What is a pressure pipeline?

2019-03-25

Pressure pipeline is a kind of special equipment, refers to the use of certain pressure, tubular equipment used for transferring gas or liquid. The scope of the provisions for the maximum working pressure is greater than or equal to 0.1MPa (g) gas, liquefied gas and steam medium or combustible, explosive, toxic, corrosive, high working temperature is higher than or equal to the normal boiling point of the liquid medium, the pipeline and the nominal diameter greater than 25mm.

Working principle

For a single pressure pipeline, is to rely on external force or the driving force of the medium itself the source of the medium pressure pipe conveyed to the pressure pipeline end point.

The characteristics of pressure pipeline

Pressure piping is a system of interacting, qianyifaerdongquanshen.
The pressure pipe has a large aspect ratio and is extremely unstable, and the force is more complicated than the pressure vessel. The fluid flow state in the pressure pipeline is complicated, the buffering space is small, and the working condition change frequency is higher than the pressure vessel (such as high temperature, high pressure, low temperature, low pressure, displacement deformation, wind, snow, earthquake, etc.), which may affect the stress of the pressure pipeline.
Types of pipe fittings and pipe supporting various, various materials have the characteristics and specific technical requirements, material selection of complex.
The pipeline may leak more than the pressure vessel, only one valve usually has five.
Pressure piping types, quantity, design, manufacture, installation, testing, application management links, and pressure vessels are not the same.

The use of pressure pipeline

The conveying medium (main purpose)
The storage function (for pipeline)
The heat exchange (for industrial piping)

The design steps of pressure pipeline

According to the selection of pipeline material type, medium pressure and temperature.
The diameter and wall thickness were calculated, the preparation or determine the scale of pipeline.
To determine the direction of pipeline, pipeline layout and laying mode.
Drawing the piping arrangement, the shaft side of the map.
Prepare piping specification.
Stress, thermal compensation, support force calculation.
Provide information to the relevant professional construction.
Complete the design drawings, the drawings.

Pressure piping layout design problems:

You want to understand the specific steps in the design of knowledge?

How to determine the design pressure?

How to determine the design temperature?

The pipeline layout

The pipeline should be laid overhead when necessary, can be buried or trench laying. (easy installation, production and maintenance)
Try to use the hanger design, make the pipe as close as possible to the existing buildings and structures, but should avoid large load bearing flexible components.
Pipes shall not be placed within the scope of the building hoisting holes, the equipment internals extraction area and the flange removal area.
The piping layout should be laid in parallel columns, try to walk straight walk less and less cross bend, this can reduce the number of pipe rack, material saving, beautiful appearance, convenient installation.
The pipeline should be concentrated into row layout, bare tube bottom and the pipe support design in order to support ground even.
When the pipe elevation or to change, should avoid the accumulation of gas or liquid pipeline to form a “bag”, if not avoided, the exhaust valve should be set in the high, low set liquid discharge valve.
The plane should be laying pipe slope, slope direction and the direction of the materials are generally the same, but there are exceptions, according to the specific process.
Above the line road, the railway should not be installed components may leak, such as flange, threaded joint with filler compensator.
When the pipeline passes through the roof, floor, wall and platform, need protection casing.
The buried pipeline should consider the influence of vehicle load, crossing the road should be added when the casing pipe top and road distance not less than 0.6m, and in the depth of frozen soil.
The branch from the level of the gas charge, should pick out from the top of the head.
For the multilayer common frame of piping, gas pipelines, boiler and heat exchanger tubes, utility piping and electrical slot rack should be in the upper layer, the corrosive medium pipeline, low temperature piping should be in the lower.
Flammable, explosive, toxic and should not be laid in the living room, stairs, corridors and other local pipeline corrosive materials. The vent pipe should lead to outdoor designated locations, or higher roof 2m.
Pipes without insulation are not required for pipe supports. Large-diameter thin-walled bare tubes and pipes with insulation shall be supported by pipe supports.
The condition is directly buried pipeline layout:

The transmission medium is non-toxic, non corrosive, non pipeline explosion, for some reason unable to lay on the ground.
The process medium pipeline associated with underground storage tank or underground pumping station.
Cooling water and fire water or foam fire pipeline.
The heat pipe temperature less than 150 DEG C operation.

The commonly used pressure pipeline material selection principle?

The use of common pipe materials for pressure piping is according to the transmission medium operating conditions (such as pressure, temperature and dielectric properties in the decision) under the conditions of the. Consider the following factors:

Preferred pipe

In the selection of pipe material, generally consider using metal materials, metal material is not suitable, then consider the non metallic materials. Metal materials preferred steel pipe, after considering the selection of non-ferrous metal materials. Steel pipe, first consider the use of carbon steel, stainless steel can be selected for. In consideration of carbon steel materials, first consider the welded steel pipe, seamless steel pipe and then choose not applicable.

The influence of medium pressure

The medium pressure is high, the wall thickness of the tube is thick, the pipe material requirements are generally higher.

Medium pressure 1.6MPa above, can use seamless steel or non-ferrous metal pipe.
The pressure is very high, such as in the production of synthetic ammonia, urea and methanol, some pipe medium pressure up to 32MPa, the general selection of materials for high pressure seamless steel pipe is steel 20 or 15MnV.
The oxygen pipeline pressure and vacuum equipment on more than 10MPa, generally use copper and brass.
Medium pressure below 1.6MPa, consider using welded steel pipe, cast iron pipe or metal pipe. But the iron pipe under medium pressure shall not be greater than 1.0MPa. Medium pressure non metal pipe can bear, with varieties of non-metallic materials, such as hard PVC pipe, using pressure of less than or equal to 1.6MPa; reinforced polypropylene pipe, using pressure of less than or equal to 1.0MPa; ABS pipe, use pressure less than or equal to 0.6MPa.
On the water, when the water pressure is less than 1.0MPa, commonly used material for welded Q235A steel pipe; when the water pressure is greater than 2.5MPa, commonly used material for seamless steel pipe of 20 steel.

The influence of medium chemical properties

The influence of medium chemical properties mainly in corrosion, should be highly valued.

The medium is neutral, the general requirements of the material is not high, can use an ordinary carbon steel pipe.
Medium acidic or alkaline, acid or alkali resistance must choose the pipe.
Transport of water and steam, using carbon steel pipe.

Effect of pipe itself function

In addition to the need to have some pipe conveying medium function, but also has the function of shock absorption, absorption of expansion and contraction function, under working condition, can often move function.

Effect of pressure drop

The initial selection of pipe materials, but also for the calculation of pipe pressure drop, determine the inner diameter of the pipe. Through the calculation of pressure drop, to see whether the material meets the requirements. Especially in the preliminary selection of plastic tubes, the review should pay more attention to the pressure drop.

Source: China Pressure Pipeline Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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What is a pressure pipeline?

What is a pressure pipeline?

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