Lifeline rope and Lifeline inspection by csgirla


									Lifeline rope

   Lifeline rope
   By Jennifer Coccimiglio, Writer, and Brian Varrasso, Project Coordinator, CSAO

                                                   This three-strand twisted rope is made from a polypropylene/polyethylene blend.
                                                   The different-coloured strand indicates that the material is a blend.

                                                   blend are good, but rope made of          Polypropylene only
                                                   only polypropylene is not.
                                                                                             Do not use polypropylene rope for
                                                                                             lifelines. Here’s why.
                                                   Nylon is a good choice for a lifeline     At a standard 5/8” diameter, a
                                                   because of its strength and               polypropylene rope will usually not
                                                   durability. It is usually more            meet the 6000-pound strength
        When you’re wearing fall                   expensive than a polypropylene/           requirement in CSA (Canadian
        protection, you trust your life to         polyethylene blend.                       Standards Association) standard
        your lifeline. Make sure it can                                                      Z259.2.1, Fall Arresters, Vertical
        actually save your life. Make sure                                                   Lifelines and Rails.
        it’s the right kind of rope.
                                                   Like nylon, polyester is also a good      To meet the strength requirement,
        Some types of rope are better than         choice for a lifeline.                    the manufacturer will often make
        others for lifelines—and some                                                        the diameter slightly larger than
        types should never be used for             Polypropylene/polyethylene                5/8”. But if you use it in a rope
        lifelines at all. This article will help   blend                                     grab, the extra diameter will mean
        you make informed decisions                                                          more wear and tear, and the rope
        when you’re selecting rope for             A good choice for a lifeline is a         will be damaged quickly.
        lifelines.                                 polypropylene/polyethylene blend.
                                                   The polyethylene makes the rope           Polypropylene also degrades quicker
        We’ll look at two aspects of rope:         much stronger than one made with          than nylon and other materials
        its material and its design.               polypropylene only. It also makes         when exposed to ultra-violet (UV)
                                                   the rope more resistant to abrasion       radiation and weathering. After a
        Rope material                              and ultra-violet (UV) radiation           few months of the sun beating
                                                   than pure polypropylene.                  down on it, a polypropylene rope
                                                                                             can lose a significant amount of its
        Nylon, polyester, polypropylene,
                                                   The blend is less expensive than          strength.
        and polyethylene are common
                                                   nylon and only slightly more
        materials used when making rope.                                                     For these reasons, do not use
                                                   expensive than polypropylene
        For lifelines, nylon, polyester, and                                                 polypropylene rope for lifelines.
        a polypropylene/polyethylene

                                                                                                              Lifeline rope

Rope design

The materials listed on the
                                          Do not use utility rope for lifelines.

                                           utility rope. Do not use utility
                                           rope for lifelines. Utility ropes are
                                           often spliced, which further
previous page can be made into             decreases their strength. Lifelines
rope according to several designs.         must be made of continuous
There are generally three styles of        unspliced rope.
rope design: twisted, kernmantle,
and braided.                               Kernmantle design
There are advantages and                   Kernmantle rope is the ideal
disadvantages to each design. Here         choice for most lifeline situations.
are the details.                           It consists of an inner core of
                                           synthetic fibre filaments running
Twisted design                             straight (they’re not twisted or
                                           braided), and an outer braided
Twisted rope is an acceptable              sheath which surrounds and
design for vertical lifelines, and it’s    protects the filaments.
certainly the most common. But a
                                           When attached to the rope, the
twisted design makes the rope
                                           load is held by the strength of the     Kernmantle rope is very durable. The
vulnerable to abrasion, which
                                           inner core filaments, while the         fibres in the core run straight. All of
decreases total rope strength.
                                           outer sheath only protects the          the rope’s strength is in the core, while
Twisted rope is more likely than           rope’s core from dirt, UV               the braided sheath protects the core.
braided rope to get caught on              radiation, and abrasion. The
things and rip or tear.                    sturdy, sheathed design of
                                           kernmantle rope can be a
Twisted ropes are often made from                                                  Braided design
                                           disadvantage in certain
a polypropylene/polyethylene
                                           applications (such as suspended
blend. The design is usually three-                                                Braided rope is more resistant to
                                           access), because it’s less flexible
strand twisted. Generally a twisted                                                abrasion than twisted rope, so it
                                           than other rope.
polypropylene/polyethylene blend                                                   will not tear or rip as easily.
rope intended for safety                   Although kernmantle rope is
applications will have a single            significantly more expensive than       Solid braid design
strand of a different colour to            other rope, it usually has a longer
show that the material is a blend          service life.                           Solid braid ropes are used mostly
rather than just polypropylene                                                     for window washing because they
alone. (See photos on page 4.)                                                     are very flexible. This allows them
                                                                                   to be twisted around suspension
If all three strands are the same                                                  devices.
colour, the rope is probably a
                                                                                              Continued on page 6

                                                      CONSTRUCTION SAFETY MAGAZINE Summer 2007                            5
Lifeline rope

   Lifeline rope
   Continued from page 5

        A solid braid rope is very flexible.     A double braid rope consists of a
        It can stretch under load.               braided sheath covering a braided
                                                 core. Both the core and sheath
                                                 support the load, so they must be
                                                                                          If the core and sheath in double-braid
        Unlike kernmantle rope, however,         aligned. If the sheath bunches up, you
                                                                                          rope are not aligned, the rope loses
        all strands give the rope its            decrease the rope’s strength by 50%.
                                                                                          half of its strength. This photo shows
        strength. This means that any
                                                                                          how the sheath can bunch up.
        wear, cuts, or variations in size will
                                                 Both the core and the sheath must
        drastically decrease the rope’s
                                                 be aligned for the rope to maintain      Twisted and braided ropes stretch
                                                 its total strength. Often, the outer     significantly while kernmantle
                                                 braid becomes caught on something        ropes stretch very little. Wet
        Double braid design                      and bunches up, which decreases          conditions can make some ropes
        Double braid ropes have a braided        the rope’s strength by 50 percent.       stretch more than others.
        core protected by an outer braided       When the sheath bunches up, the
        sheath. This construction gives the      inner core supports all of the load.     You need to take stretch into
        rope good strength and the outer         Unless you can ensure the two            account when calculating possible
        braid makes it resistant to              braids remain in the correct             free-fall distance. (See “Lifeline
        abrasion.                                position, this rope is not suitable      inspection” on the next page.)
                                                 for safety applications.                 Always check with the
        With this design, however, the
        outer and inner braids can move                                                   manufacturer to learn the
        freely and separately. This is a
                                                 Stretch                                  advantages and disadvantages of the
        problem because with double braid                                                 rope you’re considering.
        rope, both the core and the sheath       Other aspects of rope affect its
        support the weight of the load.          safety performance, such as stretch.
                                                                                          CSAO thanks Rob Ludwig from
        (This is not the case with               Some ropes stretch more than             Cancord Inc. for providing
        kernmantle rope.)                        others when subjected to a load.         information and rope samples.

                                                                                                 Lifeline inspection

Lifeline inspection
 Inspect your lifeline and lifeline        $ Decreased elasticity (a rope
 setup before each use.                      loses elasticity especially if it
                                             has been subjected to a
 1. Make sure you have the right             load).
    type of rope for a lifeline (see
    article on page 5).                4. Never reuse a lifeline that has
                                          been used for any other
 2. Look for the CSA                      purpose. Throw away a lifeline
    (Canadian Standards
                                          that has stopped a fall unless it
    Association) logo.
                                          has been recertified by the
    Lifelines must be

    CSA certified. The logo will
    be on the rope, or on the reel     5. A vertical lifeline must be used
    if it came in bulk. If the rope       by only one person at a time.
    is not CSA certified, do not
    use it for lifelines.              6. A vertical lifeline must reach
                                          the ground or a level above
 3. Inspect the rope to see if it is      ground where you can safely
    in good condition. If you find        exit if your fall is arrested.          Hitting the ground while tied off.
    any of the following things,
    the lifeline is unsafe.            7. Ensure that the                            your lanyard will extend. Also,
                                          rope grab is                               lifelines stretch under load. The
     $ Tears or cuts.                     compatible with                            CSA standard allows up to
     $ Unequal strand size or             the type of rope                           22% stretch. Find out from the
       shape variations.                  you are using for                          manufacturer how much your
                                          your lifeline.                             rope will stretch.

                                                                                     Take all of these factors into
                                                                                     account when calculating
                                                                                 9. A vertical lifeline must have a
                                                                                    positive stop—a knot or device
                                                                                    at the end of the rope to
                                                                                    prevent the rope grab from
     $ Discolouration.                                                              slipping off the end.
     $ Broken or loose strands             Check the rope-grab                   10. Ensure that the lifeline is
       inside the rope (untwist the
                                           manufacturer’s instructions for         protected from abrasive or
       rope and check inside).
                                           a compatible lifeline.                  sharp edges.
     $ Accumulated powder or
       dirt inside the rope            8. Consider the distance to the           11. Store lifelines
       (untwist the rope and              ground or level below when                   in a dry location
       check inside).                     determining where you attach
                                                                                       out of direct sunlight
                                          your rope grab. You do not
     $ Loose thimbles (ensure that        want to strike a lower surface               away from sharp objects
       thimble splices are in good                                                     away from corrosive
                                          or hit an object before your fall
       condition).                                                                      chemicals.
                                          is arrested. Calculate how long

                                                   CONSTRUCTION SAFETY MAGAZINE Summer 2007                            7

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