Evaluation of Mechanical Properties of Horticultural Galvanized Steel Pipes Based on Service Life

Mechanical properties of agricultural galvanized steel pipes with service life provide fundamental data for evaluating the structural performance and stability of aging greenhouse structures. Tensile tests (tensile strength, yield strength, elongation) were conducted in accordance with ASTM E8/E8M-16a. Soil pH and EC, in which the pipes were buried, were analyzed. Results were compared with the strength standards requirements for vinyl-house steel pipes specified in the Industrial Standard (KS D 3760). Yield strength met the standard for the 6- and 7-year samples, whereas tensile strength met the standard for the 6-, 7-, 11-, and 13-year samples. Elongation satisfied the requirements for the 7- and 21-year samples. Significant differences in the tensile strength and yield strength were observed with increasing service life, with noticeable reductions occurring after 11 years with an average reduction of about 20%. Elongation showed significant differences in all service years except the 7- and 21-year samples. The average soil pH was 5.8, indicating acidic conditions, and the EC ranged from 0.02 to 0.04 dS∙m−1. Based on these results, a service durability of 7 years is considered reasonable for greenhouses using galvanized steel pipes as structural members.