MS pipes, SHS and RHS are sold in two broad qualities, and the price gap between them is large enough that buyers need to know which they are being quoted.
| ISI pipes & hollow sections | "Patra" (non-ISI) pipes | |
|---|---|---|
| Raw material | Prime HR / GP strip | Secondary or scrap-derived strip ("patra") |
| Certification | BIS licence to IS 1239 / IS 1161 / IS 4923 | Usually none |
| Wall thickness | Within the standard's tolerance | Wider variation; can be under nominal |
| Weld and strength | Tested to the standard | Inconsistent |
| Price | Higher | Lower |
Where patra pipes are used
Temporary structures, light fencing, low-cost fabrication and other non-critical work where no standard is specified.
Where they should not be used
- Water, gas, air or any pressure line
- Fire-fighting and sprinkler systems
- Scaffolding and formwork support
- Load-bearing structures, sheds, trusses and PEB members
- Anywhere a drawing or BOQ specifies an IS standard or YSt grade
How to avoid a mismatch
Write "ISI" or "non-ISI acceptable" on the enquiry. When comparing quotations, check that both are for the same quality, class and wall thickness — a lower price on a non-ISI tube is not a like-for-like comparison.
Related: ERW pipes · SHS · RHS · MS pipe weight chart