Technical FAQ: Ammonia Based Systems

General System Engineering

What is the primary difference between IIAR and ASME standards for ammonia systems?

ASME (American Society of Mechanical Engineers) codes primarily govern the design and fabrication of the pressure vessels themselves (e.g., Section VIII). IIAR (International Institute of Ammonia Refrigeration) standards, specifically IIAR-2, provide the comprehensive requirements for the safe design, installation, and operation of the entire ammonia system. RM Technologies ensures every integration meets both the vessel-level and system-level standards.

Why is 316L Stainless Steel often preferred over 304 for Aqueous Ammonia systems?

Safety & Compliance

At what threshold does my ammonia system become subject to OSHA PSM and EPA RMP regulations?

For Anhydrous Ammonia, the threshold is 10,000 lbs. For Aqueous Ammonia (concentrations of 20% or greater), the threshold is 20,000 lbs. If your facility holds these amounts at any one time, you are required to implement a full Process Safety Management (PSM) program and submit a Risk Management Plan (RMP).

How often should ammonia sensors be calibrated?

Urea & NOx Reduction

Can I convert an existing Anhydrous Ammonia SCR system to use Urea?

Yes, but it requires significant engineering modifications. Because urea is a solid or liquid solution, you must add a Urea-to-Ammonia (U2A) hydrolysis system or a specialized decomposition chamber. RM Technologies specializes in these retrofits, allowing facilities to eliminate high-pressure ammonia storage while maintaining their existing SCR catalyst infrastructure.

What causes urea "salting out" and how can it be prevented?

Maintenance & Longevity

What are the signs of Stress Corrosion Cracking (SCC) in ammonia tanks?

SCC is often invisible to the naked eye until a leak occurs. It typically forms in the "Heat Affected Zone" (HAZ) of welds in anhydrous service. We recommend regular Non-Destructive Testing (NDT), such as Magnetic Particle Testing or Ultrasonic Testing, to identify these cracks before they lead to a catastrophic failure.