safety nets: fall protection for the construction …...nets, interior nets, perimeter nets,...

National Safety Council

Data Sheet 608 Rev. February 2006

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There are two basic kinds of fall-protec-tion systems in use in the construction

industry, namely, passive and active sys-tems. Passive systems, when installed,protect workers without the need for themto take positive action on their own behalf.Active systems, on the other hand, are pro-tection systems or devices that requireeach worker to take positive action to pro-tect against a fall, such as putting on a safe-ty belt, connecting the belt or lanyard to asafe suspension point or putting on a hardhat, etc. This data sheet will deal only withsafety nets for the safety of personnel whowork on construction projects.

Passive protection net systems

2. Passive net systems consist of twomajor types: personal nets and debris nets.Personnel nets are designed to catch per-sonnel who fall from a high place—a bridge,building, tower, dam, silo or other structure.Personnel nets are made of a variety of nat-ural and synthetic materials in the form ofrope or strips to produce a webbing thathas a mesh strength strong enough to with-stand the force of a falling person and amesh size small enough to minimize per-sonal injury. Details of personnel net speci-fications will be discussed later.3. Debris nets are designed to catch small,lightweight construction debris, tools,building materials and other items that maybe dropped, pushed or blown from a struc-ture. Debris nets are designed to preventworkers, passersby or traffic from beinghurt or damaged. The mesh size of debrisnets depends upon the job. They are avail-able in many sizes and strengths depend-

ing on the weight and size of the debris tobe contained.

Other safety nets

4. The term “safety net” is frequently usedto include any kind of net, whether it is apersonnel net, or a debris net. Also, the con-struction industry tends to categorize netsaccording to their application (e.g., bridgenets, interior nets, perimeter nets, elevatorshaft nets, roofing nets, polar crane nets,etc.). This data sheet will attempt to be spe-cific and define nets according to both typeof net and its application.5. Interior nets are used on the interior ofstructures where the fall distance is greaterthan 25 feet. Personnel nets and debrisnets are used together on such applica-tions where other means of fall protection,such as flooring or scaffolding, are notused or are not practical. Nets should becleaned on a daily basis, or as needed,depending on the debris collected.

Safety nets: Fall protection for the

construction industry

Figure 1. A typical safety net installed under steel

workers who are securing a roof beam.



6. Perimeter nets are personnel or debrisnets that are erected around the perimeterof a building to protect workers from over-board falls or to catch construction debris.7. Other examples of applications for safe-ty and debris nets exist in elevator andmechanical shafts to protect workers andguard against falling debris. Special struc-tures such as cooling towers, chimneys,containment buildings, civic centers, audi-toriums, gymnasiums and atriums of largebuildings also may be protected with a vari-ety of specialized and special-shaped safe-ty and debris nets.8. Spalling nets are designed to catchsmall- and medium-size chunks of concreteor stone that scale off or are beingremoved from decaying structures.9. Restoration nets are designed to protectworkers, the public, displays and traffic fromfalling objects during restoration projects.10. Slag nets are designed to be hungbelow cutting or welding operations tocatch the slag of the welder’s or cutter’storch and protect those below.11. Windscreen/over spray nets aredesigned to be used vertically to restrictthe spreading of paint, sandblast materialand sprayed-on insulation while still allow-ing for ventilation to the area.

Net specifications

12. Only general specifications can bedetailed in a data sheet of this kind.Specific data on the various types of netsdepends a great deal on the application.The net manufacturer should be consultedfor technical data in developing the specifi-cations for a particular job.13. This data sheet, with the aid of photos,diagrams and charts, will explain the hazardsand benefits of safety nets and what meas-ures should be followed in the use and place-ment of these nets to serve their intended

use best. In addition, recommended mini-mum design requirements and the usage ofnets made with manila rope or with rope orwebbing (tape) of synthetic fibers, filamentsand their combinations also will be discussed.

Net design

14. Safety nets that meet accepted per-formance tests may be formed of rope orwebbing. Maximum size of mesh openingsshould not exceed 36 square inches nor belonger than 6 inches on any side measuredcenter-to-center on mesh ropes or web-bing. (No mesh opening should exceed 6inches in length measured center-to-centerof mesh crossing.)15. All mesh crossings should be anchoredsecurely to eliminate friction wear and pre-vent enlargement of the mesh openings.16. Each net (or section of it) should havea border rope or bedding of the same qual-ity material as the mesh material. Themesh rope or webbing should be anchoredsecurely to the border at each crossing.The minimum size of the border ropeshould be 3⁄4-inch diameter for manila and 1⁄2-inch diameter for synthetic; no border rope,however, should have a breaking strengthof less than 5,000 pounds when new.17. Further advances in synthetic materialdevelopment may introduce additionalacceptable materials. (Substitutes shouldnot be accepted without proof of tests indi-cating at least equal durability, sun resist-ance, breaking strength and energy-absorb-ing ability. The tests should meet the mini-mum requirements of the AmericanNational Standards Institute.)18. Many satisfactory combinations ofrope and mesh size are possible in safetynet fabrication. Satisfactory performance isthe ultimate requirement of safety net qual-ification. Impact resistance will vary forseveral reasons.

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• As the overall size between supports ofidentical net increases or decreases with-in reasonable limits, the impact resist-ance will vary approximately in direct pro-portion to the minimum dimension.

• As the mesh size decreases, using thesame diameter mesh rope, the impactresistance of the net increases.

• Other pertinent factors are the methodof suspension, spacing of ties and secur-ing the border ropes to fixed structures.

19. A prototype test should be conductedby a reliable and independent agency.Qualification as a safety net should bebased on the performance of a 17 x 24 footsample net secured in a frame as detailedin Figure 2. The test frame should providean opening that is the same size as the netwhen it is hung and should have sufficientstrength to absorb the specified impact

loads, with a maximum deflection in anydirection of 4 inches. (A test frame of 12 x12 inch timbers or equivalent is recom-mended.) The frame should be elevatedsufficiently to prevent the net from contact-ing any surface or object under the net dur-ing the tests.20. Precautions should be taken so testobservers are kept at a distance in theevent the test weight bounces out or thenet fails.21. The impact resistance necessary for anet to qualify as a safety net should be suchthat it absorbs the impact of a 350-poundbag of sand 24 inches (+ 2 inches) in diam-eter dropped 50 feet into the net and ateach quarter-point of the long dimension (6feet from the end of the net) and the centerpoint of the short dimension (81⁄2 feet fromthe side of the net). There should be no bro-

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Figure 2. A drawing of a net-testing frame. Note: The dimensions are given in the English system only.



ken strands or significant distortion of thenet pattern after two drops of the testweight with a 5-minute interval betweendrops to allow time for net recovery. 22. The net should not sag more than 3feet at the center of the net (test weightimpact point) when hung. Border ropesshould be level. A typical tie of border ropeto test frame uses 3⁄4-inch manila rope, sup-ported by the frame at ends and center.The net should be supported from the ropeat approximately 3-foot intervals, center-to-center, along the 24 foot, 8 inch length (and2 foot, 10 inch, center-to-center along the17 foot, 8 inch length.23. It is accepted in the industry that anynet identical in fabrication, except for size,to a prototype net, which has met thespecified requirements, may be consideredsatisfactory for use as a safety net. Eachacceptable net shall carry a label with thefollowing information: The name of themanufacturer, identification of the netmaterial, date of manufacture, date of pro-totype test and the name of the testingagency.24. For work performed under the spon-sorship of the U.S. Army Corps ofEngineers, the net requirements given inthe remainder of this paragraph are con-tained in EM 385-1-1, April 1981.2. Safetynets shall be provided when workplacesare more than 25 feet above the ground,machinery, water surface or other surfaceswhere the use of ladders, scaffolds, catchplatforms, temporary floors, lifelines orsafety belts is impractical. Nets shall beinstalled as close under the work surfaceas practical but in no case more than 25feet below such work surface. Nets shallbe hung with sufficient clearance to pre-vent user’s contact with the surfaces orstructures below. Such clearance shall bedetermined by impact load testing. Only

one level of nets is required for bridge con-struction.• Safety nets may be provided where traf-

fic or workers are permitted to be undera work area.

• Nets for overhead protection shall belined with wire or synthetic netting ofnot more than 1-inch mesh. Wire meshshall be made of not less than 22 gagewire and synthetic mesh of not less thanNumber 18 twine.

• Operations requiring safety net protec-tion shall not be undertaken until the netis in place and has been tested.

• Nets shall extend 8 feet beyond theedge of the work surfaces where work-ers are exposed.

• The maximum mesh size of nets shall be6 inches x 6 inches.

• All new nets shall meet accepted per-formance standards of 17,500 footpounds minimum impact resistance asdetermined and certified by the manu-facturers and shall bear a label of prooftest. Edge ropes shall provide a mini-mum breaking strength of 5,000 pounds.

• The net suspension system shall bedesigned and constructed with a safetyfactor of four and as a minimum shallwithstand the test loading without per-mitting contact between the net and anysurface or object below the net.

• Forged steel safety hooks or shacklesshall fasten the net to its supports.

• Connections between net panels shalldevelop the full strength of the net.

• The net installation shall be tested bydropping a 400-pound bag of sand, notmore than 30 inches ±2 inches in diam-eter, onto the center of the net from aheight of 25 feet above the net or fromheight equal to the distance from the netto the highest surface for which protec-tion is furnished, whichever is greater.

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• Nets shall be tested immediately afterinstallation, relocation or major repair.

• Tests shall be repeated at not more than6-month intervals.

• Nets shall be inspected daily for cuts anddamage from abrasions, chemicals orheat. Repairs shall be made before workabove the net is resumed. Rapid loss ofstrength of small net componentsshould be considered.

• Debris shall be removed from safetynets at least daily and combustible mate-rials shall be removed before welding,cutting, or other operations producingsparks, slag or other ignition sources aredone above the net.

25. Nets should be installed as close underthe working level as practical and placedwith sufficient clearance to prevent contactwith surfaces or structures below, whenthe anticipated maximum impact load isapplied.26. Except under unusual conditions (suchas on some bridge construction) where thenet placement prohibits normal net erec-tion at 25 feet or makes it impractical, thedistance from the highest work level to anet should be no more than 25 feet.27. When two or more nets are securedtogether to form a larger unit, the perime-ter ropes should be wrapped—that is,laced at not over 6-inch intervals with a lac-ing rope of a diameter equal to the meshrope, and securely tied off at every 4-footinterval of the net perimeter. Otherwise,drop-forged shackles or special safetyhooks may be used for securement atintervals of not more than 1 foot.28. The perimeter suspension systemshould be installed so suspension pointsare level. Any deviation should slopetoward the structure, so that a reboundingload will be guided toward a protectedarea. When suspended, safety netsshould extend 8 feet horizontally from the

outermost projection of the structure.Perimeter nets should follow the workupward and be positioned not more than25 to 30 feet below any level at whichmen are working.29. When wire rope net supports are tiedto a structure, the tying intervals should notexceed 30 feet, except for certain types ofnet rigging used between piers on bridgeconstruction. Wire rope for such purposesshould withstand full impact stresses witha minimum safety factor of four.30. Drop forged steel safety hooks orshackles, which will support the designload, should be used to attach nets to sup-porting cables, structures or beams pro-jecting from structures. Such attachmentsshould be spaced at intervals of not morethan 4 feet.31. Hanging safety nets inside structures(such as stacks, silos and shafts, or belowfloor openings) does not present a difficultproblem. However, the nets should bearranged to provide easily removed panelsthat permit the passage of materials beinghoisted.

Materials

32. Materials for safety net fabricationshould be tested for durability, weatherresistance, breaking strength and impactresistance.33. The materials and fabrication for safetynets, recommended by American NationalStandard A10.l 1-1979, are as follows:Section 4.1. Each unit of net width andlength equal to 6 x 6 inches shall be fabri-cated of materials that provide a minimumbreaking strength of 4,000 pounds. Thismay be achieved by the use of 3⁄8 inch No.1 grade pure manila rope, 1⁄4-inch nylonrope, 5⁄16-inch polypropylene rope, 1-inchnylon webbing or their equivalent.Section 4.2. Materials used shall be com-patible with each other.

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34. Special precautions shall be taken toshield ropes 1⁄2-inch in diameter and smallerfrom the sun’s rays. Ropes of natural orsynthetic fibers can lose a significantamount of strength after prolonged expo-sure to direct sunlight. It is suggested that6-6 nylon safety netting be dyed with anultraviolet-absorbing dye stuff of knownability to significantly increase outdoordurability.

When and where to use nets

35. Safety nets should be used when theworkplace is more than 25 feet above theground, water or other surface, such asadjacent structure or intermediate floor.Where the use of ladders, scaffolds, catchplatforms, temporary floors, safety lines orsafety belts are impractical, nets should beused. (In areas where nets offer the bestprotection, it might be desirable to havethe contract provide for their use, so allcontractors can provide for safety on anequal basis.)36. The U.S. Army Corps of EngineersManual requires similar protection.37. Safety nets should be used as over-head protection where public traffic orworkers are required to be underneath thework area. In such cases, nets should belined with wire or synthetic netting of suchstrength and mesh (which is generally 3⁄4-inch) that, in normal circumstances, fallingtools or material would be prevented fromfalling on persons who may be standingbelow.

Installation

38. There are as many ways of erectingnets as there are construction jobs. Thefunction of this section is to suggest somebasic ideas and some fundamental rules,but the details of safe rigging must be theresponsibility of the persons on the job.39. Look for the most convenient way to

rig a net on every job. Each job is differentso that in each case planning is required.Even on two identical jobs, the worksequence may alter the quantity and meth-ods of netting the job.• Do as much work as possible on the

ground, and then hoist the net intoposition.

• Use a work basket wherever possible toprotect the person who must make thehigh or exposed connections to securethe net. Safety belts with lifelines,boatswain chairs or scaffolding also maybe used.

• Planning makes everything easier.• Nets must be rigged to catch and stop a

worker who falls—before he hits anoth-er surface or a net support rod.

40. The American National StandardsInstitute has these installation require-ments.• Nets shall be installed in accordance

with the net manufacturer’s specifica-tions and instructions.

• Nets shall be installed as close under theworking level as practical but not lowerthan 30 feet and shall be hung with suf-ficient clearance to prevent contact withthe surface or structures below whenthe user’s impact load testing is applied.(Exception: On bridge construction thelowest part of the structure should beconsidered the highest working surface.It is intended that only one level of netsbe required for bridge construction.)

• When two or more nets are securedtogether to form a larger unit, they shallbe laced at not more than 6-inch inter-vals with a lacing material equal instrength to the mesh rope or webbing.Drop-forge shackles or safety hooks maybe used instead of lacing.

• Drop-forge safety hooks or shackles (orother equivalent fastening means) that

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will support the design load shall beused to attach nets to supporting cables,structures or beams projecting fromstructures.

• Safety nets shall extend outward 8 feethorizontally from the outer-most projec-tion of the structure.

Rigging a net under a bridge—

ground method

41. Assuming that the span is 100 feet orless, set out one I-beam at the base ofeach pier. The length of each I-beam shouldbe the width of the bridge plus 16 feet toextend 8 feet on either side of the outsideedge of the structure. (Spans greater than100 feet usually require an extra I-beam in

the center to reduce the sag in the net.)• Connect the ends of the I-beam across

the gap with ropes, one rope on eachside (see Figure 3).

• Some nets are designed with a right anda left side. Therefore, spread the nets onthe ground across the gap and fastenthe span hooks on each net to the ropesand to each other (see Figure 4).

• Fasten the ends of the nets to ropes fas-tened to the I-beams.

• Hoist I-beam “L” to the top of pier “A”and fasten it to the pier using the insertsthat had been previously placed toaccept the I-beam (see Figure 5).

• Hoist I-beam “R” to the top of pier “B”and fasten it in place (see Figure 6).

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Figure 3. An example of rigging a net under a bridge

using the ground method.

Figure 4. The ground method for connecting nets.

Figure 5. An example of hoisting the eye beam rig-

ging from the ground.

Figure 6. A net that has been raised to position

from ground.



• The net is now in place.• It is important to have all sides of the net

raised so that if a worker falls, he is cap-tured by the net and cannot roll out.

Rigging a net under a bridge—

no access between piers

42. Proceed exactly as in the previousexample except that all rigging must bedone at the base of the pier or on a bargeadjacent to the pier. Instead of spreadingthe nets across the gap, assemble the netsbunched on a rope, accordion-fashion, likea shower curtain folded back upon itself(see Figure 7). In addition, attach a spread-er bar to the leading edge of the net. Alsoattach two lines to the spreader and runthem across the gap. The net can bespread across later by pulling the lead linesfrom the opposite side.43. It also is possible to feed the lead linesacross, around a sleeve on the net-anchor-ing I-beam and back to pier “A.” The netcan be spread across by pulling from thepier “A” side of the gap.44. If a span is too long or the space at thebottom of pier “A” is too crowded toassemble all the nets on one side, half ofthe nets can be assembled at pier “B” andtwo sets of lead lines can be used tospread the nets. Then, someone must be

lowered from the center of the bridge in awork basket or harness to clip the netstogether at the center.

Curtain nets

45. Occasionally it may be desirable to pro-vide a curtain net for a bridge to protectworkers in only the unfinished area, or dur-ing a maintenance program. A curtain net isgenerally not recommended because it isso easy for the workers to forget to movethe curtain as the work progresses. Also,very often, the work gets spread over alarger area than the curtain covers, leavingsome workers unprotected. 46. A curtain net is rigged on ropes in muchthe same fashion as shown in Figure 7, andthe lead lines are used to move the curtainto the proper location under the work area(see Figure 8). Important: A spreader barmust be used at both ends of a curtain-typenet to keep the ends of the net at the samelevel as the ropes that support it. Otherwise,it might be possible for a worker who hadfallen into the net to roll out the end and fall.

Rigging perimeter nets on buildings

47. On the ground, in position belowwhere the nets are to be used, assemblethe rope, the outrigger bars and sufficientnets to rig one side of the building.

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Figure 7. An example of rigging a net under an

access between piers.

Figure 8. An example of a curtain net rigged for use

under a bridge.



• Hoist the whole assembly to the levelwhere it is to be installed.

• Fasten the outrigger bars to the deck ofthe floor below (see Figure 9).

• Anchor the rope ends in each corner ofthe building.

• Fasten the inside edge of the net to thefloor where the rope is anchored.

• Tighten all connections and the net isready to be tested.

Decking nets in steel construction

buildings

48. The net should go up with the steel.Figure 10 shows one method used by iron-workers. Erect three beams outlining arectangular bay with ropes for anchoringthe nets fastened to brackets welded onthe I-beams. Also attach a rope for the netto the fourth beam. On the ground, attachthe net to the fourth beam. Then attachthe free end of the net to a spreader bar.Lift the entire assembly (the beams, thenet, the rope and the spreader bar) intoplace. The beam completes the fourth sideof the bay. Then, two workers starting at“A” and “A,” fasten the net to the ropeson the side I-beams and push the spread-er bar ahead of them as they crawl alongthe beams. When they reach the end ofthe bay, they unhook the net from thespreader bar and hook it onto the ropeattached to beam No. 1.

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Figure 9. An example of rigging perimeter nets.

Figure 10. The rigging of decking nets in steel construction.



49. Net panel construction is anothermethod of assembling a safety net. A rec-tangle of thin-walled aluminum conduit isassembled to act as a spreader on a specif-ic size net. The thin-walled conduit merelyshapes the net and fastens to the cablethat supports the net. The rope is anchoredin the same way as in Figure 10 and theinside edge of the net is clipped to a ropeattached to the beam. The advantage hereis that the frame provides a convenientway of spreading the net and provides amuch more convenient way of moving thenets, formed and in place.

Nets for roofing buildings

50. Figure 11 shows an end view and aplan view of a typical metal building. Ropes,across which personnel nets are hung, areinstalled along the length of the building tocover each building module. Often curtainnets are used under the section of the roofbeing assembled. This is permissible only ifthe roofing operation stops and the nets aremoved when the roofing work progressesto within 8 feet of the edge of the net.

Sidewall nets

51. Workers on the edge of a roof shouldbe protected with sidewall nets. Sidewall

nets are suspended from cables that aresupported by a bracket fastened to the col-umn as shown in Figure 12. These samenets are used along the end walls as wellas the side walls. Figure 13 shows a planview of nets in place just before the start ofa roofing operation. Because sheets ofroofing material are installed first from acorner of a building, the end-wall and side-wall nets should be in place as well as themain nets under the roof inside the build-ing, prior to starting roofing operations.

Nets for reactor buildings

52. In the construction of a nuclear reactorbuilding, personnel and debris nets areemployed around the outside during rebarwelding. Inside, both 4-inch mesh person-nel and 1⁄4-inch mesh debris nets areemployed under the dome.

Other net applications

Beneath a polar crane

53. A semicircular 4-inch mesh and a 3⁄4-inch mesh net are used in conjunction withand on one side of the polar crane in thecontainment building. The net is rigged sothat it moves with the polar crane and fur-nishes protection on one-half of the area.

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Figure 11. An example of rigging nets for the roof-

ing of a building.

Figure 12. The rigging of sidewall nets for roofing

jobs.



The other half of the area is left open toallow materials to be passed up above thepolar crane to the workers.

On the turbine pedestal in power plants

54. Personnel nets with 4-inch mesh anddebris nets with 3⁄4-inch mesh are usedaround the turbine pedestal to protect per-sonnel from falling and to protect thosebelow from falling objects.

Power plant boiler cavity

55. The boiler cavity is a large area framedby structural steel. It is open for a long peri-od of time during the erection of a power

plant. Personnel and debris nets are usedto protect all the workers in this areathroughout the length of the job—steel-workers, electricians, steamfitters, carpen-ters, painters, etc., (see Figure 17).

Elevator shaft nets

56. Elevator shafts and mechanical chasesare dangerous voids in the decks of high-rise buildings and they must be covered.Nets offer the most economical protection:lower initial cost, lower installation costcompared with the cost of materials, timeand labor required to construct a woodenplatform.

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Figure 14. An example of nets in use on a reactor

building.

Figure 15. The use of nets on a polar crane.

Figure 13. A plan view of an example of rigging safety nets for roofing operations.



They also have the following character-istics:• Lightweight, easy to handle, install,

move and store. (A 10 foot x 10 foot netweighs only 10 pounds including hard-ware). Wooden platforms are heavy andbulky.

• Long life—can be rolled into small bun-dles and moved quickly from deck todeck and job to job, compared withexpendable wooden platforms.

• Offer a “soft catch” in the event of a fall;rigid wooden covers can cause humaninjury and damage tools.

• Easily moved and replaced by one per-son (in seconds) for easy access to theshaft, compared with bulky, heavywooden platforms.

• Allow visibility and permit air, light andsound to pass through.

• Stay in place. Wood platforms may slipand slide or can be blown or kicked outof position and fall.

Inspection

57. Each safety net, mesh rope, perimeterrope, connector, suspension system, etc.,

shall be thoroughly inspected by qualifiedpersonnel before and after every installa-tion, and not less than once each weekthereafter. Additional inspections shall bemade after alterations, repairs, impact load-ing, and welding or cutting operations aremade above the net. Nets that showmildew, wear, damage or deterioration thatmight affect their strength shall be immedi-ately removed from service for completeinspection and repair.

Job testing

58. Nets and suspension systems shouldbe tested after each installation, alterationor major repair before being returned toservice and at 6-month intervals thereafter.If a net is more than 18-months old, a rea-sonable test interval should be established.59. Job tests differ slightly from prototypetests conducted by the manufacturer. Fornets of normal size, the American NationalStandards Institute says tests should con-sist of dropping a 400-pound bag of sandnot more than 30 inches ±2 inches in diam-eter from a height of approximately 25 feetabove the net into the center of the net.

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Figure 16. Nets mounted on a turbine pedestal of a

power plant.

Figure 17. The use of nets to protect construction

personnel who are working on the boiler cavity at a

power plant.



60. A job should be considered satisfacto-ry if there are no broken members and nosignificant distortion of net pattern or thesuspension system.

Care, maintenance and storage

61. Care, maintenance and storage ofsafety nets shall be in accordance with thenet manufacturer’s recommendations withdue attention being given to the factorsaffecting net safety:• Sunlight affects all fibers, including

those commonly used. All nets not inuse should be protected from direct andindirect sunlight.

• Abrasion. There is no test that will pre-dict the life of a net under the wide vari-ety of abrasion conditions that may beencountered. The adverse effects ofabrasion should be constantly borne inmind. Nets should not be dragged overthe ground or other rough surfaces.

• Sand. Embedded sand cuts fibers, reduc-ing the strength of nets. Care should betaken to keep nets as clean and free ofsand as possible.

• Rust. Prolonged contact with rusting ironor steel can cause significant degrada-tion and loss of strength. Nets shouldnot be stored in metal containers thatare rusty and should be suspended onnon-rusting hooks.

• Airborne contaminants. Extremely highconcentrations of many chemicals canadversely affect the strength of nets.Where high concentrations may exist,the chemicals should be identified andthe concentrations measured. The effecton the net material involved should bedetermined by test if it is not known.

62. Debris shall be removed from safetynets at least daily, and combustible materi-als shall be removed before welding, cut-ting or other operations producing sparks,

hot slag or other ignition sources are doneabove the net.63. Repairs to nets should be madepromptly and properly by qualified person-nel. Defective ropes should be satisfactori-ly spliced and replaced with new ropes.Dirt and grit act as abrasives and should beremoved by washing with clean water.After washing, manila ropes should bedried and re-lubricated with oil recom-mended by the rope manufacturer.64. Proper storage of nets is essential.Nets may be stored in dry/shaded areas;they may be hung or folded on pallets.Good air circulation is necessary. Confineddampness is detrimental to manila rope,but does not affect synthetic ropes.65. All types of nets should be protectedagainst damage from heated surfaces,sharp materials, fungi, rodents and fallingobjects. Synthetic fiber ropes are notaffected by mildew, and the resistance tomildew by untreated manila rope is goodexcept in humid climates. Therefore, amildew-resistant treatment of manila ropeis recommended. Treatment can be appliedduring manufacture, or nets can be dippedin a fungicide solution at the jobsite.

Fire prevention

66. Manila and synthetic rope nets can beseriously damaged by fire. Therefore, com-bustible material should not be allowed toaccumulate in suspended nets, as empha-sized in paragraph 62. When riveting, weld-ing or burning is done above nets, theyshould be under constant observation.Serious damage has resulted when weld-ing slag has fallen into nets piled or rolledup under construction work. Nets hung ver-tically when stored are least exposed tothese overhead hazards.67. Manila rope is fire-resistant to a degreeand does not support combustion under

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normal conditions. However, fire-retardanttreatments have not proved practical whennets are exposed to the weather.Furthermore, application of fire-retardantsto synthetic ropes is of no value, becausethese ropes will melt instead of burn whenexposed to heat.

Sources of informationAmerican National Standards Institute, 1819 LStreet, 6th Floor, Washington, D.C. 20036. SafetyNets used During Construction, Repair andDemolition Operations, ANSI A10.1l-1979.

OSHA, Washington, D.C. 20210: OccupationalSafety and Health Standards, Title 25 CFR ChapterXVII, Part 1926. Subpart E (Personal Protective andLife Saving Equipment), Section 1926.105.

U.S. Army Corps of Engineers, Department of theArmy, The Pentagon, Washington, DC 20314. Safetyand Health Requirements. EM 385-1-1, April 1981.

SINCO Products Inc., 3965 Pepin Avenue, Red Wing,MN 55066. Fall Protection Handbook, 4th ed., 1982.

Related standardsWhen the following related American NationalStandards are superseded by a revision approved bythe American National Standards Institute the revi-sions should be used.

Safety Requirements for Personnel Hoists, ANSIA10.4-l981.

Safety Requirements for Material Hoists. ANSIA10.5-1981.

Safety Requirements for Demolition, ANSI A 10.6-1969.

Safety Requirements for Scaffolding, ANSI A 10.8-1977.

Safety Requirements for Concrete Construction andMasonry Work, ANSI Al0.9-1982.

Safety Requirements for Window Cleaning. ANSIA39. 1-1969.

Manually Propelled Mobile Ladder Stands andScaffolds (Towers), ANSI A92. 1-1977.

Vehicle-Mounted Elevating and Rotating AerialDevices. ANSI A92.2-1979.

Acknowledgment

This data sheet was prepared by theConstruction Division of the NationalSafety Council, 1121 Spring Lake Drive,Itasca, IL 60143.

Copyright ©2007 National Safety Council.

All rights reserved.

Although the information and recommendations con-

tained in this publication have been compiled from

sources believed to be reliable, the National Safety

Council makes no guarantee as to, and assumes no

responsibility for, the correctness, sufficiency or

completeness of such information or recommenda-

tions. Other or additional safety measures may be

required under particular circumstances.

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