General Requirements for Enamelled Cast Iron Sanitary Appliances

IS 772: Scope - Key Specifications and Tables

• Scope Definition (Clause 2.0):
  Defines terms and rounding rules per IS:2-1960 for test results.

• Dimensions and Tolerances (Clause 1.2):

  • Appliances must meet specified dimensions with a tolerance of ±3%
  • Exceptions for dimensions marked as maximum, minimum, or approximate

• Sampling and Acceptance Criteria (Clause 6.2, Table 1):
  Sampling size and permissible defective counts based on lot size:

• Rounding Off (Clause 0.3):
  Final test values rounded as per IS:2-1960, maintaining significant figures equal to the specified value.

This ensures quality control and uniformity in appliance dimensions and testing.

IS 772 - Key Definitions and Specifications

1. Definitions (Clause 2.0):

   • Establishes terminology for the standard's application.
   • Numerical values must be rounded per IS:2-1960 rules, maintaining the same number of significant digits as specified.

2. Rounding Off (Clause 0.3):

   • Final test/analysis results are rounded as per IS:2-1960.
   • Retain significant figures equal to the specified value.

3. Dimensions and Tolerances (Clause 1.2):

   • Dimensions must be within ±3% tolerance unless marked as maximum, minimum, or approximate.

4. Sampling Table (Clause 6.2):

This table guides acceptance criteria for lot sampling quality control.

Summary:

• Use IS:2-1960 for rounding.
• Maintain ±3% dimensional tolerance unless stated otherwise.
• Follow sampling sizes and acceptance criteria in Table 6.2 for quality control.

flowchart LR
    A[Test Result] --> B[Rounding per IS:2-1960]
    B --> C[Final Value with correct significant figures]
    D[Dimensions] --> E{Tolerance ±3%?}
    E -->|Yes| F[Accept Dimension]
    E -->|No| G[Check if Max/Min/Approximate]
    G -->|Yes| F
   

IS 772: Materials and Manufacture — Key Specifications & Tables

1. Defects in Enamelled Cast Iron Appliances (Clause 4.4.1)

2. Sampling & Acceptance Criteria (Clause 6.2, Table 1)

• Lot conformity: A lot passes if defectives ≤ permissible number in the table for warpage, acid/alkali resistance, abrasion.

3. Manufacture Requirements

• Appliances must be inspected via an inspection window

IS 772: General Requirements - Key Formulas, Tables & Specifications

1. Sampling & Acceptance Criteria (Clause 6.2 & 6.7)

• Lot conformity: A lot passes if defectives ≤ permissible number (col 5 for tests in 6.6).

2. Rounding Off (Clause None: 0.3)

• Final test values must be rounded per IS: 2-1960.
• Retain the same number of significant figures as the specified standard value.

3. Testing Requirements (Clause 6.1 & A-6.1)

• Specimens must meet requirements specified in Clause 5.3.
• Tests include warpage, resistance to acid/alkali, abrasion.

Summary:

• Use Table 1 for sample sizes and acceptance limits.
• Defectives beyond permissible limits indicate lot rejection.
• Follow IS rounding rules for test results.
• Testing ensures quality per Clause 5.3.

flowchart TD
    A[Lot Size] --> B[Sample Size]
    B --> C{Test Samples}
    C -->|Pass| D[Accept Lot]
    C -->|Fail > Permissible Defectives| E[Reject Lot]

This ensures quality control compliance per IS 772.

IS 772 Key Specifications for Thickness of Base Metal:

• Base Metal Thickness (Clause 4.1):
  Minimum thickness of cast iron base = 6.5 mm

• Material for Base (Clause 3.1):

  • Cast iron conforming to Grade 15 of IS:210-1970
  • Base must be one piece, sound, true to form, free from porosity or defects

• Inspection Requirements (Clause 6.4):
  Appliances must be checked for:

  • Base material (per 3.1)
  • Visual defects (4.4, 4.4.1)
  • Base thickness (4.1)
  • Dimensions & tolerances (4.2)
  • Enamel thickness (4.5)

• Enamel Thickness (Clause 4.5):
  Minimum enamel thickness on flat surface = 0.5 mm (measured by electromagnetic thickness gauge)

Summary Table:

flowchart TD
    A[Base Metal] --> B[Cast Iron Grade 15 (IS:210)]
    B --> C[Thickness ≥ 6.5 mm]
    C --> D[Free from defects]
    D --> E[Enamel Coating]
    E --> F[Thickness ≥ 0.5 mm]

This ensures structural integrity and durability of cast iron appliances per IS 772.

IS 772 - Warpage Specifications and Testing

Key Specifications (Clause 4.3):

• Warpage limits:
  • Edges set against wall/floor & roll rims: ≤ 5.0 mm/m
  • All other edges: ≤ 7.5 mm/m

Testing Method (Clause 4.3.1):

• Place appliance on a flat surface.
• Use a feeler gauge equal to allowable warpage thickness.
• If gauge slides under without forcing → warpage exceeds limit.
• If appliance rocks on two opposite corners:
  • Place one gauge under a low corner.
  • Hold firmly and check if a second gauge slides under elsewhere.
  • If not, warpage is within limits.

Sampling & Acceptance (Clauses 6.6 & 6.7):

• Sub-sample size for warpage test per Table 1, Column 4.
• Maximum permissible defective units per Table 1, Column 5.
• Lot accepted if defective units ≤ permissible number.

Summary Table (Warpage Limits):

flowchart TD
    A[Place appliance on flat surface] --> B{Does feeler gauge slide under?}
    B -- Yes --> C[Warpage exceeds limit]
    B -- No --> D{Does appliance rock on opposite corners?}
    D -- No --> E[Warpage within limit]
    D -- Yes --> F[Place gauge under low corner and hold]
    F --> G{Does second gauge slide under elsewhere?}
    G -- Yes --> C
    G -- No --> E

This ensures warpage control to maintain appliance fit and function per IS 772.

IS 772: Finishing and Surface Defects in Enamelled Cast Iron Appliances

Key Defect Criteria (Clause 4.4.1)

Abrasive Powder Test (Clause 5.1.1)

• Particle size: Pass 250-micron sieve, retained on 212-micron sieve.
• Apply powder (~1.6 cm²), cover with chamois leather.
• Apply 1 kg weight (1.6 cm² base), move 10-12 times over 13 mm travel.
• Examine under 8x magnifier for scratches; no visible scratches allowed.

Sampling & Acceptance (Clause 6.2, Table 1)

Summary Diagram: Defect Acceptance Flow

flowchart TD
    A[Inspect Enamel Surface] --> B{Defect Type?}
    B -->|Crazing

IS 772: Permissible Defects in Enamelled Cast Iron Appliances

Key Defect Limits (Clause 4.4.1)

Sampling & Acceptance Criteria (Clause 6.2, Table 1)

• Lot conformity: Number of defective appliances ≤ permissible defectives (Clause 6.5).

Summary

• Defects are strictly controlled; grouping of defects is not allowed.
• Sampling size and acceptance criteria depend on lot size.
• Inspection through an inspection window under natural light is standard.

This ensures quality and durability of enamelled cast iron sanitary appliances per IS 772.

IS 772: Enamel Thickness & Testing Specifications

Enamel Thickness (Clause 4.5)

• Minimum enamel thickness on flat surface: ≥ 0.5 mm
• Measurement method: Electric magnetic layer thickness instrument

Abrasion Test (Clause 5.1 & 5.1.1)

• Enamel must resist scratching by abrasive powders on Mohs' hardness scale.
• Abrasive powders used (Mohs scale):

• Powder particle size: passes 250-micron sieve, retained on 212-micron sieve.
• Test procedure:
  • Sprinkle powder on ~1.6 cm² enamel area.
  • Cover with chamois leather.
  • Apply 1 kg weight (1.6 cm² base).
  • Draw 10-12 times over 13 mm travel.
  • Examine under 8x magnifier for scratches (none allowed).

Acid & Alkali Resistance (Clause 4.6)

• Enamel must pass all acid and alkali resistance tests as per Clause 5.

flowchart TD
  A[Measure Enamel Thickness] -->|≥0.5 mm| B[Test Abrasion Resistance]
  B --> C{Apply Powder No. 5 (Apatite)}
  C --> D[Sprinkle powder on surface]
  D --> E[Cover with chamois leather]
  E --> F[Apply 1 kg weight]
  F --> G[Draw 10-12 times over 13 mm]
  G --> H[Examine under 8x magnifier]
  H --> I{No visible scratches?}
  I -->|Yes| J[Pass

IS 772: Enamel Quality - Key Specifications & Tests

1. Enamel Thickness (Clause 4.5)

• Minimum thickness: 0.5 mm on flat surfaces
• Measurement: Electric magnetic layer thickness instrument

2. Acid & Alkali Resistance (Clause 4.6)

• Enamel must resist acid and alkali attacks and pass all tests under Clause 5.

3. Abrasion Test (Clause 5.1 & 5.1.1)

• Purpose: Resistance to scratching.
• Test Powder: Powder No. 5 (Apatite) on Mohs scale.
• Powder Particle Size: Passes 250-micron sieve, retained on 212-micron sieve (IS 460-1962).
• Test Procedure:
  • Sprinkle powder (~1.6 cm² area).
  • Cover with chamois leather.
  • Apply 1 kg weight (1.6 cm² base).
  • Draw back and forth 10-12 times over 13 mm travel.
  • Examine surface under 8x magnifier for scratches.
• Acceptance: No visible scratches allowed.

Mohs Hardness Scale for Abrasion Test Powders

flowchart TD
    A[Start Abrasion Test] --> B[Sprinkle Powder No. 5 (Apatite)]
    B --> C[Cover with Chamois Leather]
    C --> D[Apply 1 kg Weight]
    D --> E[Draw 10-12 times over 13 mm]
    E --> F[Examine under 8x Magnifier]
    F -->

IS 772: Tests for Enamel - Key Formulas, Tables & Specifications

1. Abrasion Test (Clause 5.1 & 5.1.1)

• Objective: Enamel must resist scratching by Powder No. 5 (Apatite) on Mohs' scale.
• Powders & Hardness (Mohs' scale):

• Test Procedure:
  • Abrasive powder particle size: Passes 250-micron IS sieve, retained on 212-micron sieve.
  • Sprinkle powder over 1.6 cm² enamel area.
  • Cover with chamois leather.
  • Apply 1 kg weight (circular base, 1.6 cm²).
  • Draw weight 10-12 times over 13 mm travel.
  • Examine surface with 8x magnifier for scratches.
  • No visible scratching allowed.

2. Acid Resistance Test (Clause 5.2)

• Enamel must pass the citric acid test (details in 5.2.1).
• Ensures enamel resists acid and alkali attack.

Additional Notes

• Use separate chamois leather pieces for each powder.
• Test on inconspicuous areas to avoid disfiguration.

This ensures enamel quality in durability and chemical resistance per IS 772 standards.

IS 772 Abrasion Test Key Points

Abrasion Test (Clause 5.1 & 5.1.1)

• Objective: Check enamel resistance to scratching using powders on Mohs' hardness scale.

• Test Procedure:

  • Powder particle size: passes 250 micron IS sieve, retained on 212 micron sieve.
  • Sprinkle powder (~1.6 cm²) on enamel, cover with chamois leather.
  • Place 1 kg weight (1.6 cm² base), move back and forth 10-12 times over 13 mm travel.
  • Examine surface under 8x magnifier for scratches.
  • Acceptance: No visible scratching with Powder No. 5 (Apatite).

• Note: Use separate chamois leather for each powder to avoid contamination.

Summary Diagram of Abrasion Test Setup

graph LR
A[Enamel Surface] --> B[Sprinkle Powder No. 5 (Apatite)]
B --> C[Cover with Chamois Leather]
C --> D[Place 1 kg Weight (1.6 cm² base)]
D --> E[Move Weight Back & Forth 10-12 times over 13 mm]
E --> F[Examine Surface at 8x Magnification]
F --> G{Visible Scratches?}
G -- No --> H[Test Passed]
G -- Yes --> I[Test Failed]

Reference: IS 772 Clause 5.1, 5.1.1 for detailed test procedure and specifications.

IS 772: Inspection and Sampling Key Points

Sampling (Clause 6.2 & Table 1)

• Sample size is based on lot size.
• Permissible defectives define acceptance criteria for different characteristics.

Inspection Details (Clause 6.4)

• Examine all sampled appliances for:
  • Material of base (3.1)
  • Visual defects (4.4, 4.4.1)
  • Base thickness (4.1)
  • Dimensions and tolerances (4.2)
  • Enamel thickness (4.5)

Inspection Window (Clause 2.1)

• Use a 75 mm diameter circle of flexible material to detect surface defects.

Acceptance Criteria (Clause 6.7)

• Lot passes warpage, acid/alkali resistance, abrasion tests if defectives ≤ permissible number in column 5 (Table 1).

Summary:
Use Table 1 for sampling size and defect limits. Inspect all samples thoroughly per Clause 6.4. Use a 75 mm inspection window for surface checks. Lot acceptance depends on defectives within permissible limits.

flowchart TD
    A[Lot Size] --> B[Select Sample Size (Table 1)]
    B --> C[Inspect Sample for Characteristics (6.4)]
    C --> D{Defectives ≤ Permissible?}
    D -- Yes --> E[Lot Accepted]
    D -- No --> F[Lot

IS 772: Inspection & Manufacturer's Certificate

Key Points from IS 772:

1. Inspection & Sampling (Clause 6.2 & Table 1)

• Sample size and permissible defectives depend on lot size:

• Lot acceptance: A lot is accepted if defectives ≤ permissible number for warpage, acid/alkali resistance, abrasion (Clause 6.7).

2. Manufacturer's Certificate (Clause 7.3)

• If purchaser's inspection is absent, manufacturer must provide a certificate confirming full compliance with IS 772.

3. Inspection Window (Clause 2.1)

• A 75 mm diameter circle of flexible material used to detect surface defects by sliding over the product.

Summary:

• Use Table 1 for sampling and defect limits.
• Manufacturer's certificate ensures compliance when no inspection is done.
• Inspection window helps detect surface defects practically.

flowchart LR
    A[Lot Received] --> B{Sample Size per Table 1}
    B --> C[Inspect Sample for Defects]
    C --> D{Defectives ≤ Permissible?}
    D -->|Yes| E[Accept Lot]
    D -->|No| F[Reject Lot]
    E --> G[Manufacturer’s Certificate if No Inspection]

This ensures quality control per IS 772 requirements.

IS 772: Rejection and Acceptance Criteria Summary

Sampling & Acceptance (Clause 6.2, Table 1)

Defect Limits for Enamelled Cast Iron (Clause 4.4.1)

• Crazing: No more than 1 defect.
• Dimples, rundown, sagging: Permitted only if not readily visible.
• Blisters: Max 2 on interior, non-breakable by fingernail.
• Pinholes: Max 2 for colored, 4 for white wares; no grouping; no penetration.
• Specks: Max 5, <1 mm size, no grouping; <0.25 mm not defects unless discolouration.
• Flaws:

Lot Acceptance (Clauses 6.5 & 6.7)

• Lot passes if defectives in sample ≤ permissible number (Table 1, col 3 for Clause 6.4 defects).
• Lot passes for warpage, acid/alkali resistance, abrasion if defectives ≤ permissible (Table 1, col 5 for Clause 6.6 defects).

Quick Decision Flow

flowchart TD
    A[Start Inspection] --> B