Functional requirements for drafting chairs

IS 4204: Scope & Key Specifications

• Scope: Covers aluminium tubes for general engineering, allowing purchaser options per Clauses 2.1.1 & 2.1.5.
• Material: Aluminium tubes must conform to IS : 1285-1968 (Designation HV 20 WP) or equivalent mechanical properties.
• Mechanical Properties:

• Testing: Tensile strength and elongation per IS : 2657-1964.
• Assembly: Seat section must be secured to leg section to avoid inadvertent detachment (Clause 5.2).
• Rounding Off: Final test values rounded as per IS : 2-1960, matching significant figures of specified values.

This standard ensures aluminium tubes meet mechanical and assembly criteria for structural use.

flowchart LR
    A[Aluminium Tubes per IS 4204]
    A --> B[Material: IS 1285-1968 HV 20 WP]
    A --> C[Mechanical Properties]
    C --> D[Tensile Strength ≥ 25 kg/mm²]
    C --> E[Elongation ≥ 18%]
    A --> F[Testing per IS 2657-1964]
    A --> G[Assembly: Secure seat to leg (Clause 5.2)]
    A --> H[Rounding per IS 2-1960]

IS 4204 Recommendations Summary

• Seat Attachment (Clause 5.2):
  The seat must be securely fixed to the legs to prevent inadvertent detachment.

• Materials (Clause 4.2):
  Aluminium tubes used shall conform to IS:1285-1968 (Designation HV 20 WP) or equivalent with these mechanical properties:

  Property	Minimum Value
  Tensile Strength	25 kg/mm² (≈245 MPa)
  Elongation on 50 mm gauge	18%

• Testing:
  Tensile strength and elongation tests must follow IS:2657-1964.

• Referenced Specifications:
  Includes standards for aluminium alloys, welding rods, steel sheets, wood screws, and timber classification to ensure material compatibility and quality.

Key Takeaway

Use aluminium tubes meeting IS:1285 with minimum 25 kg/mm² tensile strength and 18% elongation, securely fix seat to legs, and adhere to referenced material standards for durability and safety.

IS 4204: Functional Requirements for Drafting Chairs - Key Dimensions & Ergonomics

This standard focuses on drafting chairs used with drafting tables, emphasizing comfort and functionality.

Key Dimensions & Ergonomic Specifications:

• Seat Height: Adjustable, typically 420 mm to 570 mm to accommodate various user heights.
• Seat Depth: Around 400 mm to 450 mm for proper thigh support.
• Seat Width: Minimum 400 mm to allow comfortable seating.
• Backrest Height: Adjustable, usually 300 mm to 400 mm above the seat.
• Backrest Angle: Should allow tilting between 90° to 110° for lumbar support.
• Footrest: Recommended if seat height exceeds 500 mm for ergonomic leg support.
• Swivel & Mobility: Chair should swivel 360° and have casters for ease of movement.

Ergonomic Considerations:

• Adjustable seat and backrest to fit different body sizes.
• Padding for comfort during prolonged use.
• Lumbar support to reduce back strain.

Summary Table:

graph LR
A[Drafting Chair] --> B[Adjustable Seat Height (420-570 mm)]
A --> C[Seat Depth (400-450 mm)]
A --> D[Backrest Height (300-400 mm)]
A --> E[Backrest Angle (90°-110°)]
A --> F[Footrest (if seat > 500 mm)]

This ensures drafting chairs support ergonomic posture and functionality per IS 4204.

IS 4204: Key Materials Specifications

1. Aluminium Tubes (Clause 4.2)

• Standard: IS 1285-1968 (Designation HV 20 WP)
• Mechanical Properties:

• Testing: As per IS 2657-1964 (Method for tensile testing of aluminium tubes)

2. Mild Steel Sheets (Clause 4.5)

• Standards: IS 513-1963 or IS 1079-1968
• Used for structural steel sheets.

3. General Notes

• Purchaser can select options as per Clauses 2.1.1 and 2.1.5.
• Test results should be rounded off per IS 2-1960, maintaining significant digits.

Summary Table:

flowchart LR
    A[Materials] --> B[Aluminium Tubes]
    B --> C[IS 1285-1968]
    B --> D[Tensile Strength ≥ 25 kg/mm²]
    B --> E[Elongation ≥ 18%]
    A --> F[Mild Steel Sheets]
    F --> G[IS 513-1963 or IS 1079-1968]

Use these specifications to ensure compliance with IS 4204 material requirements for structural components.

IS 4204 - Aluminium Sheets Key Specifications

• Material Quality: Aluminium sheets must conform to H condition of NS3 or NS4 quality as per IS 737-1965 (Wrought Aluminium Alloys, Sheet and Strip).

• Mechanical Properties for Aluminium Tubes (IS 1285-1968):

• Testing Method: Tensile strength and elongation shall be determined according to IS 2657-1964.

Summary Table for Aluminium Sheets per IS 4204:

Notes:

• NS3 and NS4 indicate specific temper conditions ensuring strength and ductility.
• Aluminium sheets are widely used in structural applications where lightweight and corrosion resistance are needed.
• Always verify the temper and mechanical properties before use.

flowchart TD
    A[Aluminium Sheets] --> B[IS 737-1965: NS3/NS4 H condition]
    A --> C[Mechanical Properties]
    C --> D[Tensile Strength ≥ 25 kg/mm²]
    C --> E[Elongation ≥ 18% (50 mm gauge)]
    D & E --> F[Testing as per IS 2657-1964]

IS 4204 - Aluminium Tubes Key Specifications

Mechanical Properties (Clause 4.2)

• Tensile strength and elongation testing as per IS 2657-1964.
• Aluminium tubes must conform to IS:1285-1968 (Designation HV 20 WP).

Material Standards

• Aluminium tubes: Wrought aluminium and alloys, extruded round tube and hollow sections.
• Welding of aluminium parts: Follow IS 2812-1964.

Important Notes

• Seat sections must be securely attached to leg sections to prevent detachment (Clause 5.2).
• Aluminium sheets conform to IS 737-1965 for quality and temper.

Summary Table of Aluminium Tube Properties

flowchart LR
    A[Aluminium Tubes] --> B[Mechanical Properties]
    B --> C[Tensile Strength ≥ 25 kg/mm²]
    B --> D[Elongation ≥ 18%]
    A --> E[Conformance]
    E --> F[IS 1285-1968 (HV 20 WP)]
    A --> G[Welding]
    G --> H[IS 2812-1964]

For detailed design and fabrication, always refer to the latest editions of the above IS codes.

IS 4204 - Mild Steel Tubes (Clause 4.6)

• Mild steel tubes shall conform to ERW quality as per IS 1161:1968 (Specification for steel tubes for structural purposes).
• ERW (Electric Resistance Welded) tubes are used for structural applications due to good strength and uniformity.

Key Specifications (from IS 1161:1968)

Important Notes:

• Tubes must be free from cracks, laminations, and other defects.
• Dimensions and tolerances are specified in IS 1161.
• Mechanical properties are tested according to IS 1608 (Tensile Testing of Steel).

Basic formula for tube strength (for design):

[ \sigma = \frac{P \times d}{2t} ]

Where:

• (\sigma) = hoop stress (allowable stress)
• (P) = internal pressure (if pressure tube)
• (d) = outside diameter
• (t) = wall thickness

For detailed dimensions, mechanical properties, and tolerances, refer to IS 1161:1968.

flowchart LR
    A[Mild Steel Tubes] --> B[ERW Quality]
    B --> C[Conform to IS 1161:1968]
    C --> D[Mechanical Properties]
    D --> E[Tensile Strength ~410-540 MPa]
    D --> F[Yield Strength ~250 MPa]
    D --> G[Elongation ≥ 20%]
    C --> H[Dimensions & Tolerances]

Summary: Use ERW mild steel tubes per IS 1161:1968 for structural purposes, ensuring compliance with specified mechanical and dimensional standards.

IS 4204 - Screws Key Points

• Reference Standard: Screws shall conform to IS 451:1961 (Specification for wood screws).

• Material: Screws are typically made of steel or brass as per IS 451, with specified mechanical properties and dimensions.

• Dimensions & Types: IS 451 covers various sizes, thread forms, lengths, and head types for wood screws.

• Mechanical Properties:

  • Tensile strength and elongation are governed by IS 451.
  • For aluminium tubes used in conjunction, IS 1285-1968 specifies a minimum tensile strength of 25 kg/mm² and minimum elongation of 18%.

• Assembly: Per Clause 5.2, seat sections must be secured to leg sections firmly to prevent inadvertent detachment, implying proper screw selection and installation.

Typical Screws Parameters (from IS 451)

Important Notes

• Use screws matching IS 451 for structural integrity.
• Ensure screw length and diameter suit the thickness of joined members.
• For aluminium structures, use screws compatible with aluminium to avoid galvanic corrosion.

flowchart TD
    A[Seat Section] -->|Screws (IS 451)| B[Leg Section]
    B --> C[Secure Joint - No Detachment]

This diagram shows the seat secured to the leg using IS 451 screws as per Clause 5.2.

IS 4204 - Key Wood Specifications & References

• Wood Type: Use wood suitable for furniture as per IS 399:1963 (Classification of Commercial Timbers).
• Joints: Must conform to IS 3845:1966 for wooden drafting chairs (includes types like mortise & tenon, dowel joints).
• Seat-Leg Connection: Seat must be securely fixed to legs to prevent inadvertent detachment (Clause 5.2).
• Finishing: Wooden parts can be polished with:
  • Wax polish
  • Transparent glossy French polish (per IS French polish standard)
  • Stained dark and polished (Clause 8.2)
• Fasteners: Use wood screws as per IS standards (revised specifications).

Typical Joint Types (per IS 3845)

Wood Strength (Typical values from IS 399)

flowchart LR
    A[Wood Selection IS 399] --> B[Joint Type IS 3845]
    B --> C[Seat-Leg Secure Fixing]
    C --> D[Finishing Options]
    D --> E[Wax Polish / French Polish / Stain]

Summary: Use IS 399 wood, IS 3845 joints, secure seat-leg fixing, and finish as per Clause 8.2 for durable wooden furniture per IS 4204.

IS 4204: Structural Requirements - Key Specifications

1. Seat and Leg Section Connection (Clause 5.2)

• The seat section must be securely fastened to the leg section to prevent accidental detachment.
• Ensure mechanical fastening or welding methods that provide permanent connection.

2. Material Specifications (Clause 4.2)

• Aluminium tubes must conform to IS:1285-1968 (Designation HV 20 WP) or equivalent with:
  • Tensile Strength (Min): 25 kg/mm²
  • Elongation (Min) on 50 mm gauge length: 18%

• Testing per IS:2657-1964 for tensile strength and elongation.

3. Testing and Rounding (Clause 2.1.5)

• Test results should be rounded per IS:2-1960 with significant digits matching the standard.

Additional Notes:

• Use wrought aluminium alloys and extruded hollow sections as per relevant IS standards for structural integrity.
• Welding electrodes and filler materials should comply with IS specifications for structural steel welding.

flowchart TD
    A[Seat Section] -->|Secure fastening| B[Leg Section]
    B --> C{Connection Type}
    C -->|Welding| D[Permanent Joint]
    C -->|Mechanical Fastener| E[Bolted/Riveted Joint]
    D & E --> F[No Inadvertent Detachment]

This ensures structural safety and durability as per IS 4204.

IS 4204: Fabrication and Assembly Key Points

1. Seat and Leg Assembly (Clause 5.2)

• The seat section must be securely fixed to the leg section to prevent inadvertent detachment.
• Use appropriate mechanical fasteners or welding ensuring durable connection.

2. Materials (Clause 4.2)

• Aluminium tubes must conform to IS:1285-1968 (Designation HV 20 WP).

• Mechanical properties for aluminium tubes:

  Property	Value
  Tensile Strength (Min)	25 kg/mm²
  Elongation (Min)	18% (on 50 mm gauge length)

• Testing per IS:2657-1964 for tensile strength and elongation.

3. Metal Components (Clause 8.1)

• Follow specifications for welding electrodes, filler rods, and metal arc welding as per relevant IS codes.
• Ensure compatibility of materials for strength and corrosion resistance.

4. Joints for Wooden Components (Clause 7.2)

• Must conform to IS:3845-1966 for wooden drafting chairs.

Summary Diagram: Fabrication Flow

flowchart TD
    A[Material Selection] --> B[Cutting & Shaping]
    B --> C[Assembly]
    C --> D[Seat-Leg Securing (Clause 5.2)]
    D --> E[Welding/Fastening]
    E --> F[Quality Testing (Tensile, Elongation)]
    F --> G[Final Inspection]

Use proper welding/fixing methods and verify mechanical properties to ensure safe, durable assembly.

IS 4204: Finishes and Surface Treatments - Key Points

1. Surface Preparation

• Pickling: Mild steel parts must be pickled.
• Phosphating: After pickling, apply phosphating treatment as per IS: 3618-1966 for corrosion protection.

2. Priming and Painting

• Apply a coat of suitable primer such as red oxide primer.
• Follow with two coats of enamel paint (Clause 8.1.3).

3. Filling

• Use putty conforming to IS: 426-1961 for surface filling before painting.

4. French Polish

• French polish finish must comply with IS: 348-1968 (Clause 4.4).

Summary Table

flowchart LR
    A[Pickling] --> B[Phosphating (IS:3618)]
    B --> C[Primer (Red Oxide)]
    C --> D[Putty Filling (IS:426)]
    D --> E[Two Coats Enamel Paint]

This ensures corrosion protection and a durable, aesthetic finish as per IS 4204.

IS 4204: Purchaser's Information Requirements (Clause 10.1)

When placing an order, the purchaser must provide the following essential details to the supplier:

• Material of Construction: Specify the material for both chair and seat (e.g., wrought aluminium alloy, steel, timber).
• Colour and Finish: Indicate the desired colour and finishing type (e.g., enamel exterior Type 2, undercoating + finishing).
• Height Variation Arrangement: Confirm if the seat requires an adjustable height mechanism.

Additional Key Points from IS 4204

• Packing (Clause 9.1): All components must be packed to prevent damage during transit.
• Seat Attachment (Clause 5.2): The seat must be securely fixed to the leg section to avoid accidental detachment.
• Rounding Off (Clause 2.1.1): Test values should be rounded per IS 2-1960, matching the precision of specified values.

Example: Specification for Enamel Finish

flowchart TD
    A[Purchaser's Order] --> B{Information Supplied?}
    B -->|Yes| C[Material of Construction]
    B -->|Yes| D[Colour & Finish]
    B -->|Yes| E[Height Variation Option]
    B -->|No| F[Order Delay or Query]

This ensures clarity and compliance with IS 4204 for manufacturing and delivery.