PROCEDURE MANUAL

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Heal th and Safe ty Procedure

Form Work and False Work

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DATE : 2004. 05. 03

PROCEDURE MANUAL

HSE TRAINING

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Contents.

1. Purpose.

2. Scope.

3. Responsibility.

3.1 False work Co-ordinator.

4. Definitions.

4.1 False work.

5. Instructions.

5.1 General.

5.2 Design.

5.3 Method Statement.

5.4 Loading Sequence.

5.5 Plant and Method Loads.

5.6 Alterations in Loading Programmes.

5.7 Materials.

5.8 Foundations.

5.9 Bracing and Lacing.

5.10 Checking Points.

6. Revision Status

Appendix

I. Proprietary Equipment Check

II. Load Transfer Areas - Adjustable Jacks

III. Bracing / Lacing Connection

IV. Jack Head Bracing

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1. PURPOSE.This procedure and guidance information has been developed to ensure that all Falsework in use on SECL Projects is designed by qualified personnel, erected in accordance with the design drawings, thoroughly inspected by competent persons prior to loading and during use and dismantled as per the design and method statement.

2. SCOPE.To be used by members of the SECL Project Management Team, Supervisors and Sub-contractors who supervise and control activities for the erection, use and dismantling of Falsework.

3. RESPONSIBILITY.

3.1 Falsework Co-ordinator.

3.1.1 Co-ordinate all falsework activities.

3.1.2 Ensure the various responsibilities have been allocated and accepted by persons concerned.

3.1.3 Ensure that a satisfactory falsework design is carried out.

3.1.4 Ensure that the design is independently checked for, concept, structural adequacy and compliance brief.

3.1.5 Ensure that the design is made available to all interested parties and if applicable the structural designer.

3.1.6 Register the drawings, calculations and other documents applicable to the final design.

3.1.7 Ensure that all persons responsible for on-site supervision are provided with full details of the design including the limitations associated with it.

3.1.8 Ensure that regular inspections are carried out during the most critical factors.

3.1.9 Ensure that any proposed changes in materials or construction are checked against the original design and appropriate action is taken.

3.1.10 Ensure that any agreed changes or corrections of faults are adequately carried out on site.

3.1.11 Ensure that during use all appropriate maintenance is carried out.

3.1.12 After final check and approval, issue formal permission to load.

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3.1.13 When it has been confirmed that the permanent structure has attained its adequate strength, issue formal permission to dismantle the falsework in accordance with the method statement.

4. DEFINITIONS.

4.1 Falsework Any temporary structure used to support a permanent structure during its construction until it becomes self-supporting.

5. INSTRUCTIONS.

5.1 General.

5.1.1 During the past years, different contractors in several countries have been involved in a number of spectacular collapses of falsework, resulting in loss of life and serious injuries.

5.1.2 Safety in falsework is twofold: Safe-working conditions for the persons working on or adjacent to it, plus adequate design and construction to ensure the safety of the structure.

5.1.3 To accomplish this requires planning ahead to establish construction methods, rates of pour and works sequence, proper design of the falsework and execution of construction in accordance with the design. It also requires prudent judgement in the loading of forms and placement of concrete and understanding of safe falsework removal and reshoring practices.

5.1.4 When these requirements are met, a safe structure can be built and finally dismantled.

5.2 Design.

5.2.1 Only qualified and experienced personnel must design all falsework.

5.2.2 Calculations, drawings and sketches to explain and illustrate the design must be produced and available for all persons concerned in the construction, use and dismantling.

5.2.3 An independent design check should be carried out also considering any effects on the permanent works.

5.3 Method statement.

5.3.1 A written method statement for construction and use of the falsework is essential

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and it must include: -1) The name of the person in charge.2) Detail of the design and loading limitations.3) Construction details and erection sequence.4) Detailed loading sequence.5) Specification for plant, materials and methods to be used.6) Details of Supervision, Inspection and Checks to be made.7) Design tolerances, e.g. deflection / elongation.8) Striking times and sequences.9) Dismantling sequence.10) The method statement must be checked and signed.11) There must be no unauthorized alteration from the falsework design or

method statements.

5.3.2 Should alterations become necessary, authority to proceed must only be given in writing by the falsework co-ordinator.

5.4 Loading Sequence.

5.4.1 The method of applying loads can result in major effects on the stresses of individual sections of the support structure. The design must consider as a minimum the following conditions with the contractor.1) Sequence of pouring.2) Whether continuous or in bays concreted on different days.3) Internal and external vibration.4) Methods and sequence of specified post tensioning.5) Permanent design requirements relating to possible deflections for progressive

construction above the initial supported members.6) Unusual lateral loads expected (flash floods).7) Openings required in falsework allowing movement of plant and other

equipment.

5.5 Plant and Method Loads.

5.5.1 These loads must be incorporated in the design as they may form a major addition to the total loads to be supported, such loads include: -1) Dumping loads from concrete skips.2) Shock loading from steel or precast elements.3) Surge loads from concrete pump pipelines.4) Vibration duration.5) Rolling loads on falsework from plant, barrows, dumpers, cranes etc.6) Initial storage of material on falsework.7) British Standard 5975 recommends 50kg per square meter for formwork material

and 150kg per square meter to allow for limited heaping of concrete and impact, together with those of labor and plant involved in leveling, spreading and compacting concrete.

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5.6 Alterations in Loading Programmes.

5.6.1 Alterations in loading programmes after completion of the design can be a crucial item.

5.6.2 It is the responsibility of Site Management to notify any changes to the falsework designer and co-ordinator for re-assessments to be made.

5.7 Materials.

5.7.1 A pre-erection check of all materials must be made.

5.7.2 It is essential in all falsework erection that all materials used are in accordance with the designed drawings and standard details and are of the correct specification and in good condition.

5.8 Foundations.

5.8.1 Any structure is only as good as its foundations. Detailed design considering all loading possibilities serves of no value if the foundations have not received the same care and attention. 1) Individually designed falsework must include the relevant soil conditions and the

foundation structure designed accordingly.2) Foundations require protection and drainage from effects of the weather and

therefore require constant monitoring to prevent ponded and flowing water.

5.9 Bracing and Lacing.

5.9.1 All falsework structures are subject to horizontal forces which although are small in relation to vertical loads they are a critical element in the stability of falsework and the structure requires bracing and lacing.

5.9.2 Adequate bracing and lacing are key factors in avoiding progressive collapse in the event of local failure.

5.9.3 Horizontal forces result from: -1) Wind.2) Surge loads from pumps.3) Concrete discharge from pumps.4) Non-verticality of supports.5) Deflection of horizontal members.6) Settlement in foundations.

5.9.4 Bracing.1) Bracing is defined as diagonal members transferring the forces in the lacings

from one level to another.

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2) Where specified on falsework, bracing must be installed as illustrated on the design drawing and no attempts must be made to economise on the bracing used.

5.9.5 Lacing.1) Lacing is defined as connections from one strut to another in the horizontal

plane.2) It is normally used in two directions at right angles to link various vertical

supports together and in conjunction with suitable lateral supports to increase the carrying capacity of vertical supports.

3) All bracing and lacing must be connected as close to the node point as possible and no more than 150mm away.

5.10 Checking Points.

5.10.1 General.1) Sole plates, grillages, mud cills, etc. are in correct locations, adequately bedded

and leveled in.2) Base plates to vertical members are central to sole plates, grillages, mud cills,

etc.3) Spacing for vertical members is as figured on drawings or in accordance with

standard details.4) All vertical supports are plumb(within specified tolerance).5) All members figured in the drawings/standard details are in place.6) There is accuracy of the assembly as a whole(Symmetry makes for easier

checking and detection of distress at any stage in the pour).7) Wherever practicable, butt joints are used in primary members. Alternatively if

lapped joints are used, to avoid eccentric loading of the fork heads, the primary members should not span more than three supports.

8) All wedges, filling pieces, etc., are secure and in their correct positions.9) Where there are sloping surfaces, true contact exists between secondary and

primary members and also between primary members and fork heads.10) That load-bearing members, particularly when used in pairs, are thicknessed so

that they are evenly loaded.

5.10.2 At points of load transference.1) Correct details are applied.2) Base and head jacks are not over-extended unless detailed with adequate

special bracing.3) Steel section web stiffeners are provided as detailed. If there are none at points

of high load, query with designer.4) There is positional accuracy of all members.5) There are no eccentricities in excess of allowances specified.

5.10.3 Formwork.1) Formwork is not usually designed to carry any large additional loads. Erected

beam and soffit formwork should not therefore be used for storage purpose. Other safety considerations are :

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① Adequate space must be provided for construction of formwork. Consideration of large, bulky items, such as table forms, should be done on firm level ground, or on suspended slabs which have properly guarded edges and which may be reached by stairs or suitable access ladders.

② Formwork must be built so that it is safe to handle and be lifted only from points designed for the purpose.

③ Wall and column formwork must be properly supported during construction and dismantling.

④ Precautions must be taken to prevent falls from any height. When work is carried out from slab formwork, and persons can fall from 2m, its edges must be suitably guarded. Similarly, when persons work on formwork more than 2m above the slab, suitable and properly guarded work platforms or access ways, wide enough for the persons and material being carried, should be provided(Where it is not practicable to provide safe working platforms, etc. safety harness must be provided and worn). Safe ladder access must be provided.

⑤ Those not engaged in the construction, dismantling or inspection of formwork should be denied access, particularly during erection or when concrete is being poured.

⑥ Loose materials and plant should be secured against movement, particularly during high winds.

⑦ Proprietary formwork systems should be erected and used strictly in accordance with manufacturer’s instructions.

⑧ After stripping, formwork should be supported safely while being repaired, maintained and oiled prior to its next use.

5.10.4 Concrete operations.1) Prior to concreting, the following precautions should be taken when blowing out

the forms:① Safe access must be provided.② Compressed air lances should be fitted with suitable control valves.③ Debris should be directed away from other persons.④ Eye protection must be worn by those using lances and by other persons

nearby.2) Concreting should not start until the falsework and formwork have been checked

by the temporary works Co-ordinator and all preparations completed. Precautions to be taken when placing concrete include:① Concrete should not be poured too rapidly, or from such a height as to

overload the formwork or falsework.② Skips should be kept clean and regularly maintained and inspected. Skip

doors must be properly closed and care taken that loose concrete does not fall off during lifting. With lever operated skips, care should be taken to prevent snagging of the lever during transit. The discharge of concrete from skips should be controlled from suitable and safe platforms, account being taken of the tendency of side discharge types to kick backwards if discharged rapidly.

③ When using a crane, a properly trained banksman should be appointed to ensure good communication between the crane driver and the concrete gang.

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④ Extra strutting may be required where concrete is delivered into or close to excavations.

⑤ In the use of vibrators:ⓐ Care must be taken that form ties are not broken.ⓑ Vibrator motors on elevated platforms should be firmly secured.ⓒ External clamp-on vibrators should be used only on formwork

specifically designed to accept their use.ⓓ Poker vibrators must not be allowed to come into contact with any

person.ⓔ Guards to vibrator motor starting shafts must be in position whenever

the engine is running.ⓕ Vibrators operated by an internal combustion engine should not be used

in confined spaces unless adequate ventilation is provided.⑥ Concrete spillage should not be allowed to accumulate on falsework, the

outside of forms, scaffolding , access areas, or delivery skips.⑦ Tamping of leveling beams should be light enough to be handled

comfortably.⑧ At batching plants or concrete mixing positions :

ⓐ Slurry and washing-down water should be kept away from the mixing area by providing suitable drainage which must not be allowed to discharge into the sewer.

ⓑ If it is necessary to climb into the mixer for cleaning or maintenance purpose, a permit-to-work system must be introduced to ensure that the power is not switched on; a system of interlocking controls should also be maintained.

ⓒ Tools or implements must not be used to clean out the mixer drum whilst it is rotating, nor must persons be allowed to lean in and use their hands.

⑨ All persons handling cement and concrete should wear suitable eye protection, gloves and rubber boots, as cement can burn the skin. If skin comes into contact with fresh concrete, it should be immediately washed with clean water.

5.10.5 Concrete pumping.1) Pumping should be properly maintained and checked before use.2) Concrete pumping units should be sited to allowed safe access for truck mixers

and particular care must be taken to ensure that there is no danger of a placement boom approaching too close to overhead electric cables or other obstructions. Units should stand on firms, level ground and outriggers should be extended to ensure stability. Pumps should be operated only by trained and competent persons.

3) Pumplines should be laid to form as little hazard or hindrance as possible and care must be taken to avoid contact with or close approach to, overhead lines. Sharp bends and kinks in the hose must be avoided. All couplings and adaptors, including fixing pins, must be checked for security before pumping starts. Where it is necessary to secure pumplines against movement, scaffolds or falsework should not be used as an anchor unless designed for the purpose.

4) An effective system of communication between the pump operator and the placing gang must be established. Where any part of the boom or placement hose is out of sight of the pump operator, a competent banksman should be

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appointed.5) Covers or acoustic panels on the pump unit should be closed when the pump is

in operation. Ear protection must be provided and worn where necessary.6) Pump receiving hoppers should be guarded.7) Pumplines pressure guages should be checked at the beginning of each shift.8) When cleaning out pumplines, care should be taken that material is ejected in a

safe direction and that unnecessary debris is not caused. If a ball is used for cleaning, there should be a cage to contain the ejected ball. Compressed air should not be used to clean out pumplines, or to release blockages.

9) The pump unit should normally be cleaned with the machine running and the discharge outlet in position. If, at any time, the discharge outlet has to be removed, the pump must be switched off. Serious accidents has occurred when the outlet has been removed for cleaning with the machine running and the operative’s hands have been trapped by the gate valve. Only persons trained in the procedures involved should carry out these cleaning operations.

5.10.6 Dismantling.1) Dismantling must be carried out in a deliberate and properly planned manner.

Before dismantling starts, it must be established whether backpropping is required before release of the falsework, or repropping after release of the falsework. It is also essential to ensure that slabs which are carrying loads from stored materials are strong enough to carry those loads once the formwork has been removed.

2) Safety considerations during dismantling include:① A striking sequence should be established and followed.② Suitable temporary platforms must be provided for persons carrying out the

dismantling.③ Loose fittings and materials should be removed before dismantling begins.④ Dismantling materials should be placed directly into storage areas.⑤ Materials sticking to concrete and liable to fall should be removed as work

proceeds.⑥ Projecting nails must be removed or hammered down.⑦ Suitable nets or sheets should be fixed where necessary to prevent or

control the fall of materials.⑧ As guard rails which have been part of the soffit formwork are removed,

others should be fitted to the concrete edge.⑨ Openings must be securely covered or guarded.⑩ Debris should be cleared as work proceeds.

6. Revision Status

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Rev. No. Rev. Date Rev. Page Description

0 2004.05.03 - Newly legislated

- Prepared Team : Quality, Safety Management & Technology Support Team

- Prepared by : Mr. Kim Ho Min

- Reviewed by : Mr. Kim Seong Chul

Mr. Roger N. Wagstaff

- Approved by : Mr. Choi Kye Sik

APPENDIX.

[APPENDIX. Ⅰ Proprietary Equipment Check.]

Head Plate Flat and at right angles to tube.

Tube to be straight with no excessive pitting or dents.

H.T Pin on Chain - No substitutes.

All tubes straight no Excessive pitting or dents

No Strain at Welds.

All Brace Connections Complete and Fully Functional.

No Distortion Generally.

Tube to be straight No Excessive Pitting or Dents.

Welds intact.

Base Plate to be Flat and at right angles to tube.

All Threads in Good Condition.

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[APPENDIX. Ⅱ Load Transfer Areas - Adjustable Jacks.]

Over extension (exceeding 300 ㎜) of adjustable fork heads or base jacks without bracing.

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[APPENDIX. Ⅲ Bracing / Lacing Connection.]

Diagonal as close to node Point as possible and no more than 150㎜ away.

Right angle coupler diagonal to lacing.

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[APPENDIX. Ⅳ Jack Head Bracing.]

Main Timber. Secondary Timber.

Connecting tube on every row of standards.

Every 6th jack in both dirctions.

Tube brace will stabilise up to 6 jacks.

(a)

Bearer should be secured centrally by nailed wedges. Vibration loosens un-nailed wedges, bearers move and eccentric loading results.

When dimension ⒜ exceeds 300㎜, every row of jacks is joined at top with a tube at right angles to the main timbers and every 6th jack of every row is diagonally braced in both directions.

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