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IS 771:2000 (Part 4) is the Indian Standard (BIS) for glazed fire-clay sanitary appliances, part 4: specific requirements of postmortem slabs. This standard covers the specific material, dimensional, and manufacturing requirements for glazed fire-clay postmortem slabs used in mortuaries, hospitals, and forensic laboratories. MEP engineers and healthcare architects use this code to correctly specify heavy-duty, hygienic sanitary fixtures that meet strict autopsy facility standards.
Glazed Fire-Clay Sanitary Appliances, Part 4: Specific Requirements of Postmortem Slabs
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! This is a 'Part 4' code; it must be read in conjunction with IS 771 (Part 1) which covers the general requirements, glazing quality, and testing methods (e.g., crazing, chemical resistance).
! Ensure plumbing layouts coordinate with the specific drain outlet position and structural supports required for heavy fire-clay slabs.
! Glazed fire-clay is chosen for these applications due to its high resistance to biological fluids and aggressive cleaning chemicals.
Covers material and performance requirements for all ceramic fixtures, including fire-clay.
BS EN 997:2018+A1:2022BSI / CEN (UK / Europe)
MediumCurrent
WC pans and WC suites with integral trap
Product-specific (WCs) but includes material requirements applicable to fire-clay.
BS EN 14688:2015BSI / CEN (UK / Europe)
MediumCurrent
Sanitary appliances. Wash basins. Functional requirements and test methods
Product-specific (wash basins) but includes material and surface quality requirements.
BS 3402:1969BSI (UK)
HighWithdrawn
Specification for quality of vitreous china sanitary appliances
Historical equivalent with a similar material-centric approach to quality.
Key Differences
≠IS 771 is a general standard for 'fire-clay' material, whereas modern international standards (EN, ASME) are typically product-specific (e.g., WC Pans, Wash Basins) and performance-based, covering various ceramic materials.
≠The definition of the ceramic body differs significantly. IS 771 allows water absorption up to 12% for fire-clay, while ASME A112.19.2 requires less than 0.5% for vitreous china, a category that often includes high-grade fire-clay products in the US market.
≠International standards like EN 997 include extensive functional performance testing (e.g., solid removal tests, flush volume, trap seal replenishment) which are not part of the general material requirements in IS 771 Part 1.
≠IS 771 prescriptively specifies a minimum glaze thickness (0.4 mm), while modern international standards focus on the performance of the glaze (imperviousness, resistance) rather than its thickness.
Key Similarities
≈Both IS 771 and international counterparts mandate a crazing resistance test, typically using an autoclave at similar pressures and durations to ensure long-term glaze durability.
≈All standards require the glazed surface to be resistant to staining and chemical attack from common household acids and alkalis, ensuring the product maintains its appearance over time.
≈Requirements for the quality of the glazed surface are similar, specifying a smooth, hard, impervious finish free from visual defects like blisters, pimples, and cracks.
≈All standards specify tolerances for warpage and key dimensions to ensure the interchangeability and correct installation of fixtures.
Parameter Comparison
Parameter
IS Value
International
Source
Water Absorption of Body
≤ 12.0% by mass
≤ 0.5% by mass (for Vitreous China)
ASME A112.19.2-2018
Crazing Resistance Test (Autoclave)
0.7 N/mm² (~7 bar) for 1 hour
100 psi (~6.9 bar) for 1 hour
ASME A112.19.2-2018
Minimum Glaze Thickness
≥ 0.4 mm
Not specified; performance-based (must be impervious)
ASME A112.19.2-2018
Warpage of Flat Surfaces
Shall not exceed 6 mm
Shall not exceed 6 mm per metre of length
ASME A112.19.2-2018
Chemical Resistance
No visible stain after testing with acid and alkali solutions
No visible change after testing with a range of chemicals
BS EN 14688:2015
Test for Ink Stain
Stain from Methylene Blue dye must be removable by water after 5 minutes
Stain shall be removable with water, or if necessary, denatured alcohol
ASME A112.19.2-2018
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
Standard length of postmortem slab2000 mm
Standard width of postmortem slab700 mm
Tolerance on dimensions 75 mm and over± 4 percent
Tolerance on dimensions less than 75 mm± 3 mm
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 3 - General Requirements
Clause 4 - Dimensions and Tolerances
Clause 5 - Construction and Finish
Frequently Asked Questions3
Where are the testing methods for crazing and water absorption found?+
All primary material and performance testing methods are specified in IS 771 (Part 1).
What is the acceptable dimensional tolerance for these slabs?+
For dimensions 75 mm and above, the tolerance is ± 4 percent. For dimensions below 75 mm, it is ± 3 mm.
What are the typical standard dimensions for a postmortem slab?+
The standard specifies an overall length of 2000 mm and a width of 700 mm.