3.1.13 Student Book © 2004 Propane Education & Research CouncilPage 1 3.1.13 Identifying Procedures...

3.1.13 Student Book © 2004 Propane Education & Research Council

3.1.13

Identifying Procedures for Converting ASME Tanks in

Ammonia Service to Propane Service

Storage, cargo, and nurse tanks used in anhydrous ammonia service must not be used to store or transport propane until they have been properly converted to propane service. Ammonia contamination is a serious hazard to employees and customers.

In this training module you will identify:

(1) Physical properties, hazards and characteristics of ammonia

(2) Procedures for converting anhydrous nurse tanks to propane service

3.1.13 Student Book © 2004 Propane Education & Research Council Page 1

Physical Properties, Hazards & Characteristics of Anhydrous Ammonia

Anhydrous ammonia (NH3) is a hazardous material with the

following physical properties:

1. At room temperature and atmospheric pressure, anhydrous ammonia is a pungent, colorless gas,

approximately 40% lighter than air.

2. Compressed and cooled, it is a colorless liquid about 68% as heavy as water.

3. Its boiling point at atmospheric pressure is -28°F.





4. Anhydrous ammonia in closed, pressurized containers behaves similarly to propane.

5. Anhydrous ammonia is an inhalation hazard; at a concentration of more than 5000 parts per million, it will disable a person and suffocation results. Exposure to body tissue is harmful, resulting in caustic burns. Exposure to liquid ammonia results in frostbite. Eye exposure in concentration causes blindness.



Figure 1. Pressure Gauge and Valve on Anhydrous Ammonia Nurse Tank





6. Anhydrous ammonia is corrosive, especially to brass valves and fittings, and other metals that contain alloys

of copper and zinc.

7. Under certain conditions it may be flammable.

8. It is highly chemically reactive, and in the presence of other materials may be highly explosive.

9. Anhydrous ammonia in the presence of water will burn body tissue.



Warning: Exposure to anhydrous ammonia is dangerous and can result in injury or death.

Always use proper personal protective equipment (PPE) and handling procedures when working around it.

Be sure you read a current material safety data sheet (MSDS) provided by the chemical’s supplier & understand the information it contains.

Know how to react in the event of a chemical release or exposure.


Converting ASME Tanks in Anhydrous Ammonia Service to Propane Service

Note:

One of the steps in these procedures requires the replacement of the NH3 tank steel valves with valves used in propane

service.

In propane service, many of the valves, fittings, and distribution lines are made with copper or a metal alloy containing copper (i.e., brass, etc.).

Because of the chemical nature of NH3, any mixture of NH3 and

water can easily destroy the copper or brass equipment. For this reason, follow special procedures to ensure that all traces of ammonia are removed from the tank before placing it into propane service.

3.1.13 Student Book © 2004 Propane Education & Research Council Pages 2 - 5


Step 1: Evacuate or unload all ammonia from the tank.

(See the precautions and guidelines under this step on pages 2 – 5.)

Step 2: Completely purge the tank of ammonia according to your company’s written purging procedures or by the use of a commercial tank cleaning contractor service.

Step 3: After purging, (and testing for to assure there is no remaining NH3 present) replace the NH3

container steel valves with brass propane valves.



NOTE:

Although NH3 gauges operate in the same manner as propane gauges, the maximum permitted filling level of NH3 is not the

same as propane.

As a result, the markings on the gauge faces, as well as the length of the dip tube for a fixed maximum liquid level gauge, are not designed for propane service. If a standard NH3 gauge is

used for filling with propane, the container can be overfilled!

3.1.13 Student Book © 2004 Propane Education & Research Council Pages 5 - 6


Step 4: Purge the tank with propane vapor.

Step 5: Test the propane vapor for ammonia contamination.

Step 6: If necessary, re-mark the tank according to federal, state, and local codes. Remove the markings for ammonia. Do not place a tank into propane service until it has been properly marked and labeled in accordance with federal, state, and local regulations.

3.1.13 Student Book © 2004 Propane Education & Research Council Pages 7 & 8

Time to See If You Got the Key Points of This Module…

• Complete the Review on page 7.

• See if you are ready for the Certification Exam by checking off the performance criteria on page 8.

3.1.13 Student Book © 2004 Propane Education & Research CouncilPage 1 3.1.13 Identifying Procedures...

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