What IS 17661 is
IS 17661 (Part 1):2022 is the Indian Standard covering AUS40, the 40% aqueous urea solution used as the NOx reduction agent in marine selective catalytic reduction systems. It is published by the Bureau of Indian Standards and is the reference an Indian procurement specification will normally cite when it calls for marine urea by an Indian standard instead of an international one.
The standard is aligned with ISO 18611, the international standard for the same product. In practice a solution that meets ISO 18611 addresses the same product requirements that IS 17661 sets out for AUS40.
Where PROTICKS stands
PROTICKS holds ISO 18611 certification for AUS40, and the product meets the requirements of IS 17661 (Part 1):2022. Those are two different kinds of statement and we keep them apart: certification is held and can be evidenced by a certificate; conformance is demonstrated by test results against the standard, which is what the batch Certificate of Analysis reports. If any supplier, including this one, describes a document as a certificate, ask for the certificate number and the body that issued it, and verify it with that body.
If your purchase specification names IS 17661, say so with the enquiry. The batch Certificate of Analysis is the document that evidences conformity for a given delivery, and it is issued with every supply.
Why buyers ask for it
- Indian-flag and coastal operators whose procurement templates are written against Indian Standards instead of ISO.
- Public-sector and port-authority tenders that require an Indian Standard reference in the technical bid.
- Technical superintendents reconciling an OEM requirement written against ISO 18611 with a purchase spec written against IS 17661.
- Customs and documentation teams matching the product description on shipping paperwork to the specification cited on the order.
What to check on the batch document
Whichever standard your specification names, the checks are the same. Confirm the batch number matches the delivery note and the packaging, that the measured urea concentration is within the specified range, and that the impurity parameters are reported with their acceptance limits in consistent units.
Ask for clarification where a test is missing or a conformance statement is unclear. See the full product-document checklist.
IS 17661 or ISO 18611: which should my spec say?
If the vessel’s engine or SCR manufacturer specifies AUS40 to ISO 18611, use that reference; it is the standard the equipment was approved against. Citing IS 17661 in addition is useful where an Indian purchasing process requires an Indian Standard reference. The two are not alternatives that change the product; they describe the same 40% aqueous urea solution.
Do not substitute AUS32 for AUS40 on the basis of either standard. Compare AUS32 and AUS40.