BIS Certification for Steel Used in Internal Combustion Engine Valves IS 7494:1981

In the heart of every internal combustion engine lies a set of components that endure some of the harshest operational conditions imaginable. Among them, engine valves play a critical role, managing the intake of fuel and air and the expulsion of exhaust gases. The performance, reliability, and lifespan of these valves are directly tied to the quality of steel used in their manufacturing.

Recognizing the technical demands of valve components, the Bureau of Indian Standards (BIS) introduced IS 7494:1981, a standard that governs the specifications for wrought alloy and unalloyed steel bars intended for the production of internal combustion engine valves. This standard is part of India’s broader regulatory framework for automotive safety, quality, and compliance.

The Role of Steel in Engine Valve Manufacturing

Valves used in internal combustion engines must endure high thermal loads, mechanical stress, rapid opening and closing cycles, and corrosive combustion gases. To handle these challenges, manufacturers use special grades of steel known for their heat resistance, strength, and fatigue endurance. Some of the commonly used materials include:

● Martensitic stainless steels for exhaust valves due to their high-temperature resistance

● Austenitic stainless steels for intake valves for better corrosion resistance

●Alloy steels with chromium, molybdenum, nickel, or tungsten, tailored for high strength and thermal stability

The manufacturing process typically involves forging, machining, and heat treatment to enhance the microstructure and properties of the steel. Ensuring the steel meets specific metallurgical and mechanical standards is essential, and that’s where IS 7494:1981 plays a pivotal role.

Overview of IS 7494:1981

Titled "Steel for Internal Combustion Engine Valves – Specification", IS 7494:1981 applies to wrought alloyed and unalloyed steel bars up to 40 mm in diameter used in valve production. It sets forth minimum requirements for chemical composition, mechanical strength, surface quality, and heat treatment conditions, among other parameters.

This standard ensures that the steel used in valve manufacturing is not only capable of withstanding engine environments but also consistent in performance across different production batches. It is now a mandatory certification under the Steel and Steel Products (Quality Control) Order, 2024, requiring all such steel products manufactured, sold, or imported in India to be ISI-marked.

Key Provisions of the Standard

The IS 7494:1981 standard covers various aspects of the material and its preparation, including:

● Material Supply Conditions: The standard specifies that unless otherwise agreed upon by the supplier and purchaser, steel bars should be delivered in a specific heat-treated condition appropriate for valve manufacturing.

● Manufacturing Process: While the standard does not rigidly prescribe the exact manufacturing methods, it requires that the steel bars be free from harmful imperfections and produced using established metallurgical practices to ensure uniformity.

● Surface Condition and Finish: The bars must be clean, free from visible defects, and exhibit a smooth finish. Any machining or surface preparation must not affect the dimensional or mechanical integrity.

● Chemical Composition: The steel must conform to designated chemical ranges for elements such as carbon, manganese, chromium, nickel, molybdenum, vanadium, and others, depending on the steel grade.

● Mechanical Properties: The standard defines the minimum requirements for properties like tensile strength, hardness, and creep resistance. These are critical for performance under engine operating conditions.

Essential Tests Performed for BIS Certification

BIS certification under IS 7494:1981 involves comprehensive material testing to verify compliance with the standard’s specifications. Some of the crucial tests include:

● Freedom from Surface and Internal Defects: Ensures the steel is free from cracks, seams, laps, or other discontinuities that could lead to premature failure during valve operation.

● Chemical Analysis: Determines the exact percentage of key alloying elements and impurities to ensure proper alloy formulation.

● Tensile Test at Room Temperature: Measures the ultimate tensile strength and yield strength, ensuring the steel can handle mechanical stresses.

● Tensile Test at Elevated Temperatures: Critical for valves that operate in high-temperature zones, such as exhaust valves.

● Hardness Testing: Assesses resistance to deformation under stress, particularly after heat treatment.

● Creep Test: Evaluates the material’s ability to resist slow, permanent deformation under prolonged stress at high temperatures.

● Grain Size Determination: Finer grain size generally enhances the strength and fatigue resistance of the material.

● Dimensional and Tolerance Checks: Confirms that the diameter and other dimensional parameters meet the specified tolerance limits.

All these tests are conducted at BIS-recognized laboratories using standardized methods to maintain consistency and reliability.

Importance of BIS Certification for Engine Valve Steel

Obtaining BIS certification under IS 7494:1981 is mandatory for manufacturers, importers, and suppliers of engine valve steel in India. It ensures:

● Regulatory compliance as per the Quality Control Orders

● Improved safety and reliability in engine performance

● Access to OEMs and government tenders requiring certified materials

● Consistency in mechanical and metallurgical properties

● Reduced risk of valve failures, which could otherwise lead to severe engine damage

For manufacturers, this certification is also a mark of quality assurance and market credibility in a competitive and regulation-driven environment.

Certification Process


The process to obtain BIS certification for steel under IS 7494:1981 involves:
  1. Filing an application with BIS

  2. Product testing at a BIS-approved laboratory

  3. Factory audit and inspection by BIS officials

  4. Evaluation of results and grant of certification

  5. Regular surveillance audits to maintain certification validity

Manufacturers must also implement a robust quality management system and maintain test records for each production batch.

To Know The Process in Detail, Please Visit:

Under BIS Registration Products ISI and CRS

Documents Required for BIS Certification

To apply for BIS certification, manufacturers need to submit the following documents:

●  Application form

●  Manufacturing process details

●  Quality control plan

●  Test reports from BIS-approved laboratories

●  Factory layout and equipment details

●  Proof of business registration

●  Product specifications and technical details

●  Declaration of conformity to Indian standards

Additionally, manufacturers may be required to provide proof of compliance with environmental and safety regulations, depending on the specific type of product being certified.

BIS ISI Mark Certification Costing And Timeline

BIS ISI Mark Certification Costing And Timeline

Conclusion

Steel used in internal combustion engine valves must meet the highest standards of performance, durability, and heat resistance. The BIS certification under IS 7494:1981 ensures that only high-quality steel bars, free from defects and compliant with mechanical and chemical standards, are used in manufacturing these critical components.

With regulatory compliance becoming increasingly stringent, BIS certification is not only a legal requirement but also a commitment to product quality, safety, and reliability. It offers assurance to automotive OEMs, suppliers, and end-users that the materials used in engine valve manufacturing meet rigorous Indian standards.