Plug Valve Repair
All weld repairs and re-welding on plug valves must be performed by certified welders who meet the requirements of ASME Section IX. The welding process should be low-hydrogen, and all welding, including repairs to existing welds, must follow an approved procedure. Any repair involving the main welds requires prior approval from the owner.
Before any heat treatment is applied during production, casting repairs on the plug valve should be completed. If any welding or weld repair is required, it must be done before stress-relieving heat treatments. Hardness testing is mandatory for castings after repairs due to the limited hardness traverse across the weld, heat-affected zone, and base metal. The maximum Vickers hardness value measured with a 500-gram load should not exceed 310 HV.
For all repaired defects, the same non-destructive examination (NDE) method used originally to detect the defect must be applied, following the same standard. Before welding, the area to be welded should be thoroughly cleaned using appropriate tools to remove dirt, rust, or metal debris. Repairs are not permitted if the defect depth reaches 20% or more of the component's thickness.
The plug valve should be installed as close as possible to the reference surface, within the allowable installation location. All above-ground working valves, located on platforms or accessible areas at a height of 2100 mm or higher, must be equipped with hammer pulleys that can be operated manually. The hammer pulley should use a U-shaped bracket rather than a J-type bolt clamp. The valve must be suitable for both vertical and horizontal installations.
Additionally, it is important to ensure that all repair procedures are documented and reviewed by qualified personnel. Regular inspections should be conducted to verify that the repaired components meet the required performance and safety standards. Proper training of maintenance staff is also essential to maintain the integrity of the plug valve system over its service life.
Guangzhou Fuerle Health Technology Co., Ltd , https://www.fuerlegroup.com