TPT January 2012

A rticle

of the branch part (figure 3). Parts are directly ready for the welding process. Fix and weld For the welding process parts must be fixed together. Larikka CylinWeld has three devices for handling parts: 1) a welding cassette; 2) a positioning device; and 3) a welding chamber. The same welding cassettes can be used in welding both single Tees and manifolds. The weldable parts to pipes can be flanges, pipes, threaded nipples or any other parts where there is a hole and the material thickness is suitable. Furthermore, a very effective production situation is created by using two welding cassettes, where one cassette is in welding while the other cassette is being loaded. The handling of parts is also very cleverly and simply realised in Larikka CylinWeld. First, the base part of the cassette is dropped inside the positioning device. Next, the branch part is dropped to the guiding pins which are on the central line of the positioning device. After this the main pipe is put into the cassette so that the tip of the guiding pins goes inside the main pipe’s hole. Now the weldable parts are positioned into the welding cassette so that the branch pipe’s arc is against the main pipe’s hole. Also, the central lines of the weldable parts and inside electrode’s axis of revolution are concentric and parallel. As the welding cassette is closed the parts are pressed tightly against each other thus forming a shielding gas atmosphere for controlling the inner and outer shielding gas during the welding (figures 4 and 5). After fixing the parts, the welding cassette is removed from the positioning device and is loaded into the welding chamber (figure 6). By the start command the pneumatic actuator of the welding chamber locks the chamber to its position and connects the outside shielding gas as well as the earth current contact. The

Figure 6 : A 6x1mm Tee in the welding chamber

Figure 7 : Larikka CylinWeld Tees: welding seam from inside

fully automatic welding begins after the programmed pre-purging time and it processes according to the pre-programmed welding parameters. After the cooling time the pneumatic actuator releases the cassette which can be then unloaded from the machine and unlocked. The welded part can now be removed from the cassette and the welding result can be immediately visually checked for a full weld penetration since the root is on the part’s outer surface. During the welding the arc flame has travelled over the sharp inner corners of the tubular parts’ joining point and melted these corners into a good, round corner. The welding has a positive welding bead both inside and outside (figure 7). Thus, the welding result of Larikka CylinWeld fulfils all the characteristics of quality tubular parts: 1) the large radius of the inner corner of a branch; 2) smooth inner surface; 3) good flow technical properties; and 4) good material strength. Conclusions Small tubular parts are manufactured better from inside. Larikka CylinWeld makes the difference in manufacturing quality Tees and manifolds from stainless steel and other high alloy with its cylinder internal welding approach. It enables manufacturers of tubular parts to respond to the increasing demands on material savings, production process optimisations and reduction of the carbon footprint without compromising the quality of pipelines.

Figure 4 : A manifold and a 6x1mm Tee in a welding cassette inside positioning device

Larikka Ltd – Finland Tel: +358 20 7121 444 Fax: +358 20 7121 449 Website: www.larikka.com

Figure 5 : Manifolds in welding cassettes

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J anuary 2012

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