mark pederson application engineer acrp may 10 th 2012

Mark Pederson

•Application Engineer•ACRP May 10th 2012

Overview

• Lifting Sling Testing> Introduction to Effect of D:d ratio> Single leg tests> Grommet tests> Basket tests> Choker tests> Published Spec Sheet

• Inspection Retirement Criteria> Sources for Guidelines> Mechanisms that Cause Damage> Inspection Items

• Hardware> Class1 Rope Hardware > Class2 Rope Hardware> Synthetic Rope Specific Hardware

Intro to Effect of D/d on Efficiency

• The Tighter the Bend the greater the stress Concentration• With High Modulus fibers this effect is more dramatic

Sling on a Pin:


Sling on a Pin:


Sling on a Pin:

• Parallel Core Is effected in a bend


Sling on a Pin:

• Braided Construction is beneficial

Single Leg Testing

> Single Leg• Weakest at base of splice

• 2:1 D/d recommended

• Efficiency > 1x Rope Strength

Single Leg Testing

> Single Leg

• Single leg slings are used to baseline most rope strengths

• Theoretical load distributions

• There is a true loss in bend around pin but each leg around pin only carries ~½ T

Single Leg Testing

> Single Leg Testing

• Straight Pull

• D:d = 8 , 4 , 1

• D/d = 1 did not show significant strength loss, however break occurred at the back of the eye (on the pin)

Grommet Testing

• Grommet strength is actually <2x rope strength

• Current industry recommendations range from 1.6-1.8x entered

Grommet Testing

• Grommet configuration highlights bending losses

Grommet Testing• D/d Grommet Strength, Bearing size is

critical for assuring proper design and maintaining grommet efficiency

Grommet Testing

• Splice Placement on D:d >4 :> Splice area centered on the pin

allows the legs to more evenly adjust upon loading.

> Two splices do not produce a more efficient sling.

> Testing has proven that the splice is more efficient with lower D:d ratios

A 1.6-1.8xB 1.7-1.9xC 1.7xD 1.75x

Grommet Testing

> Grommet• Weakest on the back of pin

• 8:1 D/d recommended

• Efficiency ≤ 1.6x Rope Strength

Basket Testing

• Basket

Choker Testing

• Current recommendations:> ASME B30.9 80% (PET

roundslings)

> Flory/Richards* 60% (HMPE slings)

• Test Results*:• 12-strand, HMPE fiber

> Ranged from 60% - 75% (varied by manufacturer)

• Choke Angle is critical> Choker strength

Choker Testing

• Single leg and Grommet in Choker• 3/8” and ¾”

Lifting Sling Table

> Layout• Similar to ANSI table layout

• 5:1 Safety Factor built in

• Common horizontal angles rated for basket lifts

• Minimum D/d recommended

• Reductions for lower basket D/d

• Inspection and retirement Criteria included

Sling Table

> Updated Sling Table• Choker Slings• Adjustable Slings

Large Diameter Sling Testing

• Tested slings in a large range of sizes

• Developed a model that is used to design project specific lifts

Overview

• Lifting Sling Testing> Single leg > Grommet> Basket> Choker> Published Spec Sheet



Inspection Retirement Criteria

• Inspection Retirement Criteria> Sources for Guidelines

• Cordage Institute - International association of rope twine and related manufactures/Suppliers .

• Educating on the proper use of products through standardsCI 2001-04“Fiber Rope Inspection and Retirement Criteria

• Rope Type, Damage Description, Reference Txt, Reference Picture, Repair , Downgrade , Retire



• Handbook of fibre rope technology [Book] by Henry A. McKenna, J. W. S. Hearle, Nick O'Hear, Textile Institute (Manchester, England) in Books

• Very similar to the Cordage Institute



• Samson Rope


> Mechanisms that Cause Damage

Excessive Tension / Shock Loading Cyclic Tension WearExternal AbrasionCuttingPulled Strands and YarnsFlex Fatigue or Bending FatigueTerminationsKnotsAxial Compression and Kink BandsHockle, Twist , Kink or CorkscrewSunlight DegradationChemical and Heat DegradationDirt or Grit Particulate


Initial Inspection

• IF > Rope Displays Moderate Wear> No history of use> Potential injury or damage to equipment

= Downgrade or Retire the rope

Samson / Cordage Institute / Handbook of fibre rope technology


• Cyclic Tension Wear• IF:

> Broken Internal Filaments over Length> Matted Filaments at strand rub areas=Downgrade / Retire


Inspection Retirement CriteriaExternal Abrasion• IF:

> Rope Cross Section reduced by 10% in whole rope=Downgrade / Retire

• IF:> Rope Cross Section reduced by 25% =Repair/ Retire


Inspection Retirement CriteriaCutting• IF:

> Rope Cross Section reduced by 10% in whole rope=Downgrade / Retire

• IF:> Rope Cross Section reduced by greater than 10% =Repair/ Retire



• Pulled Strand

> Less than 15% of strands are pulled out a repair can be made.> Greater than 20% of strands are pulled out a repair should not be

made. Downgrade the rope and retire


Inspection Retirement CriteriaFlex Wear on Pulleys/ Rollers• IF:

> Internal Fusion> Wear on strand crowns> Broken filaments at strand rub points =Downgrade / Retire


Inspection Retirement CriteriaFlex Wear on Pulleys/ Rollers

Inspection Retirement CriteriaSpliced Eye• IF:

> Cuts> Splice Pulling out> Incorrect Splice> Damaged Thimble=Repair

Inspection Retirement CriteriaCreep • IF:

> Rope Exceeds limits set by manufacture> History of the rope indicates it is a concern=Retire

Inspection Retirement CriteriaCompression


Sunlight Degradation• IF:

> Polypropolene, Brittle and broken outer fibers= Retire> Ropes less than 1” diameter, 1yr plus exposure, aramid, nylon,

polypro=Retire/ Downgrade


Chemical And Heat Degradation

• IF:> Known exposure= Retire> Discoloration, Brittle Fibers, Stiff,=Retire


Dirt or Grit

• IF:> Dirt or Grit is found internally> Broken an powdery fiber present= Retire

Overview

• Lifting Sling Testing> Single leg > Grommet> Basket> Choker> Published Spec Sheet



Hardware

• Hardware> Class1 Rope Hardware Lower Strength , Higher Elongation FibersPlastic Thimbles , Non Reinforced Thimbles , Plastic Spools

Hardware

• Hardware

> Class2 Rope HardwareHigh Strength , Low Elongation FibersTubular Thimbles, Reinforced Thimbles, Aluminum Spools

Hardware

• Hardware> Synthetic Rope Specific Hardware / Shackles> Wide body shackle> Crosby Sling Saver Spool

Hardware

> Shackles

• Standard and Wide Body

• Small D/d for Grommets

• Quick Easy and readily available

• Thank you!

• Questions

mark pederson application engineer acrp may 10 th 2012

Documents

pin slide

rope strength slide

single leg testing

basket testing basket

bend slide

beneficial slide

single leg single leg

sling testing introduction