Synthetic Slings, Ropes and Winch Lines 2011 Pennsylvania REC Key Man Conference

The Good Old Days

Chains and Wire Rope -Inexpensive -Durable -They work -Heavy, -Conductive -Wire rope kinks and cuts -Easy to damage the equipment

Nylon-the First of the Common Synthetics Petroleum-Coal Based 1935 Toothbrush

WW II Uses of Nylon Replace Silk for Parachutes

WWII Use of Nylon Nylon Stockings

Nylon Very Strong Good Value Degrades at 350 o F. Melts at 460 o F. Nearly 10% stretch at working load Absorbs moisture

Polypropylene Made from Olefins Half of Nylon’s Strength Plastic Feel Lightweight-Floats Melts at 330 Degrees F. Inexpensive Will “Creep” with a sustained load Poor UV Resistance

Polyester Synthetic Polymer As strong as Nylon Less Stretch than Nylon Less Water Absorption than Nylon Melts at 480 degrees F. Costs about the same as nylon

Ultra High Molecular Weight Polyethylene (UHMWP) Trade names are Spectra or Dyneema (1980’s) Very high strength-3.5 times Nylon Very low stretch Floats Will “cold flow” Easier to shock load More expensive

Aramid Fibers Kevlar-Technora (early 1960’s) Very low stretch Not as strong as UHMWP Used in body armor and FR Clothing Very high melting point- 800 degrees F. Absorbs moisture Expensive Abrasive

Liquid Crystal Polymer Vectrus As strong as UHMWP Very little stretch 600 degree F. melting point Little moisture absorption Very expensive

Making Thread from Fiber Times have changed…

Webbing Manufacturing

3 Strand Rope Oldest style

Braided Rope No Twists-does not “unwind” when loaded No Hockling Less Stretch More design options

Rope Braider

Webbing and Rope Lifting Slings Versatile 5-1 Safety factor Lightweight Nylon and Polyester are inexpensive Available in high modulus fibers

ANSI B30.9

Sling Tags

Sewn Splices-Eye Splices-Adjustables Splices are stronger than the body of the sling Hardware rated 5/1 Splices must be sewn with a contrasting color Fabricated eye splices should have a whipping or a tie on 3 strand Adjustable slings must have an appropriate bearing area and back- spliced end

Methods of Hitching Loads Vertical Choker-Reduces capacity 30% Basket-Doubles capacity

The Effect of the Angle

Inspecting Web Slings Appropriate Tags Fuzzing Splice Integrity Broken Stitches Burns UV Degradation Cuts-Mechanical Damage Chemical Damage Hard or glazed surface

Inspecting Rope Slings Appropriate Tags Fuzzing Splice Integrity-Broken whipping Mechanical Damage to adjacent pairs UV-chemical degradation Burns-thermal or chemical Hard or glazed surface Stiffness

Tips for Using Synthetic Slings Avoid exposure to sharp edges-use pads No Knots-50% loss in strength Use appropriate lifting hardware Be aware of the lifting angles Balance the load Replace slings regularly Avoid shock loading

Lifting and Pulling Lines A variety of constructions are available for different applications including: 3 Strand 8 Strand 12 Strand Double Braid Parallel core

3 Strand Easy to manufacture Inexpensive Durable Stretches Unwinds when loaded

8 Strand Easy to splice No twisting Straighter Lay Flattens under load

12 Strand-Hollow Braid No Twisting Easy to splice Great for pulling lines

Double Braid A rope in a rope Many manufacturing options Less flattening in a sheave Not the strongest option because of the angle

Parallel Core Most efficient use of fiber-strongest Extremely durable Higher cost Harder to terminate

1 Inch Diameter Double Esterlon vs. Maxi Braid Plus Double Esterlon 44,000 lb. avg. break 4% stretch at working load Balanced construction 35 lb per 100 feet Nearly 14% stretch at break Good energy absorption Priced as Nylon Maxibraid Plus 60,000 lb. avg. break Less than 1% stretch at working load Load bearing core 28 lb. per 100 feet 2 ½ % stretch at break Poor energy absorption At least 2 times as expensive as DE

Elasticity Comparison

Energy Absorption 1” x 100’ Double Esterlon Strength: 40,200# Weight/100’: 34.4# Maximum Energy Absorption: 8,000 Ft. Lb./Lb. Maximum Energy Absorption/100’: 275,200# 1” x 100’ Maxibraid Plus Strength: 60,000# Weight/100’: 28.2# Maximum Energy Absorption: 2,645 Ft. Lb./Lb. Maximum Energy Absorption/100’: 74,589#

Work Load / Longevity

Winch Line Inspection Lay the line out Inspect the eye-whipping Working area of the line Fuzzing Adjacent strand cuts- burns Stiffness-bulges Narrowing Glazing

Tips for Pulling & Winch lines Appropriate line for vehicle and crew Minimum wraps 4 or 8 on drum Minimum 3/1 diameter sheaves No shock loading No Side loading Use a sling End for end at 6 months Clean the rope Stow the headache ball Know the rope-construction and time in service Never Assume

The Bitter End Thank you