Functional requirements for drafting chairs
1974 Edition

IS 4204: Scope & Primary Specifications

• Scope: Addresses aluminium tubes for engineering applications, offering purchaser choice as per Clauses 2.1.1 & 2.1.5.
• Material Requirements: Aluminium tubing must comply with IS:1285-1968 (Designation HV 20 WP) or possess equivalent mechanical characteristics.
• Mechanical Criteria:

• Testing Protocol: Tensile and elongation tests conducted according to IS:2657-1964.
• Assembly Instructions: Seat components must be firmly attached to leg sections to prevent accidental separation (Clause 5.2).
• Data Rounding: Test results rounded following IS:2-1960 guidelines, ensuring consistent significant figures.

This section ensures aluminium tubes meet prescribed mechanical and assembly standards 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]

Summary of IS 4204 Guidelines

• Seat Attachment (Clause 5.2):
  Ensure the seat is firmly fastened to the leg assembly to prevent unintended detachment.

• Materials (Clause 4.2):
  Aluminium tubes must adhere to IS:1285-1968 (HV 20 WP) or equivalent, with these mechanical properties:

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

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

• Referenced Standards:
  Includes requirements for aluminium alloys, welding rods, steel sheet materials, wood screws, and timber classification to guarantee compatibility and quality.

Key Insight

Utilize aluminium tubes conforming to IS:1285 with at least 25 kg/mm² tensile strength and 18% elongation, securely fix seat to legs, and comply with referenced standards for durability and safety.

IS 4204: Essential Dimensions & Ergonomics for Drafting Chairs

This standard focuses on drafting chairs intended for use with drafting tables, ensuring both comfort and utility.

Principal Dimensions & Ergonomic Features:

• Seat Height: Adjustable, generally between 420 mm and 570 mm to accommodate different users.
• Seat Depth: Approximately 400 mm to 450 mm to properly support the thighs.
• Seat Width: At least 400 mm for comfortable seating.
• Backrest Height: Adjustable, usually ranging from 300 mm to 400 mm above the seat.
• Backrest Tilt: Capable of tilting between 90° and 110° to support the lumbar region.
• Footrest: Recommended if seat height exceeds 500 mm to support legs ergonomically.
• Swivel & Mobility: Chair should rotate 360° and have casters for easy movement.

Ergonomic Considerations:

• Adjustable seat and backrest to fit various body sizes.
• Cushioning for prolonged comfort.
• Lumbar support to alleviate back stress.

Dimension Summary:

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)]

These specifications guarantee ergonomic support and functionality as per IS 4204.

IS 4204: Core Material Requirements

1. Aluminium Tubes (Clause 4.2)

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

• Test Methods: Testing follows IS 2657-1964.

2. Mild Steel Sheets (Clause 4.5)

• Applicable Standards: IS 513-1963 or IS 1079-1968.
• Utilized for structural steel sheet components.

3. Additional Notes

• Purchasers may choose options as per Clauses 2.1.1 and 2.1.5.
• Test outcomes should be rounded as per IS 2-1960 guidelines.

Material 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]

Adhering to these material standards ensures compliance with IS 4204 requirements for drafting chair components.

IS 4204 - Aluminium Sheet Requirements

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

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

• Testing: Tensile strength and elongation to be determined as per IS 2657-1964.

Aluminium Sheet Summary Table

Notes:

• NS3 and NS4 denote specific temper states guaranteeing strength and flexibility.
• Aluminium sheets are frequently used where light weight and corrosion resistance are desired.
• Verification of temper and mechanical properties before usage is essential.

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 Tube Requirements

Mechanical Criteria (Clause 4.2)

• Testing conducted according to IS 2657-1964.
• Aluminium tubes must comply with IS:1285-1968 (HV 20 WP).

Material and Fabrication Standards

• Tubes composed of wrought aluminium alloys, extruded as round tubes or hollow sections.
• Welding procedures must follow IS 2812-1964.

Important Notes

• Seat must be securely attached to leg components to prevent detachment (Clause 5.2).
• Aluminium sheets should adhere to IS 737-1965 for quality assurance.

Aluminium Tube Properties Summary

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

For detailed design and manufacturing, consult the latest editions of these IS codes.

IS 4204 - Mild Steel Tubing (Clause 4.6)

• Mild steel tubes shall be of ERW quality conforming to IS 1161:1968, designed for structural applications.
• ERW (Electric Resistance Welded) tubes are preferred due to strength consistency and reliability.

Key Parameters from IS 1161:1968

Additional Notes

• Tubes must be free from imperfections such as cracks or laminations.
• Dimensional tolerances are specified in IS 1161.
• Mechanical testing to follow IS 1608 (Steel Tensile Testing).

Basic Formula for Tube Strength (Design Calculations):

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

Where:

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

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

flowchart LR
    A[Mild Steel Tubes] --> B[ERW Quality]
    B --> C[Conformance 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[Dimensional Tolerances]

Summary: Employ ERW mild steel tubes as per IS 1161:1968 for structural elements, ensuring adherence to mechanical and dimensional standards.

IS 4204 - Specifications for Screws

• Reference: Screws must comply with IS 451:1961 (Wood Screw Specification).

• Materials: Typically manufactured from steel or brass in line with IS 451 requirements.

• Dimensions & Types: Covers a range of sizes, thread forms, lengths, and head styles suitable for wood screws.

• Mechanical Properties: Tensile strength and elongation conform to IS 451.

• For aluminium components, the aluminium tubes require minimum tensile strength of 25 kg/mm² and elongation of 18% as per IS 1285-1968.

• Assembly Requirements: Per Clause 5.2, seats must be firmly attached to legs, implying correct screw selection and proper installation.

Typical Screw Parameters (IS 451)

Important Considerations

• Utilize screws conforming to IS 451 for structural strength.
• Select screw sizes appropriate for material thickness.
• For aluminium structures, use compatible screws to prevent galvanic corrosion.

flowchart TD
    A[Seat Section] -->|Screws (IS 451)| B[Leg Section]
    B --> C[Secure Joint to Prevent Detachment]

This illustrates seat attachment to legs using IS 451 screws as required by Clause 5.2.

IS 4204 - Wood Material and Joint Specifications

• Wood Type: Use timber suitable for furniture applications as classified in IS 399:1963.
• Joint Types: Must comply with IS 3845:1966, covering joints like mortise & tenon, dowels, ensuring strength and durability.
• Seat-Leg Fixing: Secure attachment mandatory to prevent inadvertent detachment (Clause 5.2).
• Finishing Options: Wooden parts may be treated with:
  • Wax polish
  • Transparent, glossy French polish (per IS French polish standards)
  • Dark stain followed by polishing (Clause 8.2)
• Fasteners: Use wood screws as per relevant IS standards.

Common Joint Types (IS 3845)

Typical Wood Strength Values (IS 399)

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

Summary: Employ wood per IS 399, joints per IS 3845, with secure seat-leg fastening and suitable finishing to achieve durable wooden drafting chairs.

IS 4204: Structural Connection and Material Standards

1. Seat-Leg Connection (Clause 5.2)

• The seat must be firmly secured to the leg frame to avoid accidental detachment.
• Utilize mechanical fasteners or welding techniques that ensure permanent, robust joints.

2. Material Standards (Clause 4.2)

• Aluminium tubing shall conform to IS:1285-1968 (HV 20 WP) or equivalent with:
  • Minimum tensile strength: 25 kg/mm²
  • Minimum elongation (50 mm gauge): 18%

• Testing should comply with IS:2657-1964.

3. Testing and Data Rounding (Clause 2.1.5)

• Test results must be rounded according to IS:2-1960 norms, maintaining significant digits consistent with specifications.

Additional Recommendations:

• Use wrought aluminium alloy extrusions and hollow sections conforming to relevant IS codes.
• Welding materials and electrodes should meet IS standards for structural steel welding.

flowchart TD
    A[Seat Section] -->|Secure Fastening| B[Leg Section]
    B --> C{Connection Method}
    C -->|Welding| D[Permanent Joint]
    C -->|Mechanical Fasteners| E[Bolted or Riveted Joint]
    D & E --> F[No Detachment]

This ensures structural integrity and safety in line with IS 4204.

IS 4204: Key Fabrication and Assembly Practices

1. Seat and Leg Assembly (Clause 5.2)

• The seat must be securely fastened to the legs to prevent unintended separation.
• Apply suitable mechanical fasteners or welding methods to assure strong and lasting connections.

2. Materials (Clause 4.2)

• Aluminium tubes must meet IS:1285-1968 (HV 20 WP) standards.

• Mechanical properties:

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

• Testing per IS:2657-1964.

3. Metal Components (Clause 8.1)

• Follow IS codes for welding electrodes, rods, and arc welding procedures.
• Ensure material compatibility for strength and corrosion resistance.

4. Wooden Joints (Clause 7.2)

• Must comply with IS:3845-1966 for wooden drafting chair joints.

Fabrication Process Flow

flowchart TD
    A[Material Selection] --> B[Cutting & Shaping]
    B --> C[Assembly]
    C --> D[Seat-Leg Fastening (Clause 5.2)]
    D --> E[Welding or Mechanical Fixing]
    E --> F[Mechanical Properties Testing]
    F --> G[Final Quality Inspection]

Employ correct assembly methods and verify mechanical properties to guarantee safe and durable products.

IS 4204: Guidelines for Finishing and Surface Protection

1. Surface Preparation

• Pickling: Mild steel parts must be treated by pickling to remove impurities.
• Phosphating: Apply phosphating treatment according to IS:3618-1966 for corrosion resistance.

2. Priming and Painting

• Coat with a suitable primer, typically red oxide.
• Follow with two layers of enamel paint as required (Clause 8.1.3).

3. Filling

• Use putty complying with IS:426-1961 to fill surface imperfections before painting.

4. Wood Finishing

• Wooden components may be polished using wax, transparent glossy French polish (per IS:348-1968), or stained and polished (Clause 8.2).

Finishing 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]

These steps assure effective corrosion resistance and an attractive, durable finish.

IS 4204: Essential Details to be Supplied by Purchaser (Clause 10.1)

When placing an order, the purchaser must specify:

• Construction Materials: Indicate the materials for chair and seat, such as wrought aluminium alloys, steel, or timber.
• Colour and Finish: Specify desired colours and finishing types, e.g., enamel exterior Type 2 with undercoating.
• Height Adjustment Feature: Confirm if the chair requires adjustable seat height.

Additional Points per IS 4204

• Packaging (Clause 9.1): Components should be packed to prevent damage during transit.
• Seat Attachment (Clause 5.2): Seat must be securely fixed to legs to avoid accidental detachment.
• Test Data Rounding (Clause 2.1.1): Values should be rounded according to IS 2-1960, matching required precision.

Example Specification for Enamel Finish

flowchart TD
    A[Order Placement] --> B{Are Details Provided?}
    B -->|Yes| C[Material Specification]
    B -->|Yes| D[Colour and Finish Details]
    B -->|Yes| E[Height Adjustment Option]
    B -->|No| F[Order Clarification or Delay]

Providing complete information ensures orders comply with IS 4204 manufacturing and delivery standards.