Stainless Steel Pipe Fittings

Requirements for equipment layout in 19 chemical plants

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1. What are the specific requirements for the design of the side pipe of the tower?
The tower side piping design has these requirements:
(1) The pipe on the side of the tower body generally has reflux, feed, side line extraction, stripping steam, reboiler inlet and return pipe, etc. In order to make the valve closed without liquid accumulation, the valve on the pipe should be directly connected with the tower pipe. The ports are directly connected, and when the inlet (outlet) material pipe has more than two inlets (outlet) openings at the same angle, the pipe should consider a certain flexibility;
(2) If there is a regulating valve on the pipeline from the side line of the fractionation tower to the stripper, the installation position should be close to the stripper. In order to ensure that there is a period of liquid in the same adjustment. The height of the liquid column should meet the requirements of the process.
2. What are the characteristics of the tower bottom piping design?
Features of the tower bottom piping design:
(1) The operating temperature of the bottom of the tower is generally high, so the flexibility of the bottom piping should meet the requirements of relevant standards or specifications when arranging the bottom piping. In particular, when the bottom draw pipe is connected to the pump, the pipe should be short and less curved, and sufficient flexibility is required to reduce the force on the pump nozzle.
The bottom drawing line should be led to the outside of the tower skirt or the base. It is strictly forbidden to set the flange into the pipe fittings and other fittings. The extraction pipe from the bottom of the tower to the bottom of the pump shall not have a “pocket shape” on the horizontal pipe section, and it shall be “low step” to avoid cavitation of the bottom pump. The partition valve on the extraction pipe should be closest to the tower body. And easy to operate.
(2) Unless it is an auxiliary reboiler, or two or more parallel reboilers are operated at the same time, and it is required to adjust the heat load over a wide range, the bottom of the tower to the reboiler is generally not suitable for a valve.
When the bottom tank type heavy Buddha is equipped with a centrifugal pump, the elevation of the reboiler should meet the effective NPSH required by the centrifugal pump, and at the same time, the static difference between the liquid level of the bottom of the tower and the liquid level of the reboiler The indenter is sufficient to overcome the pressure loss of the downcomer, reboiler and riser. Therefore, the piping should be arranged to meet the flexibility requirements, the piping should be short, and the elbow should be small.
3. What requirements should be placed in the arrangement of manholes on the tower?
The arrangement of manholes on the tower should meet these requirements:
(1) The manhole of the tower should be located in the operating area of the tower. It is convenient, safe and reasonable to enter and exit the tower, and should be located in the same orientation.
(2) The location of the manhole must be noted that the internal components of the tower should generally be located in the bubbling area above the tray and should not be placed in the downcomer or receiver tank area of the tower;
(3) Manholes (or hand holes) on the tower body, generally one for every 3-8 layers of trays;
(4) The height of the manhole center from the platform surface is generally between 600mm and 1000mm, and the most suitable height is 750mm;
(5) The holes on a tower should be arranged on the same vertical line to make it neat and beautiful.
4. What are the requirements for the nozzle orientation of the tower?
The nozzle orientation requirements of the tower are as follows:
(1) The nozzle orientation of the tower should meet the working principle and structure requirements of the inner part of the tower. The overall structure of the inner part of the equipment and the relative orientation of the nozzle should be paid attention to during design; the gas phase opening at the top of the tower is arranged in the middle of the top cover of the tower; The opening is generally arranged on the side of the pipe above the tray; the gas feed inlet is above the tray, parallel to the downcomer; the gas-liquid mixed phase feed opening is above the tray, and a distribution pipe is provided; the stripping steam opening is stripped Below the tray, add a gas distribution tube.
The side line product extraction outlet should be provided with an extraction hopper in the arc range below the downcomer. For the double overflow tray of the intermediate downcomer, the extraction outlet can be arranged at any angle there, and the extraction hopper is provided; The mouth is located in the middle of the bottom cover of the tower, and is provided with a vortex prevention plate, and the suction outlet should extend outside the skirt of the tower;
(2) For towers with trays, the manholes should be arranged on the diameter of the tower parallel to the overflow weir of the tray. If the conditions are not allowed, the gaps may not be parallel, but the clearance between the manhole and the weir in the horizontal direction should not be Greater than 50mm;
(3) The orientation of the manhole lifting and the setting of the ladder should be arranged uniformly. In the event of an accident, the direction in which the human cover is smoothly closed should be consistent with the direction of evacuation;
(4) The level gauge interface can be directly connected to the level gauge through the root valve, or can be connected to the level gauge through the root valve. The level gauge interface must not be placed within the 60° angle of the opposite side of the inlet, unless the inlet is protected by an internal baffle. The outer float type liquid level control nozzle directly connected to the tower shall be provided with a baffle. Level gauges, liquid level control buoys, alarms and other devices are often located in the tower platform or at the end of the local platform to facilitate maintenance;
(5) The pressure gauge interface should be placed in the gas phase zone of the tower so that the pressure gauge reading is not affected by the liquid level head;
(6) Arrangement of sampling port and temperature measuring port, gas phase sampling port and temperature measuring port should avoid the gas phase zone of the tray downtake tank, liquid phase sampling port and temperature measuring port should be set in the tray holding area of the downcomer area In the layer; for the liquid phase sampling tube which is easy to crystallize, it should be directed to the tray;
(7) The top of the tower shall be positioned so that it can reach above the lifting point outside the platform and the position of all the holes in the platform.
5. What is the orientation of the device nozzle orientation map in addition to the nozzle?
In addition to the process and common media nozzles, it should also indicate:
(1) The orientation of the instrument takeover, including temperature, pressure, and liquid level;
(2) the orientation of the manhole, the hand hole and the hanging column, and the orientation of the venting hole of the skirt;
(3) the orientation of the anchor bolt holes of the equipment or the orientation of the lugs;
(4) the orientation of the lifting lugs, the grounding plate and the nameplate;
(5) The orientation of the internal ladder and the bottom of the skirt to strengthen the support.
6. How to determine the fixed side of the horizontal container support?
Find the most important (difficult or most demanding) pipe for the flexible calculation from the pipe to which the container is to be connected, such as a pipe with a large amount of compensation and a large pipe diameter, as the basis for determining the type of support. The position of the fixed side support should facilitate the flexible calculation of the pipe.
7. What are the requirements for the orientation of the horizontal container?
What are the requirements for the orientation of the horizontal container?
(1) The liquid inlet and outlet spacing on the equipment housing should be as far as possible. The liquid inlet pipe should be as far as possible from the container level gauge interface;
(2) The level gauge interface should be placed in a position that is easy for the operator to observe and convenient. Sometimes, in order to reduce the nozzle on the device, a measuring device such as a liquid level gauge, a liquid level controller, and a liquid level alarm can be installed on the header. The orientation of the wave gauge nozzle shall be arranged on the same side as the liquid level regulating valve group;
(3) Manhole covers connected by hinges (or hanging columns) shall not affect other nozzles or pipes when opened;
(4) The safety valve nozzle shall be located at the top of the vessel.
8. What are the general requirements for piping arrangements for horizontal containers?
The piping of the vessel (tank) is relatively simple; the piping arrangement of the vertical vessel is generally similar to that of the tower, and is also designed along the tank wall. The valve on the pipeline is also required to be directly connected to the opening; this avoids fluid accumulation.
When the horizontal container equipment is arranged, the tank is generally perpendicular to the longitudinal direction of the pipe gallery, so that the pipes such as the gas outlet pipe, the safety valve outlet pipe, the liquid outlet pipe, etc. are all oriented toward the pipe gallery and related to the pipe gallery; connection.
The pipe that is open at the top of the vessel should have an elevation higher than the main pipe that meets the pipe gallery to facilitate access to the top of the main pipe. When the liquid outlet pipe at the bottom of the vessel is connected to the pump under the pipe, the bottom elevation of the pipe should not affect the passage of people.
(1) For the pipe connecting the liquid outlet of the horizontal container to the pump suction port, the minimum clearance height is 2200mrn if the pipe is overhead on the channel;
(2) The pipe connected to the bottom nozzle of the horizontal container, the low discharge point of the low point is 150mm from the floor;
(3) When the outlet of the safety valve is discharged into the closed pipe system, the liquid should be avoided, and the outlet pipe of the safety valve should be connected to the top of the closed main pipe at a 45° downward flow direction, and there is no “pocket shape”. If the safety valve is installed away from the container, check the pressure drop from the container to the safety valve inlet pipe;
(4) The regulating valve group of the tank top pipe is arranged on the platform;
(5) The platform should be set according to the equipment and piping layout.
9. What are the general requirements for the layout design of the heating furnace piping?
The general requirements for the design of the furnace piping layout are:
(1) The arrangement of the heating furnace piping varies with the furnace type of the heating furnace. When the heating furnace piping is arranged, the inlet and outlet piping, fuel system piping, ash blowing gas pipeline, fire extinguishing steam pipeline, etc. should be considered uniformly;
(2) The cylindrical furnace inlet and outlet manifolds are usually arranged in a ring shape around the furnace body and can be supported on the ground or the furnace body. The annular main pipe shall be arranged above the fire door to facilitate the normal operation and maintenance of the fire door;
(3) If necessary, bend the pipe at the exit of the furnace. An anti-vibration bracket is provided in addition to the tee or the larger diameter, or from the bottom of the furnace top vertically downward;
(4) If a rupture disc is placed in the pipe, its direction shall not be directed towards the operation or equipment;
(5) The main regulating valve group is usually arranged between the pipe gallery and the furnace body and pay attention to the passage requirements;
(6) The valves on the steam, fuel oil or fuel gas pipelines should be placed on vertical pipes near the fire door and meet the requirements for regulation and overhaul;
(7) In cold areas, steam heating shall be applied to the fuel oil pipeline according to regulations;
(8) Pipes close to the nozzle shall be connected in a convenient structure for easy cleaning and maintenance;
(9) Platforms and ladders shall be provided at frequently operated valves and observation points at higher positions;
(10) The discharge point of the fuel pipeline shall be at least 15m away from the furnace and shall be discharged into the collection system and shall not be discharged directly into the sewer;
(11) Pipes connected to the furnace should be arranged as concentrated as possible to facilitate support and achieve coordination. Aesthetic purpose
(12) For the feed pipe of the heating furnace, the flow rate of each pipe should be kept uniform; for the whole liquid phase feed pipe, generally, each channel is provided with a flow regulating valve to adjust the flow of each road, otherwise the pipe should be symmetrically arranged, and the gas-liquid two phase The inlet and outlet pipes must be arranged symmetrically to ensure the same pressure drop across the roads;
(l3) The annular oil line should calculate the thermal compensation amount at the highest temperature and absorb the thermal expansion amount by natural compensation of the pipeline.
10. What are the general requirements for the fuel gas piping arrangement of the furnace?
The general requirements for the fuel gas piping arrangement of the furnace are:
(1) The fuel gas should be provided with a distribution main pipe so that the fuel gas of each nozzle can be evenly distributed; the fuel gas branch pipe is led out from the upper part of the distribution main pipe to ensure that the fuel gas entering the nozzle does not carry water or condensed oil.
At the end of the fuel gas distribution main control, a drain valve of DN20 is installed to facilitate the trial flushing and draining after the line is cleaned, and the oxygen content in the pipeline is sampled and analyzed at the time of starting. Two drain valves should be provided on the drain pipe to avoid leakage. The valve can be operated on the ground or on the platform. The fuel gas shut-off master valve should be placed 15m away from the furnace.
(2) The flame arrester can be prevented by providing a flame arrester on the fuel gas pipeline. The flame arrester can be divided into a dry flame arrester and a safe water seal according to the principle of action. A dry flame arrester of a multi-layer copper mesh is generally used on a fuel gas pipe of a heating furnace in an industrial production plant. The flame arrester should be placed close to the nozzle. The distance between the pipeline flame arrester and the burner should not be greater than 12m. In this way, the flame arrester is not subject to severe explosion conditions and the service life can be extended.
11. How to consider the piping arrangement of shell-and-tube type heat exchanger equipment?
Pipe arrangements for shell and tube and heat exchangers should consider the following:
(l) The process piping arrangement should pay attention to the flow direction of the cold and hot streams, generally the cold flow is from bottom to top, and the heat flow is from top to bottom;
(2) The piping arrangement should be easy to operate and does not hinder the maintenance of the equipment;
(3) The basic elevation of the heat exchange equipment shall be such that the lower drain pipe is not less than 150 mm from the ground or platform surface;
(4) Pipes of heat exchange equipment can only have one high point and one low point, avoiding “air bag” or “liquid bag” in the middle, and set high point to vacate and low point to clean; in the area of heat exchange equipment Try to avoid pipe crossing and bypass; try to reduce the number of layers of pipe overhead, usually 2-3 layers;
(5) Two or more parallel heat exchange equipment inlet pipes are arranged in a straight symmetrical manner, and the gas-liquid two-phase flow heat exchange equipment must be symmetrically arranged to achieve a good heat transfer effect;
(6) The measuring instrument on the inlet and outlet pipes of the heat exchange equipment shall be installed close to the operation channel and the place where it is easy to observe and overhaul;
(7) Pipes of easy-to-condensate medium or pipelines containing solid particles connected to the heat exchange equipment, the shut-off valves shall be provided on the horizontal pipes, and the formation of dead angle effusion shall be prevented;
(8) In the cold area, the upper and upper water pipes of the outdoor heat exchange equipment shall be provided with a drain valve and an antifreeze connecting pipe.
12. How should the piping arrangement of the heat exchangers arranged in groups be designed?
The piping layout design of heat exchangers arranged in groups should pay attention to the following points:
(1) In the area of heat exchange equipment arranged in groups, pipes may be laid on the ground or platform surface, but shall not impede access and operation;
(2) When there is no regulating valve or draining pipe on the pipeline, the clearance from the bottom of the pipe should be greater than or equal to 150mm;
(3) The regulating valve group shall be arranged parallel to the cold changing equipment;
(4) The clearance between the heat exchangers arranged in groups shall be greater than or equal to 650 mm;
(5) Pipe layout should consider the disassembly space of the pipe box and head cover of each heat exchange equipment;
(6) The inlet and outlet pipes of multiple sets of heat exchange equipment in parallel should be arranged symmetrically.
13. What are the requirements for the piping arrangement of the vertical reboiler?
The piping arrangement of the vertical reboiler has these requirements:
(1) Pipes must be flexible enough to compensate for thermal expansion of equipment and piping under various operating conditions;
(2) When the mouth of the reboiler is docked with the nozzle of the tower, if the load conditions permit, it is better to provide a bracket to support the reboiler on the tower body, and the position and form of the bracket should be able to meet the expansion of the tower body and the pipeline. The resulting displacement and load requirements;
(3) The piping should be left with the space required for the reboiler bundle to be removed in situ;
(4) For the one-way fixed tube-plate heat exchanger with expansion joint on the casing, the influence of the expansion joint should be considered when piping, flexibility analysis and equipment support design;
(5) When the ratio of length to diameter (L/D) of the reboiler is greater than 6.0, a guide bracket should be provided;
(6) When the valve and blind plate of the reboiler are more than 3m away from the ground, the platform should be set on the tower.
14. What are the requirements for the piping arrangement of the shell-and-shell horizontal horizontal reboiler?
The piping layout requirements for the shell-and-tube horizontal horizontal reboiler are as follows:
(1) Within the allowable stress range of thermal expansion, the downcomer and the riser pipe of the reboiler should be as short as possible to reduce the number of bends to reduce the pressure drop;
(2) When the reboiler has two rising ports, in order to make the flow green in the tube equal, the steam moving department should be arranged symmetrically. If the diameters of the riser pipes are different and the arrangement is asymmetrical, the resistance of the two pipe sections should be made equal. Otherwise, the flow rate of the pipe with a large resistance will cause uneven heat distribution;
(3) The liquid drawn from the reboiler is a saturated liquid. If the piping system produces a pressure drop, the liquid will begin to flash, resulting in a gas-liquid two-phase fluid flow, affecting the operation and accuracy of the control and measuring instruments. Therefore, when arranging a saturated liquid pipe, the basic principle is to minimize the pressure drop and not to have a vertical rise pipe section before measuring or controlling the meter;
(4) Reboiler tube The inlet pipe of the heating medium is usually equipped with a temperature regulating valve and a valve block thereof, and these valves are generally arranged on the ground or platform surface near the inlet of the reboiler tube.
15. What are the specific requirements for the design of the air cooler?
The piping design of the air cooler has these specific requirements:
(1) The “liquid bag” is generally not suitable for the top of the fractionation tower to the oil and gas pipeline of the air cooler. When there is no valve or two-phase flow in the inlet and outlet of the air cooler, the pipes must be symmetrically arranged to make the flow of each air cooler uniform;
(2) The inlet manifold of the air cooler should be connected to the nozzle of the air cooler. If the stress or installation needs, the outlet manifold may not be connected to the nozzle, and the cross-sectional area of the manifold shall be greater than the sum of the cross-sectional areas of the branch pipe;
(3) When the air-cooler population is a gas-liquid two-phase flow, each branch pipe should be inserted into the population collecting pipe from below; so that the fluid distribution at the bottom of the collecting pipe is evenly distributed; at the same time, a shutdown liquid discharging pipe is arranged below the collecting pipe, and is connected to the air cooler outlet. On the pipeline;
(4) The air cooler has a high population pipeline; if the distance is long, a special pipe rack is required in the middle to support the pipeline;
(5) The softened water returning system of the wet air cooler is a self-flowing pipe. Therefore, attention should be paid to the arrangement of the piping system, and the turning should not be excessive. The return water main pipe should have a slope along the flow direction of the medium;
(6) The operating platform of the air cooler is provided with a semi-fixed steam purging joint. The valve should be located at an easy access point, and the direction of the steam joint should be paid attention to ensure safe operation.
16. What are the general requirements for pump design for pumps?
The general requirements for pump piping are as follows:
(l) The inlet and outlet pipes of the pump shall be provided with a cutting net. The pipe must have sufficient flexibility to reduce the stress and moment of the pipe acting on the pump nozzle;
(2) The suction pipe of the pump should meet the requirements of the “cavitation allowance” of the pump. The pipe should be as short as possible and less curved. If it is difficult to avoid, the vent valve should be installed at the high point;
(3) When the pump suction pipe is long, it should be designed to have a certain slope (i=5‰); when the pump is lower than the container, it should be inclined to the pump. When the pump is higher than the container, it should be inclined to the container;
(4) In the downstream of the pump population pipeline shut-off valve, a filter or temporary filter shall be provided. In order to prevent the pump’s impeller from being reversed due to the backflow of the pump, the pump outlet shall be equipped with a check valve;
(5) The pipeline of the pump under the premise of meeting the process requirements. The valve handwheel shall not affect the space required for normal operation of the pump and maintenance inspection;
(6) The design of the inlet and outlet pipes of the reciprocating pump should consider the influence of fluid pulsation.
17. What kinds of protection lines are there for the pump? what is the function?
There are 6 kinds of protection lines for the pump, which are used to protect the pump body from damage and normal operation, and set the protection pipeline of the pump according to the conditions of use.
(1) Warm pump line——When the temperature of the medium is higher than 200 °C, when there is a spare pump, the DN20~25 warm pump line should be set;
(2) Small flow line——When the working flow of the pump is lower than 30% of the rated flow of the pump, the small flow line of the pump running normally at the lowest flow rate should be set;
(3) Balance line—for conveying a liquid with a saturated vapor pressure higher than atmospheric pressure at normal temperature or a liquid in a bubble state, in order to prevent steam from entering the pump liquid or air bubbles entering the pump, the cavitation should be balanced;
(4) Bypass line – When the pump is used for trial operation or when the outlet main valve is closed under abnormal operating conditions, the pump can still be operated. Generally, a bypass valve with a limited flow hole is provided in a case where the pressure difference between the valve and the front is very high;
(5) Anti-coagulation line – When conveying liquid with high pour point or high freezing point solidified at normal temperature, the backup pump and pipeline should be equipped with anti-condensation line to avoid plugging of spare pump and pipeline;
(6) Safety valve line——For the volumetric pumps such as electric reciprocating pump, gear pump and screw cylinder, the safety valve line is set on the outlet side. When the outlet pressure exceeds the constant pressure value, the safety valve takes off and the fluid returns to the pump population tube.
18. What are the general requirements for the arrangement of centrifugal compressor piping?
The general requirements for piping arrangements for centrifugal compressors are:
(l) Centrifugal compressor housings come in two forms: vertical split type for high pressure, no pipes and other obstacles in front of the machine; horizontal split type for medium and low pressure, no upper part of the machine Other obstacles;
(2) Arrangement of import and export pipelines Under the condition of satisfying thermal compensation and allowable stress, the number of elbows should be reduced as much as possible to reduce the pressure drop;
(3) The inlet and outlet nozzles are generally facing downwards, and the casing is centrally supported. During operation, the amount of thermal expansion should be absorbed by the pipeline;
(4) When the compressor nozzle provided in the factory is up and up, a detachable short section shall be provided on the pipe of the inlet and outlet nozzles for the compressor to be repaired.
19. What are the general points of piping design for reciprocating compressors?
The general points of piping design for reciprocating compressors are:
(1) The piping of the inlet and outlet of the compressor should be short and straight, and the number of elbows should be reduced as much as possible. However, when the outlet pipe is inflated, the pipe should be flexible;
(2) The piping arrangement should consider the liquid flowing from the liquid to the liquid separation tank. When the pipeline has a “liquid bag”, it should be set at a low point;
(3) When multiple units are arranged side by side, the valves and instruments on the inlet and outlet pipes shall be arranged in a place that is easy to operate and accessible;
(4) In order to prevent the vibration of the compressor inlet and outlet pipes, the necessary vibration analysis should be carried out. The pipe arrangement should be as low as possible, and the brackets should be laid on the ground and be an independent foundation to increase the rigidity of the brackets and pipes;
(5) When the medium of the compressor is flammable, the pipe will be condensed at a low point, and the high-point venting valve shall be provided with a wire plug, cap or flange cover to prevent leakage, and the pipe around the unit shall be filled with sand to avoid combustible gas. Accumulation
(6) When arranging the inlet and outlet pipes of the compressor, it shall not affect the walking of the maintenance crane;
(7) The pipeline of the compressor should be arranged under the operating platform, so that there is more spacious operation and maintenance space around the unit.
Source: China Stainless Steel Pipelines Manufacturer – Yaang Pipe Industry Co., Limited (

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