cast iron manhole covers and frames

IS 1726: Scope - Key Specifications & Tables

Scope:
IS 1726 covers manhole covers and frames specifying dimensions, grades, test loads, and tolerances for various types.

1. Grade Designations & Test Loads (Clause 6.1)

2. Dimensions of Covers & Frames (Clause 7.1)

Refer to IS 1726 Fig.3-9 for detailed frame & cover dimensions.

3. Permissible Tolerances (Clause 7.1.1)

IS 1726: Key References, Tables & Specifications Summary

1. Manhole Covers & Frames - Grades & Dimensions (Clause 6.1 & 7.1)

2. Frame & Cover Dimensions (Clause 7.1)

• Outer frame dimensions (F, F1), inner frame (f, f1), depth (Fd), seating (fa), thickness (T, T1) are specified per grade.
• Minimum thickness varies: 10 mm (LD-2.5) up to 30 mm (EHD-35).

3. Permissible Tolerances (Clause 7.1.1)

4. Testing & Quality Assurance (Clause 3.3)

• Lot conformity requires meeting criteria in A-3.1 and A-3.2.
• Use of BIS Standard Mark ensures compliance with quality and testing.

Visual: Manhole Cover-Frame Relationship

graph TD
    A[Frame Outer Dimension (F, F1)] --> B[Frame Inner Dimension (f, f1)]
    B --> C[Clear Opening (0,01)]

IS 1726: Grades and Types of Manhole Covers and Frames

1. Grades & Types (Clause 3.1)

2. Basic Requirements (Clause 6.1)

IS 1726: Material Requirements for Manhole Covers and Frames

Key Specifications (Clause 6.1 & 7.1)

Sampling & Quality Control (Clause 3.1 & 2.1)

Notes:

• Seating depth varies with frame design.
• Thickness and dimensions ensure structural integrity under specified test loads.
• Inspection covers material, workmanship, dimensions, and tolerances.

flowchart TD
    A[Material Selection] --> B[Inspection: Material & Workmanship]

IS 1726: Manufacture and Workmanship - Key Points

1. Inspection & Sampling (Clause 3.1, Table 4)

• Items inspected for material, workmanship, dimensions, and tolerances.
• Defective if any characteristic fails.
• Lot acceptance based on permissible defectives in sample:

2. Manhole Covers & Frames (Clause 6.1, Table 1)

IS 1726 - Performance Requirements for Manhole Covers and Frames

Key Specifications (Clause 6.1, Table 1)

• Note: Seating of 25 mm applies for tapered frame designs.
• Manufacturer may vary general design if above dimensions and test loads are met.

Sampling & Quality Control (Clause 2.1, Table 4)

IS 1726 - Dimensions of Manhole Covers and Frames

Key Specifications from Clause 7.1 & Tables:

Notes:

• Depth (fa) and Seating (S) relate to frame depth and cover seating height.
• Thickness values are minimum.
• Clear opening is the usable opening size.
• Dimensions vary by grade and shape (rectangular, square, circular).
• For other designs, dimensions are mutually agreed.

Test Load Capacity (Clause 6.1):

IS 1726: Coating Requirements for Manhole Covers and Frames

Key Specifications (Clause 8.1)

• Coating Material: Black bituminous composition base.
• Properties:
  • Smooth and tenacious.
  • Does not flow at 63°C.
  • Not brittle to chip at 0°C.

Sampling & Testing (Clause 3.2, Table 4)

• After visual/dimensional conformity, select a sub-sample from the lot for coating test.
• Sub-sample size depends on lot size as per Table 4:

Summary

• Coating must resist flow at high temp (63°C) and chipping at low temp (0°C).
• Sampling follows strict criteria to ensure coating quality.
• Sub-samples are tested individually for coating adherence and quality.

flowchart TD
    A[Lot Inspection] --> B[Visual & Dimensional Test]
    B -->|Conforming| C[Select Sub-sample for Coating Test]
    C --> D[Test Coating for Bituminous Properties]
    D --> E{Pass?}
    E -->|Yes| F[Lot Accepted]
    E -->|No| G[Lot Rejected]

This ensures durable, weather-resistant manhole covers as per IS 1726.

IS 1726: Sampling and Criteria for Conformity

Key Points from Clause 2.1 & Table A-3:

Sampling Procedure:

• Samples must be randomly selected from the lot (Clause A-2.2).
• Follow randomness procedures as per IS 4905:1968.
• Sampling and conformity criteria for load tests follow Clauses 10.1 and 10.1.1.

Summary:

• Visual & dimensional defects allowed: As per permissible defective numbers in the table.
• Coating test: Conduct on sub-sample size specified.
• Each lot is inspected separately to determine conformity (Clause A-1.2).

flowchart TD
    Lot["Lot of Items"]
    Sample["Random Sampling\n(as per IS 4905)"]
    VisualCheck["Visual & Dimensional Check"]
    CoatingTest["Coating Test on Sub-sample"]
    Conformity["Conformity Criteria\n(permissible defectives)"]

    Lot --> Sample --> VisualCheck --> Conformity
    Sample --> CoatingTest --> Conformity

This ensures quality control per IS 1726 standards.

IS 1726: Testing Procedures - Key Formulas, Tables & Specifications

1. Sampling & Acceptance Criteria (Clause 2.1, Table A-3)

2. Load Test Samples (Clause 10.1)

• Sample size: 1 sample per 50 items (or part thereof) per grade/type/size.
• Failure: If any tested sample fails, the entire batch is non-compliant unless all items are individually tested.
• Record Keeping: Manufacturer must maintain test records and provide on request.

3. Manhole Covers & Frames (Clause 6.1, Table 1)

Note: Seating depth varies with frame design; tapered frames have 25 mm seating.

4. Conformity (Clause 3.3)

• A lot

Inspection as per IS 1726: Key Points & Tables

1. Inspection Criteria (Clause 3.1)

• Items selected per sampling plan (Table 4) inspected for:
  • Material
  • Workmanship
  • Dimensions & Tolerances
• A lot is rejected if defectives exceed permissible limits.

2. Sampling & Permissible Defectives (Table 4)

3. Coating Test (Clause 3.2)

• Conducted only if lot passes visual/dimensional inspection.
• Sub-sample size as per Table 4, column 4.
• Each sub-sample item tested individually.

4. Manhole Covers & Frames (Clause 6.1, Table 1)

• Specifies Grade Designation, Type/Shape, Clear Opening, Frame Depth & Seating, and Test Load.
• Example:
  • LD-2.5 Rectangular cover: 450×600 mm opening, 35 mm depth, 50 mm seating, 2.5 tonnes load.
  • HD-20 Circular cover: 500 mm dia, 100 mm depth, 50 mm seating, 20 tonnes load.

Summary Flow for Inspection:

flowchart TD
    A[Select Lot & Sample as per Table 4] --> B[Inspect for Material, Workmanship, Dimensions]
    B -->|Defectives ≤ Permissible| C[Coating Test on Sub-sample]
    B -->|Defectives > Permissible| D[Reject Lot

Manufacturer's Guarantee - IS 1726 Key Points

1. Clause 11.1 - Inspection Rights:

   • Purchaser or authorized representative has free access to manufacturer's works during manufacture.
   • Can witness tests (Clause 10.3) with reasonable notice.
   • Can inspect covers and frames before coating application.

2. Clause 12 - Manufacturer's Guarantee:

   • Manufacturer guarantees compliance with IS 1726 requirements.
   • Products must conform to specified dimensions, test loads, and quality.
   • Guarantee covers performance under specified test loads (see Table below).

3. Key Table - Basic & Performance Requirements (Clause 6.1):

4. Sampling & Testing (Clause 3.3 & Table 4):

   • Sampling size and permissible defectives depend on lot size.
   • Visual/dimensional defects allowed: 0 for small lots, up to 2 for larger.
   • Coating tests performed on sub-samples.

5. Standard Mark & Quality Control:

   • Products with BIS Standard Mark ensure compliance with IS 1726.
   • Continuous BIS surveillance and quality control.

Summary Diagram of Manufacturer's Guarantee Process

flowchart TD
    A[Manufacturer Production] --> B[Inspection by Purchaser]
    B --> C{Witness Tests?}
    C -- Yes --> D[Manufacturer Notifies Test Dates]
    D --> E[Tests Conducted]
    C -- No --> E
    E --> F[Product Conforms to IS 1726?]
    F -- Yes --> G[Manufacturer's Guarantee Issued]
    F -- No -->

IS 1726 - Marking & Key Specifications for Manhole Covers

1. Marking Requirements (Clause 13.1)

Each manhole cover and frame must be cast with:

• Manufacturer's name or trademark
• Grade designation (e.g., LD-2.5, MD-10, HD-20, EHD-35)
• Date of manufacture
• 'SWD' or 'SEWER' if specified by purchaser
• Identification mark as required by purchaser

2. Test Load & Block Diameter (Table 3 - Clause 10.3)

3. Basic Dimensions & Loads (Table 1 - Clause 6.1 & Table 2 - Clause 7.1)

• Clear Opening: Varies by grade and shape (e.g., LD-2.5 rectangular: 450×600 mm)
• Frame Depth (fa): 35-130 mm depending on grade
• Seating (S): 25-75 mm depending on design
• Minimum thickness: Cover (10-30 mm), Frame (5-15 mm)
• Test Loads: 2.5 to 35 tonnes depending on grade

4. Summary Diagram: Marking & Testing Flow

flowchart TD
    A[Manufacture Manhole Cover & Frame] --> B[Cast Markings: Manufacturer, Grade, Date]
    B --> C[Apply Additional Markings if Required (SWD/SEWER, ID Mark)]
    C --> D[Test Load Application]
    D --> E{Pass Test Load?}
    E -- Yes --> F[Mark as Conforming to IS 1726]
    E -- No --> G[Reject/Remanufacture]

IS 1726: Sampling & Specifications for Cast Iron Manhole Covers and Frames

Sampling (Clause 10.1 & Annex A)

• Sample Size: 1 sample per lot of 50 units (or part thereof) for each grade, type/shape & size.
• Failure: If any sample fails, entire batch is rejected unless all units are individually tested.
• Record Keeping: Manufacturer must maintain and provide test records on request.

Key Dimensions & Load Tests (Table from Clause 6.1)

Additional Specifications

• Fixing Pads: 13 mm thick on inside bottom of frame.
• Screw Heads: 3 mm below cover surface.
• Strips: 3 mm high at corners and centers of sides.
• Coating: Bituminous base, smooth, tenacious; stable between 0℃ and