The 1984 edition of IS 778 outlines the specifications for copper alloy gate, globe, and check valves employed in waterworks systems. It details requirements concerning design, materials, dimensions, manufacturing processes, testing, and inspection to guarantee dependable valve functionality in water supply networks. This standard is indispensable for manufacturers, engineers, and quality inspectors engaged in creating durable and corrosion-resistant valves for water infrastructure.
Overview
The 1984 edition of IS 778 outlines the specifications for copper alloy gate, globe, and check valves employed in waterworks systems. It details requirements concerning design, materials, dimensions, manufacturing processes, testing, and inspection to guarantee dependable valve functionality in water supply networks. This standard is indispensable for manufacturers, engineers, and quality inspectors engaged in creating durable and corrosion-resistant valves for water infrastructure.
Audience
Contents
Structure
This section defines the extent and application range of the standard, including minimum flat-to-flat sizes for Class 1 and 2 valves, mandatory material testing requirements certified by suppliers, and types of valve seats as per specified tables. It also references relevant IS codes for materials such as compressed asbestos fiber, gland packing, phosphor bronze wire, and brass alloys.
Clarifies key terms and definitions used within the standard to ensure consistent interpretation related to valve types, seats, bonnets, and dimensional parameters. Includes minimum flat-to-flat sizing requirements and descriptions of valve seat configurations.
Details the required materials for various valve components, referencing specific IS codes. Covers the testing protocols for materials, supplier certification mandates, and permissible alloys such as brass, leaded tin bronze, and phosphor bronze for springs.
Explains the classification into Class 1 and Class 2 valves, types of valves and seats including gate, globe, lift check, and swing check valves, and minimum flat-to-flat sizing for valve nuts. Also includes face-to-face dimensions for flanged valves.
Specifies flange dimensions, bolt hole patterns, and tolerance limits for Class 1 and 2 valves. Emphasizes material testing requirements and references related IS specifications for manufacturing practices.
Summarizes dimensional tolerances, including permissible ±1.5 mm variation, and presents centre-to-end and centre-to-face measurements for both screwed and flanged valves, classified by valve type and nominal size.
Describes detailed construction features including face-to-face and end-to-end dimensions for various valve types. Provides dimensional data for screwed end angle valves and tolerances applicable to all measurements.
Outlines stuffing box dimension calculations based on stem diameter and packing space, including minimum depth requirements. Details minimum stem diameters for different valve sizes, and design notes on integral and separate stuffing boxes as well as thrust collars.
Details material testing, sampling procedures, hydrostatic body and seat tests, backseat tests for gate and globe valves, and leakage criteria. Includes sampling acceptance criteria and inspection guidelines.
Describes sample size determination based on lot quantity, acceptance numbers, sub-sample testing, and criteria for lot acceptance. Emphasizes random sampling for quality assurance.
Discusses inspection protocols including sampling methods, material testing, manufacturer certification, and repair materials conforming to referenced IS codes. Highlights minimum flat-to-flat sizing and repair compliance.
Specifies stuffing box dimension requirements for packing, packing materials referencing IS standards, and procedures for preparing valves for shipment to prevent damage and contamination.
Covers the use of the BIS Standard Mark, supplier certification for material compliance, and information required with orders. Details licensing regulations under the BIS Act and manufacturer responsibilities.
Lists essential details purchasers should specify, including valve type, class, end connections, additional testing requirements, and inspection arrangements. Reinforces minimum flat-to-flat dimension requirements.
Presents the sampling scale, acceptance numbers, sub-sample sizes for testing, and the procedure for evaluating lot conformity. Emphasizes random sampling and detailed testing per lot.
Frequently Asked
IS 778 (1984) permits specific copper alloys for valve manufacturing, including Dezincification Resistant Brass (DCB 2) and Leaded Tin Bronze (LTB 2) for valve bodies; Leaded Tin Bronze, Forged Brass (CuZn4 2Pb2), and Brass (DCB 2) for bonnets and covers. Stuffing boxes, discs, hinges, and nuts are made from Leaded Tin Bronze, Extruded Brass Rod, or Forged Brass. Stem components utilize Extruded Brass Rod, High-Tensile Brass, or Forged Brass, while springs are made from Phosphor Bronze Wire as per relevant IS specifications to ensure corrosion resistance and mechanical reliability.
The standard stipulates that flanged ends are integrally cast with the valve body and must be machined flat for effective sealing, with face-to-face and centre-to-face dimensions specified in designated tables. Screwed ends must conform to minimum width values for hexagonal or ribbed round shapes and have end-to-end and centre-to-end dimensions as detailed in respective tables. A tolerance of ±1.5 mm is permitted, ensuring proper fit and pressure-tight connections suitable for various applications.
IS 778 mandates hydrostatic testing including body tests where pressure is applied with the valve fully open to detect any body leakage. Seat tests apply pressure to the closed gate or globe valve seat or check valve outlet side, verifying leakage limits as per IS 6157:1971. Back seat tests for gate and globe valves ensure no leakage through the stuffing box when the valve is fully open and gland packing is loosened or removed. Sampling for these tests follows defined procedures to verify conformity.
Rising stem gate valves feature a wedge with a top slot to engage the stem's lower end and typically utilize an outside screw mechanism. Non-rising stem valves have wedges that may be attached via screwing or nuts and include an integral thrust collar on the stem to provide a pressure-tight seal against the bonnet when fully open. These valves commonly use inside screws, and minimum stem diameters are specified according to valve size to ensure structural integrity.
Manufacturers must allow purchaser inspectors reasonable access to production facilities for verification prior to dispatch. If inspection is not conducted by the purchaser, manufacturers must issue a certificate confirming full compliance with IS 778. Material testing must meet referenced IS specifications with supplier certification, and tests are preferably conducted at the manufacturer’s premises. These protocols ensure traceability and quality assurance throughout the manufacturing process.
Ask AI about any clause, requirement, or provision in IS 778. Get instant, clause-cited responses powered by our indexed library.
Free tier includes 150 queries (50 AI + 100 Reference) · No credit card required