Expansion Joints - Type MJA | Macoga

Macoga MJA Jacketed Expansion Joints

Macoga MJA expansion joints are metallic, jacketed type units with two bellows: an inner bellow for the process medium and an outer bellow for the heating, cooling, or thermal maintenance jacket. These assemblies are specified where conventional insulation is insufficient or where the process medium must be maintained at a defined temperature for process control or safety reasons.

Movement and Piping Design

The MJA series can be engineered for axial, lateral, and angular movement in single or multiple planes. These joints do not absorb pressure thrust; therefore, main anchors, guides, and supports must be calculated and installed according to piping stress analysis.

Materials and Dimensions

Typical bellows and metallic component materials:

• Stainless steels 304, 321, 316, 316L, 310, 309
• Nickel alloys: Inconel, Incoloy, Hastelloy
• Carbon/alloy steels: P265GH, 16Mo3, 13CrMo44

Documentation covers sizes from DN50 to DN10000, single or multi-ply construction, and single or multiple convolutions.

Applications

Used in lines where the product must not cool, solidify, or deviate thermally: chemical processing, heavy industry, thermal oil pipelines, viscous fluids, heated production lines, and processes with steam or hot water jackets.

Standards and Certifications

Macoga references PED 2014/68/EU Module H, ASME Certification Mark, ISO 9001:2015, TÜV AD 2000-Merkblatt HP0, DIN ISO 3834-2, Lloyd’s Register, Bureau Veritas, and DNV-GL Type Approval. Final compliance must be verified in the data sheet and unit-specific certificates.

Installation and Inspection

Not intended for misalignment correction. Bellows must be protected from impact, scoring, arc strikes, and weld spatter. Remove yellow transport bars before pressure testing; use chloride-free water for hydrostatic tests.