Patent ID: 11959148
Assignee: YAMADA INFRA TECHNOS CO., LTD.
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 0:
1. A preventive maintenance method for a steel bridge comprising:
performing, using grit as an abrasive, abrasive blast-cleaning on a portion of the steel bridge including a weld site where a first steel material is welded to another steel material, wherein the portion is subjected to surface preparation and has an abrasive blast-cleaned surface;
after the abrasive blast-cleaning is performed on the portion, applying a fluorescent coating material to the portion;
after the fluorescent coating material is applied to the portion, performing, using shot, shot peening on the portion in order to improve fatigue strength of the portion;
after the shot peening is performed, partially removing the fluorescent coating material from the portion, and then, irradiating the portion with an ultraviolet ray;
calculating coverage based on a residual fluorescent coating material that fluoresces;
in response to determining that the coverage is less than a specified standard determination value that is 90%, applying the fluorescent coating material to the portion again, performing the shot peening on the portion, and determining whether the coverage is the specified standard determination value or higher;
in response to determining that the coverage is the specified standard determination value or higher, determining that the shot peening is completed, wherein the determining that the shot peening is completed includes:
applying the fluorescent coating material to the portion of the steel bridge again, performing the shot peening on the portion;
determining whether the coverage is the specified standard determination value or higher; and
in response to determining that the specified standard determination value or higher, determining that the shot peening is completed; and

performing final finish coating to form a finishing coat on the portion after the shot peening is completed,
wherein the weld site has a weld where the first material and the second steel material are joined to form a corner, the weld existing inside the corner, in a cross-sectional view,
wherein, in the cross-sectional view, the weld site has a first gap between the weld and the first steel material and a second gap between the weld and the second material, wherein the shot peeing performs shot peening on portions of the weld adjacent to the first gap and the second gap to deform the portions to, in the cross-sectional view, (1) close the first gap and the second gap, and (2) have concave R surfaces, in order to increase an externally-visible area of the weld, and
wherein whether the concave R surfaces is properly formed is determined using a ball gauge or a non-contact measuring instrument.