PSI - Issue 33

Singgih Dwi Prasetyo et al. / Procedia Structural Integrity 33 (2021) 43–50 Prasetyo et al. / Structural Integrity Procedia 00 (2019) 000–000

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(a) (b) Fig. 7. Formed material into the coil parts: (a) Slave; (b) Nozzle.

Then, the process is continued by cutting several basic components, e.g., pipes, plates, and elbows, according to the length of the design size using plasma cutting. The pipeline will be formed into a coil by rolling, as shown in Fig. 6. The rolling process is carried out by one machine operator and one assistant. The method of making the cover plate is almost the same, namely cutting the plate, welding, punching, and bolting following the design. The process to manufacture slave and nozzle is conducted by bending the pipe, connecting each part, and grinding using a hand grinding machine. The results of making slave and nozzle are presented in Fig. 7. 3.3. Assembly stage Bolt is a connecting component with a round and threaded rod, one end formed by the head of a bolt (generally the shape of a hexagon head), and the other end is mounted with a nut/lock. Usually, bolts are used to make the construction of fixed connections, mobile connections, or temporary connections that can be dismantled/removed again. The shape of bolt rods for steel construction is generally triangular threads (sharp threads), namely as fastening bolts. In this process, the bolt connection is used to connect the coil to the L plate cover, as shown in Fig. 8a. The distance between the bolts has been set based on the design drawing. This connection type using bolt is used to maintain the gap between the coil that has been formed. Therefore, there is no contact between the coil walls, which will be dangerous if the inter coil is too close. Fitting and checking parts of the heating coil, which will then be connected with welding, are presented in Fig. 8b.

(a) (b) Fig. 8. Assembly stage of the melter parts: (a) Bolting process; (b) Fitting and welding process.

This welding process is to connect all elements, i.e., coil, cover, and slave nozzle. Full details of welding carried out based on the Welding Procedure Specification (WPS) and Detailed Welding Instruction (DWI) are discussed. In general, the fitting and welding procedures are performed as follows:  At the time of fitting, welders must also consider the shrinkage due to welding.  Weld (track weld) stage must be conducted by qualified fitters.  Welding is carried out following welding procedures (WPS. Welding is performed using a Gas Welding Machine, Tungsten Arc Welding GTAW AWS Class ER. 70S-6 with SFA Spec. 5.18, filler metal QW-404 diameter 2 mm number 6.  Welders/welding machine operators must be selected who are qualified (certified).  Welding can only be performed if it has received permission from the Quality Control. If welding is done from two sides, the root pass must be gouged and checked by a penetrant test.