STICKY UREA MEDIUM KEPT FLOWING SMOOTHLY THANKS TO JACKETED BELLOW

For a chemical plant in South Asia that produces fertilizer, Belman has successfully designed and manufactured a special replacement Jacketed Bellow. As the media is urea, which is hydroscopic and can become sticky at lower temperatures, this special Expansion Joint design was required to prevent the media from getting sticky and thus caking inside the system.

CLIENT ISSUE

The chemical plant needed a replacement Bellow for an existing worn-out Jacketed Expansion Joint. To ensure safe operation and prevent the medium from packing up, the client requested the same Jacketed Bellow design which had performed satisfactorily for many years. For this reason, the client was looking for a highly experienced Expansion Joint manufacturer with proven expertise in Jacketed Bellow solutions. It turned to Belman, as we had previously supplied other Expansion Joint designs successfully for this client. The client specified that only European, UK, US or Japanese materials were acceptable for this project.

BELMAN SOLUTION

Jacketed Bellow

As required by the client, Belman designed the new Expansion Joint according to the specifications and drawing of the previous part. As the medium is urea (CO(NH₂)₂ ), a synthetic nitrogen fertilizer, it is hygroscopic and thus has a tendency to become sticky and prone to caking. This can cause problems in connected equipment and must therefore be carefully avoided. In the client’s plant, temperature control is essential in order to prevent the urea from becoming sticky. Consequently, it needed an Expansion Joint design that could maintain the temperature of the medium and prevent it from cooling down while passing through the Expansion Joint. The Jacketed Bellow design is ideal for solving this issue, as it features a chamber for a heating medium between the two Bellows, thereby ensuring that the heating medium does not come into contact with the flow medium. With this solution, the client is able to keep the urea in a hot, fully molten state until it reaches the stage where it can solidify in a controlled setting.

What is a Jacketed Expansion Joint?

A Jacketed Expansion Joint is characterised by having a Bellow around another Bellow. The space between the two Bellows forms a sealed chamber, through which a heating medium flows via an inlet and an outlet respectively. As the heating medium passes through the Expansion Joint, the heating medium emits heat to the inner Expansion Joint. In this way, the process media (in this case urea) flowing through the inner Bellow maintains and/or increases its temperature, which improves its fluidity and thereby prevents solidification. Jacketed Bellows are thus used when it is necessary to maintain or raise the temperature of the process medium, ensuring a smooth and uninterrupted flow through the system.

What materials are used for Jacketed Bellows for chemical plant environment?

As per client request, the Bellows and inner sleeves are made from 1.4541 (AISI 321), which is a material commonly preferred for Expansion Joint Bellows due to its versability, favourable pricing and availability. It is suitable for certain chemical plant applications, as in this case, although its performance depends strongly on the process medium, operating temperature and the surroundings. Since the pipe ends, flanges and cover are exposed to a more corrosive surrounding environment, the client specified that these components must be made from 1.4307 (AISI 304L). This is an extra-low carbon version of the AISI 304 stainless steels, which provides better resistance to intergranular corrosion and is therefore suitable for more aggressive or corrosive conditions. It is also frequently used in applications involving nitric acid, as in this project.

Belman – expertise on Jacketed Bellows designs

Since 1994 Belman has engineered and produced Jacketed Bellows for clients across different industries worldwide, making Belman the go-to company for engineered Jacketed Bellows. Throughout the years, Belman has engineered Jacketed Expansion Bellows in numerous different sizes, materials and designs, many of them supplied for chemical and petrochemical plants. Due to the nature of the media and the often corrosive environments in these industries, Chamber Expansion Joints are manufactured in all types of steel materials, including high-alloy steels. Usually, the material is determined by the temperature as well as the type and consistency of the medium and the surroundings of the Expansion Joint.