800 Cranes, Rigging and Lifting

800 Crane raness, Ri Rigging ging,, and and Li Liffting Abstract This section will facilitate the practical design of rigging by Civil Engineers of all experience levels and assist other Company personnel involved in the development, planning, and execution of lifts. The section defines commonly used rigging terms; describes rigging components and equipment; establishes rigging procedure and safety guidelines; outlines methods for finding loads in slings and designing padeyes; makes recommendations for test lifts and rigging component inspection. The type of equipment that usually requires lifting in a refinery, chemical plant, or producing location includes vertical columns, vertical and horizontal vessels, pumps, heat exchangers, compressors, electrical equipment, air coolers, small shopwelded tanks, and other miscellaneous items. For requirements for lifting services, see the Model Specification CIV-MS-4782, Lifting Services, included in Section 2000 of this manual. This engineering guideline and accompanying accompanying Model Specification do not include requirements for offshore lifting.

Contents

Chevron Corporation

Page

810

Organizing a Lift

800-3

811

Genera Generall Proced Procedure ure for Eva Evaluat luating ing and and Perfo Performin rming g a Lift Lift

812

Data Re Required

813 813

Rigg Riggin ing g Res Respo pons nsib ibil ilit itie iess

814 814

Lift Lift Clas Classi siffica ication tion

820

Transportation and Lifting Methods

821 821

Trans ranspo port rtat atio ion n Meth Method od

822

Lift ifting ing Method hod

830

Safety Considerations

831 831

Good Good Rigg Riggin ing g Prac Practi tice cess

832

Working orking Around Around Power Power Lines Lines and and Near Near Elect Electrica ricall Equipme Equipment nt

833 833

Worki orking ng in in Conf Confin ined ed Spa Space cess

834

Void oids An And Ho Holes les

835

Crane Crane Capac Capacity ity Consi Consider derat ation ionss

8 00 - 1

800-4

800-11

April 1989

800 Cranes, Rigging, and Lifting

April 1989

Civil and Structural Manual

840

Inspection and Testing

841

Inspection

842

Testing

850

Rigging Diagrams, and Rigging Analysis and Design

851

Riggi igging ng Dia Diagram gramss

852

Loads

853 853

Facto actors rs of Safe Safety ty

854

Sling Forces

855 855

Wire ire Rope Rope Stre Stretc tch h

856 856

Lift Liftin ing g Lugs Lugs (Pad (Padey eyes es))

860

General Rigging Information

861 861

Types ypes Of Of Lift Liftin ing g Equi Equipm pmen entt

862

Misce Miscella llane neous ous Riggin Rigging g Equipm Equipment ent

863

Wire Rope

864

Slings

865 865

Hitc Hitche hess For For Wire ire Rop Ropee

870

Glossary

800-39

880

Model Specification

800-42

890

References

800-43

800-2

800-14

800-16

800-31

Chevron Corporation



810 Organizing a Lift 811 General General Proce Procedure dure for for Evalua Evaluatin ting g and Perform Performing ing a Lift Lift The following steps need to be completed when performing a major or critical lift: •

Coll Collec ectt all all the the req requi uire red d da data— ta—Sect Section ion 812

•

Dete Determ rmin inee safe safety ty cons consid ider erat atio ions ns— —Sect Section ion 830

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Choo hoose lifti iftin ng method hod—Secti Section on 822

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Sele Select ct tra trans nspo port rtaation tion met metho hod— d—Se Secti ction on 821

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Prepa reparre rig rigg ging ing dia diagr gram am— —Secti Section on 851

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Asse Assemb mble le lift liftin ing g equi equipm pmen entt

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Verif erify y cran cranee cap capac acit ity y cert certif ific icat atee

•

Insp Inspec ectt rigg riggin ing g equi equipm pmen entt and and comp compon onen ents ts— —Sect Section ion 841

•

Proof Proof test test slings slings and shackl shackles es where where requi require red d

•

Desi Design gnat atee qua quali liffied ied sign signaal man man

•

Make trial run

812 Data ata Requ Requiired red All rigging operations require a complete investigation in order to select the method best suited for the lift. The items to be investigated depend on the complexity of the lift. The following list outlines the basic information required before selecting a method:

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Dimensio Dimensions, ns, weight weight,, center center of of gravity gravity,, and conf configur iguratio ation n of the piece piece or piec pieces es to be lifted

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Inve Invento ntory ry of avail availabl ablee liftin lifting g equipm equipmen entt

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Method Method of attachme attachment nt for for handl handling. ing. If attac attachmen hmentt points points or or liftin lifting g lugs lugs are are provided on the piece, verify that they are intended for handling the entire piece and not a component.

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Restrict Restrictions ions by by the equipmen equipmentt fabric fabricato atorr to prev prevent ent dama damage ge to the the equipm equipment ent during handling

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Sequence Sequence of prope properr assemb assembly ly,, when when a piece piece consists consists of compo component nentss

•

Type ype, size size,, and and numb number er of slin slings gs

•

Type of hitch

•

Require Requirement mentss for shipp shipping ing skids skids or or other other handl handling ing dev devices ices and their their availa availabili bility ty

•

Path Path of mov moveme ement nt from from the the time time equipm equipment ent to to be lifte lifted d is rece receiv ived ed to point point of final setting

•

Lateral Lateral and and overhe overhead ad clear clearanc ances es in area areass of restr restricte icted d moveme movement, nt, partic particular ularly ly from power lines

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•

Crane oper operaating ting radius dius

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Load Load restr restric ictio tions ns on floo floors rs,, struc structur tures, es, and and acce access ss roads roads

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Prope Properr orie orienta ntatio tion n of of pie piece ce in final final positi position on

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Chang Changee of loa load d distr distrib ibuti ution on that that may may occur occur duri during ng upend upending ing

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Hole Holes, s, roc rocks ks,, and and soft soft gro groun und d in area area of lif liftt

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Need Need for for mats, mats, rolle rollers rs,, jac jacks, ks, comecome-alo alongs ngs,, etc etc..

•

Ratin Rating g of spre spreade aderr bars bars,, shack shackle les, s, sling slings, s, and and loa load d lines lines

813 813 Riggi Rigging ng Respon Responsi sibi bili liti ties es The ultimate responsibility for all rigging lies with the design/construction engineer or job engineer. Individual responsibility depends on whether rigging work is done by the Company or a contractor. Contractors are responsible for planning and executing the rigging operation, selecting the proper equipment and preparing rigging diagrams, all subject to review by the Company.

814 814 Lift Lift Cla Class ssif ific icat atio ion n Lifts can be classified as light, medium, heavy or critical. Suggested classification of lifts are: Light lifts

Less than 10 tons

Medium dium Lift Liftss

Gre Greate ater th than 10 10 to tons but les lesss tha than n 50 50 ton tonss

Heavy Lifts

Greater than 50 tons

Crit Critic ical al Lift Liftss

Lift Liftss over over oper operat atin ing g equ equip ipme ment nt,, lift liftss in haza hazard rdou ouss loca locati tion ons, s, lifts in confined spaces, and lifts involving nonrigid objects like tank shells.

8200 Trans 82 ranspo port rtat atio ion n and Lif Lifti ting ng Meth Method odss Introduction This section discusses choosing the type of transportation and lifting equipment.

821 821 Transp ransport ortati ation on Meth Method od Equipment is generally moved on a truck. Selecting the proper hauling unit depends on verifying the following:

April 1989

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That the size size and and weight weight of the the piece piece is within within the the dimensi dimensional onal and desig design n capacapabilities of the truck

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That That axle axle loadi loadings ngs do do not exce exceed ed acc acces esss road road limi limita tatio tions ns

800-4

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•

That That clea cleara ranc nces es alon along g acce access ss rout routes es are are adeq adequat uatee

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That That the the loa load d will will rem remai ain n leve levell and and not not tip tip

822 Lifti ifting ng Met Method hod The lift can be made by mobile crane, gin poles, derricks, bridge crane, or hoists. Figures 800-1 and 800-2 show lifting a vessel with two and with one crane respectively, and provide checklists of several items to be evaluated. Fig. 800-1

Typical Checks for Uprighting a Vessel w ith Two Cranes

Mobile Crane To choose a mobile crane for a lift, the following should be done:

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Prepare Prepare a layout layout study to determ determine ine the the cran cranee positio position n that that provid provides es the the most most favorable operating radius, boom length, boom clearance when stationary and when swinging, and the required boom height.

•

Check Check for for unde underg rgrou round nd obstr obstruc uctio tions ns whic which h may may be dama damaged ged..

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Check so soil ca capacity.

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Fig. 800-2


Typical Checks for Uprighting a Small Vessel with One Crane

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Examine Examine the the erec erection tion site to ensure ensure that outrigge outriggers rs and and mats mats can can be be accomm accommoodated.

•

Select Select a crane crane from from the manuf manufactu acturer rer’’s chart chart which which has has the capa capabilit bility y to handle handle the load. Figure Figure 800-3 800-3, a manufacturer’s safe load chart for a hydraulic crane, relates a crane’s safe working load capability to the work radius and boom length. The following example demonstrates the process for verifying the capability of a crane for a lift. Note that this chart is only for one type of crane. Crane charts are different for each type of crane.

Example: Verify that the contractor-proposed hydraulic crane “Pettibone Model 100-SC” (Figure Figure 800-3 800-3) has the capability to lift and rotate 360° the piece of equipment described below be low.. Data. 1.

Equipment Size: 6 ft W x 14 ft L x 5 ft H Weight: eight: We We = 23,500 23,500 lb Center of Gravity: at centerlines. Location (elevation) height: He = 50 ft above ground.

April 1989

800-6

Chevron Corporation


Fig. 800-3


Working Ranges and Safe Load Charts for Pettibone Multikrane Model 100-SC with 36-ft. to 84-ft. Boom (Courtesy Pettibone Corporation) (1 Corporation) (1 of 2)

Chevron Corporation

8 00 - 7

April 1989


Fig. 800-3

April 1989


Working Ranges and Safe Load Charts for Pettibone Multikrane Model 100-SC with 36-ft. to 84-ft. Boom (Courtesy Pettibone Corporation) (2 Corporation) (2 of 2)

800-8

Chevron Corporation


2.


Slings Weight, WS = 100 lb Crane hook height above ground at start of lift, hst = 18 ft. Single point pick.

3.

Crane Hook block weight, Wb = 1000 lb. Vertical length of block & lines, l b = 5 ft-6 in. Distance centerline turntable to centerline boom pivot pin, lp = 4 ft-7 in. Height of center of rotation of crane boom above ground, hcr = 9 ft-3 in. Work radius, R= 35 ft

4.

Load Load hand handli ling ng devi device cess Weight, Wl

= 200 lb

Total weight Wt = We + Ws + Wb + Wl = 23,500 + 100 + 1000 + 200 = 24,800 lb Height of boom tip above center of rotation at end of lift, h

= He + lb - hcr+ hst = 50 + 5.5 - 9.25 + 18 = 64.25 ft

Boom length, L

= [( [(R + lp)2 + h2)]1/2 = [(35 + 4.583)2 + (64.25)2]1/2 = 75.46 ft

Therefore, use crane working ranges chart with 36 ft - 84 ft boom height extended. H

= h + hcr = 64.25 + 9.25 = 73.5 ft

At the intersection of H = 73.5 ft and R = 35 ft read the boom angle, which is approximately equal to 58° from the horizontal.

Chevron Corporation

8 00 - 9

April 1989



Crane Capacity. Use load chart with 36 ft - 84 ft boom 1.

Cran Cranee on on rub rubbe berr and and 360 360° rotation Capacity = 2800 lb < 24,800 lb N.G. Therefore, outriggers are needed.

2.

Cran Cranee with with out outri rigg gger erss and and 360 360° rotation With R = 35 ft and boom length = 76 ft Capacity = 25,100 lb > 24,800 lb OK.

Conclusion: Proposed crane is marginal for the intended lift. A slight error in boom angle, lift radius or load calculation would put this lift in jeopardy. Suggest look at bigger crane or reducing lift radius for this crane.

Gin Poles The primary gin pole features to consider when electing to use them as the lifting method are lift capacity and height of poles. Of equal importance are pole foundations and guy lines. For a more detailed discussion of gin poles see Secti Section on 861 861.

Derricks Select a derrick for a lift when large load capacity at long radius is needed. If some mobility is required, be sure that there is space for a traveling gantry before choosing a derrick as part of a lift.

Bridge Cranes Bridge cranes should be considered when (a) the weight of the lift is within the crane capacity and (b) the lift will take place entirely within the crane’s area of coverage. In addition, ensure that vertical and horizontal clearances are sufficient.

Hoists Hoists are part of most lifting equipment. The most important factors to consider are:

April 1989

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The hoist hoist must have have adequate adequate capacity capacity to spool spool the total total length length of rope required for the lift.

•

When the angle angle at which which the the rope rope leav leaves es or enters enters the the drum drum produc produces es a verti vertical cal or horizontal force on the hoist, anchorage must be provided to resist these forces.

800-10

Chevron Corporation



830 Safet afetyy Cons Consid ider erat atio ions ns Introduction This section discusses general safe rigging practices. It outlines precautions to use when working around power lines, in confined spaces, and in areas where holes and voids are present. It lists inspection requirements for rigging components and crane capacity restrictions. Test lift requirements are also discussed. The Safety in Design Manual, Section 6, has more information on rigging safety.

831 831 Good Good Rig Riggi ging ng Pra Pract ctic ices es The following safe design practices apply to all types of rigging and are intended for design engineers as well as field rigging personnel.

Chevron Corporation

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Determin Determinee the weight weight of the load load before before designin designing g the equipmen equipmentt to handle handle it. it. Consider whether vessels will contain fluid, sludge, etc, or whether equipment will contain oil or cooling water. These items can and significantly to the nominal weight.

•

If poss possibl ible, e, dist distrib ribute ute the load load evenl evenly y on all all legs legs of a sling. sling.

•

When using multiple multiple leg slings, slings, keep keep in mind mind that that the load is not not alway alwayss divided equally. In a four-sling arrangement, two slings may carry the entire load.

•

Design Design guy guy lines lines for for gin gin poles poles with a minimu minimum m slope slope of one horizon horizontal tal to one one vertical unless the manufacturer specifies shallower slopes.

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Always Always specify specify the use of outri outrigger ggerss on truck truck and and hydrau hydraulic lic cranes. cranes.

•

Ascertai Ascertain n the load load carry carrying ing capac capacity ity of of the soil and, if necess necessary ary,, use mats to spread the load.

•

Call for proof prooftest testing ing of slings slings prior prior to to their their use. use. Wire Wire rope should should not not be loade loaded d to more than 50% of its breaking strength, because the approximate elastic limit of conventional rope is 55% of the breaking strength. Wire rope slings should be proof-tested to 40% of the breaking strength of the rope.

•

The crane crane capaci capacities ties listed listed in in manuf manufactu acturer rers’ s’ load load chart chartss are are based based on on the machine being level. The importance of leveling the crane cannot be overemphasized.

•

Neve Neverr walk walk or or stan stand d unde underr susp suspen ende ded d load loads. s.

•

Stay out of of the the bight bight of of a line and do not not step step over over or stand stand near near a line line under under strain.

•

When fasteni fastening ng chain chain hoist hoists, s, rope rope falls falls,, or snatch snatch blocks blocks to perma permanent nent strucstructures, make certain that the structure is strong enough to support the load.

•

Do not not touch touch a running running wire rope. rope. Do not let let your your hand or finge fingers rs get get near near blocks and sheaves.

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•

Alwa Always ys use use the the shor shorte test st boom boom poss possib ible le..

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Never Never repla replace ce the the shackle shackle pin with with a bolt; bolt; only only the the proper proper fitte fitted d pin should should be used.

•

Always Always refe referr to the the manuf manufact acturer urer’’s specifi specificati cation on chart chart for for the safe safe working working loads of shackles.

•

For lifts lifts with with travel traveling ing crane cranes, s, measur measuree the actual actual radiu radius. s. Do not not rely rely on boom angle indicators.

•

Always Always use use a tag tag line line even even on small small lifts. lifts. It is much much easier easier to mainta maintain in contr control ol of the lift than to regain control when it is swinging or spinning. For large lifts air tuggers or other mechanical tag lines should be considered.

832 Working Working Aroun Around d Power Lines Lines and and Near Electr Electrical ical Equip Equipment ment The following practices shall be used when rigging near electrical equipment. No rigging should be done over energized high voltage lines. High voltage lines are lines rated 220V or greater. However, even 110V is dangerous and caution should be used. No part of the rigging operation, including the boom, cables, and the load, shall come closer to high voltage lines than specified in Figure Figure 800-4 800-4. Fig. 800-4

Required Clearances from Overhead High-Voltage Lines

Nominal Voltage, kV (Phase to Phase)

Minimum Required Clearance (feet)

0 - 50

10

51 - 75

11

76 - 100

12

101 - 125

13

126 - 200

15

201 - 300

19

301 - 400

22

401 - 500

25

501 - 700

32

701 - 1,000

42

A safety watch monitoring these clearances should be located away from the lift. •

April 1989

In transi transitt with with no load and the boom boom lowere lowered, d, the the liftin lifting g equipm equipment ent cleara clearance nce shall be a minimum of 4 feet for voltages less than 50 kV, 10 feet for voltages over 50 kV, but less than 346 kV, and 16 feet for voltages up to and including 750 kV.

800-12

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The only only exce exceptio ption n to the the abov abovee minimu minimum m cleara clearances nces is where where the highhigh-vol voltage tage lines have been de-energized and visibly grounded or where insulating barriers have been erected to prevent physical contact with the lines.

•

Place Place guy lines lines so as to be free free of any any possib possible le conta contact ct with with electri electrical cal wire wires. s.

•

Near transmit transmitter ter towe towers, rs, an an electri electrical cal char charge ge can can be induced induced in the equipmen equipmentt being handled. Prior to work, provide an electrical ground to the upper rotating structure supporting the crane boom, and attach ground jumper cables to the equipment being handled.

833 833 Working orking in Confi Confined ned Spaces Spaces When lifting in tight quarters, take the following special precautions to assure a safe lift: •

Conduct Conduct a deta detailed iled inves investiga tigation tion to identif identify y all possi possible ble inter interfer ference encess in the the vicinity of the work including overhead, at grade or underground.

•

Plot in detail detail the location location of the the cran cranee and/or and/or other other equipm equipment ent with respect respect to the work, including location of outriggers.

•

Establis Establish h limits limits of of allow allowable able motion motion for for the boom in in both both the vertic vertical al and and horihorizonal directions for each crane location in order not to damage existing facilities.

•

Devise Devise and and provi provide de means means to to protec protectt existin existing g operati operating ng facil facilitie ities. s. Mecha Mechanica nically lly protect small protrusions on operating equipment, such as bleeder valves and brackets, which could be damaged during the lift.

•

Consider Consider shutting shutting down down and depressu depressurizi rizing ng opera operating ting equipmen equipmentt which which could could be jeopardized by the lift.

•

Determin Determinee the feasibi feasibility lity of of making making a cran cranee lift lift by estab establish lishing ing the the operati operating ng area requirements, such as the radius, the required length of boom, and the load to be lifted.

834 Voids oids And And Hol Holes es Voids under pavements, holes, rocks, and soft ground can affect the safe operation of the crane. Sudden subsidence of the ground can induce impact forces in excess of design impact loads. Outriggers must rest on level surfaces which will support the load placed on them. If outrigger floats are allowed to settle into the ground, they lose their effectiveness, thus making continued lift operations unsafe.

835 835 Crane Crane Capa Capaci city ty Cons Conside iderat ration ionss For a safe lift, the following issues must be considered: •

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Crane Crane rating ratingss are are based based on machin machinee standi standing ng level level on a firm firm unifor uniformly mly supporting surface.

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Crane Crane rating rating charts charts apply apply up to a stated stated maximu maximum m wind wind speed. speed. Avoid void operat operating ing when the wind speed exceeds the crane design wind velocity.

•

The crane crane rated rated loads loads do do not acco account unt for for the the weight weight of rigging rigging acces accessori sories, es, like like blocks, hooks, slings, spreader bars, jibs, material handling equipment, and other elements of lifting tackle. Their combined weight must be subtracted from the load chart capacity when determining the maximum allowable load to be lifted.

•

The maxim maximum um safe safe working working load of cran cranes es is is determ determined ined from from static static loads. loads. The capacity charts do not take into account impact loads due to the dynamic motions of the load or crane.

•

There There is no standard standard procedur proceduree for for determ determinin ining g the rating rating of cranes cranes tra travel veling ing with suspended loads. Crane rating charts for operation without outriggers should not be used to determine traveling crane rating unless the capacity chart so states. Check with the crane manufacturer before traveling with a load.

8400 Insp 84 Inspec ecti tion on and and Testi esting ng 841 Inspec pection Prior to use, all rigging components should be inspected by a qualified crane inspector to ensure that they do not constitute a hazard.

Cranes •

Verif erify y capa capaci city ty cert certif ific icat ate. e.

•

Insp Inspec ectt cran cranee for for over overal alll good good con condi diti tion on..

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Boom: Boom: check check for for bent bent laci lacing, ng, dama damaged ged chords, chords, damaged damaged joint joint connect connections, ions, boom joint sheave bearings and for wear in rope grooves.

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Load Load line: line: che check ck for for brok broken en wir wires es and and gene genera rall condi conditio tion. n.

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Load block: block: visual visually ly check check conditio condition n of bearing bearings, s, for for wear wear in rope rope grooves grooves,, and the operating condition of safety latch. Before every critical lift, test for non-visible defects by magnetic particle or radiography.

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Crane Crane hook: hook: visuall visually y check check for deforma deformation tion.. Before Before ever every y critical critical lift, lift, test for non-visible defects by magnetic particle or radiography. Do not use:

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April 1989

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Hooks wi with cr cracks

–

Hooks Hooks with with throat throat openin openings gs mor moree than than 15% 15% of of norm normal al

–

Hook ooks wit with h mo more tha than n 10° twist from plane of unbent hook

Boom lines: lines: check check for broken broken wires, wires, particu particularl larly y at pendant pendant fitting fittings, s, and and general condition.

800-14

Chevron Corporation



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Main clutche clutchess and brakes: brakes: check check opera operation tion of air air or hydra hydraulic ulic systems systems.. They They should be able to hold 110% of line pull with full drums.

•

Swing Swing lock lock and and brake brakes: s: check check operatio operation n and and genera generall conditi condition. on. They They should should be able to prevent load from swinging in normal operation.

•

Revie Review w history history of of crane crane to to find find out out if it it has been been used used for major major lifts lifts since since it it was last certified. The crane may have been overstressed since certification.

Shackles •

Check lo load ra rating.

•

Check Check genera generall conditi condition on visuall visually y and test by magnet magnetic ic partic particle le for for nonvisi nonvisible ble defects.

Lifting Lugs •

Check lo load ca capacity.

•

Check Check genera generall conditi condition on visuall visually y and test by magnet magnetic ic partic particle, le, radio radiograp graphy hy,, or ultrasonic gage for nonvisible defects.

Wire Rope Slings Safety of used wire rope slings depends on the remaining strength. The decision to replace the sling should be made by experienced personnel only. Visually inspect the rope for signs of deterioration to determine if further use of the rope would be unsafe. Look for the following: •

Reduc Reductio tion n of rope rope diame diameter ter belo below w nomi nominal nal diame diamete terr

•

A number number of broken broken outside outside wires wires and the degree degree of conce concentra ntration tion of such such broken wires

•

Worn ou outside wi wires

•

Corro Corroded ded or broke broken n wires wires at end conne connect ction ionss

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Corroded Corroded,, crack cracked, ed, bent, bent, worn, worn, or imprope improperly rly applied applied end connect connections. ions.

•

Seve Severe re kink kinking ing,, crush crushing ing,, cutti cutting, ng, or unst unstra randi nding. ng.

842 Testing For light and medium, both critical and non-critical lifts, the following tests should be performed before a lift: •

Lifting Lifting gear gear assemb assembly ly (slings (slings,, shackles shackles,, spreade spreaderr bars, bars, load load blocks, blocks, etc.) etc.) Test Test to a minimum of two times the lifted load or design load. When it is impractical to test the rigging assembly to twice the lifted load (i.e., heavy lifts), lifting personnel will have to rely on a careful inspection of the rigging components outlined in Sectio Section n 841. 841.

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Used Used sling slings: s: Tes Testt to two two time timess thei theirr norm normal al ratin rating. g.

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Position Position the crane crane with with all all the the riggin rigging g gear gear attac attached hed and make make a trial trial run to verify clearances and operating radii.

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Rotate Rotate the the spreade spreaderr bar bar to to make make sure that it clear clearss the the cran cranee boom. boom.

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Where Where possible possible,, pick pick up the the load load and hold hold it it low low to test test the the crane’ crane’ss ability ability to hold the load.

•

Repaire Repaired d or altere altered d crane cranes. s. Load Load test test to to 110 percen percentt of the rate rated d load load to confirm the adequacy of repairs or alterations.

•

Hooks Hooks for which which no no manufac manufacture turer’ r’ss load load recomm recommenda endation tionss are avai availabl lable: e: Test Test to twice the load.

850 Riggin Rigging g Diagr Diagrams ams,, and and Riggi Rigging ng Anal Analyysis and Design Design Introduction This section discusses how to prepare and evaluate rigging diagrams and lists the information that a complete diagram should contain. It gives the loads and the factors of safety that should be used in the design of rigging components. Methods are presented for finding forces in unequal length slings and in slings for off-center lifts. Common types of lifting lugs are shown, and the steps to be followed in their design are outlined.

851 851 Rigg Riggiing Dia Diagr gram amss Preparation of Rigging Diagrams A rigging diagram is essential for the successful transportation, lifting, and placing of equipment in final position. Before the rigging diagram is prepared, the rigging operation is first analyzed and the rigging method selected (see Sectio Section n 820 820). Small non-critical lifts up to 50 tons can be made without rigging diagrams provided the lift is below 70% of the crane’s capacity as determined from the manufacturer’s safe load chart. A complete rigging diagram must show the entire rigging process and should show the following minimum information when it applies:

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Type and capaci capacity ty of of liftin lifting g equipm equipment ent (crane, (crane, gin poles, poles, etc.) etc.)

•

Crane Crane boom length, length, radius, radius, and location location of outrigge outriggers rs if required required

•

Weight, eight, dime dimension nsionss and and cente centerr of gravity gravity of piec piecee to to be lifted lifted

•

A plot plot of the the path path of travel travel inclu including ding all verti vertical cal and and horizon horizontal tal clea clearan rances ces from from such items as adjacent equipment, power lines, and other encumbrances or hazards

800-16

Chevron Corporation



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Location, Location, size, size, and and capaci capacities ties of liftin lifting g lugs, lugs, slings, slings, and and other other riggin rigging g access accessoories as well as the method of attachment

•

Type of tow tow tract tractor or,, includin including g size, size, capacit capacity y, turning turning radius radius,, trailer trailer attac attachmen hmentt mechanism, etc. This information is particularly important in narrow, limited width plant access roads and for lifts in confined areas.

•

Descript Description, ion, size, size, capaci capacity ty,, and location location of miscel miscellan laneous eous equipmen equipmentt such such as dollies, jacks, hand winches, rollers, etc.

•

Locat Location ion of mats mats under under equipm equipmen entt if if requi require red d

•

Location Location and orientat orientation ion of equip equipment ment before, before, during, during, and and after after the lift

•

Location Location of undergr underground ound lines lines (util (utility ity,, electr electrical ical duct banks banks or cables cables,, etc.) etc.) and foundations

•

Position Position of of survey survey equip equipment ment.. For critica criticall lifts, lifts, surve surveying ying is is importa important nt to ensure ensure that loads remain within vertical and horizontal limits and stable during the lifting operation.

•

Maximum Maximum allo allowab wable le wind wind veloc velocity ity for for the the lift. lift. Exces Excessiv sivee winds winds can can cause cause the the load to drift and strike the boom, other equipment, or obstructions near by.

Evaluation of Rigging Diagrams A rigging diagram, particularly one prepared by a Contractor, must be evaluated thoroughly to make certain that it incorporates all necessary information for a safe and successful lift. The evaluation process must verify that calculations and sizing of critical items such as cranes, slings, shackles, etc., are correct, that the proper factors of safety have been used, and that all clearance diagrams are accurate. The evaluation process should address the following: •

Rigging Equipment Confirm that the type of rigging equipment selected has the capability to lift the load. If a crane has been selected, verify that the selected crane has the overthe-side and over-the-rear capacity to lift the piece, especially for critical lifts or for lifts in operating plants. For two-crane lifts both cranes should be as close in capacity and drum speed as possible, except when one crane is used as a trailing crane. For additional precautions and restrictions regarding the use of cranes, see Section Section 811.

•

Equi Eq uipm pmen entt and and Road Roadwa way y Cle Clear aran ance ce Check the rigging diagram to ensure that the path of travel shows all overhead obstructions, including pipelines, walkways, guy wires, power lines; all obstacles at grade, such as fire hydrants, drains, signs, etc.; and the location of underground lines.

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•


Soil Loads Recently excavated and backfilled areas or areas with weak soils have limited bearing capacity. Examine the rigging diagram to verify that cranes, dollies, and trailers are adequately supported and that the diagram includes cribbing or mats under the crane and outriggers where required.

•

Wind Loads The rigging diagram should also be checked for the maximum allowable wind velocity.

•

Lifting Lugs Lifting lugs are often necessary for lifts. The rigging diagram should show the type and location of lifting lugs. Lifting lug calculations accompanying the rigging diagram should be checked thoroughly. See Secti Section on 856 for more details.

•

Slings Depending on the angle of the sling, the sling load may be larger than its portion of the lifted load. If the sling is used in a choked position, the sling capacity must be derated. Loads and ratings of slings are discussed in detail in Secti Section on 852 852. The rigging diagram should specify the minimum safe working load for the slings.

•

Shac Shackl kles es,, Hook Hooks, s, and and Spr Sprea eade derr Bar Barss The rigging diagram should also be checked to assure that the size and capacities of shackles, hooks, and spreader bars are adequate for the intended lift.

852 Loads Rigging components should be designed for the following loads and forces when they exist: •

Dead Load Dead load includes the weight of the slings, blocks, shackles, clevises, hooks, spreader bars, and other special rigging devices which may be used. The weight of the crane hooks, jibs, and other crane accessories are also included.

•

Live or Lifted Load Live load is the load of the piece being lifted.

•

Impact Load Rapid acceleration or deceleration of the lifted load and the dead load induce impact forces which must be considered in the design of rigging components. The effect of impact forces on the piece of equipment being lifted must also be evaluated. Quick take-up on a hoist or crane with slack or fouling in the connecting slings or ropes produces large impact forces that may be several

April 1989

800-18

Chevron Corporation



times the lifted load. The amount of impact depends on the rate of lift from the at-rest position. To avoid large impact forces, the slack must be taken up completely before lifting the load. For the design of lifting lugs or other attachments and for slings, the live and dead load should be increased by the following percentages:

•

Lifting lu lugs or or ot other attachments

100%

Slings

25%

Wind Load The maximum allowable wind velocity is based on the ability of the boom to resist lateral loads and on the stability of the lift. Crane manufacturers can supply data regarding the lateral load capacity of crane booms. In the absence of definitive information, however, no rigging should be done when the steady wind velocity exceeds 25 mph.

853 853 Fact actors ors of Saf Safety ety A factor of safety is applied to all rigging gear to insure against failure from loads whose magnitude cannot be calculated exactly or from indeterminate material properties. The factor of safety (F.S.) is defined as follows: Breaking or Yield Strength F.S. = ----------------------------------------------------------------Working Strength From experience and common engineering practice, the following factors of safety should be used in the absence of larger values required by local regulations or equipment manufacturers. •

Wire Rope The minimum factor of safety of individual wire rope used for general hoisting purposes should be 5. Where the rope is wound around drums or sheaves smaller than the recommended minimum D/d ratio, the minimum factor of safety should be 7.

•

Manila Rope The minimum factor of safety for new grade No. 1 rope should be 5. For used rope (in service more than 6 months) the minimum factor of safety should be 10. Manila rope is recommended only for very small lifts.

•

Slings The minimum factor of safety for slings, including end connection or bending efficiencies, should be 5. As an example, a wire rope sling with an end connection efficiency of 80% would require a wire rope with 25% greater working

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strength than a wire rope in a sling with an end connection 100% efficient (100/0.8-100=25). •

Shackles and Hooks The minimum factor of safety should be 5. In the case of hooks, the hook must be centered over the load to allow for full lifting capacity, otherwise the hook capacity should be derated. The amount of derating should be calculated by experienced personnel only.

854 Sli Sling Forces ces The load in a sling depends not only on the total load but also on the geometry of the lift, i.e., length and angle of sling. To properly size a sling, the following procedure should be followed: •

Dete Determ rmin inee the the weig weight ht of the the load load

•

Choos hoosee the the desir esireed hi hitch tch

•

Calculat Calculatee the the force force in the the sling sling based based on the the geome geometric trical al arran arrangeme gement nt of the slings

•

Sele Select ct a sli sling ng of of suit suitab able le wor worki king ng str stren engt gth h

For a sling load analysis, the use of a correct free body diagram is very important. The center of gravity of the lift is always located directly underneath the lifting hook. For rated capacity of slings refer to the Safety in Designs manual.

Unequal Sling Lengths One of the most frequently encountered loading conditions is where unequal sling lengths are used to suspend a load in a level position. The load analysis for two unequal length slings is simple and straightforward as Figure Figure 800-5 800-5 shows. Three and four unequal length slings are sometimes used in equipment rigging. The sling load analysis is more difficult and in the case of four slings, unless the sling lengths are precisely calculated with respect to the center of gravity of the load and the pick point of the crane hook, two diagonally opposite slings may end up taking all the load. Instead of oversizing the slings to carry one-half the lifted load, a better solution would be to use a spreader beam which equalizes the load in each pair of slings and prevents diagonal tension. The load analysis of three or four unequal length slings should be carried out by experienced civil engineers only. only.

Off-Center Lifts Many times a load, such as a turbine rotor, has to be lifted “on an even keel.” When two equal length slings are used and the load is lifted without regard to the position of the center of gravity, the load will tilt until the center of gravity is directly below the crane hook. See Figure Figure 800-6 800-6. A load in a tilted position could be a hazard to personnel and or equipment. In order to avoid tilted loads, the size and length of slings should be designed so that the load is lifted level.

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800-20

Chevron Corporation


Fig. 800-5


Example 1—Two Unequal Length Slings

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Fig. 800-6

April 1989


Example 2—Lifting with Two Equal Length Slings without Regard to Center of Gravity

800-22

Chevron Corporation



855 855 Wi Wire re Rope Rope Stre Stretc tch h Wire rope, like all other elastic members, elongates under load. Total wire rope elongation (rope stretch) is caused by two factors. The first factor is the way the rope is constructed and starts to develop as soon as a load is applied. It is caused by the adjustment of the wires and compression of the core and it is permanent. Where precise rope length is required and adjustment for length is limited, the rope should be prestretched. This is often the case in critical lifts. The second factor is elastic elongation of the wire rope under load. Provided the load is kept below the elastic limit, the rope returns to its normal length when the load is removed. The elastic stretch can be calculated by using the following formula: ∆L = PL/AE

where: L = rope length, in lastic ic elon elonga gati tion on of of rop ropee, in ∆L = elast P = applied load, lb E = modu modulu luss of of ela elast stic icit ity y, psi psi (See (See Figure Figure 800-7 800-7) A = metal metallic lic cros cross-s s-sec ectio tiona nall are areaa of of rop rope, e, in2 The cross-sectional area can be found in wire rope catalogs. Without a catalog the cross-sectional area of most six-strand wire rope can be estimated as follows: A = 0.4d2, in2 where d = nominal rope diameter, in. As seen in Figure Figure 800-7 800-7, the modulus of elasticity varies with different rope construction. The modulus of elasticity will increase during the service life of the rope or with an increase of the applied load. The modulus of elasticity of prestretched wire rope is approximately 20,000,000 psi. Fig. 800-7

Approximate Modulus of Elasticity of Nonprestretched Wire Rope

Modulus of Elasticity (lb/in 2)

Wire Rope Construction

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6 x 7 with FC

12,000,000 to 13,000,000

6 x 7 with IWRC

14,000,000 to 15,000,000

6 x 19 Class with FC

11,000,000 to 12,000,000

6 x 19 Class with IWRC

13,000,000 to 14,000,000


10,000,000 to 11,000,000

6 x 37 Class with IWRC

12,000,000 to 13,000,000


8,000,000 to 9,000,000

6 x 25 Style BFS

12,000,000 to 13,000,000

6 x 30 Style GFS

12,000,000 to 13,000,000

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Example. Calculate the elastic stretch of 200 feet of prestretched 1 1/8 inch nominal diameter 6x19 IWRC wire rope loaded to 25,000 lb. ∆ L = P L ⁄ A E

25 ,000 × 200 × 12 = -------------------------------------------------------------------( 0.4 × 1.1252 × 20 ,000 , 000 ) = 5.93 in.

856 856 Lift Liftin ing g Lugs Lugs (Pade (Padeye yes) s) General Lifting lugs, sometimes called padeyes, are welded to the piece being lifted to facilitate lifting and erection. Not all lifts, however, need lifting lugs. For example, small pumps and electrical equipment on skids can be lifted with hooks, or with choker or basket hitches. Lifts that usually need lifting lugs include columns, vessels, heaters, air coolers, stacks, production skid mounted units, etc. The location and orientation of the lifting lugs depends on the rigging method and type of equipment. Some considerations when locating lifting lugs are: •

By placi placing ng the lugs closer closer to the cente centerr of gra gravity vity of colum columns, ns, the the tailing tailing load may be decreased.

•

For thin wall wall vessel vessels, s, the location location and numbe numberr of lift lifting ing lugs lugs may may be dicta dictated ted by the stresses imposed on the vessel shell during the lifting operation.

•

For lugs on the the side side of vert vertical ical vessels vessels,, such such as trunni trunnions, ons, the the path path the the slings slings make during upending must be clear of nozzles, support clips, platforms, or other obstacles.

Types of Lifting Lugs The types of lifting lugs most often used for lifting vessels are trunnion lugs, ear lugs, and flange lugs. All of these lifting lugs require a complete structural analysis to ensure a sound design. Trunnion lugs and ear lugs are attached to the vessel by welding, and must therefore be installed by the vessel fabricator because welds on vessel shells frequently require stress relieving. Trunnion lugs and earlugs are recommended over flange lugs for new vessels. A trunnion lug is shown in Figure Figure 800-8 800-8. This lug is used on heavier vessels. An ear lug is shown in Figure Figure 800-9 800-9. This lug is usually installed at the tangent line or transition point of a column or vessel. In contrast to trunnion lugs, ear lugs present fewer interference problems between slings and nozzles, clips, and platforms.

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800-24

Chevron Corporation


Fig. 800-8


Trunnion Lifting Lug

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Fig. 800-9

April 1989


Ear Lifting Lug

800-26

Chevron Corporation



For existing vessels or new vessels without trunnion or ear lugs, flange lugs can be used on vertical vessels with top nozzles. Flange lugs should only be used 1) when a complete structural analysis shows that the nozzle is strong enough to take the lifting load, and 2) when tailing loads do not present any special problem. Figure Figure 800-10 800-10 shows flange lugs with various weld attachments and lists several items to be evaluated.

Lifting Lug Design Designing or checking lifting lugs should be by experienced civil engineers in conjunction with experienced vessel designers. To properly design a lifting lug, the weight and center of gravity of the piece must be known as well as the rigging arrangement, i.e., the number and geometry of the slings. If the actual weight of the piece is not known, the lug can be designed for the working capacity of the attached sling. In a lift with three or four unequal length slings in a single point pick, as mentioned above, two diagonally opposite slings may end up taking the entire load. In that case, the lug should be designed to carry one-half the lift load with an impact factor, I=100%. This means that each lug is designed to lift the static weight of the entire piece. The centroid of the piece should be computed exactly so that the hook can be located directly over it. If this is not done, then the lifting lugs will not be oriented exactly towards the center of gravity and it will be subjected to out-of-plane bending stresses. The design of padeyes should follow a systematic ordered approach and should be based on the American Institute of Steel Construction (AISC), Manual of Steel Construction. Following is a suggested step-by-step procedure for the design of padeyes.

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1.

Calculat Calculatee sling sling load and and determin determinee sling orie orientat ntation, ion, if not not given. given. Both Both the sling load and direction affect the stress distribution in the padeye.

2.

Lis List desi design gn data –

Governing co code AI AISC

–

Sling load

–

Pade Padeye ye mat mater erial ial prope propert rties ies (yiel (yield d stre strengt ngth h Fy and tensile strength Fu).

–

Weldin elding g elec electr trode ode type type and and nomi nominal nal stren strength gth

3.

Sketch Sketch the padeye padeye and and show its its location location relat relative ive to to the piece piece being lifted lifted..

4.

List List allo allowa wabl blee stre stress sses es –

Tension: Ft = 0.45 Fy

–

Shear: Fv = 0.40 Fy

–

Bearing: Fp = 0. 9 Fy

–

Bending: Fb = 0. 6 Fy

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Fig. 800-10 Flange Lifting Lug (1 of 2)

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Fig. 800-10 Flange Lifting Lug (2 of 2)

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–

Welds: elds: allowabl allowablee stresses stresses in in accorda accordance nce with with Table Table 1.5.3 1.5.3 of of AISC “Spec “Specifi ifi-cation for the Design, Fabrication and Erection of Structural Steel for Buildings,” 1978

–

Combined st stresses: f cr = [f 2bx - (f bx)(f by) + f 2by + 3fv]1/2 where f cr = critical stress ≤ Fy f bx = bending stress about X - axis f by = bending stress about Y - axis f v = shear stress in xy - plane

5.

6.

Select Select shackle shackle size size based based on sling sling load, load, using using factor factor of safet safety y of 5 and list list controlling dimensions and tolerances. –

Shac Shackl klee siz sizee and and ca capaci pacity ty

–

Pin Pin dia diame meter ter and and outs outside ide of eye eye dia diame meter ter

–

Inside length

–

Insi Inside de widt width h at at pin pin and and at at bo bow

Select Select padeye padeye hole hole size to to accommod accommodate ate shackl shacklee pin diamete diameterr. The size of the the hole should be as follows: Shackle pin diameter

Hole size

1 inch and less

pin diameter + 1/8 inch

greater greater than 1 inch inch but but less than than 2 inch inch pin diame diameter ter + 3/16 3/16 inch inch greater than 2 inch

pin diameter + 1/4 inch

7.

Calculat Calculatee the padeye padeye plate plate thickne thickness ss and cheek cheek plate plate thickness thickness if requi required red or desired to minimize padeye plate size, based on allowable stresses in step 4 above.

8.

Calc Calcul ulat atee weld weld size size

9.

–

Chee Cheek k pla plate te to main main pade padeye ye plat platee

–

Pade Padeye ye to vess vessel el or othe otherr pie piece ce

Check Check adequac adequacy y of equipmen equipmentt to which which padeye padeye is attach attached ed to verif verify y that it is is capable of supporting the load from the padeye within the allowable stresses. The vessel fabricator and/or the engineering design group should be consulted first.

10. Summari Summarize ze padeye padeye design design parameters parameters 11. 11. Deta Detail il pade padeye ye

April 1989

800-30

Chevron Corporation



8600 Gene 86 Genera rall Rig Riggi ging ng Inf Infor orma mati tion on Introduction This section lists types of lifting equipment and miscellaneous rigging equipment. It discusses construction and strength of wire rope, slings, and the different kinds of hitches used in rigging.

861 861 Types ypes Of Lif Lifti ting ng Equi Equipme pment nt Different types of lifting equipment are available to fill any rigging need. A rigging operation analysis will indicate what equipment is best suited for a particular job.

Mobile Cranes Cranes are the most useful equipment in heavy rigging. The improvements which have taken place in cranes in recent years have greatly increased their lifting capacity. Crane mobility makes for a minimum amount of time for move-in, setup, and move-out, and their long boom allows access to restricted areas. •

Hydraulic cranes are readily available, can usually travel on most public streets and highways with few restrictions, and can be made ready for rigging fast because the boom requires no assembly. The majority of hydraulic cranes have maximum working capacities that range from 5 tons to 40 tons, though some models can exceed 125 tons. They are suitable for light lifts and medium lifts at short radii.

•

Truck-mounted Truck-mounted cranes have maximum working capacities to 300 tons and have longer booms. Small truck cranes, like hydraulic cranes, can travel on public streets and highways with limited restrictions. Large capacity truck cranes on the other hand are much wider than small ones (up to 16.5 feet) and require travel permits before they can move over public streets and highways. They are suitable for medium and heavy lifts, but because the boom requires assembly, it takes longer to prepare them for rigging.

•

Crawler-mounted cranes can have capacities exceeding 600 tons. The large crawler dimensions distribute the load over a larger area, thus resulting in lower bearing pressures than truck cranes of equal capacity. Depending on size, the crawler width can exceed 20 feet. As a result, travel over public streets and highways is severely restricted and they are normally disassembled for transit. Crawler cranes are suitable for heavy lifts.

Gin Poles Gin poles are used primarily for lifting tall, heavy columns and vessels in remote locations where large capacity cranes are not available or confined spaces limit their use. Compared to cranes, gin poles have larger capacities (up to 1200 tons) and lower relative cost. Gin poles are usually used in pairs. The poles are guyed from the top and pinned at the base. The load is raised or lowered by ropes reeved through sheaves or blocks at the top of the poles. Unlike cranes, however, capacity

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charts for gin poles are given for the pole as a compression member only. The load in the guy wires must be calculated from the geometry of the lift. A complete analysis should consider wind and temperature loads too. The bottoms of gin poles should rest on sound foundation and must be anchored securely to prevent kicking out under the load. The top of gin poles should be guided by at least four guy lines to maintain them in a stationary position and to prevent rotation. The guy lines can be ASTM A586 Zinc-Coated Steel Structural Strand or ASTM A603 Zinc-Coated Steel Structural Wire Rope.

Derricks Derricks have relatively large capacities at long radii. They can be mounted either on fixed foundations only a few feet above the ground or on top of high specialized gantries. They are not as flexible as mobile cranes because they cannot be moved easily. Some mobility can be provided by traveling gantries.

Bridge Cranes Bridge cranes are often used in lifting operations when the load is to be placed within a building or space already served by the crane.

Hoists Hoists are used in heavy lifting as part of the rigging system and are generally not subjected to severe use. Design of the tackle arrangement for specific lifts is generally done on a trial basis and it starts with selection of a hoist of adequate capacity. The line pull of a hoist decreases as the amount of load line on the drum increases. A check should be made to insure adequate line pull and rope capacity for the entire lift.

862 862 Misc Miscell ellane aneous ous Rigg Rigging ing Equip Equipmen mentt A rigging operation often requires the use of miscellaneous rigging equipment. Some of the most common is listed below:

Chain Hoists Chain hoists or come-alongs, as they are often referred to, provide a portable tool for applying tension. There are two types of chain hoists available: roller chain and conventional link chain. Conventional link chain is preferred in general rigging because it is less susceptible to wear than roller chain. Chain hoists range in size from a few pounds to 10 tons.

Turnbuckles Turnbuckles are positive tension fittings with limited capability for adjustment. They can be furnished with end connection combinations of eye, hook or jaw. Their working load capacity ranges from 500 pounds to 75,000 pounds.

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800-32

Chevron Corporation



Jacks Jacks, both hydraulic and mechanical, are useful in raising and supporting loads. When raising a load with jacks, it is very important that the base of the jack be on a solid surface. If the piece to be raised is of appreciable height, consideration should be given to using hydraulic jacks designed for use with a power pump. Hydraulic jacks may be used to determine the weight of a piece. The total weight being supported can be computed with the aid of a calibrated pressure gage if the effective ram area of each jack and the unit pressure on each jack are known. Jack capacities range from a few pounds to 500 tons.

Rollers Rollers are used to move loads horizontally. There are three general types of rollers: wood rollers, steel pipe rollers, and manufactured flat top roller assemblies. Moving a load on wood or pipe rollers requires a runway consisting of heavy timbers or beams capped with wood planks or steel plate. The runway should be of sufficient area to distribute the load, and an adequate number of rollers should be used to support the load without damaging the load or the rollers. Manufactured roller assemblies require a smooth concrete or steel surface on which to operate. They range in capacity from 2 tons to 200 tons.

Mats Mats provide a means for increasing the bearing area under cranes and outriggers when soil bearing capacity is limited. The ground surface on which mats are placed must be graded to provide uniform level bearing. Mats are usually made of 6-to-12 inch thick timber. They are sometimes made of steel members when greater rigidity is needed.

Shackles And Hooks Shackles are the most frequently used fitting for joining slings to rigging attachments or lifting lugs. The safe working load for shackles of the same size varies and it depends on shackle type and manufacturer. Therefore, shackles must be specified by safe working load, size, pin size, and manufacturer’s model number. Hooks are also used as sling fittings for moderate material lifts and where the loads are connected and disconnected often. Only hooks with safety latches should be used.

863 Wire Ro Rope General Wire rope is widely used in slings, hoists, boom lines, etc. Wire rope is formed by laying strands of wire around a rope core. Each strand is made up by a number of small wires laid helically around a center wire in one or more layers. The rotation of the wires and the rotation of the strands in a wire rope is referred to as rope lay. Rotation is either to the right (clockwise) or to the left (counterclockwise). The

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center of the wire rope is called the core and may be made of fiber (FC), wire, plastic, or other material. Wire cores are of two general types: independent wire rope core (IWRC) or wire strand core (WSC). Wire rope with IWRC or WSC has slightly greater capacity (approximately 6%) than rope with FC, and has greater resistance to crushing under heavy bearing pressure. Wire rope is usually designated by first the number of strands and then the number of wires in each strand. Therefore, a 6x19 wire rope would normally have six strands and each strand would contain 19 wires. However, depending on the wire rope classification, the number of wires per strand can vary. For example a 6x19 wire rope can have 16 to 26 wires per strand. The nominal diameter of the wire rope is the greatest diameter that can be measured.

Wire Rope Strength Ropes are classified into various grades according to strength and ability to withstand abrasion. In ascending strength order they are: 1.

Mild Mild Plow low Ste Steeel.

2.

Plo Plow Ste Steel el (P.S.) .S.)

3.

Impro Improve ved d Plo Plow w Ste Steel el (I.P (I.P.S. .S.))

4.

Extra Extra Impro Improve ved d Plow Plow Steel Steel (E.I. (E.I.P P.S.) .S.)

5.

Double Double Extra Extra Impro Improved ved Plow Plow Steel Steel (X.E.I. (X.E.I.P P.S.)

Manufacturers of wire rope publish breaking strength and sometimes safe working strength values. The safe working strength is typically listed as 20 percent of the breaking strength: i.e., factor of safety = 5. The manner in which wire rope is used affects its strength properties. Ropes running over sheaves or drums are subjected to bending stresses. The ratio of sheave diameter D to rope diameter d influences rope efficiency. Figure Figure 800-11 800-11 shows an empirically derived curve that relates the efficiency of wire rope to the diameter of the pin or sheave. As can be seen, the smaller the ratio of sheave diameter to nominal rope diameter the smaller the efficiency. The minimum recommended sheave diameter is 18 times wire rope diameter.

April 1989

800-34

Chevron Corporation



Fig. 800-11 Efficiency of Wire Rope when Bent Over Sheaves or Pins of Various Sizes

864 Slings General Slings are made with wire rope, steel chain, natural fiber rope, and synthetic fiber rope. Selecting the proper size sling, length, and hitching arrangement will achieve the desired orientation of the suspended load, will result in a stable lift, and will provide the required factor of safety.

Wire Rope Slings Wire rope slings are the most frequently used slings in general rigging. Wire rope slings are made by attaching fittings to the ends of premeasured wire rope lengths. Sling capacity is affected not only by the strength of wire rope but also by the type of end connection. An end connection that distorts the wire rope least is the most efficient. The various types of end connections and corresponding approximate efficiencies can be found in “Safety in Designs” manual. The appropriate end connection efficiency must be applied to the working rope strength to arrive at the working strength of the wire rope sling. If the sheave diameter D to rope diameter d (D/d) ratio results in bending rope efficiency which is less than the end connection efficiency, then bending efficiency should be applied instead of the end connection efficiency.

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Synthetic Webbing Slings Synthetic webbing slings are made of nylon, polyester, and polypropylene. Because of their relative softness and width, synthetic slings have less tendency to mar or scratch machined, polished, and painted surfaces, or to crush fragile objects. They are non-sparking and can be used safely in explosive atmospheres. Obtain manufacturer’s data on safe working loads, factors of safety, and allowable wear before using.

Steel Chain Slings Chain slings are used where flexibility, ruggedness, and resistance to abrasion or high temperatures are important. However, chain failure is sudden, and unless circumstances dictate otherwise, the use of chain slings should be discouraged in general rigging. Check chain type, grade, and working load limit before using.

Natural Fiber Rope Slings Number 1 manila rope is the only fiber rope approved for hoisting. Normally, manila rope is used for lifting men. Load capacity of manila rope slings is shown in ANSI B30.9, “Slings.” Manila rope is not recommended for general use as lifting slings. Use for very small lifts only.

865 865 Hitc Hitche hess For For Wir Wire e Rop Rope e The most commonly used hitches for wire rope are vertical hitch, choker hitch, and basket hitch.

Vertical Hitch This hitch is also called a direct connection hitch. When used singly, it does not afford the best load control nor protection against spin. It is effective when used in multiples with spreader bars or when two or more attachment points are provided on the load. See Figure Figure 800-13. 800-13.

Choker Hitch A choker hitch is made by simply threading one eye of the sling through the other and choking the load. A single choker hitch does not provide full contact with the load and should not be used to lift loose bundles or long loads. The double choker hitch is made by doubling the sling and threading the double end through both eyes. Double wrap choker hitches compress the load and prevent it from slipping out of the sling. See Figure Figure 800-12 800-12.. Bending of wire rope at a choker hitch decreases the working strength of the rope because of bending efficiency. In a choker hitch, when the load is freely suspended, the center of gravity is directly under the point of choke. The observed angle in this position is approximately 135°. Smaller angles occur when a choker hitch is used to turn a load or when the point of choke is not directly over the centerline of the piece. Figure Figure 800-14 800-14 shows the various choker hitch angles and relates the angle of choke to wire rope efficiency.

April 1989

800-36

Chevron Corporation


Fig. 800-12 Choker Hitch


Fig. 800-13 Single Vertical Hitch

Basket Hitch With a single basket hitch, two parts of the cable support the load although only one cable is used. As a load is lifted with a basket hitch, the load is equalized on each leg and therefore each leg supports half the weight. The basket hitch is easy to attach and is a good hitch when used under the right conditions. The double wrap hitch is one of the best hitches for smooth cylindrical loads such as pipes and tubes. It is the safest hitch to use. The load is held in a loop with the cable exerting equal pressure for 360°. See Figure Figure 800-15 800-15..

Reverse Basket Hitch and Single Length Double Basket Hitch In these hitches the bight of the sling bears on the crane hook. The sling is free to move over the hook so that the load in each leg of the sling is automatically equalized. These hitches can be used to lift loads with lifting lugs or trunnions located above the center of gravity of the load. They can also be used to equalize loads in a pair of legs of a four-leg sling arrangement by using two equal slings and one long sling with its bight over the hook.

Chevron Corporation

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April 1989



Fig. 800-14 Choker Hitch Efficiency

Fig. 800-15 Basket Hitch

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800-38

Chevron Corporation



870 Glossary The following terms are commonly used in rigging. Area, Metallic. Sum of the cross-sectional areas of individual wires in a wire rope or strand. Basket Hitch. Sling configuration that equalizes the load in both legs of a sling formed with a single wire rope. Bight. A loop or slack part in a rope. Boom. A metal beam or strut, pivoted or hinged at its lower end and with its upper end supported by chains, ropes, or rods reeved through sheaves or a block, used to support or guide a load to be lifted or swung. Boom Angle. The vertical angle from a horizontal line through the center of rotation of the boom and centerline of the boom. Boom Length. The straight line distance of a boom from the lower end hinge to the upper end load point or hoist sheave pin. Boom Line. A wire rope for supporting or operating the boom on derricks, cranes, drag lines, shovels, etc. Bright Rope. Wire rope made of wires that are not coated with zinc or tin. Cable. A term loosely applied to wire ropes, wire strands, manila ropes, and electrical conductors. Cable-Laid Wire Rope. A type of wire rope consisting of several wire ropes laid into a single wire rope. Cheek Plates. Doubler plates attached to the sides of and centered around the padeye hole. Chocking. Wedges used to keep round vessels from rolling. Usually of timber construction. Choker. Sling hitched to form a slip noose around the object to be moved or lifted. Core. The center of a wire rope about which the strands are laid. It may be fiber, a wire strand, or an independent wire rope. Counterweight. Weight used to supplement the weight of the machine in providing stability for lifting working loads and usually attached to rear of revolving superstructure. Also called ballast. Deflection. (a) Sag of rope in a span; usually measured at mid-span as the depth from the chord joining the tops of the two supports (b) Any deviation from a straight line. Drum (Rope). A rotating cylinder with side flanges on which rope used in machine operations is wrapped.

Chevron Corporation

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April 1989



Eye or Eye Splice. A loop, with or without a thimble, formed in the end of a wire rope. Factor of Safety (FS). Factor of safety is defined as the ratio between breaking or yield strength and working strength. Fiber Core (FC). Fiber center of a wire rope. Fitting. Any accessory used as an attachment for wire rope. Gantry. A structure for mounting a crane or derrick. It can be stationary or adapted for truck travel by towing or by independent truck power. Gantry (A-Frame). A structural frame, extending above the superstructure, to which the boom support ropes are reeved. Gin Pole. Compression member guyed from top and pinned or in a socket at its base. The load is raised and lowered by ropes reeved through sheaves and blocks at the top of the pole. Usually used in pairs. Grades, Rope. Classification of wire rope by its breaking strength. In order of increasing breaking strength: Mild Plow Steel, Plow Steel, Improved Improved Plow Steel, Extra Improved Plow Steel, Double Extra Improved Plow Steel. Guy (Line). A rope used to steady or secure the mast or other member in the desired position. Guy Derrick. A fixed derrick consisting of a mast supported in a vertical position by guys capable of being rotated, and a boom whose bottom end is hinged or pivoted to move in a vertical plane with a reeved rope between the head of the mast and boom point for raising and lowering the load. Hitch. The manner of using the sling to support a load. Hoist Line. See load line. In lifting crane service, refers to the main hoist. The secondary hoist is referred to as the whip line. Hook Block. Block with hook attached used in lifting service. It may have a single sheave for double or triple line, or multiple sheaves for four or more parts of a line. Independent Wire Rope Core (IWRC). Wire rope used as the core of a larger rope. Jib. An extension attached to the boom head to provide added boom length for handling specified loads. The jib may be in line with the boom or may be offset. Lang Lay Rope. Wire rope in which the wires in the strands and the strands in the rope are laid in the same direction. Lay. Manner in which wires are helically laid into strands or strands into rope. Lifting Lug. Attachment on equipment to be lifted. Load Block, Lower. The assembly of sheaves, pins, hook or shackle and frame suspended from the hoisting ropes.

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Chevron Corporation



Load Block, Upper. The assembly of sheaves, pins, shackle, swivel, and frame suspended from the boom by solid links or direct connection. Load Line. Another term for hoist line. See also whip line. Mats. Supports or floats used for supporting machine on soft ground. Usually of timber construction. Outriggers. Extendable arms attached to the mounting base, which rest on supports at the outer ends to increase stability. Pressed Fitting. Fittings in which wire rope is attached by pressing the shank enclosing the rope. See swaged fittings. Prestressing or Prestretching. Prestretching. Stressing a wire rope or strand before use under such a tension and for such a time that the constructional stretch is largely removed. Radius of Load. The horizontal distance from the axis of rotation to the centerline of boom point sheave. Rated Load (or Crane). Rated loads at specified radii are the lesser of a specified percentage of tipping loads or the machine’s structural competence as established by the manufacturer, and are the maximum loads at those radii covered by the manufacturer’s warranty. Reeving. A rope system in which the rope travels around drums and sheaves. Rigging. A combination of slings, shackles, hooks, load blocks, spreader bars, and other attachments that are used to support, lift, manipulate, and place equipment or other loads in their final position. Safety Factor. See Factor of Safety (FS). Safe Working Load (SWL). Proper load which the rope, shackle, etc., may carry as determined by manufacturer’s data, tests, and applicable codes. Safety Hook. A hook with a latch to prevent slings or load from accidentally slipping off the hook. Shackle. A U-shaped fitting with a pin. Sheave. A grooved pulley for use with rope. Side Loading. A load applied at an angle to the vertical plane of the boom. Sling. The rope assembly which connects the load to be lifted to the crane or other lifting device. Slings, Braided. A very flexible sling composed of several individual wire ropes braided into a single sling. Splicing. Interweaving of two ends of ropes so as to make a continuous or endless length without appreciably increasing the diameter. Also making a loop or eye in the end of a rope by tucking the ends of the strands.

Chevron Corporation

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April 1989



Spreader Bar. A member used to make slings vertical from object lifted. Theoretically a compression member. Spreader Beam. Same function as spreader bar. Uses less headroom. A bending member. Strand. An arrangement of wires helically laid about an axis, or another wire or fiber center to produce a symmetrical section. Superstructure. The rotating upper frame structure of the machine and the operating machinery mounted thereon. Swaged Fittings. Fittings in which wire rope is inserted and attached by swaging. Tackle (Hoist). Assembly of ropes and sheaves arranged for lifting, lowering, or pulling. Tag Line. Lin e. A rope used to prevent rotation of a load. Tail Swing. Distance from center of rotation to maximum rear extension of revolving superstructure. Thimble. Grooved metal fitting to protect the eye of a wire rope. Tipping Condition. A machine is considered to be at the point of tipping when a balance is reached between the overturning moment of the load and the stabilizing moment of the machine on a firm level supporting surface. Tipping Load. Tipping load is the load producing a tipping condition at a specified radius. It includes the weights of hook, hook blocks, slings, etc., plus weight on hook. Turnbuckle. Device attached to wire rope for making limited adjustments in length. It consists of a barrel and right-and-left hand threaded bolts. Whip Line. Secondary rope system. Also see load line. Wire. Single continuous length of metal, round or shaped, cold drawn from a rod. Wire Rope. A plurality of strands laid helically around an axis or a core. Wire Strand Core (WSC). Wire strand used as a core for a wire rope.

880 Mode Modell Speci pecifi fica cati tion on CIV-MS-4782, Lifting Services, is included in the Specification section of this manual. This model specification establishes the basic requirements for performing a lift, including all lift equipment and items required in rigging operations. It also discusses design requirements, inspection and testing, and safety.

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Chevron Corporation



890 References Company Standards 1.

Safety Safety in Desi Designs gns Manua Manual, l, Sec Sectio tion n6

American National Standards Institute (ANSI) 1.

B30.1 Jacks

2.

B30.2 B30.2 Over Overhea head d and and Gantr Gantry y Cra Cranes nes

3.

B30.5 B30.5 Mobi Mobile le and and Loc Locom omoti otive ve Crane Craness

4.

B30. 30.6 Derrick icks

5.

B30. B30.7 7 Base Base Mou Mount nted ed Dru Drum m Hois Hoists ts

6.

B30.9 Sl Slings

7.

B30.10 Ho Hooks

U.S. Department of Labor, Occupational Safety and Health Administration (OSHA)

Chevron Corporation

1.

29CFR191 29CFR1910.18 0.180 0 Crawler Crawler Locomot Locomotive ive and Truc Truck k Cranes Cranes

2.

29CF 29CFR1 R191 910. 0.18 181 1 Derr Derric icks ks

3.

29CFR 29CFR191 1910.1 0.184 84 Standa Standard rd Sling Slingss

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800 Cranes, Rigging and Lifting

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