Basic Scaffolding Construction – An Overview of British Standard BS 5973-1993
Introduction, basic definitions, main components
What is a scaffold?
The scaffold is a basic temporary structure that encompasses an existing or future possible structure by design that helps the construction worker to have safe and ergonomic access to the work intended and widely used in industries and private properties, to some extent.
For the construction and use of a scaffold, optimal protection, supervision, etc. They are mandatory, as failure to do so may result in death and injury. Incidents also contribute to the loss of work hours, resources, human lives, effects on the environment and countless other aspects of our personal and professional lives.
There are a number of standards that could be considered for scaffolding construction, for example, the US OSHA standard, British standard, Australian standard, etc. The choice and implementation of the standard by businesses and individuals depends primarily on compliance with local legislation and, of course, what is established by an individual standard.
The British Standard for Scaffold Construction provides definitive exposure to the relevant aspect of construction and safety from the beginning of construction and daily inspection that encourages safe work practices and maintenance of the temporary structure built to meet the requirements business or personal needs.
Considering the most potential hazards associated with construction, maintenance, and work on scaffolds, common problems observed are:
to. Removing boards from work platform without proper communication and meeting standard requirements
B. Removing bracing on deck levels
vs. Remove handrails and skirting boards
D. Remove the stairs from their intended places and
me. Not stacking the material correctly
Definitions
The basic definitions related to scaffolds are as follows:
Standard: A vertical component support tube that rests on the ground.
Ledger: A horizontal component / tube that supports the transom.
Transom: A tube attached through two or more components that balances unbalanced lateral force and provides stability.
Swinging support: Restricts the movement from left to right of the scaffold considering the front view of the structure.
Base plate: used to distribute the load of the standards to the ground.
Sole plate / boards: A piece of wood suitable for distributing the load.
Standing Riser: A riser is installed close to the ground to reinforce the scaffold base and allow clearance for that base from ground level.
Scaffold Bay – The spans of the vertical / standard members along the front view of the scaffold. A rule of thumb to follow when calculating the load is “The smaller the bay, the higher the Safe Working Load (SWL) of that scaffold.”
Height: The vertical distance considering the base and top assembly of the cross member and cross members.
Width: The width of a scaffold measured at right angles to the stringers from the center of the standards. Another measure for calculating width is calculating the number of boards between two adjacent Standards.
Length – The length of a scaffold between standards that are located at either end of a scaffold structure.
Lift Height – The vertical length between the main horizontal members that are called Ledgers.
Puncheon: a standard that does not rest from the ground.
Spur: An inclined support tube used to reinforce the structure of a rickety or wobbly movement along the longitudinal or lateral direction.
Needle: The needle is a horizontal cantilever tube.
Stop tube: any comparatively short length bearing tube.
Scarf: The length of a Standard / Upright above the work lift.
Lapping: Lapping means joining standards or ledgers that reinforce the structure.
Decking out: Means boarding off the work platform.
Exterior sheathing: Horizontal or vertical component fixed on sloped sheets of material, such as plastic or corrugated sheets, attached to the scaffold to provide protection.
Footboard: a barricade installed at the platform ground level next to the “foot” that prevents accidental falling of tools, objects, small construction work debris to the lower platform and level.
Railing: Railing is an engineering control for falling from a height and has set vertical distances. Along the horizontal direction of a structure, there are usually a pair of rails, namely the upper and middle railing. There is also a butt end guard rail and drop bars in place.
Scaffold Tie – This is another reinforcement process used when attaching the scaffold to an existing structure / building for added stability. A tie that is attached to a building is called a physical tie.
Revealing tie: tube embedded in the opening of the building.
Foot Tie: An added tube to secure the base of the standard.
Scaffold Pipes: Pipes must be manufactured and tested in accordance with Specification BS 1139 Part 1 for pipes for use in scaffold construction.
The variety of scaffold tubes included the following:
to. Black steel
B. Galvanized steel
vs. Aluminum Alloy Tubes
The details of the aluminum tubes are as follows:
Outside 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 due to additional heat treatment.
Apart from the aluminum tubes, the black and galvanized steel tubes are similar in dimensions. However, galvanized ones are preferred over the others because they are resistant to corrosion and are protected from the effect of the elements.
The details of the galvanized pipes are as follows:
Outside diameter 48.3 mm
Nominal wall thickness 4 mm
Weight 4.37 kg / m
Length 6.4 m
One precaution to follow when choosing construction material is that different types of tubes should not be mixed due to their differences in material properties, such as yield stress, elasticity, fatigue, volume modulus, etc. .
The end of the tube must be square with the axis of the tube. If cutting is necessary, the cut surface containing the sharp edge should be trimmed to form a fillet; otherwise, it creates a good chance of being cut, lacerated or impaired during construction and use of the structure.
Before use, all tubes should be inspected for cracks, defects, corrosion, etc. The marginal value of the weight of said scaffold tube is 3.75 kg / m beyond which, the tube must be discarded from the cluster.
BS 1139 Part 1 dictates that the tube must not deviate more than 1/600 of its length.
Scaffold Accessories: Scaffold accessories can be forged steel, spring steel, or pressed steel. The standard followed for scaffold accessories is the BS 1139 Part 2 specification for couplers and accessories for use on tubular scaffolds.
Mass: for steel coupler, it ranges from 1kg to 2.5kg.
Caution: Couplers and accessories should be checked for rust, thread damage, wear, breakage, and deformation.
Types:
Right Angle Coupler – Used to connect tubes at a right angle, eg standard connection to stringer.
Specification: Pressed steel is used and the safe working load is 6.25 kilo newtons.
Swivel Coupler – Used to connect tubes at any desired angle as it has a higher degree of freedom than the previous type. This could be used for a support to a standard.
Specification: Pressed steel is used. The safe working load is 6.25 kilo newtons.
Sleeve Coupler: The end-to-end connection between the tubes is constructed 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 / Simple Clamp – This type of coupler is used for any of the purposes mentioned below:
to. Fixing a putlog
B. Attaching a transom to a ledger and
vs. Connect a tube used as a railing
Specification: Pressed steel is used and the safe working load is 0.5 kilo newton.
Beam Coupler / Beam Clamp: This type of coupler is used with I-beam in a structure or the like and used in pairs.
Specification: Forged steel is used and the safe working load is 30 kilo newtons.
Base Plate – This is a square-shaped, ground-supported connecting piece on scaffolding that:
to. Distributes the load from the standard to the ground
B. Restrictions to lateral movement or rocking and
vs. Helps prevent damage to tube material.
Specification: Pressed steel is used and the dimensions are 150mm x 150mm x 7mm. There is a vertical pin in the center with an outer diameter of 50.8mm.
There is a special type of base plate in addition to the basic shape of this fixture, namely the adjustable base plate which allows the adjustment of standards to suit different floor levels.
Base Plate – Base plates are used in conjunction with the base plate to ensure adequate load transfer to the ground for the designed balance of the scaffold nodes.
Specification:
Material Pressed steel
Dimension (firm ground) 500mm x 225mm x 35mm
Dimension (soft ground) 765mm x 225mm x 35mm
Dimension (two standard scaffolds) 1550mm x 225mm x 35mm
There is a special type of base plate in addition to the basic shape of this fixture, namely the adjustable base plate which allows the adjustment of standards to suit different floor levels.
Scaffold boards (wood):
According to the BS 2482-1981 specification for wooden scaffolding boards, it is considered necessary to check the condition before each use and the corresponding color code.
The expected dimension of each piece should be as follows:
Material Sawn softwood
Dimension 3000/2500/2000/1500/1000 mm x 200 mm x 38 mm
Vertical pin in the center Outside diameter 50.8 mm
Caution:
It is required that the piece of wood legibly marked with BS 2482 accompanied by the trade mark / supplier identification, the machine gradation symbol (M) / visual (V), the length of the support span followed by the designation MAX are in place before use. The boards must also be flame retardant.
Thickness relationship to span, cantilever, and pressure reference table:
Dimension (firm ground) Dimension (firm ground) Dimension (firm ground) Dimension (firm ground) Dimension (firm ground)
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