What the licence actually covers
An NS licence is granted for specific products and specific sizes, not for a company in general. A licence covering HDPE pipe from 16 mm to 200 mm says nothing about a manufacturer's garden hose or lay-flat delivery pipe. When a supplier claims to be “NS certified”, ask which product and which size range the licence names.
What is tested
Certification is not a paper exercise. Pipe is tested against the standard for:
- Mean outside diameter, ovality and wall thickness
- Internal pressure creep rupture at 80 °C
- Longitudinal reversion
- Carbon black content and dispersion
- Melt flow rate and density
- Oxidation induction time
- Elongation at break and yield strength
Carbon black matters more than it sounds. It is what protects buried and exposed pipe from ultraviolet degradation, and both the quantity and how evenly it is dispersed are checked.
Licences expire
An NS licence runs for three years from issue and must be renewed. A certificate copy proves nothing on its own if the date has passed — check that the licence is current.
How to verify a supplier
- Ask for the licence number and the product and sizes it names
- Check the issue date and confirm it is still within three years
- Ask for recent test reports, not just the certificate
- Check the pipe itself — markings should state standard, grade, size and class
Written by the technical team at Maruti Pipes Pvt. Ltd., Nepalgunj, Nepal.