Process Pipeline (1)

Some people say that the role of pipelines in petrochemical plants is as important as the role of blood vessels in the human body, which is aptly described. The pipeline length of a large refinery unit is 50-80 kilometers. A 300,000-ton ammonia plant is over 100 kilometers. A 520,000-ton urea plant has 10 kilometers of photosynthetic gold steel and stainless steel pipelines. Pipeline design calculation accounts for more than 60% of the process calculation. According to investment calculation, a petrochemical plant accounts for 10% and 20% of the total pipeline investment. As far as construction is concerned, pipeline construction quantity and construction period play a decisive role in the whole network planning. For the above reasons, developed countries are all concerned with industrial pipelines. Design, manufacture, construction, acceptance and management have formulated very detailed standards or specifications. Major engineering companies will also formulate their own special pipeline specifications based on international advanced standards and their own experience.

20190725020245 76336 - Process Pipeline (1)

Steel pipe Seamless steel pipe Carbon seamless steel pipe
Low alloy seamless steel pipe
Stainless acid-resistant seamless steel pipe
High pressure seamless steel pipe
Low temperature steel pipe
Seamless stainless steel pipe
Welded steel pipe
Steel sheet coiled pipe
Copper pipe Copper pipe
Brass pipe
Titanium pipe
Pipe fittings Elbow Euma steel elbow
Europium press elbow
Stamping welding elbow
Welding elbow
High pressure elbow
Tee Sauma steel tee
Europium steel tee
Eu high pressure tee
Reducer Euma steel reducer
Europium steel reducer
Other fittings Europium head
Flanges,gaskets, bolts Flanges Threaded flanges
Socket-weld flanges
Slip-on flanges
Lap joint flanges
Weld neck flanges
Blind flanges
Special flanges
Gaskets Spiral wound gaskets
Camprofile gaskets
Metal jacketed gaskets
Bolts Double-headed bolt
Single head bolt

According to the production method, steel pipes can be divided into two categories: seamless steel pipes and seam steel pipes. Seam steel pipes are abbreviated as straight-seamed steel pipes.

  1. Seamless steel pipes can be divided into hot-rolled seamless pipes, cold-drawn pipes, precision pipes, hot expansion pipes, cold spinning pipes and extruded pipes according to production methods.
  2. Seamless steel pipe is made of high quality carbon steel or alloy steel, which can be divided into hot rolling and cold rolling (drawing).
  3. Welded steel pipe is divided into furnace welded pipe, electric welded pipe (resistance welded pipe) and automatic arc welded pipe because of its different welding process. Because of its different welding form, it is divided into straight welded pipe and spiral welded pipe. Because of its end shape, it is also divided into circular welded pipe and special-shaped (square, flat) welded pipe.

Welded steel pipe is made of steel plate rolled into tubular shape by butt or spiral seam welding. In manufacturing method, it is divided into low-pressure fluid conveying welded steel pipe, spiral seam welded steel pipe, directly coiled welded steel pipe, electric welded pipe and so on. Seamless steel pipes can be used in various industries such as liquid pressure pipes and gas pipes. Welded pipelines can be used in water pipelines, gas pipelines, heating pipelines, electrical pipelines, etc.
According to material quality
Steel pipe can be divided into carbon seamless steel pipe, low alloy seamless steel pipe, stainless acid-resistant seamless steel pipe, high pressure seamless steel pipe, low temperature steel pipe, stainless steel pipe and so on.
Carbon pipes can also be divided into ordinary carbon pipes and high quality carbon structural pipes.
Alloy pipe can be divided into low alloy pipe, alloy structure pipe, high alloy pipe and high strength pipe. Bearing pipes, heat and acid resistant stainless pipes, precision alloy (such as Kovar alloy) pipes and superalloy pipes, etc.
Steel sheet coiled pipe
Steel sheet coiled pipe is made of steel sheet by coiling and welding, which is divided into straight seam coiled steel pipe and spiral seam coiled steel pipe.
Copper pipe
Copper pipe is divided into two kinds: copper pipe and brass pipe.
Titanium pipe
Titanium pipe is a new kind of pipe in recent years. Because of its light weight, high strength, strong corrosion resistance and low temperature resistance, it is often used in incompetent process parts of other pipes.

Welded steel pipe
Welded steel pipes, also known as seamed steel pipes, are generally formed by coiling welding of steel plates or strips.
According to the surface treatment form of pipe:
It can be divided into galvanizing and non-galvanizing. The surface of galvanized white, also known as white iron pipe or galvanized steel pipe; the surface of non-galvanized ordinary welded steel pipe, also known as black iron pipe.
Galvanized welded steel pipes are often used for pipelines with relatively clean medium requirements, such as domestic water, purified air, instrument air, etc. Non-galvanized welded steel pipes can be used for transporting steam, gas, compressed air and condensate water, etc.
According to user’s requirement, welded steel pipe can be divided into two kinds when it leaves the factory:
One is with threads at the end of the pipe, the other is without threads at the end of the pipe. The length of each pipe is 4-9 m for the welded pipe with threads at the end, and 4-12 m for the welded pipe without threads.
Welded steel pipe is different according to the thickness of pipe wall.
It is divided into thin-walled steel pipe, thickened steel pipe and ordinary steel pipe. The common steel pipe is the most used in the process pipeline, and its test pressure is 2.0 MPa. The test pressure of the thickened steel pipe is 3.0 MPa.
There are many connection methods for welded steel pipe.
There are threaded connection, flange connection and welding. Flange connection is divided into threaded flange connection and welded flange connection, and welding methods are divided into gas welding and arc welding.
Specification range of commonly used welded steel pipes:
The nominal diameter is 6-150 mm.
Seamless steel pipe
Seamless steel pipe is the most used and the most variety and specification pipe in industrial pipeline.
Basically divided into:
Seamless steel pipes for fluid transportation and seamless steel pipes with specificity are two major categories. The former is the steel pipe commonly used in process pipeline, and the latter is the steel pipe for boiler, cracking furnace and heat exchanger, etc.
According to the material, it can be divided into:
Carbon seamless steel pipe, chromium-molybdenum seamless steel pipe and stainless, acid-resistant seamless steel pipe.
According to the nominal pressure, it can be divided into:
Low pressure (0 < 1.0MPa), medium pressure (1.0 < 10MPa=), high pressure (> 10MPa).
Seamless steel pipes for fluid transportation are commonly used in process pipes.
The classification is as follows:

Europium Carbon Seamless Steel Pipe

Commonly used manufacturing materials are 10, 20, 16Mn steel.
The specifications range from 32 mm to 630 mm for hot rolling, 6 mm to 200 mm for cold drawing, 4 to 12 m for single root canal, and the allowable operating temperature is – 40 to 450 C.
It is widely used to transport various non-corrosive media for steel, such as steam, oxygen, compressed air, oil and gas, etc.

Europium Low Alloy Steel Seamless Steel Pipe

It refers to the alloy steel pipe containing a certain proportion of alloy elements.
Usually there are two kinds:
One is low-alloy steel pipe containing manganese element, called ordinary low-alloy steel pipe, such as 16Mn, 15MnV, etc. The other is low-alloy steel pipe containing chromium, molybdenum and other elements, called chromium-molybdenum steel pipe.
Commonly used are 12CrMo, 15CrMo, 12Cr2Mo, 1Cr5Mo, etc. The specifications range from outer diameter 10-273mm, single root canal length 4-12m, and the applicable temperature range of chromium-molybdenum steel pipe is – 40-550 C.
Low alloy seamless steel pipes are mostly used to transport all kinds of high temperature oil products, oil and gas, salt water with low corrosivity, low concentration organic acids, etc.

Stainless and acid-resistant seamless steel pipe

According to the different contents of chromium, nickel and titanium, there are many kinds of metals, such as Cr13, 00Cr17Ni14Mo2, 1Cr18Ni12Mo2Ti and 1Cr18Ni9Ti.
The largest amount of these steel grades is 1Cr18Ni9Ti. Simplified material code 18-8 is commonly used in construction drawings. The applicable temperature range is -196-700 C.
In chemical production, it is used to transport various corrosive media, such as nitric acid, acetic acid and urea.

High Pressure Seamless Steel Pipe

Its manufacturing material is basically the same as the seamless steel pipe mentioned above, except that the pipe wall is thicker than the medium and low pressure seamless steel pipe, and the thickest pipe wall is up to 40 mm.
For example, the specification of high pressure seamless steel pipe for fertilizer equipment is 14 *4 (mm) ~273 *40 (mm), the length of single root canal is 4-12 m, the applicable pressure range is 10-32 MPa, and the working temperature is – 40-400 C.
The above high-pressure seamless steel pipe is used in petrochemical plant to transport raw gas, hydrogen and nitrogen, synthetic gas, water vapor, high-pressure condensate and other media.

Low Temperature Steel Pipe

In the cold zone of the imported project, there is a large amount of usage. The material grades are STPL-39 and STPL-46, and the working temperature can reach -105 C.
The cryogenic steel pipe is divided into seamless steel pipe and seamless steel pipe. The nominal diameter of the seamless cryogenic steel pipe is 15-400 mm and the wall thickness is the same as that of the carbon steel pipe. The nominal diameter of the seamless cryogenic steel pipe is 400-1100 mm, the wall thickness is 6-10 mm, and the standard length of the single pipe is 6 m.
It is suitable for transporting all kinds of non-corrosive cryogenic medium pipelines. At present, there is no mass production of steel pipes corresponding to this standard in China.

Steel sheet coiled pipe

Steel sheet coiled pipe is made of steel sheet by coiling and welding, which is divided into straight seam coiled steel pipe and spiral seam coiled steel pipe.
Longitudinal seam welded pipe:
Most of them are manufactured on the construction site or entrusted to a processing plant. Professional steel pipe plants do not produce them.
The steel plate material has Q235A, No. 10, No. 20, 16Mn, 20g, etc. Its specification range is nominal diameter 200-3000mm, the largest is 4000mm, and the wall thickness is generally 4-16mm.
The nominal diameter of a single root canal is 6.4 m, and the nominal diameter of a single root canal is 4.8 m, ranging from 1 000 mm to 3 000 mm.
Applicable working temperature: Q235A is – 15 – 300 C, No. 10, No. 20, 16Mn, 20g is – 40 – 450 C, all suitable for low pressure range.
Spiral seam coiled steel pipe:
Produced by steel pipe manufacturer with Q235A and 16Mn.
Its specifications range from 200 to 700 mm in nominal diameter, 7 to 10 mm in wall thickness and 8 to 18 m in single root canal length.
Applicable working temperature: Q235A is – 15 – 300 C, 16Mn is – 40 – 450 C, operating pressure: Q235A is 2.5 MPa, 16Mn is 4 MPa.
Longitudinal seam and spiral seam welded pipes are mostly used to transport medium with low corrosion at room temperature and low pressure, such as low pressure steam, underground circulating water, gas and oil and gas. Spiral seam coiled steel pipe has a long single pipe, which is especially suitable for long-distance transportation pipeline.
According to the engineering requirements, there are also straight seam stainless steel sheet coiled welded pipes, which are rolled in the construction site, and the manufacturer does not produce them. Most of the materials used are 1Cr18Ni9Ti steel plate. Its nominal diameter ranges from 200 mm to 1000 mm, its nominal diameter from 200 mm to 400 mm is 4 mm, its nominal diameter from 700 mm to 1000 mm is 6 mm to 8 mm, and the length of a single root canal is 4.5 mm. Suitable for temperature and medium range with low pressure stainless steel pipe.

Copper pipe

Copper pipe is divided into two kinds: copper pipe and brass pipe.
The materials used for making copper pipes are T2, T3, T4 and TUP, which contain more than 99.7% copper.
The brass pipes are made of zinc and copper alloys such as H62, H68, etc. The brass pipes are made of 60.5%-63.5% copper, 39.6% zinc and less than 0.5% other impurities.
The manufacturing methods of copper pipes can be divided into drawing and extrusion.
The outer diameter of drawn copper pipe is from 3 mm to 200 mm, the outer diameter of extruded copper pipe is from 32 mm to 280 mm, and the wall thickness is from 1.5 mm to 5 mm.
The specification range of copper sheet coiled brazed pipe is from outer diameter of 155 to 505 mm. There are two ways of supply: single and finished.
Copper pipes are usually used in oil pipelines, thermal insulation accompanying pipes and air separation oxygen pipelines.

Titanium pipe

Titanium pipe is a new kind of pipe in recent years. Because of its light weight, high strength, strong corrosion resistance and low temperature resistance, it is often used in incompetent process parts of other pipes.
Titanium has metallic luster and ductility. The density is 4.5 g/cubic centimeter. The melting point is 1660 +10. Boiling point 3287℃. Chemical valence + 2, +3 and + 4. The ionization energy is 6.82 electron volts. Titanium is characterized by low density, high mechanical strength and easy processing. The plasticity of titanium depends mainly on its purity. The more pure titanium is, the greater the plasticity is. It has good corrosion resistance and is not affected by atmosphere and sea water. At room temperature, it will not be corroded by hydrochloric acid under 7%, sulfuric acid below 5%, nitric acid, aqua regia or dilute alkali solution; only hydrofluoric acid, concentrated hydrochloric acid, concentrated sulfuric acid can act on it.
Titanium is an important alloy element in steel and alloy. Its density is 4.506-4.516 g/cubic centimeter (20℃), higher than that of aluminium and lower than that of iron, copper and nickel. But the specific strength is the highest in metals. The melting point is 1668 (+4). The latent heat of melting is 3.7-5.0 kcal/g, the boiling point is 3260 (+20). The latent heat of vaporization is 102.5-112.5 kcal/g. The critical temperature is 4350 (+1 300) and the critical pressure is 1130 atmospheric pressure. Titanium has poor thermal and electrical conductivity, approximate or slightly lower than stainless steel. Titanium has superconductivity. The superconducting critical temperature of pure titanium is 0.38-0.4K. Titanium has a heat capacity of 0.126 calories/g [9] atoms per degree, an enthalpy of 1149 calories/g atoms, an entropy of 7.33 calories/g atoms per degree, and a paramagnetic material with a permeability of 1.00004.
Titanium has plasticity, the elongation of high purity titanium can reach 50-60%, the section shrinkage can reach 70-80%, but the shrinkage strength is low (i.e. the strength produced during shrinkage). The presence of impurities in titanium has a great influence on its mechanical properties, especially interstitial impurities (oxygen, nitrogen, carbon) can greatly improve the strength of titanium and significantly reduce its plasticity. Titanium as a structural material has good mechanical properties, which is achieved by strictly controlling the appropriate impurity content and adding alloying elements.
Titanium pipe is made of TA1 and TA2 industrial pure titanium. The suitable temperature range is – 140 – 250℃. When the temperature exceeds 250℃, its mechanical properties decrease.
The specifications of commonly used titanium pipes range from 20 mm to 400 mm in nominal diameter. It is suitable for low and medium pressure, low pressure pipe wall thickness 2.8-12.7 mm, medium pressure pipe wall thickness 3.7-21.4 mm.
Titanium pipe has many advantages, but it is difficult to weld because of its high price, so it has not been widely used.

Pipe fittings

Pipe fittings are the general name of the parts and components that play the roles of connection, control, direction change, diversion, sealing and support in the pipeline system.

Steel pipe fittings are all pressure fittings. According to the different processing technology, it can be divided into four categories: butt welded pipe fittings (welded and non-welded), socket welded pipe fittings, threaded pipe fittings and flanged pipe fittings.

There are many kinds of pipe fittings, which are classified according to their uses, connections, materials and processing methods.
By use

  1. The fittings used for interconnecting pipes are: pipe nipple and pipe union.
  2. Pipe fittings that change the direction of pipe: elbow, bend
  3. Pipe fittings for changing pipe diameter: Olet, Lateral Tee, Reducer
  4. Pipe fittings with additional branch of pipeline: Pipe tee and pipe cross
  5. Pipe fittings for pipeline sealing: Gasket, pipe cap, blind flange, head, welding plug
  6. Fittings for pipeline fixing: Pipe support, pipe hanger, etc.
  7. Others: Lap Joint Stub End


The elbow is used to change the direction of the pipe.
The bending angles of the commonly used elbows are 90 degrees, 45 degrees and 180 degrees. 180 degrees elbows are also called U-shaped elbows. There are also special angle elbows, but the number is very few.
Euma steel elbow
Magang elbow, also known as malleable cast iron elbow, is the most common thread elbow.
The sizes of elbows in Maanshan Iron and Steel Co. are relatively small, and the commonly used sizes range from 1/2 to 4 inches. According to their different surface treatments, the elbows can be divided into galvanized and non-galvanized.
This kind of Ma steel pipe fittings are mainly used in heating, upper and lower water pipes and gas pipes. In the process of technology, except for low-pressure pipes which need to be disassembled frequently, other material pipes are seldom used.
Europium Press Elbow
Pressing elbows, also known as stamping elbows or seamless elbows, are formed by pressing seamless pipes of high quality carbon steel, stainless acid-resistant steel and low alloy steel in special moulds.
The bending radius is one and a half of the nominal diameter (R = 1.5DN), and the bending radius equal to the nominal diameter (R = 1DN) can also be used in special occasions.
Its specification range is within DN20-600mm.
Its wall thickness range is consistent with the table number of seamless steel pipe.
Pressing elbows are usually stamped with standard seamless steel pipes by professional manufacturer or factory, and grooves should be machined at both ends of elbows when they leave the factory.
Stamping Welding Elbow
Stamping and welding elbows are formed by stamping plates into half-ring elbows through dies, and then welding two half-ring elbows together.
Its bending radius is the same as that of the seamless elbow, and its specification range is more than 200 mm in nominal diameter.
Welding elbow
Welded elbow, also known as shrimp waist or shrimp body elbow.
There are two ways to make it:
One is to cut the steel sheet in the processing plant, and then roll and weld it. Most of them are used for matching the steel sheet and pipe.
The other is pipe blanking, which is formed by pair welding. Its specifications are generally more than 200 mm. Use temperature can not be greater than 200 C, generally can be made in the construction site.
High pressure elbow
High pressure elbow is forged from high quality carbon steel or low alloy steel.
According to the connection form of pipeline, both ends of elbow are processed into threads or grooves. The precision of processing is very high. It is required that the threads of pipe orifice and flange orifice can be tightly matched and freely screwed in without loosening.
It is suitable for petrochemical pipelines with pressures of 22.0 and 32.0 MPa. The commonly used specifications range from DN6 to 200 mm.


The tee is the pipe fittings connecting the main pipe and the branch pipe. It can be divided into many kinds according to the different material and use.
From specifications:
It can be divided into the same-path three-way and the different-path three-way. The same-path three-way is also called the equal-path three-way.
The same diameter tee means that the diameter of branch nozzle is the same as that of the main pipe.
Different-diameter tee refers to the branch nozzle with a diameter smaller than that of the main pipe, so it is also called unequal-diameter tee, which has more general usage.
Sauma Steel Tee
Material and specification range of Maanshan Steel Tee is the same as Maanshan Steel Elbow. It is not used in petrochemical process pipeline. It is mainly used for indoor heating, water supply and gas pipeline.
Europium steel tee
Before the 1970s, the development of industrial production technology in China was relatively slow, and the engineering technology of process pipeline was relatively backward.
In the design of all kinds of medium and low pressure steel pipes, when three-way pipe fittings are needed, the method of hole-digging nozzle is usually used to solve the problem. That is to say, in the main pipe which needs to take over the branch pipe, a hole is excavated first according to the diameter of the branch pipe, and then the branch pipe is welded. This method has many shortcomings, the welding quality is not easy to guarantee, the pipe is easy to deform after welding, and the main content is easy to enter impurities.
In the late 1970s, with the introduction of large-scale modern production facilities such as metallurgy and petrochemical industry, the development of process pipeline engineering technology has been promoted. At present, China has been able to produce formulated tees for medium and low pressure pipeline steel, and has formed a series of products. The specifications of seamless tees are DN20-600 mm, and welded tees of steel plate are DN150-1500mm. 。
The production of stereotyped tee is made of high quality pipe as raw material, through cutting, drilling, heating, drawing with die, and then processing, it becomes stereotyped product tee. Medium and low pressure steel tees are welded when installed on site. There are two kinds of tees used for steel pipe coiling: one is the cutting of steel plate used in the processing plant, which is rolled and welded; the other is the hole-digging nozzle in the installation site.
Eu High Pressure Tee
There are two kinds of high-pressure tees, one is welding high-pressure tees, the other is forging high-pressure tees as a whole.
Welded high-pressure tee, high-quality high-pressure steel pipe is used as material, the manufacturing method is similar to hole-digging nozzle, the hole on the main pipe should be consistent with the diameter of the connecting branch pipe. Welding quality requirements are strict, usually requiring preheating before welding and heat treatment after welding. Its specifications range from DN16 to 200 mm, pressure 22 MPa and 32 MPa.
The integral forging of high-pressure tees is usually connected by threaded flanges. Its specification range is SCH160, DN15-600 mm, table number plus “XXS”, and its diameter range is DN15-300 mm.


The function of different-diameter pipe is to make the pipe diameter change. From the direction of fluid movement, most of them are from big to small, and some from small to big, such as steam return pipe and sewer pipe diameter pipe is from small to big. Reducer is commonly known as reducer.
Euma Steel Reducer
There are two kinds of different-diameter pipes in Maanshan Steel. One is internal thread reducer, also known as external joint; the other is internal thread pipe and external thread pipe fittings, called core-filling. Although it is not called different-diameter pipe, it plays the role of different-diameter pipe.
Europium Steel Reducer
Steel pipe with different diameters is divided into seamless and seamless. Seamless pipe with different diameters is pressed by seamless steel pipe. Seamless pipe with different diameters is cut by steel plate and rolled and welded. It is also called welded pipe with different diameters.
Both types of pipe have concentric and eccentric specifications. There is a straight side at the bottom of the eccentric diameter pipe. When used, the bottom of the pipe can be made into a horizontal plane, so that the material in the pipe can be discharged during shutdown and maintenance.
The specification range of seamless diameter pipe is DN25-600mm, and that of seamless welded diameter pipe is DN200-1500mm.
Steel pipe with different diameters, as the finished pipe fittings on the pipeline, began to exist after the 1970s. In the early process, most of the pipe with different diameters were made on the spot. The pipe diameter varies greatly when the pipe end is welded by strip drawing and directly processed into different diameter pipe.
The pipe diameter changes little when heated directly at the end of the pipe. Drawing rod welding for making different-diameter pipes costs a lot of manpower and welds, and the welding quality is not easy to guarantee. At present, the process pipes with high welding quality requirements have been forbidden to adopt this method.

Other fittings

Europium Head
The head is a plug used for sealing the end of the pipe. There are two kinds of common heads: ellipse and flat cover.
Elliptical head is also known as pipe cap. Its specifications range from DN25 to 600mm, and it is mostly used in low and medium pressure pipelines.
Flat cover head can be divided into two types according to its installation position. One is that the flat cover head is slightly larger than the outside diameter of the pipe and welded outside the pipe.
The other is that the flat cover head is slightly smaller than the inner diameter of the pipe, and the head plate is welded in the pipe. Commonly used specifications range from DN15 mm to 200mm. This kind of head is mostly used in pipelines with low pressure.
Euclidean convex platform
The convex platform, also known as nozzle, is a component of the automatic control instrument specialty in the process pipeline. It is installed by the process pipeline specialty, so the convex platform is also listed as the pipe fittings.
One-sided pipe joints for process pipelines are also of this kind. One end is welded on the main pipe, the other end is installed with other parts, or another takes over. The specifications range from DN15 mm to 200mm. High, medium and low pressure pipelines are used.

Source: China Process Pipeline Manufacturer – Yaang Pipe Industry Co., Limited (

(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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