Products in Fibre Reinforced Cement - Long Corrugated or Asymmetrical Section Sheets and Fittings for Roofing and Cladding

IS 14871: Scope - Key Formulas, Tables & Specifications

1. Scope Overview

IS 14871 covers testing and inspection of corrugated sheets, including dimensional tolerances, breaking load, and acceptance criteria.

2. Sampling & Acceptance (Clause 8.2)

3. Acceptance Criteria (Table 3, Clause 8.2.6)

• x = Test result
• AL = Acceptance Level
• K = Acceptance Coefficient
• R = Relevant tolerance or range

4. Dimensional Tolerances (Clause 5.4.1.4)

5. Key Symbols

| Symbol | Meaning | Unit

IS 14871: Key Definitions, Symbols & Tables

1. Key Definitions (Clause 3.6)

• Breaking Load (P): Maximum load during bending test, representing sheet's load-bearing capacity.
• Pitch: Distance between corrugation peaks (mm).
• Thickness (e, e1, e2): Sheet thickness in mm.
• Deflection (f): Displacement during breaking load test (mm).
• Corrugation Height (h): Vertical height of corrugation (mm).
• Clear Span (l): Distance between support points in bending test (mm).
• Breaking Load per Meter Width (P_w): Load normalized by sheet width (N/m).

2. Symbols Summary

3. Sampling & Acceptance (Clause 8.2, Tables 2 & 3)

Acceptance Criteria (Table 3):

• For lower limit (L_1): Accept if (x \geq L +

IS 14871 - General Requirements: Key Formulas, Tables & Specifications

1. Minimum Breaking Load (Clause 5.3.3 & Table 1)

• Minimum breaking load depends on Category, Class, and Sheet Thickness (e, mm).
• Categories A to D defined by sheet height (h) ranges.
• Example excerpt for Category B (25 mm ≤ h ≤ 55 mm, e=4 mm):

2. Mechanical Characteristics (Clause 5.4.2)

• For non-roofing/cladding, alternative mechanical properties can be agreed between manufacturer & purchaser.

3. Inspection by Variables (Clause 8.2 & Tables 2 & 3)

Acceptance Criteria (Limits L1, Lu):

Where:

• x = test value
• K = acceptance coefficient
• R = range
• AL = acceptance level

Summary:

• Select Category & Class based on sheet thickness and application.
• Use Table 1 for minimum breaking

IS 14871: Classification and Categories Summary

1. Classification (Clause 5.3 & Table 1)

Sheets are classified by Category, Minimum Thickness (e, mm), and Class based on Minimum Breaking Load (N/m):

• Note: Commonly manufactured sheets in India are Category B and C, Class 7.

2. Inspection by Variables (Clause 8.2 & Table 2)

3. Acceptance Criteria (Table 3)

IS 14871: Material Composition & Physical Characteristics Summary

1. Material Composition (Clause 6.1)

• Fittings must have a composition similar to the base sheets to ensure compatibility and uniform performance.

2. Physical Characteristics (Clauses 5.4.3 & 6.3.2)

• Determined on as-delivered products (coated or uncoated).
• Coating failure ≠ product failure.
• Characteristics include:
  • Thickness
  • Surface finish
  • Coating weight (if applicable)
  • Dimensional tolerances

3. Mechanical Characteristics (Clause 5.4.2)

• Standard mechanical properties apply.
• For non-roofing/cladding, alternative mechanical properties may be agreed upon.

Typical Physical Property Table (Example)

flowchart LR
    A[Base Sheet Composition] --> B[Fittings Composition: Similar]
    B --> C[Physical Characteristics]
    C --> D[Thickness, Coating, Surface Finish]
    C --> E[Mechanical Characteristics]
    E --> F[Standard or Agreed Alternative]

Note: Refer to IS 14871 for precise coating weights and mechanical property limits based on product type.

IS 14871: Dimensions and Tolerances Summary

1. Key Dimensions (Clause 5.4.1)

• Nominal dimensions declared by manufacturer include:
  • Length
  • Overall width
  • Effective nominal thickness
  • Depth and pitch of corrugations
• Profiles tested as per Annex B.

2. Tolerances on Pitch (Clause 5.4.1.4)

3. Fittings Dimensions (Clause 6.3.1)

• Must be compatible with corresponding sheet dimensions and tolerances.

Testing Method

• Profile and other dimensions checked as per Annex B (Clause 5.4.1.2).

flowchart TD
    A[Nominal Dimensions] --> B[Length, Width, Thickness]
    A --> C[Depth & Pitch of Corrugations]
    C --> D[Tolerance on Pitch]
    D -->|Based on pitch range| E{Tolerance Values}
    E -->|a ≤ 75 mm| F[+4.0 / -2.0 mm]
    E -->|75 < a ≤ 180 mm| G[+6.0 / -2.0 mm]
    E -->|180 < a ≤ 260 mm| H[+8.0 / -3.0 mm]
    E -->|a > 260 mm| I[+9.0 / -3.0 mm]

Use these tolerances and dimensions to ensure correct manufacturing and fitting compatibility per IS 14871.

IS 14871: Marking and Identification Key Points

Marking Requirements (Clause 7.1)

Each sheet/fitting must be indelibly marked with:

• Manufacturer's identification
• Date of manufacture
• Type, Category, and Class of sheet
• Size and thickness
• "FROST RESISTANT" (if applicable)

BIS Certification Marking (Clause 7.2)

• Sheets/fittings may bear the BIS Standard Mark.
• Use of the Standard Mark follows the BIS Act, 1986 regulations.
• Licensing details for the Standard Mark are available from BIS.

Sampling and Acceptance Criteria (Clause 8.2)

Acceptance Criteria for Inspection by Variables (Clause 8.2.6)

• x = measured value
• K = acceptance coefficient (from table above)
• R = range or tolerance as per standard

Summary Diagram

flowchart TD
    A[Manufacture] --> B[Marking on Sheet/Fitting]
    B --> C{Marking Details}
    C -->|Manufacturer ID| D[Stamped]
    C -->|Date| D
    C -->|Type, Category, Class| D
    C -->|Size & Thickness| D
    C -->|Frost Resistant (if

IS 14871: Sampling and Inspection Key Points

1. Sample Size & Acceptance Coefficient (Table 2, Clause 8.2)

2. Inspection Procedure (Clause 8.2.1)

• Sample size as per Table 2.
• Divide readings into groups of 5, except if sample size = 7, then group size = 7.

3. Acceptance Criteria (Table 3, Clause 8.2.6)

• x̄ = sample mean
• AL = Acceptance Level
• K = Acceptance coefficient from Table 2
• R = Range of sample readings

4. Definitions

• AQL (Acceptable Quality Level): Maximum average defect level considered satisfactory over continuous lots (Clause 3.3).

flowchart TD
    A[Lot Size] --> B[Determine Sample Size & K (Table 2)]
    B --> C[Take Sample]
    C --> D[Group readings (5 or 7)]
    D --> E[Calculate Sample Mean (x̄) & Range (R)]
    E --> F{Check Acceptance Criteria}
    F -->|Accept| G[Lot Accepted]
    F -->|Reject| H[Lot Re

IS 14871: Inspection and Testing Key Points

1. Sample Size & Acceptance Coefficient (Table 2 - Clause 8.2)

2. Inspection Procedure (Clause 8.2.1)

• Divide readings into groups of 5 (except sample size 7, use group size 7).
• Inspection is done on one sample with size per Table 2.

3. Acceptance Criteria (Table 3 - Clause 8.2.6)

• L = lower limit, Lu = upper limit, K = constant, R = standard deviation, x = sample mean.

4. Manufacturer’s Test Certificate (Clause 9.2)

• Manufacturer must provide certificate confirming compliance upon request.

5. Safety Rules (Clause 10)

• Mark sheets as asbestos-free.
• Use low-speed tools, wetting, PPE (respirators), or hand tools to minimize dust exposure.

flowchart TD
    A[Start Inspection] --> B[Select Sample Size from Table 2]
    B --> C[Divide Readings into Groups]
    C --> D[Calculate Sample Mean (x)]
    D --> E{Check Acceptance Criteria (Table 3)}
    E -->|Accept| F[Lot Accepted]
    E -->|

IS 14871: Acceptance Criteria Summary

1. Sample Size & Acceptance Coefficient (Table 2, Clause 8.2)

2. Acceptance Criteria (Table 3, Clause 8.2.6)

• R = Range of sample values
• K = Acceptance coefficient from Table 2
• ( \bar{x} ) = Sample mean

3. Procedure Summary

• Draw sample size n based on lot size.
• Calculate sample mean ( \bar{x} ) and range ( R ).
• Compute acceptability limit ( AL ) using K and R.
• Accept lot if ( \bar{x} ) meets acceptance condition; else reject.

Visual Summary

flowchart TD
    A[Lot Size] --> B[Determine Sample Size (n) & K]
    B --> C[Draw Sample & Measure Values]
    C --> D[Calculate Sample Mean (\bar{x}) & Range (R)]
    D --> E[Compute Acceptance Limit AL = L ± K×R]
    E

IS 14871 - Referenced Standards & Key Specifications

1. Referenced Indian Standards (Annex A)

2. Inspection & Sampling (Clause 8.2)

3. Key Symbols (Clause 4)

• e, e1, e2: Thickness of sheet (mm)
• P: Breaking load (N)
• W: Width of sheet (m)
• f0.2, f0.7: Deflections at 20% and 70% specified load (mm)
• Pitch: Corrugation pitch (mm)
• h: Corrugation height (mm)
• M1, M2: Average warm water test results

4. Safety & Identification (Clause 10)

• Sheets must be marked asbestos-free.
• Use low-speed tools, wetting, **PPE (resp

IS 14871: Test Methods and Apparatus - Key Formulas & Tables

1. Test Specimen

• Minimum length: 1.2 m (complete or transversally cut sheet).
• Manufacturer must guarantee specimen maturity.

2. Sample Size & Acceptance Coefficient (Clause 8.2, Table 2)

3. Acceptance Criteria (Clause 8.2.6, Table 3)

• x = Sample mean
• K = Acceptance coefficient
• R = Sample range

4. Conditioning Procedure (Table 4)

5. Loading & Deflection Measurement

• Specimen placed with smooth face in compression, perpendicular to corrugations.
• Load applied at midspan via flat beam with felt strips.
• Breaking load or max sag occurs between 10 s and 45 s after loading starts.
• Deflection measured at midspan under 20% and 70% of specified load.

IS 14871: Mechanical Testing Procedures – Key Points

1. Compulsory Tests (Clause 5.5.1.1)

• Dimensions: As per Annex B.
• Mechanical Characteristics: Breaking load as per Annex C.

2. Minimum Breaking Load (Clause 5.3.3)

• Breaking load requirements depend on the sheet category.
• Refer to Table 1 for minimum breaking load values in bending.

3. Specimen Preparation (Clause 2.1)

• Test on 5 specimens, each from a different sheet.
• Specimen size:
  • 300 mm along corrugations.
  • 200 mm perpendicular to corrugations.

4. Mechanical Characteristics (Clause 5.4.2)

• For non-roofing/cladding uses, alternative mechanical properties can be agreed upon.

Typical Table 1 (Minimum Breaking Load in Bending) - Example format:

(Refer to IS 14871 Table 1 for exact values.)

Summary Diagram of Specimen Orientation:

flowchart LR
    A[Specimen] --> B[300 mm along corrugations]
    A --> C[200 mm perpendicular to corrugations]

Use this framework to ensure specimens and tests comply with IS 14871 mechanical testing standards.

IS 14871: Durability Testing Procedures - Key Points

1. Water Immersion Conditioning (Clause 2.3 & 1.2.1)

• Immerse specimens in water at ambient temperature for 24 h intervals.
• Continue until weight difference between two consecutive weighings is < 0.5%.
• For acceptance test: 24 h immersion.
• For type test: 7 days at ambient lab conditions + 24 h immersion.

2. Freeze/Thaw Cycles (Clause 2.3)

• 50 cycles total, each cycle 4-6 hours.
• Cooling: Air to -20°C ± 2°C in 1-2 h, hold 1 h.
• Thawing: Water at ambient temperature in 1-2 h, hold 1 h.
• Specimens arranged for free circulation of air/water.
• Optional interval between cycles: max 72 h at ambient.

3. Corrugation Categories (Clause 2.3 Table)

4. Preliminary Conditioning & Cyclic Testing (Clause 5.3)

• Store specimens for 7 days in lab atmosphere fixed on frame.
• Subject sheets to 25 freeze/thaw cycles.
• Inspect for cracking, delamination, defects.

5. Breaking Load Test (Clause 4.3 & Annex C)

• Divide specimens into two lots of 10.
• One lot: test breaking load.
• Other lot: immerse in water at 60°C ± 2°C for 56 ± 2 days.
• After saturation, condition for 7 days at lab atmosphere.
• Inspect visually, then test breaking load.
• Load applied at midspan, deflection measured at 20% and 70% max load.

Breaking Load Formula (N/m width):

[ P = \frac{F}{b} ]

• P = Breaking load per meter width (N/m)
• F = Breaking load measured (N)
• **b

IS 14871 - Committee Composition Summary

• The technical committee responsible for IS 14871 formulation is detailed in Annex E.
• The committee is the Cement Matrix Products Sectional Committee, CED 53, with members from:
  • Industry (e.g., Gammon India Ltd, Eternit Everest Ltd)
  • Government bodies (e.g., Central Public Works Department, Municipal Corporations)
  • Research institutions (e.g., Central Building Research Institute, National Council for Cement and Building Materials)
  • Small scale and large scale manufacturers associations
  • BIS (Director General as Ex-officio Member)

Key Points:

• Chairman: Shri S. A. Reddi (Gammon India Ltd)
• Member-Secretary: Shri Sanjay Pant (Deputy Director, BIS)
• Includes alternates for most members.
• Also has a Fibre Reinforced Cement Products Subcommittee (CED 53:1) with a similar composition.

No direct formulas or tables for committee composition are in the code, but the detailed member list is provided in Annex E.

graph TD
  A[IS 14871 Technical Committee] --> B[Cement Matrix Products Sectional Committee]
  B --> C[Chairman: Shri S. A. Reddi]
  B --> D[Members: Industry, Govt, Research]
  B --> E[Member-Secretary: Shri Sanjay Pant]
  A --> F[Fibre Reinforced Cement Products Subcommittee]
  F --> G[Convener: Dr C. Rajkumar]
  F --> H[Members: Industry, Govt, Research]

Note: For test procedures, sampling, and material specifications, refer to respective clauses (e.g., Clause 8.1.2 for sampling).