Hancock 1500, 2500 and 4500 Pound Forged ... - Industrial Controls

pressure as a safe practice and ! CAUTIONtherefore discourages sech repackingwhen not indicated byoperational necessity. (Again,see “Safety Precautions”Do not repack a fixed backseat valveSection 2.)under pressure unless it is absolutelynecessary to avoid possible personalinjury.2. Specific StepsIf operational considerations dictatethat adding or changing! DANGERpacking in a fixed backseat valveis absolutely necessary, adherenceto the following steps is recommendedto reduce the possibil-If a valve nameplate cannot be read oris missing, do not add or change packingunder pressure, as this will result insevere personal injury or deathity of personal injury.a. Check the valve nameplate to be sure it ismarked “fixed backseat”. If it does not sayfixed backseat, or the nameplate cannotread or is missing, DO NOT attempt to addpacking if the valve is under pressure.b. Once it has been determined that the valveis of the fixed backseat design, rotate thetee handle counterclockwise until the discnut contacts the yoke bushing. Firmly backseatthe valve by applying torques as listedin Table 2, Section 4 of this manual.c. Remove the valve tee handle to preventaccidentally rotating the stem.d. Loosen the packing gland stud nuts byrotating them one full turn counterclockwise.e. Wait 2 to 3 minutes, then visually check thevalve packing for leakage.f. If no leakage is detected, slowly loosen thestud nuts until the gland flange is no longertight against the packing gland. Do notremove the nuts at this point. Again, wait 2to 3 minutes and check to be sure that thegland flange has not been forced tightagainst the gland by pressure.g. Once assured the backseat is not leaking,remove the two packing gland stud nutsand packing gland nut.k. Spread open the cut in the individual compressedgrafoil ring just enough to slip itonto the stem. Slide the individual rings intothe gland stuffing box, being careful toplace the split on successive rings 90°apart. This will ensure that no possible leakpath exists when re-packing is complete.l. The last ring to be installed must be a braidedgraphite filament “bull ring”.m. Reassembly the packing gland, gland studnuts and tee handle as described in the Reassemblyinstructions (Section 4.m) of thismanual.n. Tighten the packing as described in Section4.l of this manual.K. Disassembly1. Loose Backseat Valves(For parts nomenclature, refer to Figure 1Section 4 of this manual.)Remove the two packing stud nuts which arelocated above the packing gland flange by acounterclockwise rotation. Remove the twopacking gland studs and two remaining studnuts. Move the packing gland flange along thestem toward the tee handle, then remove thetwo halves of the packing gland.Rotate the tee handle counterclockwise untilthe disc nut contacts the backseat. Removethe tee handle locknut by a counterclockwiserotation. Observe that the thread bushing hasbeen stake locked at the factory to prevent it’srotation during valve operation, (see Figure 4).Because of this factory stake locking, theraised boss must now be removed before thethread bushing can be removed from the yoke.The stake lock may be removed by peering, orby a hand held grinder or a file. Remove thethread bushig by rotating it counterclockwise.Note: The stem should br prevented fromrotation while the bushing is being rotated.Notes: If packing is only to be added to thevalve, it may be done at this point.If the packing is to be totally changed in thevalve, adhere to the requirements of stepsh-n, below.h. Remove the old packing by using a corkscrew or wire hook.i. A new split ring packing set can now beinstalled in the valve.j. Place a bull ring around the stem at thearea between the yoke arms, then slide thering into the gland stuffing box.FIGURE 4—Stake Lock7