What Are Ammonia Service Valves?

Ammonia is a type of special fluid medium. Valves used for conveying ammonia are called ammonia service valves. These valves not only adopt special sealing materials and structural designs, but also feature stable sealing performance, safe and reliable operation, strong corrosion resistance, zero internal and external medium leakage, and easy operation. Their sealing performance, maintainability and safety are all superior to those of ordinary valves.

Ammonia service valves successfully solve the problems of ammonia-induced shell corrosion and perforation as well as high sealing requirements. They are particularly suitable for the transportation of chlorine and liquid chlorine pipelines in the chemical industry, and can meet the requirements of long-term reliable use. Ammonia-specific valves effectively address the drawbacks of ordinary valves used in chemical pipelines, such as poor corrosion resistance, easy shell perforation, inferior sealing performance and high leakage risk. They are especially applicable to the transportation of chlorine and liquid chlorine pipelines in the chemical industry, satisfying the demand for long-term stable operation.

Structural Features of Ammonia Service Valves

a.  As valves for medium isolation and connection, imported ammonia service globe valves are widely adopted for ammonia handling. Aiming at overcoming the shortcomings of ordinary valves, such as poor corrosion resistance and easy shell perforation, ammonia-specific valves are made of corrosion-resistant steel for the valve body according to the specific properties of the medium. This material can resist corrosion from ammonia and liquid ammonia, and adapt to low temperatures down to -40℃, maximizing the satisfaction of working condition requirements.

b.  Ammonia reacts chemically with copper and copper-containing materials. Therefore, all components of imported ammonia service valves shall not use copper-based materials.

c.  The sealing surfaces are all made of Babbitt metal. The structural characteristic of Babbitt metal is that hard phase particles are uniformly distributed on a soft phase matrix. The soft phase matrix endows the alloy with excellent embedability, conformability and anti-seizure performance. After running-in, the soft matrix becomes concave while the hard particles protrude outward, forming tiny gaps between the sliding surfaces. These gaps serve as oil storage spaces and lubricating oil channels, which are beneficial to reducing friction. The protruding hard particles play a supporting role, which is conducive to load bearing. Ammonia is prone to leakage, while Babbitt metal is relatively soft and deformable, enabling the valve core and valve seat to fit closely and ensuring excellent sealing performance.

d.  The sealing pair of ammonia-specific valves adopts a ball-and-plane matching structure with automatic sealing compensation, achieving double insurance effects. It features stable sealing performance and no adhesive wear, effectively solving the problems of poor sealing performance and high leakage risk of ordinary valves used in chemical pipelines.

e.  The middle flange of the product adopts a tongue-and-groove sealing structure, which ensures absolute reliable sealing of the middle flange even when the pipeline pressure fluctuates.

f.  The upper sealing device adopts multi-stage PTFE sealing materials to form a combined seal. This design ensures no medium leakage from the stuffing box during the service life of the valve, eliminating the possibility of medium leakage from the stuffing box—a weak point of ordinary valves—which may even lead to accidents.

g.  Although J41B valves are more suitable for ammonia service and have better sealing performance than J41Y valves, the following points must be noted during actual operation: the sealing surfaces of J41B valves are softer than those of J41Y valves. Never use an F-type wrench to close them excessively tightly. Manual closure is recommended as far as possible to prevent damage to the sealing surfaces caused by excessive force with the wrench.