PSI - Issue 57

Kaushik Iyer et al. / Procedia Structural Integrity 57 (2024) 469–477 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

473

5

Figure 3: Lifecycle of a welded structure

3.3. Post-Weld Treatment: Automated HFMI The cost of implementing the automated post-weld treatment was calculated using an activity-based costing model adapted from the work performed by (Karlsson Hagnell and Åkermo 2015). The automated HFMI line was split up into a set of individual activities, with the corresponding machines used, as shown in Figure 4 respectively. The production cost of the sample can be divided as a constituent of two types of costs: Indirect costs, such as capital costs, investment, storage, etc which depend on the production volume, and Direct costs such as variable electricity consumption, and material costs which are independent of the production volume (Table 3)

(a)

(b)

Figure 4 (a): Automated HFMI treatment-Process flowchart (b): Corresponding machines

Table 3: Direct and Indirect Costs

Direct Costs Material costs

Indirect Costs

Capital Investment

Variable power consumption

Labor Fixed Electricity Consumption

The samples were manufactured using an S355 steel with a yield strength of 355 MPa. Since the current cost model is a predictive model, the material prices were derived from steel price indices. The material cost is calculated using equation 2, while the scrap rate of the production process is derived from (Hagnell, et al. 2021) . Prior to the PWT stage, the sample is assumed to have been machined and welded together by a manual metal Active Gas Welding (MAG) process. Two types of samples are considered for this current comparison study: As welded and post-weld treated. The weld cost was estimated using a predictive cost modeling methodology while the relevant process parameters such as welding speed, power consumptions, and wire feed speed were derived from a study conducted by (Kuss, et al. 2017). The cycle time of the PWT can be assumed to be comprised of: Scanning time, t transfer , t scan , and t pass . While the transfer and scanning times were approximated as 10 seconds, the pass time of the HFMI treatment can be estimated