## 1 Introduction  
HDPE pipes are widely used in numerous national projects, including the transmission of natural gas, due to their constructability, maintainability, impact resistance, chemical resistance, flexibility, lightweight, and long service life [1, 2, 3]. Polyethylene gas pipes must also have a service life of at least 50 years, according to standard 4437. Given the diversity of the local natural surroundings, different factors can affect corrosion to which HDPE gas pipes are susceptible [4]. For instance, different acidic and alkaline corrosive elements in the soil, such as NaOH, H\({}_{2}\)SO\({}_{4}\), HCl, HClO, CH\({}_{3}\)COOH, H\({}_{2}\)O, etc., would have varied degrees of corrosive effects on underground gas pipes, so the pipes cannot avoid deformation, or even failure and damage [5]. During transportation, natural gas also comes into contact with polyethylene piping materials. Natural gas may contain acidic components like hydrogen sulfide (H\({}_{2}\)S), carbon dioxide (CO\({}_{2}\)), and some organic acids (such as acetic and propionic acid), which may lead to the corrosion of polyethylene piping materials. Gas leaks, flames, and explosions will result from the corroded underground gas pipeline, which will also disrupt the regular, uninterrupted flow of gas into the city, affecting output and user safety. This not only causes the country to suffer enormous financial losses, but it also seriously jeopardizes public safety. Therefore, it is essential to conduct research on the lifespan of buried natural gas polyethylene pipes for both academic and pipeline construction objectives, as well as for technical assistance in the study of HDPE pipeline life prediction methodologies under alkaline and acidic conditions.  
In the investigation of PE pipe failure, one of the research issues of considerable interest has been the aging life prediction of PE materials. First, the aging of PE pipes must be sped up using the proper techniques. Presently, corrosion immersion experiments and saline spray testers are frequently used in corrosion-accelerated pipe aging experiments. This experiment accelerates the aging of polyethylene pipe by applying an acid and alkali corrosion immersion experiment because the saline spray tester cannot replicate the intense acid corrosion in a real working environment. It is also necessary to measure several physical characteristics of old polyethylene pipes. Using differential scanning calorimetry, [PERSON] [6] investigated the aging of HDPE caused by several variables under accelerated aging circumstances. [PERSON] and [PERSON] used tensile and fatigue studies to study the fluctuation of HDPE characteristics in the circumferential and axial orientations [7; 8]. The tensile test was utilized to evaluate the mechanical characteristics of the aged polyethylene pipe because the strain-hardening modulus algorithm used in this experiment is dependent on its outcomes. Third, suitable algorithms are also required to forecast the lifespan of PE pipes. A strain-hardening method is employed in this experiment to forecast the lifespan of aging PE pipes. Under the effect of complex environmental and external factors, HDPE pipes are prone to failure modes such as quick crack development, delayed crack expansion, and material aging [9; 10]. The strain-hardening test (SH) can more accurately describe the slow crack extension resistance of polyethylene, although slow crack extension (SCG) has been employed as one of the crucial technical indicators to assess the failure resistance of PE materials [1; 2; 3; 4]. By using the correlation between the strain-hardening modulus and failure time, [PERSON] et al. determined the failure time of natural gas PE pipes [11; 12]. In this study, the service life of municipal gas polyethylene pipes was predicted using immersion corrosion accelerated aging tests and tensile testing.