BULK GASES & SYSTEMS TECHNICAL CONTENT

During the day-to-day operation of heat treat departments, many habits are formed and procedures followed that sometimes are done simply because that’s the way they’ve always been done. One of the great benefits of having a community of heat treaters is to challenge those habits and look at new ways of doing things. Heat Treat Today‘s 101 Heat Treat Tips, tips and tricks that come from some of the industry’s foremost experts, were initially published in the FNA 2018 Special Print Edition, as a way to make the benefits of that community available to as many people as possible. This special edition is available in a digital format here.

In today’s Technical Tuesday, we continue an intermittent series of posts drawn from the 101 tips. The category for this post is Industrial Gases, and today’s tip #39 comes from Dan Herring, “The Heat Treat Doctor®”, of The Herring Group. 

Heat Treat Tip #39

How to Install an Ammonia System

One of the keys to any successful ammonia system installation in the heat treat shop is to find a supplier who is capable of providing premium grade (also known as metallurgical grade) anhydrous ammonia. This product has little or no water, which could contaminate your process. Look for a specification of 99.995% ammonia.

Once you have picked a supplier, there are several choices when it comes to ammonia storage. For the lowest product price, you should consider a tank of at least 10,000 gallons (43,000 pounds of ammonia.) This allows you to purchase full 38,000-pound tanker trucks of ammonia to reduce your supply costs. One pound of ammonia yields 22.5 cubic feet of vapor or 45 cubic feet of dissociated ammonia (75% H2, 25% N2).

In most states, you must comply with these standards if you have more than 10,000 pounds of anhydrous ammonia on site. So, you need to make sure you comply with OSHA’s Process Safety Management (PSM) and EPA’s Risk Management Plan (RMP).

The second option is to keep below the 10,000-pound threshold by installing a 1,000 gallon (4,400-pound capacity) or a 2,000 gallon (8,800-pound capacity) storage tank. Pricing for ammonia into these tanks runs about 50% higher in the smaller quantities. Even with the lower inventory, you will need to comply with OSHA 1910.111 and any applicable state, city, or county laws. It is critical to check with local agencies to make sure you are in full compliance with these regulations.

Another option for smaller usages are ammonia cylinders, but if stored inside the factory, special containment cabinets are required. Check with your ammonia supplier for the details.

With regard to the installation, in most cases, you need to pour a foundation for the tank, provide electricity to the tank for a sidearm vaporizer (used to maintain pressure in the tank since you will be withdrawing ammonia vapor to the process) and provide piping from the tank to your process. Most suppliers can lease the tank and valves/attachments for a nominal monthly fee depending on your ammonia consumption. You can also add a telemetry unit that allows your supplier to monitor your tank level via an Internet site. You will need to install a water shower near the tank and have gas masks close to the tank. It is a good idea to provide a fence around the tank if your company does not have security. Your supplier should provide hazardous awareness training for ammonia.

You can expect relatively trouble-free operation from a properly installed and well-maintained ammonia supply. Maintenance problems, other than an occasional paint job, are usually minimal but good inspection (including all valving) and frequent leak checks are mandatory. The tank should be visually inspected yearly, probably by your supplier, and the pressure relief valves should be changed every five years.

Submitted by The Herring Group

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