safe rigging practices.ppt

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Safe Rigging Practices

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OVERVIEW

• Rigging Selection• Fundamentals of rigging

– Basic Rules– Rigging

Devices/Attachments– Sling angle– Rope

• General use guidelines

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Rigging

The process of lifting and moving heavy loads with ropes, chains, and mechanical devices.

“The art of lifting heavy objects”

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SAFE

LIFTING

THE SAFETY TRIANGLE

EFFECTIVE, EQUIPMENT

MAINTENANCE

TRAINED, QUALIFIED

OPERATORS

PROPER EQUIPMENT

DESIGN

Rigging Selection• The rigging capacity and the material to

be lifted must match. Using too small capacity rigging or components is just asking for an accident to happen.

1. Who is responsible (competent/qualified) for the rigging?

a. Communications Established?

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Rigging Selection

• 2. Is the Equipment in Acceptable Condition?

a. Appropriate Type?

b. Proper Identification?

C. Properly Inspected?

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Rigging Selection

1. Are the Working Load Limits Adequate?

a. What is the weight of the load?

b. Where is the center of gravity?

c. What is the sling angle?

d. Will there be side loading?

e. Capacity of the gear?7

Rigging Selection

4. Will the Load be Under Control?

a. Tag Line available?

b. Is there any possibility of fouling?

c. Clear of Personnel?

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Rigging Selection

1. Are there any Unusual Loading or Environmental Conditions?

a. Wind?

b. Temperature?

c. Surfaces? (Ice, Suction, Water)

d. Unstable Object(s)?

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Rigging Basics

• Weight of the object• Capacity of rigging device• 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.

Center of gravity

¼ L

Fa

Fb

Total Weight = W

Fh

Fh

Rigging Devices/Attachments • Shackles

• Hooks

• Wire Rope Clips

• Wedge Sockets

• Eyebolts

• Spreader Beams

• Turnbuckle

• Slings

SHACKLES

• Anchor ShacklesHas a rounded eye

which makes it suitable for attaching one or more lifting devices, such as hooks or slings.

• Chain ShacklesHas a straight eye

designed for connecting to a single lifting device

12Shackle size is determined by the diameter of the bow or body.

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• 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

SHACKLES

Avoid eccentric loads

Do not pull shackle at an angle - thelegs may open up or cause distortionat maximum loads.

Pack the pin with washers to centralize the shackle.

SHACKLES

Proper chocking of shackles.

Bad Good

SHACKLES

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1. Never replace the shackle pin with a Bolt

2. Shackles shall not be used if the pin cannot be completely seated. The pin need be only hand tight for lifting. Useonly shackles with screw pin. Round pin with cotter should not be used

3. Screw pin shackles shall not be used if the pin can roll under load and unscrew

SHACKLES

FREQUENT (PRE-USE) INSPECTION

1) Check pin to see if it seats completely.2) Check to see that pin threads easily by and into and out of the shackle.3) The pin shall show no signs ofdeformation.4) Check for excessive thread exposure when pin is seated completely.5) Check for opening of shackle throat.6) Check for excessive wear, cracks, and corrosion.

SHACKLES

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Hooks

1.The safe working load (SWL) for a rigging hook shall be equal to or exceedthe rated load of the chain wire rope, or other suspension member to which it is attached . The designed SWL applies only when the load is applied inthe saddle of the hook.

1. It is a good practice to use a shackle when two or more sling eyes are used on a hook . This allows the load to be centralized on the hook for full capacity. Never tip load a hook

1. The load hook should be the weakest member of the lifting equipment, so it will bend if overloaded before any other piece of equipment fails.

1. Hook tips should point out and away from the load, to assure when slack is taken

up, the hook will not tip load

Hands, fingers, and body shall be kept away from between the hook and load.

Hooks

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FREQUENT (PRE-USE) INSPECTION

1. Look for distortions such as bending, or twisting exceeding 10 degrees from the plane of the unbent hook.2. Check for an increase in throat opening exceeding 15% of original throat opening. 3. Check for wear in the saddle area of the hook. Wear exceeding 10% of the original dimension is sufficient enough to take the hook out of service.4. Check for cracks, severe nicks, and gouges. Transverse cracks are more critical to a hook's performance than longitudinal cracks.5. Check the hook attachment and securing means for defects.6. Rigging hooks shall be inspected as a part of the slings to which they are attached.

Hooks

Wire Rope Clips

•The most common use of wire rope clips on cranes is at wedge and socket-end fittings.

•The clip does not provide strength to the wedge and socket connection.

•It is there to prevent the wedge from accidentally being released.

Clips should not be reused as they may not torque properly on the second application.

CLIPS FREQUENT (PRE-US E) INSPECTlON

1. Before use, clips shall be visually inspectedfor damage, corrosion, wear, and cracks.

Installing Wire Rope Clips

Installed properly as to number, direction, spacing and torque.

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Operation Practices1. Assure clips are orientated correctly2. When using single grip clips, be sure toput the saddle on the live end of therope.3.Be sure to torque clips to properspecification. 4. Check torque after use and re torqueafter use if necessary.5. Follow the proper procedure wheninstalling clips A. Apply first clip one base width from dadend of wire rope. Tighten nuts evenly torecommended torque.B. Apply second clip nearest the loop.Turn evenly but do not tighten.C. Apply all other clips spaced equally inbetween the first two. Apply tensionand tighten all nuts to recommendedtorque.D. Recheck torque after use.

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EYE BOLTS• 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

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• 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

EYE BOLTS

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• Eye bolt - rigging

EYE BOLTS

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• 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.

SPREADER BEAM

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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

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• 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?

SPREADER BEAM

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• Spreader beam

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

Spreader Beam

Load

SPREADER BEAM

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• 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

SPREADER BEAM

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• Turnbuckles– Turnbuckles can be used to adjust sling

length. – Be sure to use only load rated components

TURNBUCKLES

Types of SlingsTypes of Slings

1) Wire Rope Slings

1) Chain Slings

1) Synthetic Web Slings

Wire RopeWire Rope

Components of Wire Rope

1.Core

2.Wire

3.Strand

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There are three types of cores:

Fiber - synthetic or sisal, which is theweakest,

Strand - the core is a wire strand, justlike the other strands of the rope.

Independent Wire Rope (IWRC) -this isa separate wire rope. It is the strongestof the three types. The core provides7-1/2% strength of the wire rope. Thisis the core used in the wire rope slingsprovided on site.

Wire RopeWire Rope

Most wire is high carbon steel

Left Lay

Right Lay

Crushing

Because of loose winding on drum, rope was pulled in between underlying wraps and crushed out of shape.

Birdcaging

The sudden release of a load cause birdcaging .Here individual strands open away from each other, displacing the core.

Locking of strands

Premature breakage of wires resulted from "locking" of strands, which was caused by insufficient lubrication.

Abrasion

Neglect of periodical inspection left this rope in service too long, resulting in considerable abrasion.

Kinking

Kink or "dog leg“ was caused by improper handling and/or installation. A kink causes excessive localized or spot abrasion.

Reverse bending

Running this rope over one sheave and under another caused fatigue breaks in wires.

Pitting

Too much exposure combined with surface wear and loss of lubrication caused corrosion and pitting.

Wear

Too long in service. Repeated winding and overwinding of this rope on a drum while it was under heavy stress caused the unusually severe wear.

Wire RopeWire RopeWire Rope Sling Identification

Rated Load (rated capacity)

•Load test date

•Manufacturer’s name

•Periodic inspection due date

•Broken wires (10 in one lay or 5 in one strand)

•Severe corrosion

•Localized wear

•Reduction in outer wire

•Damaged end fittings

•Distortion, kinking, etc…

Before Lifting any load check for hazards

• The sling must not be attached to the load at a point lower than the loads center of gravity– Exception to this rule

when lifting loads on pallets or skids

– Then apex of sling must be above the center of gravity

Horizontal Force

• When a sling angle is 300 the total force is twice that of the load

• Sling Angles of 450 are not recommended

Wire Rope Slings

single-rope legs

Wire Rope Slings

sling with single-rope legs, Torpedo loop-locks and choker hook

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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

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Rigging Basics - HitchesBasket - 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.

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Rigging Basics - HitchesChoker – 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

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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

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

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• Choker hitches are not suited to long loose bundles

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• 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)

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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

Copyright Pro Crane Services 59


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



• 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


General Use Guidelines

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

OSHA 1926.251, 1910.184

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Periodic inspection frequency/records

Periodic inspection performed by ?

Frequent inspection frequency/records

Label*

Chain slings

OSHA 1910.184(e)(3) – at least annually with recordsASME: normal – annually; severe service – monthly to quarterly with records

OSHA – competent personASME - 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., & reachASME: 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 materialASME – 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 loadingASME – 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

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

OSHA 1926.251

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

OSHA 1926.251

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• During lifting, personnel shall be alert for possible snagging

ASME B30.9

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• 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.

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• Shock loading should be avoided

ASME B30.9

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

ASME B30.9

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

ASME B30.9

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• Slings shall not be shortened by knotting or twisting

ASME B30.9

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

ASME B30.9

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• Slings should not be dragged on the floor

ASME B30.9

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• Sharp corners in contact with the sling should be padded

ASME B30.9

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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.

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

ASME B30.9

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• Personnel shall not ride the sling (or load)

ASME B30.9

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• Personnel should stand clear of suspended load.

ASME B30.9



• And not “Be” the suspended load!!

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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)

Barricades

• During rigging and lifting activities, areas in a construction zone must be barricaded or blocked off from the public as well as construction workers to maximize safety precautions.

• The route the rigger takes to move an object through the air must be clear to eliminate the danger of the object dropping onto someone below.

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Questions?

safe rigging practices.ppt

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