Bimetallic Transition Joints

Join Contrasting Metals


The Transition Joint is a prefabricated, non-separable, metallurgically bonded joint used for field butt welding of dissimilar metal piping components which are not weldable to each other. Typical metals include aluminum to stainless steel for cryogenic applications.


TUBE TURNS® Transition Joints have been manufactured for over 40 years in pipe sizes ranging from 1/2" to 36" diameter and have been produced from a variety of stainless steels (304, 304L, 316, 316L, 321, 347) and aluminum alloys (3003, 5082, 5083, 6061). They are used to join stainless piping to aluminum piping for cryogenic services down to minus 320° F and are installed in heat exchangers, liquefied gas storage tanks and transfer lines. They are used in many applications for pressures ranging from full vacuum to in excess of 6,000 psi.

Rugged Construction

The construction of these Transition Joints utilizes flanges and lap joint stub ends in accordance with ASME\ANSI dimensions that are proven to be reliable in all service conditions. These components are continuously seal welded to a bimetallic ring to provide a leak-proof joint. This bimetallic ring consists of a layer of type 304 stainless steel and a layer of 1100 aluminum joined together by pressure welding to produce a strong, ductile solid-phase bond. The flanges are then bolted together and the bolts tightened to a predetermined torque. The bolts and nuts are then tack welded to provide a non-separable unit. These joints are constructed in accordance with ASME B31.3 Chemical Plant and Petroleum Refinery Piping and ASME Boiler and Pressure Vessel Code, Section IX, Welding and Brazing Qualifications.

Two Designs Available

To meet the varied requirements of the cryogenic industry, Tube Turns® offers two types of aluminum/stainless steel Transition Joints. The Type "T" uses aluminum and stainless steel flanges and the Type "K" uses all stainless steel flanges and an aluminum stub end. The Type "T" design is generally a more economical design for systems using high strength aluminum alloys such as 6061-T6 whereas the Type "K" design is usually more economical for higher pressure systems utilizing the lower strength alloys such as 3003 and 5083.