The standard outlines the specifications and testing protocols for specials used with steel cylinder reinforced concrete pipes having nominal internal diameters from 200 to 1800 mm. It details the types of specials such as bends, branches, flanged ends, and fittings essential for water supply, sewerage, and irrigation projects. This guideline assists manufacturers and engineers in material selection, design, reinforcement, fabrication, and marking to ensure performance and compatibility with IS 1916 pipes.
Overview
The standard outlines the specifications and testing protocols for specials used with steel cylinder reinforced concrete pipes having nominal internal diameters from 200 to 1800 mm. It details the types of specials such as bends, branches, flanged ends, and fittings essential for water supply, sewerage, and irrigation projects. This guideline assists manufacturers and engineers in material selection, design, reinforcement, fabrication, and marking to ensure performance and compatibility with IS 1916 pipes.
Audience
Contents
Structure
This section defines the coverage of the standard including design and dimensional requirements for steel cylinder reinforced concrete pipes and their specials like bends, tees, and reducers.
Minimum steel plate thickness values based on nominal internal diameter are provided in tabular form, ensuring structural adequacy.
Reinforcement design references IS 1916-1963 for cage and longitudinal reinforcement details.
Essential dimensions for pipe specials such as bend radii and lengths are specified with example tables.
Specials are classified in accordance with the classification of steel cylinder reinforced concrete pipes per IS 1916-1963. This includes specifying minimum steel plate thicknesses based on diameter ranges.
Marking requirements are outlined, detailing the information to be stamped on each fitting for identification and traceability.
Dimensional data for various bend angles and diameters are presented to assist in accurate manufacturing.
This section lists the approved steel reinforcement materials such as mild and medium tensile steel bars, high strength deformed bars, hard-drawn wire fabric, and structural steel conforming to relevant IS codes.
Minimum steel plate thickness requirements are tabulated.
Bend dimensions and minimum clearance values from the pipe crown are also specified, referencing IS 1916 for detailed end dimensions.
Design provisions include reinforcement specifications for different steel types per IS standards.
Minimum steel plate thicknesses relative to pipe diameter are reiterated.
Bend radii and lengths are detailed according to bend angle and internal diameter.
Minimum clearances from the pipe crown are specified to ensure adequate flow and structural integrity.
Key dimensions including nominal flange thicknesses across diameter ranges are outlined.
Steel plate thickness minimums and bend dimensions (radius and length) for various nominal internal diameters are provided.
Minimum clearances from the crown for bends and tees are specified to maintain hydraulic and structural requirements.
This section describes the types of reinforcement steels allowed and their relevant IS standards.
The reinforcement cage construction is explained, including methods of applying spirals or rings and straight bars throughout the special.
Design clauses from IS 1916 for cage reinforcement, longitudinal reinforcement, and concrete cover are referenced.
Manufacture of specials requires marking each fitting with size, class, bend radius (for bends), manufacturing date, and manufacturer identification.
Minimum steel plate thickness per diameter range is restated.
Detailed tables for bend radius and length by angle and diameter are included.
Minimum clearance from crown values are specified to maintain design integrity.
Testing includes verifying fitting compliance, dye-penetration tests to detect surface flaws, and compressive strength tests on concrete cubes.
Specific IS codes for testing methodology are referenced to ensure compliance and quality assurance.
Minimum clearance and length requirements for pipe specials are summarized.
Surface quality requirements mandate smooth, dense, and hard finishes on internal and external surfaces without cement washes unless agreed upon.
Mandatory marking details on specials are reiterated.
Dye-penetration tests are required to identify surface defects.
Test result rounding follows IS 2-1960 guidelines to maintain consistency.
Each special must be permanently marked with size, class, bend radius (if applicable), manufacture date, and manufacturer’s name or trademark.
The optional ISI certification mark may be included to demonstrate conformity to Indian Standards.
Tables on minimum steel plate thickness and bend dimensions support marking accuracy and traceability.
Frequently Asked
IS 7322 (1985) permits the use of mild and medium tensile steel bars conforming to IS 432 (Part 1)-1982, high strength deformed steel bars as per IS 1786-1985, hard-drawn steel wire fabric meeting IS 1566-1982, and structural steel conforming to IS 226-1975. The reinforcement cages must extend throughout the special and consist of spirals or rings combined with straight bars, which may be wound directly on the steel special or on collapsible frames before installation. This ensures appropriate structural support within the concrete pipe specials.
According to IS 7322 Clause 4.2, the minimum steel plate thickness depends on the nominal internal diameter of the special: 2.5 mm for diameters 200 to 500 mm, 5.0 mm for 600 to 900 mm, 6.0 mm for 1000 to 1100 mm, 8.0 mm for 1200 to 1500 mm, and 10.0 mm for 1600 to 1800 mm. Plates should comply with mild steel specifications per IS 226-1975 or steel per IS 2062-1980. The steel shell is fabricated by welding plates with complete fusion and penetration following IS 816-1969 to ensure strength and durability.
The curing process starts with inside concreting, which must be cured continuously for a minimum of 3 days or until the concrete attains a cube strength of at least 11 N/mm². Only then may outside concreting begin, which should be performed using vibration or pressure methods. Post concreting, wet curing should be maintained for 14 days when using OPC, PSC, PPC, or hydrophobic cement, and for 7 days if rapid hardening or high strength OPC is used. Curing methods include immersion, covering with wet gunny bags, or mechanical sprinkling. All concrete must comply with IS 456:2000, and steel plates need to be cleaned and coated with neat cement slurry prior to concreting.
Compliance testing under IS 7322 involves fitting conformity tests to ensure specials meet standard specifications, dye-penetration tests as per IS 3658-1981 to detect surface cracks or flaws, and compressive strength tests on 150 mm concrete cubes following IS 456-1978 and IS 516-1959. These tests collectively verify the structural integrity and quality of the pipe specials and their fittings.
Each special must be clearly marked with its nominal size, class, radius of bend (if applicable), date of manufacture, and the manufacturer's name or registered trademark. Additionally, the ISI certification mark may optionally be included to indicate conformity with Indian Standards. This marking facilitates traceability, quality assurance, and compliance verification.
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