acid-resistant bricks
1968 Edition

Acid-Resistant Bricks Standard Overview - Essential Specifications & Tables

1. Brick Dimensions and Allowable Deviations (Clause 2.2)

2. Performance Compliance Criteria (Clause 2.2.1)

• Average denotes the mean test results; range is the difference between maximum and minimum values.

3. Authorization to Use Standard Mark (Clause 7.1.2)

• Governed under the Bureau of Indian Standards Act, 1986.
• Licensing details available from BIS.

Summary:

• Ensures consistency in brick size through tolerance limits.
• Defines quality through specified performance parameters.
• Regulates use of certification mark.

flowchart TD
    A[Check Brick Dimensions] --> B{Within Tolerance?}
    B -- Yes --> C[Conduct Performance Tests]
    B -- No --> D[Reject Batch]
    C --> E{Meets Performance?}
    E -- Yes --> F[Classify Brick Class]
    E -- No --> D
    F --> G[Obtain BIS Standard Mark License]

This section provides a concise introduction to the acid-resistant bricks standard.

Scope of Acid-Resistant Bricks Specification

• Addresses dimensional specifications, tolerances, and performance benchmarks for acid-resistant bricks.

1. Dimensional Specifications and Tolerances (Clause 2.2)

2. Rounding Off Test Results (Clause 0.6)

• Final test outcomes should be rounded following IS 2-1960 guidelines.
• Maintain the number of significant figures as per original measurements.

3. Compliance Evaluation (Clause 2.2.1)

• Lot acceptance is based on meeting all performance criteria listed in Table 3.

Process Flow:

flowchart TD
    A[Begin with Product Dimensions] --> B[Verify Tolerances]
    B --> C{Dimensions Within Limits?}
    C -- Yes --> D[Conduct Required Tests]
    C -- No --> E[Reject Product Batch]
    D --> F[Round Off Results]
    F --> G{Conform to Performance Standards?}
    G -- Yes --> H[Accept Batch]
    G -- No --> E

This ensures dimensional accuracy and performance adherence for acid-resistant bricks.

Brick Dimensions and Tolerance Limits as per Standard

Specifications (Clause 2.2)

• These tolerances apply to the nominal brick dimensions defined in Clause 2.1.
• Aligns with ISO R 475-1966 standards for rectangular refractory bricks.

Warpage Limit (Clause 2.4)

• Maximum allowable warpage from a flat surface: 2.5 mm.
• Measurement method detailed in Clause 2.4.1.

Summary:

• Length: 230 mm ± 3.5 mm
• Width: 114 mm ± 2.0 mm
• Height: 64 mm ± 1.0 mm
• Maximum warpage: 2.5 mm

Ensures precise dimensions and flatness critical for acid-resistant brick applications.

flowchart LR
    A[Nominal Brick Dimensions] --> B[Check Tolerances]
    B --> C[Length 230 ± 3.5 mm]
    B --> D[Width 114 ± 2.0 mm]
    B --> E[Height 64 ± 1.0 mm]
    A --> F[Evaluate Warpage]
    F --> G[Max deviation 2.5 mm]

Summary of Physical and Mechanical Criteria for Acid-Resistant Bricks

1. Dimensional Tolerances (Clause 2.2)

2. Performance Standards (Clause 2.2.1, Table 3)

3. Additional Requirements

• Weight loss due to acid attack:
  • Class I: ≤ 1.5%
  • Class II: ≤ 4%
• Wear resistance (optional): average wear ≤ 2 mm (per IS 1237-1959 Appendix A).

Notes:

• Lot acceptance requires all criteria to be fulfilled.
• Testing involves averaging and considering variability of results.

flowchart TD
    A[Sample Testing] --> B[Measure Water Absorption]
    A --> C[Measure Flexural Strength]
    A --> D[Measure Compressive Strength]
    A --> E[Evaluate Acid Resistance]
    B & C & D & E --> F{All Criteria Met?}
    F -- Yes --> G[Accept Lot]
    F -- No --> H[Reject Lot]

Classification Categories for Acid-Resistant Bricks

1. Brick Classes:

• Class I
• Class II

2. Performance Characteristics (Table 1):

3. Conformity Criteria (Table 3):

4. Additional Requirements:

• Bricks must be dense, uniform in texture, accurately shaped, flat, and free from defects (Clause 3.1).

Summary:

• Classification guides selection based on expected chemical exposure and mechanical properties.

Key Performance Parameters and Calculation Methods

1. Conformity Conditions (Table 3, Clause 2.2.1)

• x̄ = mean of test results
• R = range between highest and lowest values

2. Dimensional Tolerances (Clause 2.2)

3. Additional Notes

• Individual test results must be documented.
• Acid resistance tests utilize specified concentrations of nitric and sulfuric acid as per updated standards.

flowchart TD
    A[Collect Test Samples] --> B[Compute Average (x̄) & Range (R)]
    B --> C[Evaluate Water Absorption: x̄ + 0.6R < Limit]
    C --> D[Evaluate Flexural Strength: x̄ - 0.6R > Limit]
    D --> E[Evaluate Compressive Strength: x̄ - 0.6R > Limit]
    E --> F[Evaluate Acid Resistance: x̄ + 0.6R < Limit]
    F --> G{Are All Criteria Met?}
    G -- Yes --> H[Accept Batch]
    G -- No --> I[Reject Batch]

Sampling Methodology and Acceptance Criteria for Acid-Resistant Bricks

Sampling Details (Clause 1.2 & Table 2)

• Sample size and allowable defective bricks depend on lot size:

• Bricks are randomly selected for sampling.
• Each lot is tested independently for conformity.

Lot Acceptance (Clause 2.2.1 & Appendix E)

• A lot passes if the number of defective bricks is within permissible limits.
• All performance parameters in Table 3 must be satisfied.
• Sampling and testing procedures are detailed in Appendix E.

Process Overview:

flowchart TD
    A[Determine Lot Size] --> B[Select Sample Size]
    B --> C[Randomly Choose Bricks]
    C --> D[Conduct Tests on Sub-sample]
    D --> E{Defective Bricks ≤ Permitted?}
    E -- Yes --> F[Lot Accepted]
    E -- No --> G[Lot Rejected]

This framework ensures adherence to quality standards.

Marking Requirements and Key Specifications

Marking Guidelines (Clauses 7.1.1 & 7.1.2)

• Bricks may bear the Standard Mark to signify compliance.
• Use of the Standard Mark is regulated by the Bureau of Indian Standards Act, 1986.
• Licensing and conditions for mark usage are provided by BIS.

Performance Criteria Recap (Table 3, Clause 2.2.1)

Notes:

• Average and range calculations apply.
• Lot conformity requires all criteria satisfied.
• Water absorption test specimen preparation is described in Appendix A.

flowchart LR
    A[Manufacture Bricks] --> B[Perform Quality Testing]
    B --> C{All Criteria Met?}
    C -- Yes --> D[Apply Standard Mark]
    C -- No --> E[Reject or Reprocess Bricks]

Ensures only compliant bricks receive certification marking.

Testing Water Absorption for Acid-Resistant Bricks

Procedure Summary:

• Use whole bricks; measure dimensions to nearest 1 mm.
• Immerse bricks in distilled water at 27 ± 2°C for 24 hours.
• Boil bricks in distilled water for 2 hours without contact with container base.
• Post boiling, immerse bricks in cold water for 20 hours.
• Wipe surface with damp cloth and weigh immediately (Ww).
• Oven-dry bricks and weigh again (Wa).

Formula for Water Absorption (%):

[ \text{Water Absorption} = \frac{W_w - W_a}{W_a} \times 100 ]

Where:

• Ww = weight after boiling and immersion (g)
• Wa = oven-dry weight (g)

Important Notes:

• Weighing accuracy should be within 5 g.
• Support bricks during boiling to avoid direct contact with container bottom.
• Minimum of 5 bricks tested for averaging.

flowchart LR
    A[Weigh Oven-Dried Brick (Wa)] --> B[Boil in Distilled Water for 2 Hours]
    B --> C[Immerse in Cold Water for 20 Hours]
    C --> D[Wipe Surface & Weigh (Ww)]
    D --> E[Calculate Water Absorption Percentage]

Ensures bricks meet durability standards against moisture absorption.

Flexural Strength Test for Acid-Resistant Bricks

Formula (Clause B-3.1)

Flexural strength (F) in kg/cm² is calculated as:

[ F = \frac{3PL}{2BD^2} ]

Where:

• P = breaking load (kg)
• L = span length between supports (cm)
• B = brick width (cm)
• D = brick thickness (cm)

Test Setup (Appendix B & Fig. 2)

• Support rods: mild steel, 40 mm diameter, aligned horizontally.
• Span length between outer supports: ¾ of brick length.
• Load applied centrally at a controlled rate not exceeding 30 kg/min.
• Dry brick specimen placed on supports.

Reporting

• Record breaking load for each specimen.
• Compute and report flexural strength individually.

flowchart LR
    A[Place Brick on Supports A & B] --> B[Apply Load at Center (C)]
    B --> C[Record Breaking Load (P)]
    C --> D[Calculate Flexural Strength using Formula]

Standardizes flexural strength testing for quality assurance.

Compressive Strength Testing for Acid-Resistant Bricks

Test Specifications (Clause 2.1)

• Bricks soaked in water, then surface wiped dry before testing.
• Specimen placed between two 3 mm thick plates (plywood or asbestos).
• Loading applied via compression machine with spherical seating plate centered on specimen.
• Load applied uniformly at approximately 140 kg/cm² per minute until failure.

Compressive Strength Calculation (Clause 3.2)

[ \text{Compressive Strength} = \frac{P}{L \times B} \quad (kg/cm^2) ]

Where:

• P = load at failure (kg)
• L = length of loaded face (cm)
• B = width of loaded face (cm)

Reporting

• Individual compressive strength values recorded.
• Final strength reported as average of multiple tests.

Summary Table

flowchart LR
    A[Soak Brick] --> B[Dry Surface]
    B --> C[Place Between 3 mm Plates]
    C --> D[Load in Compression Machine]
    D --> E[Apply Load at 140 kg/cm² per min]
    E --> F[Record Failure Load (P)]
    F --> G[Calculate Compressive Strength]

Ensures consistent compressive strength evaluation.

Testing Acid Resistance of Bricks

Overview (Appendix D, Table 1, Item iv)

• Objective: Assess durability of bricks under acid exposure.
• Specimens prepared according to standard sizes (IS 1077 or IS 2185).
• Procedure:
  • Immerse bricks in specified acid solution (e.g., 5% sulfuric acid or hydrochloric acid) for 24–48 hours.
  • Remove, wash, dry, and measure weight loss.

Specifications:

• Compressive strength as per Clause 3.2.
• Weight loss must not exceed 5%.
• No visible surface degradation or softening permitted.

Weight Loss Calculation:

[ \text{Weight Loss 7} = \frac{W_1 - W_2}{W_1} \times 100 ]

Where:

• W1 = initial weight
• W2 = weight after acid immersion

Notes:

• Purchasers may specify acid resistance requirements.
• Essential for bricks used in chemical plants and sewage systems.

flowchart TD
    A[Prepare Specimen] --> B[Measure Initial Weight (W1)]
    B --> C[Immerse in Acid Solution (5% H2SO4)]
    C --> D[Duration: 24-48 hours]
    D --> E[Remove & Dry Specimen]
    E --> F[Measure Final Weight (W2)]
    F --> G[Calculate Weight Loss Percentage]
    G --> H{Weight Loss ≤ 5%?}
    H -- Yes --> I[Pass Acid Resistance]
    H -- No --> J[Fail Acid Resistance]

Refer to IS 4860 for detailed test methodology.

Sampling and Acceptance Procedures

1. Sampling Details (Clause 1.2 & Table 2)

• Sampling size and permissible defective bricks depend on lot size:

• Samples are randomly selected.
• Each lot tested individually.

2. Acceptance Criteria (Clause 2.2.1 & Appendix E)

• Lot accepted if defective bricks ≤ permissible limits.
• All performance parameters in Table 3 are met.
• Sampling and test procedures are per Appendix E.

Workflow:

flowchart TD
    A[Identify Lot Size] --> B[Determine Sample Size]
    B --> C[Select Random Samples]
    C --> D[Test Sub-samples]
    D --> E{Defective Count ≤ Allowed?}
    E -- Yes --> F[Accept Lot]
    E -- No --> G[Reject Lot]

Refer to Appendix E for detailed instructions.