Valve installation knowledge and matters needing attention petrochemical plant valve installation requirements

Valve installation knowledge and matters needing attention petrochemical plant valve installation requirements

Valve installation requirements
The quality OF the valve installation is good or bad, directly affect the use of the valve after, therefore, the construction unit and production unit should be introduced to attach great importance
Valve installation shall be carried out in accordance with the valve instruction manual and relevant regulations. In the process of construction, we should check carefully and construct carefully. Before THE VALVE IS INSTALLED, IT SHOULD BE INSTALLED after THE pressure test is qualified. Carefully check whether the specification and model of the valve are consistent with the drawings, check whether the parts of the valve are intact, whether the opening and closing valve is flexible and free, and whether the sealing surface is damaged, etc., and install the valve after confirmation.
When the valve is installed, the operating mechanism of the valve should be about 1.2m from the operating ground, which will be flush with the chest. When the center of the valve and the handwheel are more than 1.8m away from the operating ground, the operating platform should be set up for the valves and safety valves with more operation. For pipes with more valves, try to concentrate the valves on the platform for easy operation.
Equipment such as sprockets, extension rods, movable platforms, and movable ladders may be used for individual valves over 1.8m and infrequently operated. When THE VALVE IS INSTALLED BELOW THE OPERATING SURFACE, THE EXTENSION ROD SHALL BE provided, and the ground VALVE shall be provided with a ground well, which shall be capped for safety.
The stem of the valve on the horizontal pipe must be vertically upward. It is not suitable to install the stem downward. Valve stem downward installation, inconvenient operation, inconvenient maintenance, but also easy to corrosion valve accident. Do not install the floor valve askew to avoid inconvenient operation.
The valve on the side by side pipeline should have space for operation, maintenance and disassembly, and the net distance between the handwheels should not be less than 100mm. If the distance between the pipes is narrow, the valve should be staggered.
For the valve with large opening force, low strength, large brittleness and large weight, the valve frame support valve should be set before installation to reduce starting stress.
When installing the valve, use a pipe wrench for the pipe adjacent to the valve and a regular wrench for the valve itself. At the same time, installation, to make the valve in a half-closed state to prevent the valve rotation and deformation.
The correct installation of the valve should make the internal structure form in line with the flow direction of the medium, the installation form in line with the special requirements of the valve structure and operation requirements. Special attention should be paid to the medium flow requirements of the valve should be installed according to the requirements of the process pipeline. The ARRANGEMENT OF THE VALVE SHOULD BE CONVENIENT AND ACCESSIBLE TO THE OPERATOR. For lifT-stem valves, there should be room for operation. The stem of all valves should be mounted upward and perpendicular to the pipe as far as possible.
Installation of valve connection surface
If the end of the valve is threaded, the screw should be screwed into the depth of the valve. If the screw is screwed into the deep pressure seat, it will affect the good coordination of the seat and the gate. If the screw is screwed into the shallow part, it will affect the sealing reliability of the joint, and it is easy to introduce leakage. At the same time, the thread sealing material should be made of PTFE raw tape sealant, and be careful not to give the sealing material to the valve cavity.
For VALVES WITH FLANGE END CONNECTIONS, FIRST FIND THE CONNECTING FACE OF THE FLANGE, WITH THE FRONT FACE PERPENDICULAR TO THE LINE AND THE BOLT HOLE ALIGNED. The VALVE flange should be parallel to the pipe flange, the flange gap is moderate, there should be no wrong mouth, tilt and other phenomena, the center gasket between flanges should be placed in the middle, can not be skewed, the bolt should be symmetrical and evenly tightened. Prevents an additional residual force from being forced to tighten the connection during valve installation.
Before installation, the pipe inner wall and external thread should be thoroughly cleaned of dirt; *** Burr and foreign matter that hinder the flow of medium and may affect the operation of equipment, blow the dirt, slag and other sundries in the pipe before connecting. Prevent damage to the sealing surface of the valve or plug the valve.
When installing the valve connected at the end of welding, the welding seam at both ends of the valve after spot welding should be arranged first, then the valve should be opened, and the welding seam should be welded according to the welding process. After welding, the appearance and internal weld quality of the weld should be checked to ensure that there is no porosity, slag inclusion, crack, etc., and the weld should be inspected by ray or over control when necessary.
Installation of heavier valves
When INSTALLING HEAVY VALVES (DN100), USE LIFTING TOOLS OR EQUIPMENT, LIFTING ROPE SHOULD BE TIED TO THE flange OR bracket OF THE VALVE, not TO the handle type valve stem, so AS to avoid damage to the valve.
What are the general requirements for valve installation?
Answer: The general requirements for valve installation, appropriate installation height, valve on horizontal pipe, valve stem direction are as follows:
(1) The valve should be located in a place that is easy to access, easy to operate and maintain. The VALVES ON a row of pipes (such as the pipes to and from the device) should be centrally arranged, and the operation platform and ladder should be considered. Parallel arrangement of the valve on the pipeline, its center line should be as close as possible. The net distance between the handwheels should not be less than 10Qmm. In order to reduce the distance between the pipes, the valves can be staggered.
(2) The installation position of the frequently operated valve should be easy to operate, and the appropriate installation height is 1.2m from the operating surface. When the height of the center of the valve handwheel exceeds 2m of the operating surface, the platform should be set for the valve group or the frequently operated individual valve and the safety valve, and the appropriate measures should be taken for the infrequently operated individual valve (such as sprocket, extension rod, movable platform and movable ladder, etc.). The chain of the sprocket should not obstruct access. Valves on pipelines and equipment with dangerous media shall not be installed within the height of the head of the person, so as not to hurt the head, or directly hurt the person’s face when the valve leaks;
(3) The valve used in the partition equipment should be directly connected with the pipe mouth of the equipment or close to the equipment. The valve on the pipe line connected with the equipment of extremely hazardous and highly hazardous toxic medium should be directly connected with the mouth of the equipment, and the valve shall not use the chain vertical;
(4) The accident treatment valve such as fire water valve, fire steam valve and other two valves should be scattered, and take into account the safe operation of the accident. This type of valve should be placed behind the control room. Behind the safety wall, outside the factory door, or with a certain safe distance from the accident place; In order to fire accident, the operator can operate safely;
(5) In addition to the special requirements of the process, the valve on the bottom pipe of the tower, reactor, vertical vessel and other equipment shall not be arranged in the skirt;
(6) the cut-off valve of the horizontal branch pipe led from the dry pipe should be located near the root of the horizontal pipe section;
(7) lift check valve should be installed in the horizontal pipeline, vertical lift check valve should be installed in the pipe medium flow from bottom to top of the vertical pipeline. Swing check valve should be preferentially installed in the horizontal pipeline, can also be installed in the pipe medium flow from the bottom to the vertical pipeline; The bottom valve should be installed in the centrifugal pump suction installation height, can choose butterfly check valve; Pump outlet and the connected pipe diameter is not consistent, can choose reduced diameter check valve;
(8) the center distance between the handwheel of the valve arranged around the operating platform and the edge of the operating platform should not be greater than 450mm, when the stem and the handwheel extend above the platform and the height is less than 2m, it should not affect the operation and passage of the operator;
(9) The valve of the underground pipeline should be located in the pipe trench or the valve well, and if necessary, the valve extension rod should be set. Fire water valve well should have obvious marks;
(10) For the valve on the horizontal pipeline, the direction of the stem can be determined in the following order: vertical upward; Level; An upward tilt of 45; Downward sloping 45; No vertical downward;
(11) Valve stem horizontal installation of open rod type valve, when the valve is opened, the valve stem shall not affect the passage.
Check valve installation needs attention
(1) Installation position, height, import and export direction must meet the design requirements, pay attention to the medium flow direction should be consistent with the arrow direction marked by the valve body, the connection should be firm and tight.
(2) The appearance of the valve must be checked before installation, and the nameplate of the valve should comply with the provisions of the current national standard “General Valve Logo” GB 12220. For the working pressure is greater than 1.0mpa and in the main pipe to cut off the role of the valve, should be installed before the strength and strict performance test, qualified after the use. During the strength test, the test pressure is 1.5 times of the nominal pressure, and the duration is not less than 5min. The valve shell and packing shall be qualified without leakage. Tightness test, test pressure is 1.1 times of the nominal pressure; The duration of the test conforms to the requirements of GB 50243.
(3) Do not make the check valve bear weight in the pipeline, large check valve (AETV one-way valve) : should be ** * supported, so that it is not affected by the pressure produced by the pipe system.