What Is a Scaffold?
Scaffolding is an elevated structure which is created on temporary basis to facilitate for the erecting, construction, repair & maintenance when the work is to be carried out at the height.
Types of Scaffolding
Generally scaffolding are categorized into three parts:
- Suspended Scaffoldings : Suspended scaffolding are the platforms which are hanging with an overhead/top structure.
- Supported Scaffoldings: It is a most common types of scaffolding which are supported with the posts from the ground base.
- Aerial lift type Scaffoldings: It is a vehicle mounted device which are use for lift the persons for the job as a man lifter.
Scaffold duties / Rated capacity
As per the OHSA standards scaffolds are created with the consider with three types of its duties.
(a) Light duty: Approx 125 kg/m2
(b) Medium duty: Approx 250 kg/m2
(C) Heavy duty: Approx 375 kg/m2
Scaffolding Components/ Parts
Sole plates / Boards
Boards are made by the Steel, Aluminum, or wood that can be used for the preparing platform for the base of the work area.
The sole plate is a big plate of size 300 x 300 x 6 mm . Where there is a soft surface, a sole plate must be used under the base plate of the scaffold.
Plates provide solid base to the post of the scaffolding. The base plate is a metal plate of size 150 x 150 x 6 mm on which the post/standards are mounted. Base plates are mainly of two types.
(a) Fixed base plate : Fixed type its has center circular shank. Shank/ Spigot diameter is 80% of the standards diameter, 20% margin available for the movement of standards on it.
(b) Adjustable base Jack plate : Its used for the levelling of the scaffold at initial. Its load taking capacity is 3000 Kg. Lift of jack nut is not allowed more than two third (2/3) of its total height.
Standards or Posts
It’s a metal tubes that transfer the load of the weight to the base of the bottom plates to increase the length or height of the scaffolding by using pins and the socket joints for the connection of the standards.
As per the fitting types of the scaffolding many types of standards are comes as follows:
(a) Plane (Coupler) tubes type standards
(b) Cup lock type standards
(c) Ring lock rosette type standards
(d) Quick lock type standards
It’s a horizontal tube that joints the two standards in the bay of length is known as ledger. Ledgers are used as decide the height of the working platform for connecting the standards.
Transoms are used for the supporting of the posts of standards in the bay of width is known as transom/ bearer and transom are always fixed at the right angles to the ledgers.
Its used for the strengthening of the scaffold structure to carry more loads.
Scaffolding Clamps/ Couplers
Couplers are the jointing tools to fix the tubes together. Their are some main types of coupler with SWL as follows; Right-Angle Coupler, Swivel Couplers, Sleeve and Putlog Couplers.
(a) Right angle coupler (fixed or double coupler) SWL 630 kg : Used to connect horizontal and vertical tubes.
(b) Swivel coupler SWL 530 kg :- Used to two connect any angle tubes.
(C) Sleeve coupler (box clamp) SWL 300 kg :-Used to joint two straight tubes.
(d) Putlog coupler SWL 53 kg :- Used to fix plank with the transom.
Scaffolding Guard (Top, Mid) Rails
Handrail & Mid rail used for the safety of the workmen.
Scaffolding Toe boards/guards
Toe boards (width 150 mm) are used for the safety of the workmen and also to protect the objects to fall down.
Plank provide the fixed platform fixed with transoms. Size comes in 2100 x 280 x 38/50/63 mm and its should be defect free. Transoms tube should be install maximum 1.5 meter below platform. If two plank overlap it should be minimum 12 fit.
Ladder is equipment which is used for the safely climbing up and down at the required place. Ladder should be fix and follow all safety rules during installation and its use.
Scaffolding training and its requirements
OSHA requires the employers that have to provide a proper training by competent authority and develop scaffold skill of their workers who will be erected or dismantle a safe scaffolding.
As per the OSHA guidelines scaffolding training shall include for each employee who will be participated in the scaffolding work with the following topics:
- Types of Scaffolding hazards
- The right & systematic procedures for all types of the scaffold jobs like erecting, disassembling & inspecting of the scaffolding.
- Scaffolding load capacity & duty type.
Pre Planning for the Safe Scaffolding
A qualified or a trained person have to do proper pre planning for the safe scaffold. These planning must include :
- Insure scaffold materials are inspected and fit to use.
- Maximum load of the scaffold.
- Type of the scaffold require.
- Good & leveled Foundation of the scaffold.
- Electrical hazard availability.
Some sequence/ procedures and note should be follow for the safe erection of the scaffolding.
- Request Permit to work (PTW) for the erection of type type and duty of the scaffolding.
- Check for the ground conditions.
- Sole plate (If required as per the ground conditions)
- Base plate (Fixed type for the plane surface or adjustable jack type for uneven surface)
- Scaffolding tube fitting (Standards) install on the base plate ( Standards joints will not comes at the same height for the safety)
- Base/ Kicker lift placed by ledger (length) and transoms (width) maintain water lever at the height of 150mm from base plate. Projection of ledgers and transoms should be between 50 to 150 mm.
- First lift (2.1 to 2.7 meter from the base lift)
- Second and every next lift should be every 1.8 meter till required height.
- Create service platform at the required height with the planks on the transoms (gap between plank should not more than one inch). Always transoms should be fitted above the ledger for the safety of the platform.
- Top handrail (Height 1050 mm), middle handrail (Height 525 mm) with the toe board (Height 150 mm) should be provide for safety at the service platform.
- Cross bracing should be provide for the rigidness and stability of the scaffolding. Cross bracing should be maintain between 35 to 55 degree width help of swivel clamp not more than 300 from the node.
- Swing gate with locking system should be provide for the safety of entry/ exit point at service platform near ladder.
- Ladder should be provide (more than the 3 fit height, left or right side of the landing platform, ) for the safe access till service platform with the maintaining of 4:1 ratio (75 deg.). A single ladder will be provide up to six meter height sequentially with landing platform. ladder step area 300×300 mm and step capacity minimum 225 to 235 kg.
- Barrication of the all side area of the scaffolding to avoid hit by the vehicle movement and safety for others.
- Provide suitable tags at the visible area during erection, modification and after inspection for ready to use of the scaffolding.
Scaffold Safety Tagging
Every scaffoldings are required to inspect and tagged properly. Tags are define the current status of the scaffolding. Untagged Scaffoldings are never to use. Tagged are locate near access of scaffoldings at eye level. Scaffolds tags are as follows.
- Red Tags :- Scaffolding is unsafe to use or incomplete.
- Yellow Tags :- Scaffolding some modification required to meet work requirement.
- Green Tags :- Scaffolding is a safe to use.
Hard Hat Stickers for Scaffold workers
Hard Hat sticker is required for Trained and qualified scaffold workers for the creating safe environment. sample Hard hat sticker for sample as below.
Scaffolding Hazards and Risks
As per the case studies of OSHA found approx. 65% of the project or construction work required scaffoldings to perform their work on height. Therefore, scaffolding hazard will be increased as its height can be increases. Their are some major scaffolding hazards the can occur :
- Falls from height due to improper guardrail during installation of the scaffolding.
- The Scaffold collapse due to improper erection.
- The falling Material from the scaffolds due improper protection on scaffolding.
- Electrical hazards due to improper planning.
- Slips & falls from the boards.
- The platforms felled due to overloading
- Hazards due to wheel not locked of the rolling scaffolding.
Therefore, you should always require to inspect the scaffolding every day before starting any jobs on the scaffolding. The world Occupational Safety and Health Administration (OSHA) given a clear guidelines to follow the checklists for the confirmation of the healthiness of the scaffoldings. Maximum organizations follow the checklist before use of the scaffolding.
Safety of Scaffolding Do’s and Don’ts
Do’s of the Scaffoldings :
Don’ts of the Scaffoldings :
Scaffolding Codes for IS standards
IS : 3696 ( Part 1 & 2 ) : 1987 (Ladders) Safety code of scaffolds and ladders
IS 4014-1 (1967): Code of practice for steel tubular scaffolding
OHSA 1926.451 – General requirements for scaffolds
Section 32 in The Factories Act, 1948 : Floors, stairs and means of access.—In every factory
Scaffolding Inspection and checklist
Before the use of scaffolding its regular inspection and certification must require for the Strength and stability of the scaffolding. Scaffolding should be inspected by qualified or competent person only at regular basis.
- Checked after installation or before first use of the scaffolding
- Checked minimum every week.
- Checked every time after adverse weather conditions.
Scaffolding Inspection Checklists download :
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Also Read : Job Safety Analysis || JSA