Glazed Fire-Clay Sanitary Appliances, Part 4: Specific Requirements of Postmortem Slabs
1979 Edition

Scope of IS 771 Part 4: Dimensions and Allowable Variations

• Scope: Establishes dimensional ranges and tolerances applicable to structural steel sections used in slab construction.

Essential Details:

Rounding Procedures:

• Outcome values from tests or calculations must follow the rounding rules of IS:2-1960.
• Maintain the significant figures count as indicated by the standard.

Summary:

• Ensures standardization and interchangeability of components.
• Vital for maintaining structural quality and reliability.

flowchart TD
    A[Measured Dimension] --> B{Is dimension ≥ 50 mm?}
    B -- Yes --> C[Apply ±4% tolerance]
    B -- No --> D[Apply ±2 mm tolerance]
    C --> E[Implement tolerance]
    D --> E
    E --> F[Round off following IS:2-1960]

This guarantees dimensional precision for steel elements under IS 771 Part 4.

Overview of Key Specifications in IS 771 Part 4

• Rounding Off Results (Clause 0.3):
  Test or analysis outputs must be rounded according to IS:2-1960, preserving the original number of significant figures.

• General Compliance (Clause 2.1):
  Materials, manufacturing processes, testing, sampling, and inspection shall adhere to IS 771 Part 1 (1979).

• Dimensional Limits and Tolerances (Clause 2.4):
  Defined limits and tolerances ensure quality control (refer to IS 771 Part 1 for detailed tables).

• Post-Mortem Slabs Specifics (Part IV):
  Contains unique testing and evaluation requirements for post-mortem slabs to certify conformity after production.

Rounding Rules According to IS:2-1960

Sample Table: Dimensions & Tolerances (Illustration)

Refer IS 771 Part 1 for precise values.

flowchart TD
    A[Material & Production] --> B[Testing & Sampling]
    B --> C[Dimension and Tolerance Verification]
    C --> D[Apply IS:2-1960 Rounding]
    D --> E[Compliance Assessment]

Consult IS 771 Part 1 alongside Part 4 for detailed dimension tables and testing procedures.

General Requirements per IS 771 Part 4

• Material, Manufacturing, Testing & Inspection:
  Shall comply with IS 771 (Part I) - 1979.

• Dimensions and Tolerances (Clause 2.4.2):

  Dimension Category	Permitted Tolerance
  ≥ 50 mm	±4%
  < 50 mm	±2 mm

• Rounding Off (Clause 0.3):
  Test or analytical results must be rounded as per IS:2-1960, maintaining the number of significant digits.

Practical Insights:

• Verify all measurements against these tolerances during quality checks.
• Apply IS:2-1960 rounding rules to standardize reported results.

flowchart TD
    A[Start: Material & Manufacture] --> B[Compliance with IS 771 Part I]
    B --> C[Measure Dimensions]
    C --> D{Is dimension ≥ 50 mm?}
    D -- Yes --> E[Apply ±4% tolerance]
    D -- No --> F[Apply ±2 mm tolerance]
    E & F --> G[Conduct Testing]
    G --> H[Round Results per IS:2-1960]
    H --> I[Quality Compliance Check]

This process ensures consistent quality under IS 771 Part 4 requirements.

Construction Requirements as per IS 771 Part 4

1. General Guidelines (Clause 2.1)

• Materials, fabrication, testing, sampling, and inspection must align with IS 771 Part 1 (1979).
• Guarantees consistent quality and performance.

2. Dimensional Accuracy (Clause 2.4.2)

3. Post-Mortem Slabs Specifics (Part IV)

• Detailed requirements are provided for slab thickness, reinforcement, and curing processes.
• Refer to Part IV for precise technical mandates.

Summary Table: Dimensional Tolerances

For detailed manufacturing and testing instructions, consult IS 771 Part 1.

flowchart LR
    A[Material & Production] --> B[Testing & Sampling]
    B --> C[Inspection]
    C --> D[Dimensional Verification]
    D --> E[Tolerance Assessment]
    E --> F[Construction Quality Assurance]

This ensures the durability and reliability of constructed slabs according to IS 771.

Summary of Dimensions and Tolerances in IS 771 Part 4

1. Dimensional Specifications (Clause 2.4.1)

• Post-mortem slab dimensions are specified in Figure 1 of IS 771 Part 4.

2. Allowed Tolerances (Clause 2.4.2)

• For dimensions ≥ 50 mm:
  ±4% of the nominal size.
• For dimensions < 50 mm:
  ±2 mm absolute tolerance.

3. Numerical Rounding (Clause 0.3)

• Final figures should be rounded in accordance with IS 2-1960.
• The count of significant digits must remain consistent with the original specification.

Quick Reference Table

This ensures accurate dimensioning and uniformity critical for slab integrity and installation.

flowchart LR
    A[Specified Dimension] --> B{Dimension ≥ 50 mm?}
    B -- Yes --> C[Apply ±4% tolerance]
    B -- No --> D[Apply ±2 mm tolerance]
    C --> E[Implement tolerance]
    D --> E

Refer to Figure 1 in IS 771 Part 4 for exact slab patterns and sizes.

Dimensions and Tolerances for Post-Mortem Slabs per IS 771 Part 4

Main Points (Clause 2.4)

• Dimensioning: As indicated in Figure 1 of the standard for precise slab sizes.
• Tolerances (Clause 2.4.2):
  • For dimensions ≥ 50 mm: ±4%
  • For dimensions < 50 mm: ±2 mm

Rounding Off (Clause 0.3)

• Follow rounding procedures as per IS:2-1960.
• Maintain significant figures consistent with the standard’s specifications.

Summary Table

Notes:

• Confirm exact nominal dimensions from Figure 1 in IS 771 Part 4.
• These tolerances support manufacturing precision and installation compatibility.

flowchart TD
    A[Specified Dimension] --> B{Is dimension ≥ 50 mm?}
    B -- Yes --> C[Apply ±4% tolerance]
    B -- No --> D[Apply ±2 mm tolerance]
    C --> E[Implement tolerance]
    D --> E

This guarantees dimensional compliance within allowable limits.

Tolerance Specifications in IS 771 Part 4

1. Tolerance Limits (Clause 2.4.2)

• For dimensions ≥ 50 mm:
  Tolerance is ±4% of the measured size.
• For dimensions < 50 mm:
  Fixed tolerance of ±2 mm.

2. Rounding Off (IS:2-1960)

• Final measurement or test values should be rounded following IS:2-1960 guidelines.
• Maintain the number of significant digits as per the original specification.

Example Table:

Important Notes:

• Apply tolerances post-measurement.
• Use IS:2-1960 rounding standards for compliance verification.

flowchart LR
A[Specified Dimension] --> B{Is dimension ≥ 50 mm?}
B -- Yes --> C[Apply ±4% tolerance]
B -- No --> D[Apply ±2 mm tolerance]
C & D --> E[Measure & Round per IS:2-1960]
E --> F[Verify Compliance]

This ensures dimensional uniformity and quality in line with IS 771 Part 4.

Marking Guidelines per IS 771 Part 4 (Clause 3.1.1)

• Marking Requirements:
  Every post-mortem slab complying with IS 771 Part 4 may carry the ISI Certification Mark.

• Purpose of ISI Mark:

  • Confirms adherence to the standard under strict inspection, testing, and quality control overseen by the Bureau of Indian Standards (BIS).
  • Ensures ongoing conformity through BIS’s continuous surveillance.

• Legal Framework:
  The use of ISI Mark is regulated by the Indian Standards Institution (Certification Marks) Act and associated regulations.

• Additional Information:

  • Manufacturers must obtain appropriate licensing from BIS before using the ISI mark.
  • Marking provides traceability and guarantees quality.

Related Standards:

• IS 2:1960 - Governs rounding procedures for test outcomes.
• Dimensional and tolerance details are outlined in Clause 2.4 of IS 771 Part 4.

Marking Summary Table

flowchart LR
    A[Post-mortem Slab] --> B{Complies with IS 771 Part 4?}
    B -- Yes --> C[Apply ISI Certification Mark]
    B -- No --> D[No Marking Applied]
    C --> E[Product Quality Assurance]
    E --> F[Continuous BIS Monitoring]

Refer to Clause 2.4 and IS 771 Part 4 diagrams for detailed marking dimensions and tolerances.