The extensive application of polyethylene pipes for the transportation of water, oil, and gas across diverse sectors, including the oil and gas industry, and refining operations, has rendered the connection of these pipes a significant area of interest for researchers. The butt-fusion welding technique has been presented as an effective alternative to the electro-fusion method, which is hindered by drawbacks including insufficient joint strength and elevated expenses . In this study, an investigation was conducted on the four samples, comprising the base material sample and three additional samples each subjected to varying conditions of welding temperature and pressure. The investigation utilized a range of polymer analysis techniques, including Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) that were performed on both the body sample and the optimal high-density polyethylene weld sample, which were joined through a butt-welding process. Both FT-IR and Raman spectroscopy analysis indicated that there was no reduction was observed in crystallinity of the sample welded in optimized conditions compared to the body sample. Additionally, XRD analysis revealed a relative increase in the amorphous fraction when compared to the body sample. The thermal analysis conducted on the samples indicated that there was no significant difference in the melting temperatures of both the body sample and the welded sample, with both exhibiting melting points of around 133 °C. Additionally, the SEM images revealed a nearly identical sheet-like morphology for both the body sample and the optimized sample.