Presentation is loading. Please wait.

Presentation is loading. Please wait.

Mark Pederson Application Engineer ACRP May 10 th 2012.

Similar presentations


Presentation on theme: "Mark Pederson Application Engineer ACRP May 10 th 2012."— Presentation transcript:

1 Mark Pederson Application Engineer ACRP May 10 th 2012

2 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

3 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:

4 Intro to Effect of D/d on Efficiency Sling on a Pin:

5 Intro to Effect of D/d on Efficiency Sling on a Pin: Parallel Core Is effected in a bend

6 Intro to Effect of D/d on Efficiency Sling on a Pin: Braided Construction is beneficial

7 Single Leg Testing >Single Leg Weakest at base of splice 2:1 D/d recommended Efficiency > 1x Rope Strength

8 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

9 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)

10 Grommet Testing Grommet strength is actually <2x rope strength Current industry recommendations range from x entered

11 Grommet Testing Grommet configuration highlights bending losses

12 Grommet Testing D/d  Grommet Strength, Bearing size is critical for assuring proper design and maintaining grommet efficiency

13 Grommet Testing D/d  Grommet Strength, Bearing size is critical for assuring proper design and maintaining grommet efficiency

14 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 x B x C1.7x D1.75x

15 Grommet Testing >Grommet Weakest on the back of pin 8:1 D/d recommended Efficiency ≤ 1.6x Rope Strength

16 Basket Testing Basket

17 Choker Testing Current recommendations: >ASME B % (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

18 Choker Testing Single leg and Grommet in Choker 3/8” and ¾”

19 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

20 Sling Table

21 >Updated Sling Table Choker Slings Adjustable Slings

22 Large Diameter Sling Testing Tested slings in a large range of sizes Developed a model that is used to design project specific lifts

23 Overview Lifting Sling Testing >Single leg >Grommet >Basket >Choker >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

24 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 standards CI “Fiber Rope Inspection and Retirement Criteria Rope Type, Damage Description, Reference Txt, Reference Picture, Repair, Downgrade, Retire

25 Inspection Retirement Criteria >Sources for Guidelines 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

26 Inspection Retirement Criteria >Sources for Guidelines Samson Rope

27 Inspection Retirement Criteria >Mechanisms that Cause Damage Excessive Tension / Shock Loading Cyclic Tension Wear External Abrasion Cutting Pulled Strands and Yarns Flex Fatigue or Bending Fatigue Terminations Knots Axial Compression and Kink Bands Hockle, Twist, Kink or Corkscrew Sunlight Degradation Chemical and Heat Degradation Dirt or Grit Particulate

28 Inspection Retirement Criteria 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

29 Inspection Retirement Criteria Cyclic Tension Wear IF: >Broken Internal Filaments over Length >Matted Filaments at strand rub areas =Downgrade / Retire Samson / Cordage Institute / Handbook of fibre rope technology

30 Inspection Retirement Criteria External Abrasion IF: >Rope Cross Section reduced by 10% in whole rope =Downgrade / Retire IF: >Rope Cross Section reduced by 25% =Repair/ Retire Samson / Cordage Institute / Handbook of fibre rope technology

31 Inspection Retirement Criteria Cutting IF: >Rope Cross Section reduced by 10% in whole rope =Downgrade / Retire IF: >Rope Cross Section reduced by greater than 10% =Repair/ Retire Samson / Cordage Institute / Handbook of fibre rope technology

32 Inspection Retirement Criteria 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 Samson / Cordage Institute / Handbook of fibre rope technology

33 Inspection Retirement Criteria Flex Wear on Pulleys/ Rollers IF: >Internal Fusion >Wear on strand crowns >Broken filaments at strand rub points =Downgrade / Retire Samson / Cordage Institute / Handbook of fibre rope technology

34 Inspection Retirement Criteria Flex Wear on Pulleys/ Rollers

35 Inspection Retirement Criteria Spliced Eye IF: >Cuts >Splice Pulling out >Incorrect Splice >Damaged Thimble =Repair

36 Inspection Retirement Criteria Creep IF: >Rope Exceeds limits set by manufacture >History of the rope indicates it is a concern =Retire

37 Inspection Retirement Criteria Compression

38 Inspection Retirement Criteria Sunlight Degradation IF: >Polypropolene, Brittle and broken outer fibers = Retire >Ropes less than 1” diameter, 1yr plus exposure, aramid, nylon, polypro =Retire/ Downgrade

39 Inspection Retirement Criteria Chemical And Heat Degradation IF: >Known exposure = Retire >Discoloration, Brittle Fibers, Stiff, =Retire

40 Inspection Retirement Criteria Dirt or Grit IF: >Dirt or Grit is found internally >Broken an powdery fiber present = Retire

41 Overview Lifting Sling Testing >Single leg >Grommet >Basket >Choker >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

42 Hardware >Class1 Rope Hardware Lower Strength, Higher Elongation Fibers Plastic Thimbles, Non Reinforced Thimbles, Plastic Spools

43 Hardware > Class2 Rope Hardware High Strength, Low Elongation Fibers Tubular Thimbles, Reinforced Thimbles, Aluminum Spools

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

45 Hardware >Shackles Standard and Wide Body Small D/d for Grommets Quick Easy and readily available

46 Thank you! Questions


Download ppt "Mark Pederson Application Engineer ACRP May 10 th 2012."

Similar presentations


Ads by Google