUCH WHERE THEY CROSS. IF THEY ARE MORE THAN 1/8" APART AT THEIR INTERSECTION OR IF THEY PRESS ON EACH OTHER SO MUCH THAT ONE STRING VISIBLY DISTORTS THE OTHER, THE TWIST OF THE KNIFE EDGE OR FRAME IS EXCESSIVE AND THE CLOSURE WILL PROBABLY HAVE TO BE REPLACED.