Page 12 - Wire Rope News & Sling Technology - February 2020
P. 12

continued from page 10
         into the crane  industry.  When  these
         “counter-helix”  ropes are bent around
         sheaves, the friction wear starts be-
         tween the top of the inner strands and
         bottom of the outside layer of strands
         where they make contact with each
         other, just where you can’t see it.
           Also, when used as a single part reev-
         ing, if the load is great enough to over-
         come the counteracting force of Category
         3 rope, spin resistant characteristics will
         allow the rope to rotate then loaded. The
         inner counter lay strands will spin tight
         enough to break, thus losing about 40%
         of the rope’s strength. When used with
         one part, a swivel must not be used. It
         is assumed that when the rope turns
         the load, the riggers will attach tag lines
         to the load to stop from spinning, thus,
         stopping the rope from twisting.                                                                Fig. 5

         SYNTHETIC ROPES                    ic  polyamide  (aramid,  most  common),   tion methods for their ropes, Fig. 6.
           The crane community was waiting for   and liquid crystal polyester (LCP), and   Second,  is the cable-laid type with
         a synthetic rope chapter. The guidance   Standard Performance  rope: poly-  three or four-strand construction. This
         was needed because of the increased   ester, and nylon (probably more famil-  type is also the standard natural fiber
         use of synthetic ropes, as opposed  to   iar). These two categories are listed as   rope construction.
         natural fiber ropes, being installed on   examples – but there is no limit set for   Third, also the latest type to our mar-
         mobile cranes.  The B30.30 standard   the use of other materials recommended   kets (to my knowledge), is jacketed,
         sets the general types and uses of this   by crane or rope manufactures. So, user,   double braid, core dependent rope type.
         product for the American market.   this is your first training obstacle or op-  This style is a rope designed for multi-
           Interesting to note, ASME included   portunity. It is up to you to make the   reeving and keeping its shape on the
         somewhat of a disclaimer (in my view),   proper selection of the material of the   drum. Manufacturers say the outer jack-
         required  training  for  the  user.  Users   synthetic rope you employ.   et is for wear only and is not included in
         shall be trained in the “use, selection,   Rope construction is split  into four   the rope’s published breaking strength.
         inspection,  installation, maintenance,   categories for use on hoisting equip-  Because the interior strands are not vis-
         attachment, replacement, and effects   ment. First is a single braid type,   ible for inspection, the outer jacket is an
         of the environment” covered in  this   which  is  constructed  with  either   indicator of wear. You must be careful
         chapter. ASME doesn’t want to be sued   eight or twelve strands. Its shape is   to read and follow the manufacturer’s
         either. This application is much differ-  round  when  new,  but,  can  flatten  on   inspection and replacement criteria. An-
         ent from the average synthetic sling   the drum with use. One maintenance   other training obstacle or opportunity!
         knowledge,  Fig. 5,  warning  the users   recommendation is to “hand form”   Fourth,  and the  last type listed in
         that they need to learn new methods!   the rope back into it’s original shape.   B30.30 is  the  most complex of  con-
           The material is divided into two cate-  Manufacturers  state  that  flattening   struction, parallel core, braided jacket:
         gories: High-performance rope:  high   does NOT reduce the strength of the   three-strand core type. Again, this is a
         modulus polyethylene (HMPE), aromat-  rope. Manufacturers  provide inspec-  very specific used and maintained rope.
                                                                               The user and their employees must be
                                                                      Fig. 6   trained, preferably by factory person-
                                                                               nel, on-site, if possible.
                                                                                 There is more good general informa-
                                                                               tion  in  the  standard about inspection
                                                                               and end attachments that need to be
                                                                               studied by the user.  The standard
                                                                               shows  pictures  of damaged  ropes and
                                                                               replacement criteria.  However,  every
                                                                               rope manufacturer  has informative,
                                                                               well illustrated brochures  that show
                                                                               and explain their particular rope. I rec-
                                                                               ommend  you obtain a copy and learn
                                                                               about the  products  you  use  to  hoist
                                                                               tons of material in the air!
                                                                                 This Standard’s greatest contribu-
                                                                               tion  to  safety (my opinion)  is  that it
                                                                               provides the reader information to ask
                                                                               better questions,  which  improves the
                                                                               answers received!  WRNWRN

         12     Wire Rope News & Sling Technology   February 2020
   7   8   9   10   11   12   13   14   15   16   17