TM 10-8400-203-23 3-5.  REPAIR  AND  MAINTENANCE  OF  BODY  ARMOR–Continued (2) (3) (4) (5) When replacing the vinyl casing, remove the ballistic insert from old casing. If the ballistic insert (after examination)  is  found  to  be  dry,  not  damaged,  and  contains  stiffeners,  place  it  into  a  new  casing, insuring that the ballistic insert lies flat and unbunched in the casing and that the collar is inside the casing collar. Force excess air out of the casing then heat seal the bottom opening of the vinyl casing to form a water tight closure. Heat sealing of vinyl casing. Insure that ballistic insert is properly positioned in the vinyl casing; force excess air out of casing: smooth the bottom open end so as to be free of wrinkles or folds, and seal the end in the dielectric heat sealer platens. The closing seal shall be not more than 3/8 inch (0.953 cm) from the end. Care should be taken in the sealing operation that no loose threads, fuzz, or any other foreign matter is in the area to be heat sealed. The heat seal on the end should intersect and cross both  of  the  side  heat  seal  areas.  The  closing  seal  shall  be  obtained  in  accordance  with  good  heat sealing practice to produce a seam of equal strength to that of the side seams. It is recommended prior to each production run that machine settings be checked on a vinyl casing by performing at least three or four trials to insure an adequate seal. Heat  sealing  of  vinyl  casings  by  hand.  Perform  hand  sealing  in  the  same  way  as  described  above except as follows: (a) (b) (c) (d) (e) (f) (9) (h) An electric hand sealing iron (para 3-11) shall be used. The sealer shall be set at its maximum high setting. The heat sealing shall be done on a smooth wooden or  hardboard  surface. The wooden or hardboard working surface shall be covered in the heat sealing area with a 5 MIL teflon film to prevent sticking of the film to the surface when sealing. Alternatively, the heat sealing area may be covered with silicone coated release paper, coated side up. The envelope open end to be heat sealed shall be placed on the working surface, smoothed out, and covered by a transparent or translucent ironing film (5 MIL thick teflon (sec Ill) ). The ironing film allows the operator to see whether thorough fusion of the two layers of vinyl casing has taken place along the entire closure. The sealing shall be aided by the use of a guide, such as 1/4 inch (0.635 cm) thick steel bar stock, along which the sealing iron shall be drawn. The sealing iron shall be tilted approximately 20° so that the sealing is done by the edge of the sole plate only, to produce a seal line between 1/16-to 3/16-inch (0.159 to 0.476 cm) wide. The sealing shall be conducted at an approximate rate of one inch per second. After sealing, allow several seconds of cooling to take place, then peel off the ironing film slowly. After  heat  sealing,  place  the  casing  with  ballistic  insert  into  the  nylon  outer  cover.  Fold  the  excess bottom  length  of  the  vinyl  casing  under  and  stitch  the  end  of  the  outer  shell,  taking  care  that  the stitching does not pass through any portion of the vinyl casing, 3-11