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First, confirm if the liner is compatible with the chemical at its actual concentration and temperature. Then, check the valve’s pressure-temperature rating and sealing requirements. For wet-process phosphoric acid, account for suspended solids and impurities. For ammonia, specify whether it is aqueous or anhydrous and liquid or gas before choosing the valve.

What Should You Check for Phosphoric Acid Service?

Operating temperature and acid concentration are the first things to check. Although PFA and PTFE generally offer strong chemical resistance to phosphoric acid, you cannot determine whether a lined valve is suitable based on chemical compatibility alone.

Higher temperatures put greater demands on the lining. PTFE becomes more susceptible to creep, and permeation can increase as temperature rises. Check the operating temperature and pressure against the finished valve’s published limits.

Give extra attention to wet-process phosphoric acid, as the stream may contain suspended solids and other impurities. These particles can cause abrasive wear, even when the lining itself is chemically compatible with the acid.

Before specifying a phosphoric acid valve, provide the acid concentration, operating and design temperature and pressure, solids content, and known impurities. Include vacuum conditions too if the line can experience them.

Why Does Sealing Need More Attention in Ammonia Service?

A compatible lining is only one part of safely handling ammonia. You also need to prevent leaks around the stem, seats, gaskets, and body joints, especially with anhydrous ammonia.

Start by identifying whether the ammonia is aqueous or anhydrous. Then determine whether it reaches the valve as a liquid or gas. It is also important to check the sealing arrangement against the actual pressure and temperature of the service.

In case of anhydrous ammonia, pay particular attention to potential leakage paths around the stem and other sealing points. Choosing a compatible PTFE or PFA lining does not by itself confirm that the complete valve can safely contain the medium.

Di YOUFUMI GB stainless steel globe valve lists ammonia gas and ammonia among its applicable media. It has a published temperature range of -29°C to 200°C, with nominal pressure options of 1.0 MPa, 1.6 MPa, and 150LB.

But even with ammonia listed as an applicable medium, the valve’s pressure and temperature ratings, materials, and sealing arrangement must be checked to make sure they suit your operating conditions.

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What Information Should Go Into the Valve Specification?

Asking for a phosphoric acid valve or ammonia valve without providing the process conditions leaves out information needed to make a reliable selection.

At minimum, specify the medium, concentration, operating and design temperature, and operating and design pressure.

Also include any conditions that could affect the choice. For wet-process phosphoric acid, this can include solids, vacuum exposure, flow conditions, and impurities. For ammonia, make sure to state whether it is aqueous or anhydrous and liquid or gas.

Finally, state what you need the valve to do. Isolation, throttling, control, and overpressure protection place different demands on the valve. Operating frequency and required shutoff performance can also affect the selection.

A practical RFQ for phosphoric acid service could look like this:

These figures are just examples. Use the actual conditions from your process when requesting a quote. This gives a chemical valves manufacturer enough information to evaluate the valve construction, lining, and sealing requirements for the application.

Which Valve Type Fits Each Fertilizer-Plant Job?

Choosing the right fertilizer plant valve starts with the job it needs to perform. The conditions in phosphoric acid, ammonia, and urea lines can place very different demands on the valve.

For wet-process phosphoric acid, pay particular attention to abrasion from suspended solids. The lining may resist the acid chemically, but the valve still has to withstand the physical conditions of the slurry.

Cleaner phosphoric acid streams can be evaluated differently. Start with the concentration and temperature, then match the liner and valve design to the pressure, required flow function, and sealing requirements.

Ammonia service puts greater emphasis on containment. With anhydrous ammonia in particular, sealing performance needs to be evaluated alongside liner compatibility.

Urea service depends heavily on where the urea plant valve sits in the process. Downstream urea solutions can crystallize and plug internal spaces. High-pressure synthesis service is much more severe because it involves corrosive ammonium carbamate at high temperatures and pressures. These conditions require specialized severe-service materials and valve designs.

Where internal accumulation is a concern, valve geometry becomes especially important.

At YOUFUMI, our valvola a otturatore rivestita uses a cavity-free and dead-zone-free design to prevent process media from accumulating inside the valve. It is available with PFA or FEP lining in sizes DN15–DN300 and pressure classes PN10, PN16, and 150LB.

The right valve selection comes from matching the complete process conditions to the complete valve construction. Give us the process conditions and required valve function so the lining, sealing system, and valve design can be evaluated together.