Continuous (Piano) hinges -Specification
1992 الطبعة

According to IS 3818:1992, continuous hinges are produced from several materials: the flaps can be fabricated using mild steel sheets conforming to Grade 0 of IS 1079:1988, aluminum alloy sheets as per IS 739:1977 (64 430 WP), or cold-rolled low carbon steel sheets meeting IS 737:1986 (grades 19000 H2 or 31000 H2) and IS 513:1986 (Grade D). The hinge pins are made from mild steel wire complying with IS 280:1978 with a minimum tensile strength of 400 MPa or aluminum alloy wire conforming to IS 739:1977. These materials ensure the hinges are durable and suitable for various applications.

The dimensional tolerances for continuous (piano) hinges as per IS 3818 cover Types I through IV. All measurements are in millimetres, with detailed dimensions and tolerances provided in Figures 1, 2, and 3 of the standard. Typically, tolerances range from ±0.2 mm to ±0.6 mm depending on the hinge type and nominal size. Hinges must comply with these requirements; otherwise, they are considered defective. The standard also permits hinges with or without holes, countersunk or otherwise, based on mutual agreement.

Per Clauses 7.1 and 7.2 of IS 3818, each hinge must bear a permanent and legible marking indicating the manufacturer or source of production. Additionally, hinges may carry the BIS Standard Mark, reflecting conformity with the standard and adherence to quality assurance protocols. This marking facilitates traceability and verifies compliance during inspection or installation.

IS 3818 mandates that hinges be bundled using polyethylene sheets or waterproof paper. Bundles typically contain 5, 10, or multiples of 5 hinges and are then placed inside cardboard cartons lined with weather-resistant paper. Each carton must be labeled with details including the manufacturer’s name, hinge type, size, and quality grade. This packaging approach safeguards hinges from moisture and damage during transit and storage, while ensuring clear identification for quality control.

Sampling under IS 3818 requires selecting samples randomly from each lot independently. At least 10% of the packages in a lot, with a minimum of three packages, are chosen, and an equal number of hinges are drawn from each selected package. The sample size and acceptable number of defective hinges depend on the total lot size, following a table specified in the standard. A lot is deemed acceptable if the number of defectives does not exceed the permissible limit, ensuring statistically valid quality control.

Mild steel hinges must possess anti-corrosive finishes such as bright polishing, chromium plating, or oxidation. Aluminum hinges require anodizing, with a minimum quality of Grade AC 10 as per IS 1868:1982. Aluminum alloy pins must be hard anodized with a thickness not less than 0.025 mm and sealed with oil wax or lanolin to prevent corrosion. These treatments enhance the durability and aesthetic quality of the hinges.

Screw holes in continuous hinges must be clean, accurately countersunk, and conform to IS 6760:1972. The countersunk hole dimensions vary with the nominal hinge size, with minimum distances from the flap edge specified (e.g., 2.0 mm for 25 mm size, 3.5 mm for 30 mm size). Hinge pins for mild steel hinges are made from mild steel, while aluminum hinges use galvanized mild steel or aluminum alloy pins. Aluminum pins are hard anodized to at least 0.025 mm thickness and sealed. Pins must fit snugly within the knuckles to prevent play but allow smooth movement.