plain hard-drawn steel wire for prestressed concrete, Part 1: Cold-drawn stress-relieved wire
1983 Edition

IS 1785 Part 1: Overview & Application Highlights

• Purpose: Defines requirements for cold-drawn, stress-relieved plain steel wire used in prestressed concrete.
• Measurement Units: All requirements use SI units.
• Rounding: Testing values are rounded in accordance with IS 2-1960, preserving significant digits.

Representative Tables from the Standard

Important Updates:

• Chemical composition, relaxation, and corrosion resistance requirements revised.
• Harmonized with international standards.
• Applicable exclusively to cold drawn, stress-relieved wires.

flowchart TD
    A[Cold Drawn Steel Wire] --> B[Stress-Relieved Wire]
    B --> C[Nominal Diameter & Mass]
    B --> D[Tensile Strength Specifications]
    B --> E[Testing & Tolerance Requirements]

This overview supports adherence to IS 1785 Part 1 for prestressing steel wire.

IS 1785 Part 1: Scope and Key Specifications

Scope Overview (Clause 2.0)

• Establishes dimensional, tolerance, chemical, and mechanical property requirements for steel wire.
• Excludes nominal diameters 2.5 mm and 3.0 mm as these entries are removed from the standard.

Critical Tables (Clauses 5.1 & 5.1.2)

Note: The values for 2.5 mm and 3.0 mm wires have been withdrawn from the code.

Quality Control Formula (Clause 8.3.2)

For chemical composition, diameter, tensile strength, and proof stress:

[ Mean + 0.6 \times Range \leq Maximum Limit ] [ Mean - 0.6 \times Range \geq Minimum Limit ]

Where Range is the difference between maximum and minimum test values.

This methodology confirms that test values stay within specified limits with acceptable variation.

Visual Summary of Quality Control:

flowchart LR
    A[Test Data] --> B[Calculate Mean & Range]
    B --> C{Verify Against Limits}
    C -->|Mean + 0.6×Range ≤ Max| D[Upper Limit Passed]
    C -->|Mean - 0.6×Range ≥ Min| E[Lower Limit Passed]
    D & E --> F[Material Approved]
    C -->|Fail| G[Material Rejected]

This scope ensures dimensional precision and mechanical property compliance per IS 1785 Part 1.

IS 1785 Part 1: Definitions and Technical Terms

1. Key Definitions (Clause 2.0)

• Provides standard definitions related to wire size, mass, tolerance, chemical elements, tensile and proof stress for consistent interpretation.

2. Nominal Size, Mass & Tolerance (Clauses 5.1 & 5.1.2)

• Entries for smaller diameters 2.50 mm and 3.00 mm as well as their mass and tolerance data have been officially removed.

3. Chemical and Mechanical Testing (Clause 8.3.2)

• For chemical composition, diameter, tensile strength, and proof stress:

[ Mean + 0.6 \times Range \leq Maximum Limit ] [ Mean - 0.6 \times Range \geq Minimum Limit ]

• Range equals the maximum minus minimum test result.

This method ensures batch results adhere to specification limits considering variability.

flowchart LR
    A[Test Results] --> B[Calculate Mean & Range]
    B --> C{Validate Limits}
    C -->|Mean + 0.6×Range ≤ Max| D[Pass Upper Threshold]
    C -->|Mean - 0.6×Range ≥ Min| E[Pass Lower Threshold]
    D & E --> F[Batch Accepted]

Summary: Definitions provide clarity; smaller diameter data removed; quality control relies on mean and range limits.

IS 1785 Part 1: Manufacturing Procedures and Chemical Composition

1. Chemical Composition Control (Clause 8.3.2)

• For each property (chemical elements %, diameter, tensile strength, proof stress):

[ Mean + 0.6 \times Range \leq Max Limit ] [ Mean - 0.6 \times Range \geq Min Limit ]

• The Range is the difference between highest and lowest test values.

2. Tensile Strength Definition (Clause 2.6)

• Tensile strength is calculated as the maximum load during tension testing divided by the original cross-sectional area.

3. Production Process (Clauses 3.2 & 8.2.1)

• Steel rods or bars are cold-drawn through dies progressively reducing diameter.
• Subsequent treatments include stretching, straightening, and strain-ageing to minimize creep and relieve internal stresses.
• Testing covers chemical composition, dimensional checks, tensile strength, proof stress, and elongation.

Summary Table: Chemical and Mechanical Testing

flowchart LR
    A[Steel Rolling Mill Bars/Rods] --> B[Cold Drawing Through Dies]
    B --> C[Stretching, Straightening, Strain Ageing]
    C --> D[Wire Coiling]
    D --> E[Testing: Chemical, Dimensional, Mechanical Properties]

Note: Refer to the full IS 1785 Part 1 (1983) document for exact chemical composition limits and detailed testing protocols.

IS 1785 Part 1: Wire Dimensions and Tolerances (Clauses 5.1 & 5.1.2)

1. Diameter Tolerance by Nominal Size

2. Ovality Assessment (Clause 5.1.2)

• Diameter is measured in two perpendicular directions.
• If ovality is less than or equal to half the total diameter tolerance, weighing check is not required.
• If ovality exceeds half the allowed tolerance, sectional mass verification by weighing is mandatory.

3. Nominal Mass and Mass Tolerance

Key Points:

• Diameter tolerances ensure dimensional precision.
• Ovality restrictions maintain wire roundness.
• Mass tolerances confirm uniform cross-section.

flowchart TD
    A[Measure Diameter in Two Directions] --> B{Ovality ≤ 0.5 × Tolerance?}
    B -- Yes --> C[No Weighing Required]
    B -- No --> D[Verify Cross-Section by Weighing]

These provisions guarantee wire dimensional quality as per IS 1785 Part 1.

IS 1785 Part 1: Wire Mass and Diameter Tolerances Overview

1. Diameter Tolerance (Clause 5.1)

2. Nominal Mass and Tolerance (Clause 5.1.2)

3. Ovality Protocol (Clause 5.1.2)

• When ovality is less than or equal to half the diameter tolerance, weighing checks are not necessary.
• If ovality surpasses this threshold, sectional mass must be verified through weighing.

Note: The wire mass per meter can be estimated using:

[ Mass = \frac{\pi}{4} \times d^2 \times \rho ]

where:

• (d) is diameter in meters
• (\rho) is steel density in kg/m³

flowchart TD
    A[Measure Diameter Twice] --> B{Ovality ≤ 0.5 × Tolerance?}
    B -- Yes --> C[Skip Weighing]
    B -- No --> D[Weigh Wire to Confirm Section]

These requirements ensure the wire meets IS 1785 Part 1 mass and size standards.

IS 1785 Part 1: Summary of Physical Criteria

1. Chemical Composition, Diameter, Tensile Strength & Proof Stress (Clause 8.3.2)

• Each characteristic must satisfy:
  • ( Mean + 0.6 \times Range \leq Max Limit )
  • ( Mean - 0.6 \times Range \geq Min Limit )
• The Range is the difference between the highest and lowest test values.

2. Diameter Measurement (Clause 5.1.1)

• Diameter is measured using a micrometer:
  • Two perpendicular readings
  • Across three points spaced at least 250 mm
• The average of six readings is taken as the wire diameter.

3. Minimum Tensile Strength (Clause 6.1, Amendment 3)

4. Elongation Requirements (Clause 6.4, Amendment 3)

• The previous elongation minimum of 2.5% for 2.50 mm and 3.00 mm wires has been removed.

flowchart TD
    A[Begin Wire Testing] --> B[Measure Diameter (6 readings)]
    B --> C[Compute Average Diameter]
    C --> D[Confirm Diameter Within Tolerance]
    D --> E[Conduct Tensile Test]
    E --> F[Calculate Mean & Range of Tensile Strength]
    F --> G{Check Compliance: Mean ± 0.6×Range}
    G -- Within Limits --> H[Test Passed]
    G -- Outside Limits --> I[Test Failed]

Note: Use the above approach and tables to verify wire physical properties conformance for IS 1785 Part 1.

IS 1785 Part 1: Essential Testing Procedures

1. Test Sample Quantity (Clause 8.2)

• From each coil, a single test specimen is taken for each required test (Clause 8.2.1.1).
• Tests performed include chemical composition, diameter, tensile strength, and proof stress.

2. Acceptance Limits for Test Data (Clause 8.3.2)

For each measured property:

• ( Mean + 0.6 \times Range \leq Max Specified Limit )
• ( Mean - 0.6 \times Range \geq Min Specified Limit )

Where:

• Mean is the average of test results
• Range is the difference between maximum and minimum result

3. Ductility Testing Pass Criteria (Clause 8.3.4)

• Defective specimens fail to meet ductility criteria.
• The count of defective specimens must not exceed allowable limits.

These testing criteria ensure uniform quality and reliability of prestressing steel wire as per IS 1785 Part 1.

IS 1785 Part 1: Sampling and Conformity Requirements

Sampling Plan (Clause 8.1.2, Table 2)

• Number of coils selected randomly depends on total lot size:

Conditions for Lot Acceptance (Clause 8.3)

• The lot is deemed conforming if all tested characteristics meet the requirements in Clauses 8.3.2 through 8.3.4.
• Each sampled coil must comply with mechanical and dimensional specifications.

Relaxation Testing (Clause 7.7)

• Initial load is set at 70% of minimum specified tensile strength.
• Load applied smoothly over 5 minutes and held constant for 1 minute.
• Relaxation measurement starts after 6 minutes at ambient temperature of 20 ± 2°C.
• No overstressing permitted during the test.
• This ensures the wire can retain stress under long-term loading.

This approach ensures statistical verification of lot quality and confirms wire performance in prestressing applications.

IS 1785 Part 1: Inspection and Testing Overview

1. Sampling and Test Specimens (Clause 8.2.1.1)

• One specimen per coil is selected for each test.
• Testing follows the applicable IS methods.

2. Chemical Composition, Diameter, Tensile Strength, and Proof Stress (Clause 8.3.2)

• Each property must satisfy:
  • ( (Mean + 0.6 \times Range) \leq Max Limit )
  • ( (Mean - 0.6 \times Range) \geq Min Limit )
• Here, Range is the difference between highest and lowest values.

3. Ductility Acceptance (Clause 8.3.4)

• Defective means specimens failing ductility standards.
• The number of defective samples must not surpass allowed limits.

4. Inspection and Testing Facilities (Clause 9.1)

• General inspection and testing should comply with IS 1387-1967 unless otherwise specified.

Testing Workflow Diagram

flowchart TD
    A[Select Coil] --> B[Choose Test Specimens]
    B --> C{Conduct Tests}
    C --> D[Assess Chemical Composition]
    C --> E[Measure Diameter]
    C --> F[Test Tensile Strength]
    C --> G[Test Proof Stress]
    C --> H[Evaluate Ductility]
    D --> I[Apply Mean ± 0.6×Range Criteria]
    E --> I
    F --> I
    G --> I
    H --> J[Count Defective Samples]
    I --> K{Are Criteria Met?}
    J --> L{Are Defectives ≤ Allowed?}
    K --> M[Accept Lot]
    K --> N[Reject Lot]
    L --> M
    L --> N

This inspection protocol guarantees compliance with IS 1785 Part 1.

IS 1785 Part 1 (1983): Identification and Marking Guidelines

• Coil Sizes:

  • For wire diameters ≤ 5 mm, coils should be approximately 1.5 meters in diameter.
  • For wire diameters > 5 mm, coils should be approximately 2 meters in diameter.

• Coil Integrity:

  • Coils must be free from breaks, joints, or welds.
  • Each coil must be secured with at least four tight binding ligatures.

• Coil Weight:

  • No fixed standard; mass must be mutually agreed upon between buyer and manufacturer.

• Marking Details:

  • Although not explicitly detailed in this clause, common practice includes:
    • Manufacturer’s name or logo
    • Wire grade and size
    • Batch or heat number
    • Reference to IS 1785 Part 1 standard

Summary Table

flowchart LR
    A[Wire Diameter] -->|≤ 5 mm| B[Coil Diameter ~1.5 m]
    A -->|> 5 mm| C[Coil Diameter ~2 m]
    B & C --> D[No breaks, joints, or welds]
    D --> E[Minimum 4 Ligatures]
    E --> F[Marking: Manufacturer, Grade, Batch, IS Number]

Refer to general IS marking standards or buyer specifications for detailed marking requirements.

IS 1785 Part 1 (1983): Packaging and Storage Guidelines

• Ductility Test Acceptance Limits (Clause 8.3.4):

• Packaging and Storage Practices:

  • While explicit formulas aren't provided, recommended best practices are:
    • Shield wires from moisture and mechanical damage.
    • Use rust-resistant wrapping materials.
    • Place coils on wooden pallets.
    • Store in dry, well-ventilated spaces to preserve ductility and avoid corrosion.

• Testing and Inspection Facilities:

  • Although specific clauses are not detailed, facilities should comply with IS standards for testing wire ductility and mechanical characteristics.

flowchart LR
    A[Packaging] --> B[Protection Against Moisture]
    A --> C[Protection From Physical Damage]
    B --> D[Use of Waterproof Covers]
    C --> E[Placement on Wooden Pallets]
    F[Storage] --> G[Dry Environment]
    F --> H[Ventilated Storage Area]

These measures help maintain wire quality and ensure compliance with IS 1785 Part 1.