Introduction, basic definitions, basic components of scaffolding (BS 5973-1993)
Basic Scaffolding: A Review of British Standard BS 5973-1993
Introduction, basic definitions, basic components
What is scaffolding?
Scaffolding is a basic temporary structure covering an existing or future possible design structure that helps the construction worker to have safe and ergonomic access to the intended work and is widely used in industries and private properties to some extent.
Optimum protection, supervision, etc. are required for the construction and use of scaffolding, as failure to observe them may cause injury leading to death. Incidents also contribute to loss of man-hours, resources, lives, environmental impact and countless other aspects of our personal and professional lives.
There are a number of standards that can be taken into account when constructing a scaffold, for example the American OSHA standard, the British standard, the Australian standard, etc. Business and personal choice and application of the standard depends mainly on compliance with local legislation and, of course, as determined by an individual standard.
The British Standard for Scaffolding offers a definitive exposition of the relevant aspect of construction and safety from the start of construction and daily inspection which promotes safe working practice and the maintenance of a temporary structure built to meet business or personal needs.
Considering the most potential hazards associated with the construction, maintenance and operation of scaffolding, the commonly observed problems are:
a. Removing planks from a work platform without proper communication and compliance with the standard requirement
b. Subtraction of platform level reinforcement
° C. Removal of handrails and toe boards
e. Removing ladders from their designated places and
e. Improper arrangement of material
Definitions
The main definitions related to scaffolding are as follows:
Standard: An upright component bearing a tubular bearing on the ground.
Ledger: A horizontal component/tube that supports the transom.
Transom: A tube fixed through two or more components that balances the lateral unbalanced force and provides stability.
Sway Brace: Constrains the movement of the scaffold from left to right, considering the front view of the structure.
Base plate: Used to distribute the load from the standards to the ground.
Base plate/boards: A suitable piece of wood to distribute the load.
Leg Lift: A lift is raised close to the ground to reinforce the base of the scaffold and allow for the clearance of that base from ground level.
Scaffold Division: The spacing of uprights/standards along the front view of the scaffold. A basic load calculation rule to follow is “The smaller the corridor, the greater the Safe Working Load (SWL) of that scaffold.”
Height: The vertical distance considering the base and top mounting of Ledgers and Transoms.
Width: The width of the scaffolding measured at right angles to the registers from the center of the standards. Another measure of width calculation is by calculating the number of boards between two adjacent standards.
Length: The length of the scaffold between the standards located at either end of the scaffold structure.
Lift height: The upright length between the main horizontal members, which are called ledgers.
Puncheon: a standard not supported by the ground.
Spur: Inclined support tube used to brace a structure against rocking or oscillating movement in a longitudinal or transverse direction.
Needle: The needle is a single horizontal cantilever tube.
Back tube: any supporting tube of relatively short length.
Shawl: The length of the stand/standard above the working lift.
Adhesion: Adhesion refers to the linking of standards or registers that reinforces the structure.
Paving: This means exiting the work platform.
Capping: A horizontal or vertical component fixed to inclined sheets of material, such as corrugated or plastic sheeting, attached to the scaffolding to provide protection.
Toe Board: A barricade installed at the ground level of the platform next to the “toe”, preventing the accidental release of tools, objects, small debris from construction work to a lower platform and level.
Handrail: The handrail is designed to control falls from a height and has set vertical distances. Along the horizontal direction of the structure, there are usually several guardrails, namely the upper and middle guardrail. It also has a safety rail and drop bars in place.
Scaffolding Tie: This is another strengthening process used by attaching the scaffolding to an existing structure/building for stability. A connection that is fixed to a building is called a physical connection.
Disclosure Link: Pipe stuck in opening in building.
Foot Link: A tube added to attach to the base of the standard.
Scaffold pipes: Pipes shall be manufactured and tested in accordance with BS 1139 Part 1 Specification for pipes for use in scaffold construction.
The scaffold tube array consists of the following:
a. Black steel
b. Galvanized steel
° C. Aluminum alloy pipes
The specifications of the aluminum tubes are as follows:
Outer diameter 48.3 mm
Nominal wall thickness 4.5 mm
Weight 1.7 kg/m
Heat treatment: Aluminum tubes are tempered and subject to weakening by additional heat treatment.
Apart from aluminum pipes, black and galvanized steel pipes are similar in size. However, galvanized ones are preferred over others as they are corrosion resistant and weatherproof.
The specifications of the galvanized pipes are as follows:
Outer diameter 48.3 mm
Nominal wall thickness 4 mm
Weight 4.37 kg/m
Length 6.4m
A precaution to be observed in the selection of construction material is that different types of pipes should not be mixed together due to their difference in material properties such as yield strength, elasticity, fatigue, bulk modulus, etc.
The end of the pipe must be perpendicular to the axis of the pipe. If it is necessary to cut, the cutting surface containing a sharp edge should be trimmed to a fillet; otherwise, it creates a good chance of being cut, torn, or worse during construction and use of the structure.
Before use, all pipes should be checked for splits, defects, corrosion, etc. The weight limit for such scaffold pipe is 3.75 kg/m above which the pipe must be rejected from the group.
BS 1139 Part 1 dictates that the pipe should not deviate more than 1/600 of its length.
Scaffolding Fittings: Scaffolding fittings can be forged, spring steel or pressed steel. The standard followed for scaffold fittings is BS 1139 Part 2 Specification for couplings and fittings for use in tubular scaffolding.
Mass: For steel coupling it varies from 1 kg to 2.5 kg.
Precaution: Couplings and fittings should be inspected for rust, thread damage, wear, tears and distortion.
Kinds:
Right Angle Coupling: Used to connect pipes at right angles, for example a standard connection to a ledger.
Specification: Pressed steel is used and the safe working load is 6.25 kilo newtons.
Swivel Coupling: Used to connect pipes at any angle as it has a greater degree of freedom than the earlier type. This can be used to clamp to a standard.
Specification: Pressed steel is used. The safe working load is 6.25 kilonewtons.
Sleeve Coupling: The end-to-end connection between pipes is made using this external fitting and works practically like a metal sleeve.
Specification: Pressed steel is used and the safe working load is 3.1 kilo newtons.
Putlog Coupler/Single Clamp: This type of coupler is used for any of the following purposes:
a. Fix putlog
b. Fixing a cross beam to the chord and
° C. Connect a pipe used as a handrail
Specification: Pressed steel is used and the safe working load is 0.5 kilograms newton.
Beam Coupler/Beam Clamp: This type of coupler is used with an I-beam in construction or similar and is used in pairs.
Specification: Forged steel is used and the safe working load is 30 kilo newtons.
Base Plate: This is a square shaped part of a scaffold fitting which:
a. Distributes the load from the standard to the ground
b. Limits lateral movement or rocking and
° C. Helps prevent damage to pipe material
Specification: Pressed steel is used and dimensions are 150mm x 150mm x 7mm. There is one vertical pin in the center with an outer diameter of 50.8 mm.
There is a special type of base plate separate from the basic form of this assembly, namely the adjustable base plate, allowing the standards to be adjusted to fit the different floor level.
Base Plate: Base plates are used in conjunction with the base plate to provide adequate load transfer to the ground for designed balance of scaffold assemblies.
Specification:
Material Pressed steel
Dimensions (solid base) 500mm x 225mm x 35mm
Dimensions (soft base) 765mm x 225mm x 35mm
Size (Two standard frames) 1550mm x 225mm x 35mm
There is a special type of base plate separate from the basic form of this assembly, namely the adjustable base plate, allowing the standards to be adjusted to fit the different floor level.
Scaffold boards (wooden material):
According to the BS 2482-1981 specification for timber framing boards, it is considered necessary to check the condition before each use and the color code accordingly.
The expected size of each piece should be as follows:
Material Chopped coniferous wood
Dimensions 3000/2500/2000/1500/1000 mm x 200 mm x 38 mm
Center vertical pin Outer diameter 50.8mm
Precautions:
A piece of wood legibly marked with BS 2482, accompanied by trade mark/supplier identification, machine grade (M)/visual (V) symbol, reference span length followed by MAX designation is required prior to use. The plates must also be of fire-resistant application.
Thickness Ratio to Span, Overhang and Pressure Reference Table:
Size (solid base) Size (solid base) Size (solid base) Size (solid base) Size (solid base)
38 mm 1.5 m 50 mm 150 mm 24 kg/m2
50 mm 2.6 m 50 mm 200 mm 33 kg/m2
63 mm 3.25 m 50 mm 250 mm 41 kg/m2
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