Copyright Pro Crane Services1. 2 Introduction Terry Elmy –retired, 31 years, Pt. Comfort, Massena, Pt. Henry, and Tennessee Pro Crane Services –started

Copyright Pro Crane Services 1


Introduction

Terry Elmy– retired, 31 years, Pt. Comfort,

Massena, Pt. Henry, and Tennessee

– started Pro Crane ServicesPro Crane Services in 1996

– services include operator & maintenance training, systems audits, crane procurement, accident investigation, and expert witness services

– recently added structural and BTH device analysis capability


SAFE

LIFTING

THE SAFETY TRIANGLE

EFFECTIVE, EQUIPMENT

MAINTENANCE

TRAINED, QUALIFIED

OPERATORS

PROPER EQUIPMENT

DESIGN


Training Objectives:

• Review fundamentals of rigging– the load– the hitch– attachments– sling angle– D/d ratio

• General use guidelines• Provide answers to

technical questions


Rigging

The handling, setting and erection of materials and equipment is a hazardous occupation. Each operation presents its own peculiar problems and no two jobs are alike. With proper consideration taken, each job can be performed free of bodily harm to the employee and without damage to the equipment.


Rigging

Rarely does the typical worker get the opportunity to actually select the rigging. It is normally provided at the work site by others. This in itself can create serious problems. Workers need to be trained in the proper use of rigging and not to use rigging improperly because “it’s all I had to work with.”


Rigging - Plan

• Who is responsible for the rigging?

• Is the equipment in safe condition?

• Are the working load limits adequate?

• Will the load be under control?

• Are there any unusual loading or environmental conditions?


Rigging Basics – The Load

• Load weight shall be within rated capacity of the sling* ASME B30.9

*such that no part of the rigging is overloaded

A COMPLETE UNDERSTANDING OF THE LOAD FORCES IS REQUIRED!



• Load weight may be obtained from:– equipment nameplate– packing list– drawings– shipping tag– weighing the load– an estimate or calculation of

load weight



Load information:

• Size

• Weight

• Center of gravity



Load information:• Size• Weight• Center of gravity

– The center of gravity is the point at which a load will balance - and that point must be directly below the hook or principal lifting point.





– An object will tilt until its center of gravity IS directly below the hook.






– If an object is evenly shaped measure to find the center of gravity







– Determination of center of gravity of unevenly shaped objects can be very complicated – mistakes or bad assumptions can result in disastrous consequences







– Determination of center of gravity of unevenly shaped objects can be very complicated – mistakes or bad assumptions can result in disastrous consequences

– Always make the load connection point is above the center of gravity


Center of GravityFinding the center of gravity based on weights

3000 #6000 #

2000 #



6000 #

2000 #

6000/(6000+2000)= 3/4 = 75%

75%



8000 #

8000/(8000+3000)= .73 = 73%

3000 #73%


Center of Gravity

• Other methods of establishing COG– require supplier to mark COG– find by trial lifts– find by trial and error


Center of Gravity

• Other methods of establishing COG– require supplier to mark COG– find by trial lifts– find by trial and error

Caution: weight must be known and rigging may need to be oversized before using any

trial method


Rigging Basics - Hitches

Vertical – having the load suspended vertically on a single part or leg of the sling.

Characteristics:• Load capacity is 100 % that of a single part• Taglines should be used if the load tends to rotate

as rotation can damage the sling.• Use on items with lifting eye bolts or shackles or

when a second sling is used in a spreader bar application

• Do NOT use when lifting loose or lengthy material, anything difficult to balance



Basket - loading with the sling passed under the load and both ends on the hook, master link, or lifting device

Characteristics:• Effectively doubles the capacity of a single vertical sling

• Stress on each leg tends to be equalized• Use on straight lifts when the load is shaped so that the sling (or slings) will not slide over the surface.

• Do NOT use on loads that are difficult to balance and could tilt or slip out of the sling(s).

• When terminating to a common point (like a hook), sling angle can reduce sling capacity.



Choker – loading with the sling passed through one eye or choker hook and suspended by the other end

Characteristics:• Choker hitch is easy to attach & forms a noose that tightens as the load is lifted• Rated capacity is 75% of the single part*.• Use to turn a load (if possible use a double choker hitch) or when handling bundles of bars or pipes• Do NOT use on loads difficult to balance or which

may slip out the choke

* based on wire rope and chain slings, 120 degree angle of choke



Choke angle – the angle formed between the load line and the noose

Angel of Choke Rated Capacity Factor*120 - 180° = 100% 90 - 119° = 87% 60 - 89° = 74% 30 - 59° = 62% 0 - 29° = 49%

*based on wire rope slings



• Do not confuse choke angle with angle of inclination of the load



• Choker hitches are not suited to long loose bundles



• Double Wrap Basket Hitch– adjustment of slings is required while taking

up slack to avoid overloading one side of the sling (this applies to all basket hitches)



• Turning loads with a choker hitch

Loads in legs will equalizeduring lifting

Loads in legs will tend not to equalize during lifting


Rigging Basics – Sling Angle

Sling angle has a dramatic effect on the actual load on the sling. Take a sling that has a 1000 pound vertical lifting capacity in a basket hitch:

Sling with 500# vertical hitch capacity



As angle decreases - tension on each leg increases - increasing the strain on each leg

Sling with 500# vertical hitch capacity



A different look, with the same load and sling, changing the angle has a similar dramatic effect



A different look, with the same load and sling, changing the angle has a similar dramatic effect



• The sling angle factor equals H divided by L, the inverse, L/H, can also be used to calculate sling load

L/H is useful to calculate sling load when the vertical force is known. L/H for common angles is approximately: 60º - 1.2; 45º - 1.4; 30º - 2


Rigging Basics


Sling Angle Example Problem Select slings to pick up the load shown below.

CG2’8’

10,000#



CG2’8’

10,000#

First, we need to know the vertical load at eachconnection point, A and B to support the load.

A B



CG2’8’

10,000#

The vertical load is offset, proportioning givesthe following information:

ForceA x 10’ = 10,000# x 2’

ForceA = 2,000#

therefore, ForceB = 8,000#

A B

FAFB


Sling Angle Example Select slings to pick up the load shown below.

CG2’8’

10,000#

We know we want to position the hookdirectly over the center of gravity



CG2’8’

10,000#

Next we know the sling furthest away from the hookwill have the smallest angle, so we’ll size it first andbase our sling angle at the optimal angle of 60º.

60º



CG2’8’

10,000#

Since the angle is 60º, the height of the hook is nowfixed as is the sling length. Because the angle is 60º,the sling length is twice the base length (2 x 8’ = 16’).

60º

16’

Cosine 60º = 0.5



CG2’8’

10,000#

Knowing the L/H = 1.2 for 60º sling angle, the height of the hook is

L/H = 1.2H = 16/1.2H = 13.3 feet

60º

16’

13.3’



CG2’8’

10,000#

Additionally, knowing that L/H = 1.2 for 60º sling angle, the load

on sling A = 1.2 x ForceA or 1.2 x 2,000# = 2,400#.

60º

16’

2,400#

13.3’



CG2’8’

10,000#

Sling B’s length can now be calculated to an exact number.

Length of Sling B = √(13.3)2 + (2)2 = 13.44 feet

60º

16’

2,400#

13.3’

13.44’



CG2’8’

10,000#

Sling B’s load can now be calculated:

L/H = 13.44/13.3 = 1.01LoadB = 1.01 x 8,000# = 8,084#

60º

16’

2,400#

13.3’

13.44’

8,084#



CG2’8’

10,000#

Using wire rope slings, EIPS grade, 6x19 class ropewith a mechanical splice, Sling A needs to be 3/8-in. diameter min.Sling B needs to be ¾-in. diameter min.

60º

16’

2,400#

13.3’

13.44’

8,084#


Rigging Basics – D/d Ratio

• D/d ratio is the ratio of the diameter around which the sling is bent divided by the body diameter of the sling. Whenever a sling body is bent around a diameter, the strength of the sling is decreased.

Application: 6x19 and 6x37 Class rope, may not apply to cable laid or braided slings


Rigging Attachments

• Sockets– swaged and poured

socket assemblies shall be proof tested

– mechanical splice single vertical leg slings test shall be 2 times vertical load limit

ASME B30.9


Rigging Attachments

• Shackles– used only those rated

for overhead lifting


Rigging Attachments

• Shackles– synthetic web slings

connected to shackles of sufficient size to not cause bunching or pinching of the sling

Use wide shackles to prevent pinching or bunching


Rigging Attachments

• Hooks – inspect before use, use ASME B30.10 or a recognized Engineering Standard

Spreadhook

Where is the hook latch??


Rigging Attachments

• Hooks – avoid eccentric loading of hooks


Rigging Attachments

• Hooks– do not exceed 90

degrees included angle when connecting two slings in a hook. If you have an included angle more than 90 degrees, or more than two legs, use a shackle or a master link to connect.


Rigging Attachments

• Turnbuckles– Turnbuckles can be used to adjust sling

length. Be sure to use only load rated components


Rigging Attachments

• Eye bolts– use only forged eye bolts rated for lifting– never use if damaged, bent, elongated– never use regular eye bolts for angular lifts– always seat shoulder against the load


Rigging Attachments

• Eye bolts– always shim eye bolts to seat shoulder in-line for

angular loading– for angular lifts reduce working load

• 45 degrees – 30% of rated working load• 90 degrees – 25% of rated working load

Angle of pull


Rigging Attachments

• Eye bolt - rigging


Rigging Attachments

• Eye bolt - rigging

How to prevent load buckling?


Rigging Attachments• Spreader beam - A below-

the-hook lifting device that utilizes two or more hooks (attaching devices) located along a beam and the spreader beam attaches to the hoist by means of a bail. The spreader beam is used to handle long or wide load and serves to "spread" the load over more than one lifting point. Often used in conjunction with slings.

Note: a common misconception of spreader beams is that they equalize the loadingalong the beam. They do not! Spreaders only eliminate horizontal forces from affectingthe load being hoisted.


Rigging Attachments

• Spreader beam

Spreader Beam

Center of gravity

¼ L

1/2 L

Fa

FbWith the CG off center of the hook as shown, the verticalforce at Fa will be 75% of theload weight and the vertical forceat Fb will be 25% of the totalload weight. No horizontal forces will be exerted on the load.

Total Weight = W

1/2 L

Load


Rigging Attachments

• Spreader beam

Spreader Beam

Center of gravity

¼ L

1/2 L

Fa

FbWith the CG off center of the hook as shown, the verticalforce at Fa will be 75% of theload weight and the vertical forceat Fb will be 25% of the totalload weight. No horizontal forces will be exerted on the load.

Total Weight = W

1/2 L

Load

As shown, will the load be level duringhoisting?


Rigging Attachments

• Spreader beam

The load will tilt untilthe center of gravityaligns with the hook.

Spreader Beam

Load


Rigging Attachments

• Spreader beam

Center of gravity¼ L

¼ L

Fa

Fb

Without the use of a spreaderbeam, the vertical forces remainthe same, however, the sling loadis a function of the sling angle andthe sling load will be higher thanthe sling between the spreaderand the load.There will, in this case, behorizontal forces exerted uponthe load, dependent upon thesling angle.

Total Weight = W

Fh

Fh


General Use Guidelines

• Pre-use and periodic inspection is required on all sling and rigging components

OSHA 1926.251, 1910.184


Periodic inspection frequency/records

Periodic inspection performed by ?

Frequent inspection frequency/records

Label*

Chain slings OSHA 1910.184(e)(3) – at least annually with records

ASME: normal – annually; severe service – monthly to quarterly with records

OSHA – competent person

ASME - competent person

OSHA – before use(1910.184(d) w/o recordsASME: normal –monthly;

severe service – daily to weekly w/o records

OSHA – size, grade, rated cap., & reach

ASME: mfgr., grade, size, no. of legs, reach, rated load for hitches

Wire rope slings

OSHA – noneASME – based on service, at

least annually with records

OSHA – no periodicASME – competent

person

OSHA – before use(1910.184(d)ASME – daily w/o records

OSHA – noneASME – mfgr., size, rated

load for type of hitch & angle

Synthetic web slings

OSHA – noneASME – recommended at

least annually based on service, records recommended

OSHA – no periodicASME - competent

person

OSHA – before use(1910.184(d)ASME - daily w/o records

OSHA – rating @ each type of hitch, type of material

ASME – mfgr., mfgr. Stock no., rated load for each type of hitch, material type & construction

Metal mesh slings

OSHA – noneASME - based on service, at

least annually; records recommended

OSHA – no periodicASME - competent

person

OSHA – before use(1910.184(d)ASME – daily w/o records

OSHA – rated @ vertical and choker hitch loading

ASME – mfgr., rated load for hitch & angle, width and gauge

* Sling I.D., per ASME B30.9, shall be maintained to be legible for the life of the sling



• Rigging equipment shall not be loaded beyond its recommended working load limit (WLL)

OSHA 1926.251



• When not in use, rigging shall be removed from work area and properly stored

OSHA 1926.251



• During lifting, personnel shall be alert for possible snagging

ASME B30.9



• Slings should be long enough so that rated load is adequate

ASME B30.9



• Multiple leg slings shall be selected so as not to introduce into the leg, a load greater than permitted

ASME B30.9

Note: select multiple leg slings based on twolegs supporting the entire weight of the load andthe other leg(s) balancing the load.



• Shock loading should be avoided

ASME B30.9



• The load shall be applied to the center of the hook (unless the hook is designed for point loading)

ASME B30.9



• When used in a choker hitch, prevent the load on any portion of the sling from exceeding the rated load

ASME B30.9



• Slings shall not be shortened by knotting or twisting

ASME B30.9



• Slings should not be pulled from under a load when the load is resting on the sling

ASME B30.9



• Slings should not be dragged on the floor

ASME B30.9



• Sharp corners in contact with the sling should be padded

ASME B30.9



The following slide is not for the faint of heart. If you are are botheredby accident scenes, do not look at the screen until the “All Clear” signal is given.



• Do not place body, fingers, etc. between the sling and load or hook

ASME B30.9



• Personnel shall not ride the sling (or load)

ASME B30.9



• Personnel should stand clear of suspended load

ASME B30.9



• And not “Be” the suspended load!!


No Homemade Slings

WARNINGWARNINGNo wire rope sling shall be fabricated using wire rope clips!!

Preferred sling construction is to usea Flemish eye splice with a mechanicalsleeve (turn back construction is notrecommendable)


Questions?

Documents

Copyright Pro Crane Services1. 2 Introduction Terry Elmy –retired, 31 years, Pt. Comfort, Massena, Pt. Henry, and Tennessee Pro Crane Services –started