网络优化资料：

The main materials, equipment and products lack technical quality appraisal documents or product qualification certificates that meet the current national or ministerial standards.

Result: The quality of the project was unqualified, there were potential safety hazards, and it could not be delivered on time. It must be reworked and repaired, the construction period was delayed, and labor and material input were increased.

Method: The main materials, miniature solenoid valve equipment and products used in water supply and drainage and heating and sanitation engineering must have technical quality appraisal documents or product qualification certificates that comply with current national standards; product name, model, specification, and national quality standard code must be indicated , Date of delivery, name and location of the valve manufacturer, and product inspection certificate or code number.

The necessary quality inspections were not carried out in accordance with the regulations before installing the check valve. This will cause the check valve in the operation of the system to be inflexible, not tightly closed, water leakage (steam), rework and maintenance, and even the proportional solenoid valve affects the normal water supply (steam).

Method: Before installing the check valve, conduct a compressive strength and strength test. Each batch of products (same brand, same specification, and same model) shall be randomly inspected for 10%, not less than once. For the closed-circuit check valves installed on the main pipe to cut off, the strength and tightness tests should be carried out one by one. The strength and sealing test pressure of the stop valve should meet the requirements of "Code for Construction Quality Acceptance of Building Water Supply and Drainage and Heating Engineering" (GB50242-2002).