Additional recommendations for safe piping practices.

Several technical specifications13 that result in safer ammonia piping are the following:

• Use A106B or A53B pipe for low-temperature service. Some engineers also specify seamless pipe for liquid and hot-gas lines.
• Use 3000 lb socket weld fitting (A-181) for up to 37 mm (1–1/2 in) schedule 80 pipe.
• Use long radius weld ells and A-105 butt weld fitting on 50-mm (2-in) and larger pipe.
• Use no threaded joints on liquid lines larger than 25 mm (1 in) or on gas or vapor lines larger than 37 mm (1–1/2 in). If at all possible, seal weld the joint and paint after assembly to prevent external corrosion and leaks.
• Use a minimum of bolted flange joints. Use seal caps on the stems of all manual valves that are not frequently operated.

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