Custom Metallic Bellows for Pressure Vessel Nozzle Flexibility

Challenge:

An EPC contractor required custom-engineered expansion joints for large vertical pressure vessels, including separators and heat exchangers. The nozzle-to-piping connections needed to absorb thermal expansion and prevent stress transfer to vessel shells during start-stop cycles. The bellows had to meet pressure design codes and integrate seamlessly into ASME-stamped vessels.

Solution Provided:

FlexiBel designed and fabricated metallic expansion bellows in SS 316L, integrated with weld-end pipe spools, tailored to client-supplied nozzle orientations. The bellows were designed in accordance with ASME Section VIII, Division 1 and EJMA standards, and included:

• External shrouds for protection
• Root rings for added pressure stability
• Hydro and dye-penetrant testing as per project ITP

The assemblies were shipped with full design calculations, finite element reports, and welding documentation.

Why FlexiBel:

• Experience in pressure equipment code-compliant bellows design
• Coordinated with vessel fabricator to ensure nozzle alignment and stress compliance
• Delivered ready-to-weld assemblieswith material traceability and inspection records
• Supported EPC during design approval and client submittal phase

Result:

The expansion joints were successfully welded to vessel nozzles and passed inspection by a third-party authority. During commissioning and pressure testing, no deformation or stress leakage was observed. The EPC included FlexiBel as a listed vendor for future pressure vessel packages across midstream and downstream projects.