BIS Certification for Seven-Wire Prestressing Strand

BIS Certification Consultant for Uncoated Stress Relieved Low Relaxation Seven-Ply Strand | IS 14268:1995 | Qualitance India

Important Update: IS 14268:1995 vs IS 14268:2022

The original edition IS 14268:1995 – Uncoated Stress Relieved Low Relaxation Seven-Ply Strand for Prestressed Concrete is a legacy edition. BIS has subsequently published IS 14268:2017 and the current product manual refers to IS 14268:2022, Second Revision. The official BIS Product Manual published in December 2022 is based on IS 14268:2022. <Cite refs={["turn321721search27","turn321721search5","turn991699view0"]}/> Manufacturers planning a new BIS application should confirm the currently applicable edition, amendments, licence requirements and transition arrangements with BIS before applying. This article uses the requested IS 14268:1995 title for search relevance while discussing the current certification reference where appropriate.

Introduction

Uncoated stress relieved low relaxation seven-wire strand is an important prestressing steel product used in prestressed concrete construction. It is designed to provide high tensile strength while limiting the loss of prestressing force over time. The strand consists of seven steel wires twisted together and subjected to a stabilising treatment. Its mechanical properties and relaxation performance are important to the long-term behaviour of prestressed concrete structures. Typical applications include bridges, flyovers, precast concrete elements, industrial structures and other infrastructure projects using prestressed concrete. The relevant Indian Standard for this product is the IS 14268 series. BIS certification involves checking the strand against the applicable requirements for raw materials, manufacturing, dimensions, mechanical properties, relaxation, workmanship and testing. Qualitance India provides BIS Certification Consultancy for prestressing strand manufacturers, including product-scope assessment, documentation, testing coordination and factory inspection preparation.

What Is Uncoated Stress Relieved Low Relaxation Seven-Wire Strand?

Uncoated stress relieved low relaxation strand is a high-strength steel product made by twisting seven individual steel wires into a strand and subjecting it to a controlled stabilising process. The product is described as:

Uncoated: The strand does not have a separate protective coating of the type used for coated prestressing products.
Stress relieved: The manufacturing treatment helps control residual stresses.
Low relaxation: The strand is designed to limit the reduction in tensile stress over time under specified conditions.
Seven-wire strand: It comprises seven individual wires formed into one strand.
For prestressed concrete: It is intended for applications where tensile prestressing force is introduced into concrete.

The applicable standard defines the required material, dimensional and performance characteristics. Manufacturers must verify conformity with the edition relevant to their certification and supply obligations.

What Is IS 14268?

IS 14268 is the Indian Standard for Uncoated Stress Relieved Low Relaxation Seven-Wire (Ply) Strand for Prestressed Concrete. The 2022 edition covers three strand types:

Plain strand
Indented strand
Compacted strand

The current BIS Product Manual identifies the designation of a strand by its nominal diameter, nominal tensile strength and type of strand. <Cite refs={["turn991699view0","turn321721search26"]}/> The standard and associated product manual address requirements such as:

Raw-material wire
Chemical composition
Surface condition and workmanship
Wire and strand geometry
Strand lay length and joints
Nominal diameter and dimensional tolerances
Nominal cross-sectional area and mass per unit length
Breaking strength and 0.2% proof load
Elongation
Relaxation properties
Straightness and behaviour during cutting
Inspection, testing and product marking

The exact limits, test methods and acceptance criteria must be taken from the applicable edition of IS 14268 and its amendments.

Is BIS Certification Required for Seven-Wire Prestressing Strand?

BIS certification requirements depend on the applicable Indian Standard, certification scheme and any government notification or Quality Control Order covering the product. BIS explains that certification is generally voluntary unless the Central Government makes compliance mandatory through a relevant Quality Control Order or other applicable legal provision. <Cite refs={["turn321721search1","turn321721search3"]}/> Before manufacturing, importing or supplying this product, businesses should verify:

Whether the product is covered by a currently applicable mandatory certification order.
Which edition of IS 14268 applies.
Whether any amendments, transition provisions or exemptions apply.
Whether the product is listed under the relevant BIS certification scheme.
The current application, testing and marking requirements.

Do not rely solely on an old standard number or historical licence document to establish current legal applicability.

Applicable BIS Certification Scheme

The official BIS Product Manual for IS 14268:2022 specifies certification under Scheme-I of the BIS (Conformity Assessment) Regulations, 2018. <Cite refs={["turn991699view0"]}/> Where the applicable certification requirements call for a BIS licence, the process generally includes:

Confirming the applicable standard and product description.
Identifying the intended strand sizes, tensile strengths and types.
Reviewing the manufacturing process and quality-control arrangements.
Preparing company and factory documentation.
Establishing appropriate laboratory and testing arrangements.
Submitting the application and applicable fees.
Arranging testing and factory assessment as required.
Responding to observations raised during application scrutiny or inspection.
Obtaining the required licence before applying the Standard Mark to covered products.

The precise process depends on the applicable BIS requirements and the manufacturer's circumstances.

Product Sizes and Licence Scope Under IS 14268:2022

The current BIS Product Manual lists the following nominal strand diameters:

S. No.	Nominal diameter
1	6.4 mm
2	6.9 mm
3	7.0 mm
4	8.0 mm
5	8.6 mm
6	9.0 mm
7	9.3 mm
8	9.6 mm
9	11.0 mm
10	11.3 mm
11	12.5 mm
12	12.7 mm
13	12.9 mm
14	13.0 mm
15	15.2 mm
16	15.7 mm
17	18.0 mm

The listed nominal tensile strengths are 1670, 1770, 1820, 1860, 1960, 2060 and 2160 MPa. The product manual also identifies plain, indented and compacted strands. <Cite refs={["turn991699view0"]}/>

Grouping guidelines

The product manual provides grouping guidelines for determining the scope of the licence:

Strands with the highest size in each tensile-strength group are tested for all requirements to cover sizes up to and including the tested size in that group.
Testing one type of strand may cover other strand types under the stated grouping provisions and based on the manufacturer's manufacturing capabilities.
The manufacturer must declare the varieties intended to be included in the licence.
BIS may restrict the licence scope based on manufacturing and testing capabilities.

<Cite refs={["turn321721search24"]}/> These provisions should be applied carefully. Manufacturers should not assume that all sizes, strengths and types will automatically be included without assessment against the current product manual.

Raw Materials and Manufacturing Process

The BIS Product Manual identifies wire as the raw material and refers to the applicable provisions of IS 14268 and IS 7904. <Cite refs={["turn991699view0"]}/> The manufacturing unit should maintain traceability for the incoming wire and records demonstrating conformity with the applicable requirements. A typical manufacturing process involves the following stages.

1. Incoming wire inspection

The incoming wire is checked against the relevant specification and accompanying test documentation. Records should identify the supplier, consignment and material lot.

2. Wire preparation and stranding

Individual wires are prepared and formed into a seven-wire strand using the appropriate manufacturing equipment. Strand geometry and lay length are controlled according to the product requirements.

3. Stabilising or stress-relieving treatment

The strand undergoes a controlled stabilising process intended to achieve the required mechanical and low-relaxation properties. The manufacturer should document and control the relevant process parameters.

4. Dimensional and visual inspection

The strand is inspected for diameter, geometry, surface condition, workmanship, joints and other applicable characteristics.

5. Mechanical and relaxation testing

The finished product is tested for the required strength, proof load, elongation and relaxation properties.

6. Identification and dispatch

Conforming production is identified and linked to the relevant production and test records. Where BIS certification applies, marking and certification records must follow the applicable licence requirements. The precise process parameters and acceptance criteria must be taken from the relevant standard and approved manufacturing procedures.

Testing Requirements for IS 14268

Testing verifies that the finished strand conforms to the applicable product specification. The principal test areas include the following.

1. Chemical composition

Chemical testing verifies the specified composition of the wire. The current product manual identifies chemical composition requirements and sampling arrangements.

2. Surface condition

The wire and strand are examined for surface defects and other imperfections that may affect conformity or performance.

3. Strand geometry and lay length

The strand is checked for the specified configuration, geometry and lay length. The difference in diameter between the central wire and surrounding wires is also addressed in the applicable requirements.

4. Dimensions and mass

Testing verifies nominal diameter, dimensional tolerances, nominal cross-sectional area and mass per unit length.

5. Breaking strength

The tensile test determines whether the strand meets the required breaking-strength value for its designation.

6. 0.2% proof load

This test assesses the specified proof-load characteristic of the strand.

7. Elongation

The elongation test measures the extension of the strand under the prescribed conditions.

8. Relaxation properties

Relaxation testing evaluates the loss of stress over time under specified test conditions. The 100-hour and 1,000-hour test durations are addressed in the BIS Product Manual's inspection and testing plan. <Cite refs={["turn991699view0"]}/>

9. Straightness

The strand is assessed for straightness according to the relevant test procedure.

10. Behaviour during cutting

The strand is examined for the specified behaviour during cutting. The current product manual also identifies requirements for joints, treatment, workmanship and finish. The applicable standard should be consulted for the detailed test methods and acceptance criteria.

Sample Requirements for BIS Testing

The BIS Product Manual for IS 14268:2022 specifies the following sample quantities. <Cite refs={["turn991699view0"]}/>

Testing purpose	Sample quantity specified
Mechanical testing, excluding relaxation	3 specimens, each 1 metre long
Chemical testing	5 pieces, each 5 cm long
Relaxation testing	1 specimen, 3 metres long

These quantities are based on the 2022 product manual and should not be assumed to be identical to those in the 1995 edition. Before sample preparation and dispatch, confirm the applicable standard edition, sampling instructions, identification requirements and any additional directions from BIS or the designated testing laboratory.

Laboratory and Testing Equipment Requirements

The BIS Product Manual states that the manufacturer must maintain a suitably equipped and staffed laboratory for the tests assigned to the factory laboratory. A calibration plan and test records are also required. <Cite refs={["turn991699view0"]}/> The manual identifies the following major equipment for relevant tests:

Micrometer
Vernier caliper
Weighing balance
Steel scale and measuring tape
Universal testing machine or tensile testing machine
Extensometer
Relaxation testing machine
Suitable air-conditioning arrangement for relaxation testing
Equipment for checking strand straightness

The list is indicative and is not necessarily exhaustive. Equipment must be suitable for the prescribed test methods and maintained in appropriate working and calibrated condition.

Can relaxation testing be subcontracted?

The inspection and testing plan in the current product manual permits subcontracting of specified relaxation tests to a laboratory recognised by BIS or a government laboratory empanelled by BIS. It identifies provisions for 100-hour and 1,000-hour relaxation testing. <Cite refs={["turn991699view0"]}/> Manufacturers should confirm the currently accepted laboratory and applicable subcontracting conditions before relying on an external testing arrangement.

Factory Inspection and Quality-Control Requirements

Factory assessment evaluates whether the manufacturer has the capability and controls needed to consistently produce conforming strand. The current BIS Product Manual addresses laboratory arrangements, calibration, test records, labelling and marking, control units and the inspection and testing plan. It defines a control unit by reference to strands of the same designation manufactured from the same material on each machine under similar manufacturing conditions in a day. <Cite refs={["turn991699view0"]}/> Manufacturers should prepare the following:

Raw-material inspection and supplier test certificates
Production and stabilising-process records
Dimensional and visual inspection records
Mechanical and relaxation test records
Calibration and equipment-maintenance records
Production-lot and coil traceability
Nonconforming-product controls
Product identification and test certificates
Procedures for applicable BIS marking and certification records

The final inspection requirements and control frequencies must be confirmed from the current product manual and applicable certification documents.

Documents Required for BIS Certification

The exact checklist depends on the application and the manufacturer's facilities. The following list is a practical preparation guide.

Company and factory documents

Business registration or incorporation documents, as applicable
PAN and GST registration, where applicable
Manufacturing-unit address and contact details
Authorisation for the person signing the application
Details of the authorised signatory and responsible personnel

Manufacturing documents

Manufacturing process flow chart
Details of wire stranding and stabilising facilities
List of manufacturing machinery
Details of intended strand diameters, tensile strengths and types
Raw-material specifications and supplier information
Production capacity and quality-control arrangements

Quality-control documents

Quality-control procedures and inspection formats
Raw-material inspection records
Production and coil identification records
Mechanical and dimensional test records
Relaxation test arrangements and results, where available
Calibration plan and relevant certificates
Nonconforming-product handling procedure
Product traceability and dispatch records

Laboratory and testing documents

Details of in-house testing facilities
List of testing equipment
Details of testing personnel
Records of test equipment calibration
External laboratory details, if subcontract testing is proposed
Available test reports for the proposed product scope

The final document list should be verified against the latest BIS application requirements and the current edition of IS 14268.

Common Challenges in BIS Certification

Manufacturers may experience delays if the product scope or quality-control arrangements are not adequately prepared. Common challenges include:

Applying against an outdated edition of IS 14268
Unclear declaration of strand diameter, strength and type
Incomplete raw-material traceability
Inadequate testing arrangements for mechanical properties
Insufficient arrangements for long-duration relaxation testing
Missing calibration or inspection records
Inadequate production and coil identification
Assuming that one tested variety automatically covers every size and type
Failure to verify current certification and legal requirements

A pre-application review can help identify documentation, testing and scope-related gaps before submission.

How Qualitance India Can Help

Qualitance India provides BIS Certification Consultancy for Uncoated Stress Relieved Low Relaxation Seven-Wire Strand for Prestressed Concrete. Our consultancy support can include:

Review of the applicable standard and certification route
Assessment of the proposed strand sizes and types
Guidance on tensile-strength grouping and licence scope
Preparation and review of application documentation
Review of manufacturing and quality-control arrangements
Guidance on laboratory and calibration requirements
Coordination support for mechanical, chemical and relaxation testing
Preparation for BIS factory inspection
Support in addressing application observations
Guidance on product marking and ongoing compliance

The scope of consultancy is finalised according to the manufacturer's requirements and the services agreed for the project. BIS retains authority over application scrutiny, test acceptance, factory assessment and licence decisions.

Frequently Asked Questions (FAQs)

1. What is IS 14268?

IS 14268 is the Indian Standard for uncoated stress relieved low relaxation seven-wire strand for prestressed concrete. The 2022 edition covers plain, indented and compacted strand types. <Cite refs={["turn321721search26"]}/>

2. Is IS 14268:1995 still the applicable edition?

BIS has published later editions, including IS 14268:2017 and IS 14268:2022. Manufacturers should confirm the currently applicable edition and any transition requirements before filing a new application. <Cite refs={["turn321721search5","turn991699view0"]}/>

3. Which strand diameters are listed in the 2022 product manual?

The listed sizes range from 6.4 mm to 18.0 mm and include 6.4, 6.9, 7.0, 8.0, 8.6, 9.0, 9.3, 9.6, 11.0, 11.3, 12.5, 12.7, 12.9, 13.0, 15.2, 15.7 and 18.0 mm. <Cite refs={["turn991699view0"]}/>

4. Which tensile strengths are covered in the product manual?

The current manual lists nominal tensile strengths of 1670, 1770, 1820, 1860, 1960, 2060 and 2160 MPa. The licence scope depends on the declared varieties and applicable grouping guidelines. <Cite refs={["turn991699view0"]}/>

5. What tests are required?

The key test areas include chemical composition, surface condition, strand geometry, dimensions, mass per unit length, breaking strength, 0.2% proof load, elongation, relaxation, straightness and behaviour during cutting.

6. What sample quantity is specified for mechanical testing?

The 2022 product manual specifies three specimens of 1 metre each for mechanical testing, excluding relaxation testing. It specifies one 3-metre specimen for relaxation testing and five 5 cm pieces for chemical testing. <Cite refs={["turn991699view0"]}/>

7. Can one strand size cover multiple sizes in the licence?

The current manual contains grouping guidelines based on the highest size in each tensile-strength group, subject to the applicable conditions. The manufacturer must declare the proposed scope, and BIS may restrict it based on manufacturing and testing capabilities. <Cite refs={["turn321721search24"]}/>

8. Can relaxation testing be performed externally?

The current product manual permits specified relaxation testing to be subcontracted to a BIS-recognised laboratory or a government laboratory empanelled by BIS, subject to its requirements. Confirm the laboratory's current status and accepted scope before arranging testing. <Cite refs={["turn991699view0"]}/>

9. Is BIS certification mandatory for this product?

Mandatory status must be verified against the latest applicable government order and BIS product-certification information. The fact that an Indian Standard exists does not by itself establish that certification is mandatory for every supply situation. <Cite refs={["turn321721search1","turn321721search3"]}/>

10. Can Qualitance India assist with BIS certification?

Yes. Qualitance India can assist with product-scope assessment, documentation, testing coordination, quality-control review and factory inspection preparation for the applicable BIS certification route.

Official References

BIS Product Manual for IS 14268:2022: Uncoated Stress Relieved Low Relaxation Seven-Wire Strand
BIS Laboratory Information Management System: IS 14268 Testing Facilities and Laboratory Information
IS 14268:1995 – Legacy Edition Reference: Indian Standard Document
BIS Products Under Compulsory Certification: Official BIS Certification Information
BIS Product-Specific Guidelines: Official Product Certification Guidelines
BIS Standards Portal: Official Standards Information

Always check the latest published standard, amendments, QCO applicability and BIS application requirements before proceeding.

Conclusion

Uncoated stress relieved low relaxation seven-wire strand is a critical prestressing material used in concrete infrastructure. Its conformity assessment involves raw-material control, strand geometry, mechanical strength, elongation, relaxation properties, testing facilities and documented quality-control arrangements. For manufacturers planning BIS certification, one of the most important initial steps is to confirm the applicable edition of IS 14268. Although the requested title refers to IS 14268:1995, the current BIS Product Manual is based on IS 14268:2022. The correct standard edition and certification route should therefore be confirmed before an application is filed. Qualitance India supports manufacturers seeking BIS certification for uncoated stress relieved low relaxation seven-wire strand, including documentation, product-scope planning, testing coordination and factory inspection preparation. Qualitance India – Improving Quality & Competence Call/WhatsApp: +91 9310615170 Email: info@qualitanceindia.com Website: https://qualitanceindia.com