Injection Moulded/Machined High-Density Polyethylene (HDPE) Fittings for Potable Water Supplies, Part 7: Specific Requirements for Sandwich Flanges

IS 8008 Part 7: Scope - Key Points

• Scope: Specifies requirements for reducing tees in piping systems.
• Dimensions & Tolerances: Must comply with Table 1 and Fig. 1 (Clause 3.2.2).
• Rounding Off: Final test or calculation values are rounded per IS 2:1960 rules, maintaining the same significant figures as specified.
• Related Parts:

  Part	Description
  Part 1	General requirements for fittings
  Part 2	90° bends
  Part 3	90° tees
  Part 4	Reducers
  Part 5	Ferrule reducers
  Part 6	Pipe ends
  Part 7	Reducing tees (this part)
  Part 8	Reducing tees (specific req.)
  Part 9	End caps

Table 1 (Dimensions & Tolerances) - Summary

(Refer to IS 8008 Part 7 Fig. 1 for dimensional layout.)

Rounding Off Rules (IS 2:1960)

• Round off the final value to the same number of significant digits as the specified value.
• Example: If specified value = 12.3 (3 significant digits), round 12.3456 to 12.3.

flowchart LR
    A[Start: Dimension Specified] --> B[Check Table 1 & Fig. 1]
    B --> C{Dimension within tolerance?}
    C -- Yes --> D[Apply IS 2:1960 rounding]
    C -- No --> E[Reject / Rework]
    D --> F[Final value accepted]

Summary: IS 8008 Part 7 defines dimensional, tolerance, and rounding requirements for reducing tees, referencing other parts for related fittings.

IS 8008 Part 7: 2003 - Key References & Specifications

1. Related Parts of IS 8008 Series:

• Part 1: General requirements for fittings
• Part 2: Specific requirements for 90° bends
• Part 3: Specific requirements for 90° tees
• Part 4: Specific requirements for reducers
• Part 5: Specific requirements for ferrule reducers
• Part 6: Specific requirements for pipe end
• Part 7: Sandwich flanges (this part)
• Part 8: Specific requirements for reducing tees
• Part 9: Specific requirements for end caps

2. Sandwich Flanges Dimensions (Table 1, Clause 3.2.2)

IS 8008 Part 7 (2003) - Manufacture: Key Specifications

1. Manufacture Clause (3.2)

• Manufacture of sandwich flanges must follow dimensions and tolerances as per Table 1.
• Tolerances on dimensions:
  • Inside Diameter (DI), Pitch Circle Diameter (D2), Outside Diameter (D3): ±1 mm
  • Thickness of Flange (Z): ±1 mm

2. Table 1: Dimensions of Sandwich Flanges (in mm)

(Refer full Table 1 for all sizes)

3. Additional Notes

• Thickness of Mild Steel Insert is critical for strength and sealing.
• Number and diameter of bolt holes ensure proper flange fastening.
• Manufacture must comply with BIS licensing and Standard Mark usage per Clause 4.2.1.

Diagram: Flange Dimensions Reference

graph LR
  A[Inside Diameter (DI)] --> B[Pitch Circle Diameter (D2)]

IS 8008 Part 7 (2003) — Dimensions and Tolerances for Sandwich Flanges

Key Dimensions (Table 1 Summary)

Typical Dimensions for Nominal Flange Size 50 (example)

Notes:

• Thickness of mild steel insert varies with flange size (6 to 22 mm).
• Number and diameter of bolt holes increase with flange size.
• Dimensions are in millimeters.
• Tolerances ensure interchangeability and proper fit.

Visual Concept (Mermaid Diagram)

graph TD
    A[Pipe Outside Diameter] --> B[Inside Diameter (D1)]
    B --> C[Pitch Circle Diameter (D2)]
    C --> D[Outside Diameter (D3)]
    D --> E[Thickness of Flange (Z)]
    E --> F[Thickness of Mild Steel Insert (T)]
    F --> G[Diameter & Number of Holes]

Summary:
Use Table 1 for exact flange dimensions and apply ±1 mm tolerance on D1, D2, D3, and Z. Thickness of the mild steel insert has tighter tolerances as specified per size. This ensures compatibility and standardization in sandwich flange manufacture.

IS 8008 Part 7: Marking of Sandwich Flanges

Key Specifications (Clause 4.1 & 4.2)

Each sandwich flange shall be clearly marked with:

• Manufacturer identification (source of manufacture)
• Size of the fitting
• Grade of material
• Appropriate class (working pressure rating)

Additionally, the Standard Mark (BIS Certification Mark) may be applied as per Clause 4.2, governed by the Bureau of Indian Standards Act, 1986.

Table: Dimensions of Sandwich Flanges (Clause 3.2.2)

Tolerance on dimensions: ±1 mm on diameters and thicknesses.

Summary

• Markings ensure traceability and specification compliance.
• BIS Standard Mark use is regulated and requires licensing.
• Dimensions and tolerances per Table 1 ensure interchangeability and quality.

flowchart

IS 8008 Part 7 (Testing) does not provide explicit formulas or tables within the given context. However, based on IS 8008 series and general testing principles for pipe fittings, here are key points:

Testing Specifications (General)

• Rounding Off Results:
  Follow IS 2:1960 for rounding numerical test results.

  • Retain the same number of significant figures as specified values.

• Types of Tests Commonly Applied:

  • Hydrostatic Test: To check pressure resistance.
  • Dimensional Test: Verify dimensions against standard tolerances.
  • Visual Inspection: Check for defects like cracks or surface irregularities.
  • Material Test: Chemical and mechanical properties confirmation.

Typical Formula for Hydrostatic Pressure Test

[ P = \frac{2 \times \sigma_t \times t}{D} ]

Where:

• (P) = Test pressure (N/mm²)
• (\sigma_t) = Allowable tensile stress of material (N/mm²)
• (t) = Wall thickness (mm)
• (D) = Outside diameter (mm)

Reference Table (Example) for Hydrostatic Test Pressure

Summary

• Testing follows IS 2:1960 for rounding.
• Hydrostatic pressure test is fundamental; formula depends on material and geometry.
• Refer to IS 8008 Parts 1-9 for specific fitting types and their testing requirements.

flowchart TD
    A[Start Testing] --> B{Type of Test}
    B --> C[Hydrostatic Test]
    B --> D[Dimensional Test]
    B --> E[Visual Inspection]
    B --> F[Material Test]
    C --> G[Calculate Test Pressure]
    G --> H[Apply Pressure]
    H --> I{Pass/Fail}
    I -->|Pass| J[Accept]
    I -->|Fail| K[Reject/Retest]

Inspection and Sampling - IS 8008 Part 7: Key Points

1. Rounding Off (per IS 2:1960):

• Final test or analysis values must be rounded to the same number of significant digits as specified in the standard.

2. Sampling & Compliance:

• Inspection follows Bureau of Indian Standards (BIS) certification rules (Clause 4.2.1).
• Manufacturer's license and Standard Mark use governed by BIS Act, 1986.

3. Dimensions & Tolerances (Table 1 - Sandwich Flanges):

4. Sampling Procedure (General Engineering Practice):

• Use random sampling from batches.
• Sample size depends on batch size and acceptance criteria (refer IS 2500 series for sampling plans).
• Tests include dimensional checks, material tests, and functional tests.

Summary Diagram of Inspection Process

flowchart TD
    A[Start: Batch Received] --> B[Random Sampling]
    B --> C{Sample Tests}
    C -->|Pass| D[Batch Accepted]
    C -->|Fail| E[Rejection or Re-test]
    E --> F{Re-test Pass?}
    F -->|Yes| D
    F -->|No| G[Batch Rejected]

Note: For detailed sampling plans and inspection criteria, refer to IS 2500 (Sampling Procedures) and IS 8008 Part 7 clauses on testing.

Certification and Standard Mark - IS 8008 Part 7 (Clause 4.2.1)

• Standard Mark Usage: Governed by the Bureau of Indian Standards Act, 1986 and related rules.
• License for Use: Manufacturers/producers must obtain a license from BIS to use the Standard Mark.
• Marking on Products: Each sandwich flange may be marked with the BIS Standard Mark to indicate conformity.
• Rounding Off: Test/analysis results should be rounded per IS 2:1960 rules, matching the significant figures of the specified values.

Key Points on Dimensions (Table 1 - Clause 3.2.2)

Summary Diagram: Certification Process Flow

flowchart TD
    A[Manufacturer applies for BIS License] --> B[BIS reviews application]
    B --> C{Compliance with IS 8008?}
    C -- Yes --> D[License granted]
    C -- No --> E[Application rejected]
    D --> F[Manufacturer marks product with BIS Standard Mark]

Contact for BIS Licensing

• Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110 002
• Regional Offices across India (Delhi, Kolkata, Chennai, Mumbai, Chandigarh)
• Refer to BIS for detailed licensing conditions and permissions.

Note: For detailed licensing terms, contact BIS directly or visit their official website.

IS 8008 Part 7 (2003) does not explicitly provide detailed clauses on welding and re-welding provisions but mentions:

• Rewelding is permitted if a weld is rejected.
• Weld length must remain constant with uniform tolerance during rewelding.
• Weld dimensions and tolerances are standardized in the respective parts of IS 8008 covering various fittings (Parts 1 to 9).

General Welding/Rewelding Guidelines (based on IS standards and good practice):

• Weld length (Lw): As per design or fitting specification; maintain original weld length after rewelding.
• Weld quality: Must comply with IS 816 or IS 9595 for welding procedure and acceptance criteria.
• Rewelding procedure:
  • Remove defective weld metal completely.
  • Clean and prepare the joint surface.
  • Use the same welding process and filler material.
  • Maintain preheat and interpass temperature as required.
  • Inspect weld after rewelding (visual, radiographic, or ultrasonic).

Typical Weld Length Tolerance:

Summary Table of IS 8008 Parts (for fitting types and welding details)

flowchart TD
    A[Weld Rejection] --> B[Remove Defective Weld]
    B --> C[Clean & Prepare Surface]
    C --> D[Reweld with Same Procedure & Material]
    D --> E[Inspect Weld Quality