Valve Installation Taboos And Troubleshooting （Ⅰ）

Valve Installation Taboos and Troubleshooting （Ⅰ）

A valve is a device used to control the direction, pressure, and flow of a fluid in a fluid system. It is a device that enables the medium (liquid, gas, powder) in piping and equipment to flow or stop and can control its flow. During the construction process, the way the valve is installed will directly affect the normal operation in the future. This article will summarize some precautions during the installation of the valve, and I hope it will help the reader.

Taboo 1: The main materials, equipment and products used in construction lack technical quality appraisal documents or product qualification certificates that meet the current standards issued by the state or the Ministry.

Consequences: The quality of the project is unqualified, there is a hidden danger of the accident, and it cannot be delivered and used on time, and it must be reworked and repaired; resulting in the delay of the construction period and the increase in labor and material input.

Measures: The main materials, equipment and products used in the water supply and drainage and heating and sanitation projects should have technical quality appraisal documents or product qualification certificates that comply with the current standards issued by the country or the ministry; they should indicate their product names, models, specifications, and national quality standards Code, date of manufacture, manufacturer's name and location, product inspection certificate or code.

Taboo 2: Before the valve is installed, the necessary quality inspection is not carried out according to the regulations.

Consequences: During the system operation, the valve switch is not flexible, the closing is not strict, and the phenomenon of water leakage (steam) occurs, causing rework and repair, and even affecting the normal water supply (steam).

Measures: Before the valve is installed, the compressive strength and tightness test should be done. The test shall be conducted with 10% of each batch (same brand, same specification, same model) quantity, and not less than one. For the closed-circuit valves installed on the main pipe to cut off, the strength and tightness test shall be carried out one by one.

Taboo 3: The specifications and models of the installed valves do not meet the design requirements. For example, the nominal pressure of the valve is less than the system test pressure; the gate valve is used when the pipe diameter is less than or equal to 50mm; the cut-off valve is used for the dry and riser pipes of hot water heating; the butterfly valve is used for the suction pipe of the fire pump.

Consequences: affect the normal opening and closing of the valve and adjust the resistance, pressure and other functions. It even caused damage to the valve and forced repairs during system operation.

Measures: Familiar with the application range of various valves, and select the valve specifications and models according to the design requirements. The nominal pressure of the valve must meet the requirements of the system test pressure. According to the requirements of the construction specifications: the water supply branch pipe diameter is less than or equal to 50mm should be used globe valve; when the pipe diameter is greater than 50mm should be used gate valve. Gate valves should be used for hot water heating dry and vertical control valves, and butterfly valves should not be used for suction pipes of fire pumps.

Taboo 4: The valve installation method is wrong. For example, the flow direction of the water (steam) of the globe valve or check valve is opposite to the mark. The valve stem is installed downward. The horizontally installed check valve is installed vertically. There is no open or closed space for the open stem gate valve or butterfly valve handle. The valve stem is concealed. Not facing the inspection door.

Consequences: Valve failure, difficulty in overhauling the switch, and valve stem down often causes water leakage.

Measures: Install in strict accordance with the valve installation instructions. The open stem gate valve should have sufficient length to open the stem. The butterfly valve fully considers the turning space of the handle. Various stems should not be lower than the horizontal position, let alone downward. Concealed valves should not only be equipped with inspection doors that meet the opening and closing needs of the valves, but also the valve stem should face the inspection doors.

Taboo 5: Ordinary valve flanges are used for butterfly valve flanges.

Consequences: The size of butterfly valve flanges and common valve flanges are different, and some flanges have small inner diameters, and the flaps of butterfly valves are large, which can not be opened or rigidly opened to damage the valve.

Measures: The flange should be processed according to the actual size of the butterfly valve flange.

Taboo 6: No holes or embedded parts are reserved in the construction of the building structure, or the size of the reserved holes is too small and the embedded parts are not marked.

Consequences: During the construction of the heating and sanitation project, cutting the building structure and even cutting off the stressed steel bars will affect the safety performance of the building.

Measures: Seriously familiar with the construction drawings of the heating and sanitation project, actively reserve the holes and embedded parts according to the needs of the pipeline and the support and hanger installation, and refer to the design requirements and construction specifications.

Taboo 7: When the pipeline is welded, the misalignment of the pipe after the alignment is not on a center line, the alignment does not leave a gap, the thick-walled pipe does not shovel the groove, and the width and height of the weld do not meet the requirements of the construction specifications.

Consequences: The misalignment of the pipe does not directly affect the welding quality and perception quality in the center line. There is no gap at the mouth, thick wall pipe does not shovel the groove, when the width and height of the weld do not meet the requirements, the welding cannot meet the strength requirements.

Measures: After welding the pipe to the butt, the pipe must not be misaligned. The center should be on a center line. The butt should have a gap. The thick-walled pipe should be shoveled. In addition, the width and height of the weld should be welded acaccording to the specifications.