On-site Setup and Integration

The installation of an ammonia system at an end-user facility is the culmination of the design and fabrication phases, requiring meticulous execution and a paramount focus on safety. This phase involves assembling the prefabricated components, installing piping, electrical wiring, controls, and ultimately preparing the system for safe, efficient operation. The rigorous requirements are often codified by ANSI/IIAR 4 (Installation) and ANSI/IIAR 5 (Start-up and Commissioning) standards.

I. Site Preparation and Safety Infrastructure

Before any process equipment is connected, the facility environment must be prepared to handle a hazardous substance like anhydrous ammonia (NH3).

• Machinery Room Compliance: The room housing the compressors and vessels must comply with design standards, including adequate, tested emergency ventilation systems that prevent recirculation of exhaust air. Emergency ventilation switches must be installed in remote, safe locations outside the room.

• Safety Equipment Installation: Essential safety infrastructure must be installed and verified as functional:

• Safety Shower and Eyewash Stations: Must be readily accessible and continuously functioning.

• Ammonia Leak Detectors: Must be strategically placed to monitor the system for leaks. These detectors are tied into the safety interlocks and emergency shutdown (ESD) mechanisms.

• Protective Barriers: Physical barriers must be installed to protect critical equipment (pipes, valves, tanks, evaporators) from accidental damage by forklifts, hand trucks, or other mobile equipment.

II. Mechanical Assembly and Piping Installation

The core of the installation involves connecting the system components using certified, code-compliant piping.

• Component Placement and Labeling: Equipment, including compressors, vessels, and heat exchangers, must be positioned according to the finalized Piping and Instrumentation Diagrams (P&IDs) and mechanical drawings. All equipment, piping, and emergency shutdown valves must be clearly labeled and color-coded to match the engineering drawings.

• Piping Construction: All piping must adhere to standards like ASME B31.1, ASME B31.3 or ASME B31.5 depending on application). This includes:

• Using materials approved for ammonia service, such as steel, and strictly avoiding copper or its alloys.

• Installing isolation valves (like quick-turning ball valves) on tanks and vessels to function as emergency stop points.

• Properly installing insulation to prevent efficiency loss and corrosion where applicable.

• Overpressure Protection: Dual pressure relief valves (PRVs) are installed on vessels and piping where necessary, with each sized correctly to protect the equipment. The PRV common manifold must be properly sized for discharge and may include a sensor to detect relief events.

III. Commissioning and System Start-up

Once the physical installation is complete, a rigorous series of checks, tests, and procedures ensures the system is safe to charge with ammonia.

• Pressure Testing and Integrity Check: The entire system is subjected to a pressure test using an inert gas, typically dry air or nitrogen, to verify the structural integrity of the components and welds.

• Evacuation and Dehydration: After successful pressure testing, the system is evacuated using a vacuum pump to an extremely low absolute pressure (e.g., 1,500 microns) to remove all non-condensable gases, air, and, most importantly, moisture (dehydration). The vacuum must hold steady for a set period (e.g., 24 hours) to confirm a leak-tight system.

• System Charging and Leak Checking:

• Ammonia is introduced into the system using a dedicated charging line, with the ammonia source located in an open-air location away from personnel.

• As the vacuum is broken, the system is inspected for leaks using approved methods (e.g., sulfur tapers or litmus paper).

• Final Verification and Training: All protection devices (e.g., pressure cut-outs, high-pressure switches) are tested and set. System controls and HMI software are programmed with the correct operational parameters. The final stage is comprehensive operator training on safe handling, operating procedures, and emergency response before the final handover.