# AUS 40 Storage, Handling & Shelf Life: Onboard Best Practice

AUS 40 is a near-saturated 40% urea solution with a narrower storage comfort zone than automotive AdBlue.

## Temperature window

| Condition | Threshold | Effect |
|---|---|---|
| Crystallisation onset | ~0 °C | Urea crystals form (AUS 32 tolerates −11 °C; AUS 40 does not) |
| Ideal storage | 5–30 °C | Longest in-spec life |
| Sustained >30–35 °C | n/a | Faster urea hydrolysis → ammonia, rising alkalinity, shorter shelf life |
| Direct sunlight | any | Local heating + UV degrade fluid and HDPE packaging |

Crystallised AUS 40 redissolves on gentle warming (~5–10 °C) with recirculation, unchanged in concentration if uncontaminated. In Indian coastal conditions: keep drums/IBCs shaded and ventilated.

## Shelf life

**12+ months** stored sealed in the ideal window. Rules: first-in-first-out; record batch numbers from each Certificate of Analysis; keep containers sealed; verify aged stock (refractive index/density vs CoA) before dosing.

## Compatible materials

| Compatible | NOT compatible |
|---|---|
| Stainless 304/304L, 316/316L | Copper, brass, bronze |
| HDPE, PP, PVDF | Mild/carbon steel (unlined) |
| Fluoro-elastomer & EPDM seals | Aluminium, zinc, galvanised surfaces |

Dissolved metals travel straight to the SCR catalyst and poison it.

## Contamination control at bunkering

- Dedicated hoses/pumps/funnels, never shared with fuel, lube oil or seawater
- Inspect couplings; match delivery batch number to the CoA
- Never return drained fluid to storage; never dilute with water (under-doses like AdBlue)

Safety: AUS 40 is non-flammable, low-hazard; rinse spills with fresh water; consult the MSDS (https://aus40.in, footer download).

Related: [What is AUS 40](https://aus40.in/what-is-aus-40-marine-urea.html) · [SCR dosing & consumption](https://aus40.in/how-marine-scr-systems-work-urea-dosing.html) · [Port-side delivery](https://aus40.in/marine-urea-supply-ports-india.html)

PROTICKS: ISO 18611 & IS 17661 certified AUS 40, Jamnagar, India. info@proticks.com · +91-74909-17799