Welding of Pipe Heating Systems

Purely practical article on this topic.

Welding of pipe heating systems

general view of the assembly stand; 1 - Shelf 2 - pipe, 3-protective tent;

Assembly and welding of pipes of different lengths lashes up to 36 meters is on the metal racks with external chain of centralizers (Fig. a). The requirements for clearances and displacements of the edges depending on the used welding methods may be different. For example, if the process provides for jelly inside the pipe joints, the gaps can range from 0 to 1.5 mm. Conversely, if the process provides for a one-sided welding with subsequent control by a rentgenoprosvechivanii clearance must be strictly regulated in the case of welded joints in the assembly nonslewing position should be 3 5-4,0 mm. The welding joints with higher clearances than the welding joints with standard clearances by about 25-35%.

For example, the duration of the assembly and welding of pipe joints d820x9 mm. When the gap in the joint is equal to 1.5 mm, respectively, of 46 and 50 min. When the gap in the joint 3.5-4 mm during assembly and welding are, respectively, 30 and 80 min. Thus, at the expense of quality of welding, provided the necessary continuity of the weld metal and the formation of the back of the root layer.

The technology of welding pipe whip on the shelves

The first option. According to this variant (Fig. lb), the entire circumference of the ring interface is divided into five equal parts, two of which (№ 1 and 3) brewed in the ceiling and polupotolochnom positions.

The remaining sections of the joint brewed in an upright position, which contributes to the formation of the deposited weld metal and the higher productivity of welders. For the welding area number 5 the product is turned by 90 °.

The sequence of welding seam of the base layer is shown in Fig. 34, c. It is seen that the two welders welding is done by the "bottom up" and with the rotation of the product. Electrodes used for welding d4 mm mark SSSI or TMU-1355-21U.

The second option. Under the second option (Fig. c) joint is divided into four sections, which are brewed in pairs in an upright position, for which the product is turned on 180g This sequence of welding eliminates the welding in the overhead and bottom positions, which are characterized by a more unfavorable conditions for the formation of weld metal and the formation of defects such as sag, and menisci.
Welding seam of the base layer is made in the sequence shown in Fig. 34, the We see that the seams are imposed in the formation of metal-friendly provisions and permitted application of high-welding conditions. This contributes to better development of chemical and metallurgical processes and degassing of molten metal weld pool.

The sequence of jelly inside of pipes is shown in Fig. Overlay on the layers podvarochnyh seam produced, usually without transverse oscillation of the electrode. On the one hand, allows you to locate the thermal capacity of the arc at the fusion line edges and, thus, to be sure that the fusion joined pipe edges and on the other hand, increases in labor productivity.

See also:
Welding of Water Pipe Network
Welding of Pipe Heating Systems