IS Standards
Fasteners, Flanges
& Fittings

1.1 — What “IS” Means and the Role of the Bureau of Indian Standards

“IS” followed by a number (e.g., IS 1363, IS 2062) refers to a standard published by the Bureau of Indian Standards (BIS), the national standards body of India, operating under the Bureau of Indian Standards Act, 2016. BIS develops and maintains standards across essentially every engineering and industrial discipline, including the fastener, structural steel, flange, pipe, and hydraulic component standards most relevant to EPC and industrial procurement. For a significant category of products — including certain fasteners, cement, steel products, and other items designated under mandatory Quality Control Orders (QCOs) issued by the Government of India — compliance with the applicable IS standard, evidenced by a BIS licence and the ISI mark, is a legal requirement for manufacture, sale, or import into India, not merely a voluntary quality reference.

Indian industry, having developed under a strong British engineering and metrication influence historically, and subsequently aligning substantially with ISO international standards from the mid-20th century onward, produces IS standards that are frequently closely modelled on, or directly harmonised with, the corresponding ISO standard — a considerable number of IS fastener and material standards (e.g., IS 1367 mechanical properties of fasteners) are technically near-identical or fully aligned with their ISO 898 counterparts, reflecting India’s active participation in ISO technical committees and its practice of adopting international standards into the national IS framework where suitable. This alignment makes IS-to-ISO cross-referencing generally more straightforward than the DIN-to-ISO legacy cross-referencing challenge described in RR Hydraulic’s DIN standard reference, though the specifier must still confirm the specific IS standard edition and any India-specific clauses (particularly around BIS certification marking, sampling/testing frequency, and domestic manufacturing content requirements on government-funded projects) before assuming full interchangeability with an ISO-referenced specification.

1.2 — Mandatory BIS Certification: The ISI Mark

1.3 — IS Standard Numbering and Structure

IS standards are numbered sequentially without the systematic categorical numbering logic of some other national systems, meaning the numerical IS designation itself does not indicate product category — practical familiarity with the specific commonly-used numbers (covered in Part 2) is the practical working knowledge required, rather than an ability to infer a standard’s subject from its number. Many IS standards are published in multiple parts (e.g., “IS 1367 (Part 3)”) covering different aspects of a related product family — mechanical properties, dimensional tolerances, surface defects, and coating requirements for fasteners are frequently split across different parts of the same base IS number, requiring the specifier to cite the complete part number, not merely the base standard number, for an unambiguous technical requirement.

2.1 — Fastener Standards: Bolts, Screws, Nuts, and Washers

2.2 — Structural Steel Standards

2.3 — Stainless Steel and Corrosion-Resistant Fastener Standards

2.4 — Flange and Pipe Fitting Standards

2.5 — Surface Treatment and Coating Standards

3.1 — Fastener Material Grades per IS 1367

3.2 — Structural Steel Grades per IS 2062

3.3 — Manufacturing Process

IS-standard fasteners, flanges, and pipe fittings are manufactured using the same cold heading, hot forging, thread rolling, and quench-and-temper heat treatment processes described throughout RR Hydraulic’s DIN and EN 14399 references — the underlying metallurgical and manufacturing principles are universal across national standard systems; the IS standards define the specific dimensional tables, mechanical property requirements, and (where applicable) BIS certification testing frequency that Indian-manufactured product must demonstrate. For BIS-licensed products, the manufacturer’s factory undergoes periodic BIS surveillance audit and product sample testing (at BIS-recognised or in-house BIS-approved laboratories) as a condition of maintaining the licence and ISI mark, in addition to the manufacturer’s own routine production QC testing described in Part 4.

3.4 — IS-to-ISO-to-ASTM/EN Cross-Reference Discipline

A significant proportion of EPC projects executed in India, or by Indian manufacturers supplying export markets, involve specifications that mix IS, ISO, ASTM, and EN/DIN standard references across different parts of the same project — structural steel to IS 2062, pressure piping to ASME B16.5, and fasteners to IS 1367 or ISO 898-1 depending on the specific package and the origin of the governing engineering specification. Because IS 1367 mechanical property classes are numerically identical to ISO 898-1 (property class “8.8” means the same tensile/yield requirement in both standards), cross-referencing fastener mechanical properties between IS and ISO is generally straightforward. Dimensional cross-referencing requires more care: IS 1363 (grade C, black finish) and IS 1364 (grades A/B, precision finish) do not map one-to-one onto a single ISO series — the specifier must confirm which IS 1364 grade (A, B) and which corresponding ISO 4014/4017/4016 tolerance class is intended before treating an IS-numbered fastener callout as directly interchangeable with an ISO-numbered one on a mixed-standard project specification.

3.5 — Surface Finish and Coating Options

• Plain / black finish (IS 1363 grade C): Bare or lightly oiled carbon steel for general, non-critical, low-precision-tolerance fastening applications
• Zinc electroplating (per IS 1367 Part 13 / IS 2629 for general galvanizing practice): Standard mild corrosion protection finish for general industrial IS-standard fasteners
• Hot-dip galvanizing (IS 4759 / IS 1367 Part 13): Robust corrosion protection for outdoor and structural steelwork applications, following the same de-embrittlement and thread over-tapping principles described for other galvanizing standards in RR Hydraulic’s EN 14399 and DIN references
• Stainless steel (per IS 6603/6911, cross-referenced to ISO 3506 property classes): For corrosion-resistant fastening without a supplementary coating, per RR Hydraulic’s dedicated stainless steel threaded rod reference

4.1 — Inspection & QC Protocol

4.2 — EN 10204 / Material Certification Requirements

4.3 — Applications by Industry

4.4 — Export Packaging Specification

• Fasteners packed in labelled cartons or bulk bins by IS number, part, size, grade, and coating, cross-referenced to the applicable IS standard year/amendment on the packing documentation to avoid ambiguity at site receiving inspection
• Flanges and pipe fittings individually protected (bore caps, face protectors) and crated per NPS/PN class, with heat number and IS designation stamped and legible for traceability
• Rust-preventive oil or VCI treatment for uncoated carbon steel components; coating integrity protection (separation/dunnage) for galvanized items during transit
• ISI-marked domestic-market goods packed and labelled separately from export-market goods where the destination does not require or recognise the ISI mark, to avoid confusion at customs and site receiving inspection regarding the applicable compliance marking
• Documentation in a waterproof pocket: EN 10204 3.1/3.2 MTC, dimensional inspection report cross-referenced to the confirmed IS standard edition, mechanical test report, PMI report (alloy/stainless items), coating thickness report, BIS licence copy (where ISI-marked goods are supplied), and packing list with IS number, part, size, grade, and coating breakdown per item
• ISPM-15 timber or export cartons for international shipment, with country of origin and HS tariff code documentation matched to the specific component category for correct customs classification

4.5 — Complete Documentation Package for EPC Project Supply