Methods of sampling of steel for prestressed and reinforced concrete, Part 2: Reinforcing steel

IS 10790 Part 2 - Scope: Key Formulas, Tables & Specifications

1. Scope Overview

• Applies to sampling, inspection, and testing of materials for visual, dimensional, weight, mechanical, and surface characteristics.
• Defines sampling sizes, acceptance criteria, and routine inspection levels for production lots.

2. Sampling & Acceptance (Clause 4.3.1.2, Table 3)

3. Routine Inspection Levels (Clause 3.1.2, Table 2)

4. Additional Notes

• Samples must be selected per lot for conformity.
• Statistical data presentation and tests (Normal, F, Chi-square) are referenced in Part 1 and Part

IS 10790 Part 2 - Key Definitions & Sampling Specifications

Definitions (Clause 2.0)

• Defines terms related to statistical sampling, testing, and data presentation.
• Emphasizes separate sampling and examination for each lot (Clause 4.2).

Sampling & Acceptance (Clause 4.3.1.2, Table 3)

Notes:

• Sample Size: Number of units to be tested from the lot.
• Acceptance Number: Maximum allowable defects for acceptance.
• Visual checks are stricter (lower acceptance numbers) compared to dimensional/weight checks.

Statistical Tests & Data Representation

• Part 1 covers tabulation, summarization, normal, F-tests.
• Part 2 covers diagrammatic data representation and χ²-tests.
• Regression, correlation, and ANOVA methods are referenced.

This standard ensures quality control via statistically valid sampling and acceptance criteria for visual, dimensional, and weight characteristics.

IS 10790 Part 2 – Process Inspection Key Points

1. Acceptable Quality Level (AQL)

• Max % defective acceptable as process average in sampling inspection (Clause 2.11).

2. Routine Process Inspection Levels

• Samples spread uniformly over the heat.

| Production Without Melting Facilities (Clause 3.1.2, Table 2) | Daily production basis | Samples per daily production:

3. Purpose

• Ensure conformity to specs and maintain uniform quality.
• Sampling at regular intervals during manufacture.

Summary Diagram

flowchart TD
    A[Start Manufacturing] --> B{Melting Facility?}
    B -- Yes --> C[Process Control on Heat Basis]
    C --> D[Take Samples per Table 1]
    B -- No --> E[Process Control on Daily Production]
    E --> F[Take Samples per Table 2]
    D & F --> G[Perform Tests: Visual, Dimensional, Tensile, etc.]
    G --> H[Assess Quality & Conformity]
    H --> I[Continue Production or Adjust Process]

This ensures systematic

IS 10790 Part 2 — Lot Inspection Key Points

Sampling & Acceptance (Table 3 Summary)

Procedure Summary

• Step 1: Inspect sample for visual defects (size per col 2).
• Acceptance: Defectives ≤ acceptance number (col 3) → lot accepted visually.
• Step 2: From visually accepted items, randomly sample for dimensional & weight checks (col 4).
• Acceptance: Defectives ≤ acceptance number (col 5) → lot accepted overall.

Notes

• If visual inspection fails, full lot inspection & defect removal may be done if agreed.
• Random sampling methods must be used for dimensional/weight checks.
• This procedure applies when test certificates are unavailable or purchaser requests.

Mermaid Diagram: Lot Inspection Flow

flowchart TD
    A[Start: Lot Received] --> B[Visual Inspection Sample]
    B --> C{Defectives ≤ Acceptance No.?}
    C -- Yes --> D[Dimensional & Weight Sample]
    C -- No --> E[Full Lot Inspection & Defect Removal]
    D --> F{Defectives ≤ Acceptance No.?}
    F -- Yes --> G[Lot Accepted]
    F -- No --> H[Lot Rejected]
    E --> G

This ensures systematic quality control per IS 10790 Part 2.

IS 10790 Part 2 - Visual, Dimensional and Weight Characteristics

Key Points from Clause 4.3.1 & Table 3:

• Sampling & Acceptance Criteria depend on lot size.
• Visual inspection is done first; if satisfactory, dimensional & weight checks follow.
• Sampling is random, per IS 4905:1968.

Procedure Summary:

1. Select visual sample size from lot randomly.
2. If number of defective items ≤ visual acceptance number, proceed.
3. Select dimensional & weight sample from visually conforming items.
4. If defective items ≤ dimensional & weight acceptance number, lot is accepted.

Random Sampling Reference:

• Follow IS 4905:1968 for random selection methods.

flowchart TD
    A[Select Lot] --> B{Visual Inspection}
    B -- Defectives ≤ Acceptance --> C[Dimensional & Weight Inspection]
    B -- Defectives > Acceptance --> D[Reject Lot]
    C -- Defectives ≤ Acceptance --> E[Accept Lot]
    C -- Defectives > Acceptance --> D

This ensures quality control based on statistically valid sampling.

IS 10790 Part 2: Physical Characteristics Summary

Key Clauses:

• 4.3.1: Visual, Dimensional, and Weight Characteristics
• 4.3.2: Physical Characteristics (focus of your query)
• 4.3.1.2: Sampling and Acceptance Criteria for Visual, Dimensional, and Weight Characteristics

Sampling and Acceptance Table (Clause 4.3.1.2)

Notes on Physical Characteristics:

• Physical characteristics include density, moisture content, and other properties affecting performance.
• Visual and dimensional checks ensure conformity to specified sizes and appearance.
• Weight checks confirm material consistency and quality.

Practical Use:

• Use the table to determine sample size and acceptance number for quality control.
• If the number of defects exceeds acceptance number, reject the lot.
• This ensures reliability in physical properties and dimensional accuracy.

If you need formulas for specific physical properties (e.g., density), please specify!

IS 10790 Part 2 - Chemical Characteristics (Clause 4.3.3)

• Sampling: Drillings from selected items are combined to form a composite sample for chemical analysis.
• Compliance: The lot passes if the composite sample meets the chemical constituent limits specified in the relevant standard.

Key Points:

• Chemical constituents must conform to the relevant IS specifications.
• Composite sampling ensures representative testing of the lot.
• Typical chemical parameters include limits on elements like Sulfur, Phosphorus, Carbon, etc., depending on material type.

Typical Chemical Analysis Table (Example Format):

Refer to the relevant IS standard for exact limits per material.

Summary Flow for Chemical Compliance:

flowchart TD
    A[Select Items] --> B[Take Drillings]
    B --> C[Prepare Composite Sample]
    C --> D[Chemical Analysis]
    D --> E{Meets IS Limits?}
    E -->|Yes| F[Lot Accepted]
    E -->|No| G[Lot Rejected]

For detailed chemical limits, consult the relevant IS specification linked to your material type.

Sampling for Visual, Dimensional, and Weight Characteristics
(IS 10790 Part 2, Clauses 4.3.1 to 4.3.1.3)

Key Points:

• Sampling is random, following IS:4905 (1968) for randomness.
• Visual inspection is done first.
• Only items conforming visually are then checked for dimensional and weight characteristics.
• Acceptance depends on the number of defectives ≤ acceptance number.

Table 3: Sample Size & Acceptance Number

Procedure Summary:

1. Select sample size from the lot as per lot size (columns 2 & 4).
2. Inspect for visual defects; accept if defectives ≤ visual acceptance number.
3. From visually accepted items, randomly select sample for dimensional & weight checks.
4. Accept lot if defectives ≤ dimensional & weight acceptance number.

This method ensures quality control by progressive inspection focusing first on visual, then on dimensional/weight criteria.

Sampling for Physical Characteristics as per IS 10790 Part 2 (1984):

1. Sampling for Visual, Dimensional & Weight Characteristics (Clauses 4.3.1.1 to 4.3.1.3)

• Procedure:
  1. Randomly select items as per the lot size for visual inspection (IS 4905 recommended for randomness).
  2. If visual inspection passes, select items for dimensional & weight checks.
  3. If defectives ≤ acceptance number, lot is accepted.

2. Sampling for Physical Tests (Proof Stress, Elongation, Tensile, Bend Tests) (Clause 4.3.2.2)

• Samples for physical tests are taken only from items passing visual, dimensional, and weight tests.

Summary:

• Random sampling is essential for all stages.
• Visual inspection → Dimensional & weight checks → Physical tests.
• Acceptance depends on defectives ≤ acceptance number from tables.

flowchart TD
    A[Start

Sampling for Chemical Characteristics - IS 10790 Part 2

• Clause 4.3.3.1: Chemical samples are taken at random from items that conform to visual, dimensional, and weight checks.
• Sample Size Reference: Use Table 4 (not provided here) for chemical sampling size, aligned with lot size (see Table 3 for visual/dimensional sampling).
• Lot-wise Sampling: Each lot is sampled separately to verify chemical conformity (Clause 4.2).

Table 3: Sampling Scale for Visual & Dimensional Characteristics

Key Points:

• Chemical samples are randomly selected from conforming items.
• Sampling size for chemical tests follows Table 4 (similar scale as Table 3).
• Statistical methods (normal, F, χ² tests) are used for data analysis (Part 1 & 2).

flowchart TD
    A[Lot of Items] --> B{Visual, Dimensional & Weight Check}
    B -->|Conforming Items| C[Random Sampling for Chemical Analysis]
    C --> D[Chemical Testing]
    D --> E{Conforms?}
    E -->|Yes| F[Accept Lot]
    E -->|No| G[Reject Lot]

This ensures chemical properties meet the specification after passing physical checks.

IS 10790 Part 2: Sampling Scales & Acceptance Criteria

Key Points from Clause 4.3 & Table 3

Procedure Summary:

• Step 1: Inspect the lot visually using sample size & acceptance number from columns 2 & 3.
• Step 2: If visual inspection passes, randomly sample for dimensional & weight checks using columns 4 & 5.
• Step 3: If defectives ≤ acceptance number, lot is accepted; else rejected.

Notes:

• Sampling follows AQL = 2.5% (acceptable quality level).
• Dimensional & weight samples are taken from visually accepted items.

flowchart TD
    A[Start: Lot Received] --> B{Visual Inspection}
    B -- Pass --> C[Dimensional & Weight Inspection]
    B -- Fail --> D[Reject Lot]
    C --> E{Defectives ≤ Acceptance Number?}
    E -- Yes --> F[Accept Lot]
    E -- No --> D

This ensures a statistically controlled quality check per IS 10790 Part 2.

Statistical Methods & Sampling per IS 10790 Part 2

Key Points:

• Sampling and Acceptance: Samples are selected per lot to verify conformity (Clause 4.2).
• Statistical Approaches:
  • Variables approach for tensile strength, elongation, dimensions, weight, etc.
  • Attributes approach for bending test, visual characteristics (Clause 3.2.2.1).
• References for Statistical Methods: IS 7200 (Parts 1 & 2), IS 6200 (Parts 1 & 2), IS 7300, IS 7600.
• Random Sampling: Follow IS 4905 (1968) for random selection (Clause 4.3.1.1).

Sampling & Acceptance Table (Clause 4.3.1.2):

Summary of Statistical Tests:

• Normal and F-tests: For variables (Part 1).
• Chi-square (χ²) test: For attributes (Part 2).
• Regression, Correlation, ANOVA: For detailed analysis.

Practical Notes:

• Use variables approach for dimensional and weight data.
• Use attributes approach for visual inspections.
• Acceptance number = maximum defects allowed for lot acceptance.
• Sampling size increases with lot size to maintain statistical confidence.

flowchart TD
    A[Lot] --> B[Random Sampling per IS 490