Engineering materials can be divided into metallic materials (ferrous and nonferrous metals), non-metallic materials (polymer materials and inorganic non-metallic materials) and composites and so on. (A) metal materials 1 ． Ferrous metals (1) pig iron, ferroalloys. Pig iron is divided into steelmaking pig iron and casting pig iron. Iron and any kind of metal or non-metal alloys are called ferroalloys. (2) cast iron. Has excellent casting properties and good wear resistance, shock absorption and low notch sensitivity. Also has good heat resistance and corrosion resistance. Cast iron including: gray cast iron, pregnant cast iron, malleable cast iron, ductile iron, alloy cast iron. (3) Steel. ① steel is categorized as follows: A ． According to the chemical composition, steel can be divided into carbon steel and alloy steel. B ． According to the smelting quality classification, steel can be divided into ordinary steel, high quality steel and advanced quality steel. C． According to the use classification, steel can be divided into structural steel, tool steel, special performance steel, etc.. D． According to the classification of smelting method, steel can be divided into flat furnace steel, converter steel, electric furnace steel. E． Classified according to the degree of deoxidation, steel can be divided into sedentary diamond, semi-sedentary steel and boiling steel. F． According to the classification of metallurgical organization, in the annealed state, the steel can be divided into sub*** precipitation steel, *** precipitation steel, over *** precipitation steel; in the normalized state, the steel can be divided into pearlite steel, bainite steel, austenitic steel. G ． According to the supply of guaranteed conditions of classification, steel can be divided into Class A steel, Class B steel and special steel. ② The method of indicating the grade of steel. According to the grade can be seen in the category of steel, carbon content, alloying elements and their content, smelting quality and should have the performance and use. For example, Category A steel grade with "A" word plus Arabic numerals 0, 1, 2, 3, 4, 5, 6, 7 said. Another example is No. 20 steel number, said the average carbon content of 0.20% of the steel. Again, such as 9Cr18 that the average carbon content of 0.9%, the amount of Cr for 18% of stainless steel. ③ The main features of foreign steel grades (omitted). ④ The main features and uses of several commonly used steels. A ． Ordinary carbon steel is divided into Category A steel and Category B steel two kinds. Category A steel is mostly used in the construction industry for the use of reinforcing bars, machinery manufacturing in the use of ordinary screws, nuts, washers, bushings, etc., but also can be rolled into plates, profiles (such as I-beam, channel steel, angle steel, etc.); Category B steel use and the same number of the same category of steel. B ． Ordinary low alloy steel is on the basis of ordinary carbon steel. A small amount of alloying elements are added, which not only have excellent properties such as corrosion resistance and wear resistance, but also have higher strength and good mechanical properties. C ． Cast steel has higher mechanical properties, especially high plasticity, toughness, good weldability, but it is poor casting, can be used in the casting of large parts, such as axle box, water pump body, gears and so on. D ． High-quality carbon steel structural steel mainly applies to high-quality steel or advanced high-quality steel, mainly used in the manufacture of mechanical parts. E ． Alloy structural steel belongs to the high-quality steel or advanced high-quality steel, mainly used in the manufacture of mechanical parts. F ． Tool steel is divided into carbon tool steel, alloy tool steel and high-speed tool steel three categories; can also be divided into cutting tool steel, mold steel and gauge steel. G． Special performance steel, including stainless steel, heat-resistant steel, wear-resistant steel, ultra-high strength steel and magnetic steel. In addition to excellent corrosion resistance, stainless steel also has high strength, hardness and wear resistance. Commonly used stainless steels are Cr13, 1Cr18Ni9Ti, Mo2Ti, 00Cr17Ni13Mo2. H ． Oxidation-resistant steel, such as 3Cr18Mn12Si2N, 2Cr20Mn9Ni2Si2N, etc., mostly used in the manufacture of furnace parts and heat exchangers. I. Heat-strengthened steel, such as 15CrMo, 1Cr11MoV, 1Cr14Ni14W2MoNi, 4Cr14Ni14W2Mo, etc., used in the manufacture of gas turbine and steam turbine rotors and blades, boiler superheaters, high-temperature work of the bolts and springs, internal combustion engine inlet (exhaust) valves and so on.
J. The main grades of low-temperature steel 09Mn2V, 09MnTiCuXt, 06MnNb, 06A1NbCuN, 15Mn26A14, etc., are widely used in refrigeration equipment, oxygen equipment and liquefied petroleum gas manufacturing, storage, transportation and other equipment. 2. Non-ferrous metals (1) copper and copper alloys. Copper is very strong corrosion resistance to the atmosphere and water, is an antimagnetic material. Copper has excellent friction reduction and wear resistance, as well as high elastic limit and fatigue limit. Brass is easy to process into demise, the general atmosphere, marine atmosphere and water, etc. have quite good corrosion resistance, casting is also very good. (2) aluminum and aluminum alloy. Aluminum can be used for the production of concentrated acid containers, tank cars, but dilute acid and alkali dissolving power of aluminum is very strong. Aluminum alloy is divided into cast aluminum alloy and deformed aluminum alloy. Cast aluminum alloys include aluminum-silicon alloy, aluminum-copper alloy, aluminum-magnesium alloy, aluminum-zinc alloy, etc.; deformed aluminum alloys include rust-proof aluminum alloy, hard aluminum alloy, super-hard aluminum alloy and forged aluminum alloy. (3) Magnesium and magnesium alloy. Magnesium in the casting of copper or nickel alloys can be used as a sulfur removal agent and deoxidizer, in the casting of ductile iron, magnesium is an important spheroidal agent. Magnesium alloy to join the elements are aluminum, zinc, manganese, silicon and so on. (4) titanium and titanium alloy. Titanium has excellent corrosion resistance and heat resistance, not corrosive, in sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide and other media are very stable. Titanium's oxidation resistance to most austenitic stainless steel. Titanium can still maintain high strength under high temperature conditions. Titanium alloys commonly used alloying elements are chromium, manganese, vanadium, aluminum and molybdenum. ( 5 ) nickel and nickel alloys. Nickel has good chemical stability, corrosion resistance in humid air and seawater, in alkaline solutions and mechanical acids have corrosion resistance. Nickel also has high thermal stability. (6) Lead and lead alloy. Lead in cold salt and sulfuric acid is very stable, has a strong resistance to acid, and with sodium hydroxide and potassium carbonate and other carbonaceous solutions do not have a chemical reaction. Commonly used lead pipes are mainly manufactured with lead-antimony alloys, hard lead, extra hard lead and lead-silver alloys. (B) non-metallic materials non-metallic materials, including polymer materials and inorganic non-metallic materials 1. Common inorganic non-metallic materials, etc. (1) cast stone. Its characteristics are wear-resistant, corrosion-resistant, and has excellent insulation and high compressive strength. (2) Graphite. As a corrosion-resistant non-metallic inorganic material, impermeable graphite is widely used in chemical anti-corrosion. (3) Glass. There are quartz glass, high silica glass, borosilicate glass, low alkali boron free glass. (4) Industrial ceramics. Building, sanitary ceramics and electrical ceramics and chemical, chemical ceramics. 2. Commonly used polymer materials (1) polyethylene (PE), polypropylene (PP). Low-pressure polyethylene is more rigid, wear-resistant, corrosion-resistant, insulating better, commonly used to manufacture plastic pipes, plastic plates, plastic ropes and bearing parts, such as gear bearings. High-pressure polyethylene is softer. Polypropylene (PP) lighter weight, good heat resistance, strength, modulus of elasticity, hardness and other mechanical properties are higher than low-pressure polyethylene; at the same time, superior insulation. (2) polyvinyl chloride (PVC). Common products are hard, soft two kinds. Hard polyvinyl chloride specific gravity is very small, good tensile strength, good water resistance, oil resistance and chemical resistance, many properties better than polyethylene. (3) Polystyrene (PS). Has excellent corrosion resistance, high resistance, is a very good heat insulation, shock, moisture and high frequency insulation materials, with greater rigidity. The disadvantage is poor impact resistance, not resistant to boiling water, limited oil resistance. (4) engineering ABS plastic. Comprehensive mechanical properties are good, dimensional stability, easy plating and easy to form, heat and corrosion resistance is good, low temperature still has a certain mechanical strength. (5) Polyamide (PA). Very good toughness, high strength, good corrosion resistance. But poor heat resistance. (6) polytetrafluoroethylene (F-4). Has very good resistance to high and low temperatures, almost all chemical corrosion resistance, very low coefficient of friction, non-absorbent, excellent electrical properties.
(7) phenolic plastic (PF). Have a certain degree of mechanical strength and hardness, good abrasion resistance, good insulation, high heat resistance. Excellent corrosion resistance. Disadvantage is that the sex is brittle, not resistant to reduction. (8) epoxy plastic (EP). Higher strength, good toughness; high dimensional stability and durability, with excellent insulating properties. Heat resistance, cold resistance, high chemical stability, good molding process performance. The disadvantage is that there are certain toxicity.
(iii) Composite materials 1. Performance characteristics of composite materials
Composite materials have high specific strength and specific modulus, good fatigue resistance, good vibration damping performance of structural components, good high temperature performance, good fracture resistance. 2． Several commonly used composite materials (1) thermoplastic FRP is a glass fiber as a reinforcing agent, with high mechanical properties, dielectric properties, heat resistance and aging resistance, and process performance is also very good. Thermosetting glass is light in mass, high specific strength, good corrosion resistance, superior dielectric properties, is a good engineering material with good molding properties. But the stiffness is poor, easy to aging, easy to creep. (2) carbon fiber composite materials. Carbon fiber has higher strength and ideal modulus of elasticity than glass fiber, the strength and modulus of elasticity at high temperatures remain basically unchanged, is the highest of all heat-resistant fibers. (3) Boron fiber composites have high compressive and shear strength, low creep, high hardness and modulus of elasticity, high fatigue strength, and radiation resistance. It is stable to water, organic solutions and fuels, lubricants. ( 4 ) metal fiber composite materials. These materials are characterized by higher strength and high temperature strength in addition to the main plasticity and toughness, and easier to manufacture. Second, profiles, plates, tubes, pipe fittings, valves, flanges and other commonly used materials, classification (specifications), performance;
(a) steel profiles steel profiles, including ordinary steel, high-quality profiles, wires, rails (b) plate plate plate, including steel plate, sheet steel, steel strips, silicon steel sheet (c) tubes 1. Ferrous metal pipe (1) seamless steel pipe, including boiler seamless steel pipe, boiler high-pressure seamless steel pipe, seamless steel pipe for geological drilling, seamless steel pipe for oil cracking, stainless acid-resistant steel seamless steel pipe. (2) Welded steel pipe includes straight seam welded pipe and spiral seam steel pipe. ( 3 ) cast iron pipe. 2． Non-ferrous metal pipes Non-ferrous metals include lead and lead alloy pipes, copper and copper alloy pipes, aluminum and aluminum alloy pipes, titanium and titanium alloy pipes. 3. Non-metallic pipes Non-metallic pipes Non-metallic pipes include concrete pipes, ceramic pipes and clay pipes, glass pipes, glass fiber reinforced plastic pipes, graphite pipes, cast stone pipes, plastic pipes, rubber pipes. (D) Fittings Fittings include elbows, tees, crosses, reducers, steel fittings, screw plugs, threaded fittings, pipe couplings, blowing fittings, headers, bosses (nozzles), vertices and so on. (E) Valves Valves, including gate valves, globe valves, check valves, plug valves, safety valves, regulating valves (throttle valves), ball valves, pressure reducing valves, traps, right-angle valves, butterfly valves, diaphragm valves, solenoid valves and so on. (F) Flange Flange including equipment flange, pipe flange, flange gasket, flange fasteners.
Three, commonly used anti-corrosion, insulation materials, classification, basic performance and use (a) anti-corrosion materials can be divided into polymer materials, inorganic non-metallic materials, composite materials and coatings. (1) plastic products are mainly polyvinyl chloride, polyethylene, polypropylene, polytetrafluoroethylene. (2) rubber products commonly used natural rubber, chlorinated rubber, chloroprene rubber, chlorosulphonated polyethylene rubber, styrene butadiene rubber, butyl rubber. (3) Glass fiber reinforced plastic and its products. (4) Ceramic products (5) Paints and coatings, including inorganic zinc-rich paint and antirust primer. (6) Acid-resistant stone including cast stone, acid-resistant ceramic products, impermeable graphite plates and bricks impregnated with bitumen are acid-resistant stone. (7) acid-resistant mud, including water glass mud, resin mud, etc.. (B) insulation materials 1 ． Classification of insulation materials (1) can be divided into organic materials and inorganic materials according to the material. (2) According to the applicable temperature is divided into cold materials, thermal insulation materials, heat insulation materials and refractory heat insulation materials. ( 3 ) According to the hardness and shape of the material can be divided into hard materials, soft materials, semi-hard materials, loose cotton intangible materials and bulk materials.
2. Insulation material performance requirements
(1) thermal conductivity is small, its value is not greater than 0.12W/(m-K) (at 350 ℃ conditions). Cold insulation materials, the value shall not be greater than 0.064 W / (m-K) (average temperature 27 ℃). (2) The density is small, generally below 400kg/m3. The density of cold-insulating materials does not exceed 220 kg/m3 (3) Stable material performance, with a clear equation of thermal conductivity, with a wide range of applicable temperatures. (4) Can withstand certain vibration, with a certain mechanical strength, such as perlite, microporous calcium silicate products; compressive strength should not be less than 0.15MPa. (5) Good chemical stability, no corrosion. (6) Good waterproof performance, hygroscopicity is small. (7) Less combustible components, should be self-extinguishing or non-enzymatic. Fourth, the classification of welding materials (specifications), performance and scope of application
Welding rod by the core and wrapped in the outside of the flux skin composition. (1) the role of the electrode core is mainly conductive current, ignite the arc, as a transition alloy, filler metal. (2) welding rod flux skin is ore powder, ferroalloy powder, organic and chemical products and other raw materials in a certain proportion of the preparation of pressure coated on the surface of the core of a layer of paint. Welding rod flux skin according to the role played by raw materials in welding is divided into: gas making agent, slagging agent, deoxidizer, alloying agent, arc stabilizer, binder, plasticizer. (3) several commonly used electrodes are as follows: ① carbon steel electrode type and performance is based on the tensile strength of the molten metal, type of flux skin, welding position and type of current to be divided; ② low alloy steel electrode type and performance is based on the mechanical properties of the molten metal, chemical composition, type of flux skin, welding position and type of current to be divided; ③ stainless steel electrode type and performance is based on the chemical composition of the molten metal, electrode flux and type of welding current to be divided; ③ stainless steel electrode type and performance is based on the chemical composition, electrode flux skin and Welding current type to be divided; ④ Surfacing electrode type and the main performance is based on the chemical composition of the molten metal and the type of electrode flux skin to be divided. (4) The brand name of the welding rod is based on the main purpose and performance characteristics of the welding rod to name, divided into 10 categories. (5) The principle of selection of welding electrodes, please refer to the "Welding Equipment Manual".
The second section of the installation project construction machinery
First, the installation project hoisting machinery. Lifting machinery, including: crawler cranes, truck cranes, tire cranes, tower cranes, one-legged holders, herringbone holders, mast cranes, cable cranes. Second, the installation of horizontal transportation machinery. Horizontal transportation machinery includes: load car, trailer set, pipe trailer.
Three, the installation of welding machinery. Welding machinery including; butt welding machine, spot welding machine, arc welding machine (including hand arc welding machine, submerged arc welding machine, argon arc welding machine), electric slag pressure welding machine, gas pressure welding equipment. Section III engineering construction organization design
A, installation engineering construction organization design role, classification and content; (a) the role of engineering construction organization design (1) to participate in the project bidding and signing of the project contract, as part of the contents of the tender and contract documents. (2) To guide the process of one-time preparation before construction and the whole process of engineering construction. (3) As a planning document of project management, it puts forward the objectives and technical organization measures of progress control, quality control, cost control, safety control, site management, and management of various production factors in the construction of the project in order to achieve the purpose of improving the comprehensive benefits. (ii) Classification and content of engineering construction organization design 1. Classification of engineering construction organization design According to the engineering object classification of construction organization design, construction organization design can be divided into three categories.
2. Engineering construction organization design content
Engineering construction organization has: the content of the pre-bid design; the content of the general design of the construction organization; the content of the construction organization design of a single or unit project: the content of the construction organization design of the branch project.
Two, the installation of construction organization design of the preparation of principles and procedures;
(1) the preparation of principles (1) strict compliance with the duration of the quota and contractual provisions of the completion of the project and the delivery of the use of the deadline. (2) Reasonable arrangement of construction procedures and sequences. (3) Arranging the progress plan by flow operation method and network planning technique. (4) Arrange the construction projects in winter and rainy season appropriately. (5) Implement the technical policy of multi-level technical structure, and promote the technical progress and the development of construction industrialization according to the time and place. (6) From the practical point of view, do a good job in the comprehensive balance of manpower and material resources, and organize balanced construction. (7) Utilize existing facilities and local resources as much as possible, and carry out site planning and arrangement carefully. (8) Implement target management. (9) Combined with construction project management.
(2) the preparation of procedures for the preparation of procedures, including the preparation of pre-bid design and the preparation of post-bid design procedures. Third, the principle of construction flow operation (a) the elements of flow operation
The elements of flow operation include process parameters, spatial parameters, time parameters. (B) the classification of running water operation running water operation according to the classification of the scope of the organization of running water construction, according to the rhythmic classification of running water construction, (C) running water network diagram running water network diagram, including crosswalk running water network diagram, running water step-by-step running water network diagram, lap type running water network diagram.
(iv) crosswalk diagrams crosswalk diagrams include horizontal indication charts and vertical indication charts. (E) flow parameters to determine the flow parameters to determine the flow parameters, including process parameters (construction process, flow intensity), spatial parameters (working surface, construction section, construction layer), time parameters (flow beat, flow step, technical intervals, organizational intervals, flat lap time) to determine.
Four, construction engineering network schedule (a) the basic concepts of network planning technology The basic concepts of network planning technology include the basic principles of network planning technology. The basic model of network planning technology. Network plan has certain advantages over the crosswalk plan. (ii) Classification of network plan network plan is divided into dual-code and single-code network plan, single-objective and multi-objective network plan, time scale network plan, lap network plan, sure-type and hundred-type sure-type network plan, local, unit engineering, integrated network plan.
(iii) Engineering network diagrams 1. Dual code network diagram
Dual code network diagram is composed of three basic elements: work, event and line.
(1) Work refers to the implementation of activities that can exist independently, such as work processes, construction processes or construction projects and other implementation activities. There are real work and virtual work.
(2) The event is a circle with a number at both ends of the arrow line in the network diagram, also called a node. An event indicates the moment when work begins or ends.
(3) Line refers to the passage from the original event of the network diagram, in the direction of the arrow line to reach the end event of the network diagram, in the middle of a series of events and the arrow line composed of. It can be categorized into critical line and non-critical line work.
(4) Judging critical work and critical lines. The work with zero total maneuver time is the critical work, and the line composed of critical work is the critical line.
2. Single-code network diagram
Single-code network diagram is required by the two basic elements of work and line.
(1) Work. In a single code network diagram, the work consists of nodes and associated arrow lines.
(2) Line. In a single-code network diagram, the concept, type and nature of the line is basically similar to the two-code network diagram.
(3) Single-code network drawing.
(4) Determination of critical work and critical lines. Work with a total time difference of zero is the key work, and the line composed of key work is the poor key line.
V. Principles and methods of preparation of the general design of construction organization
(1) Preparation of the construction program
The preparation of the construction program includes the preparation of construction deployment, the main building construction program, and the determination of the procedure for carrying out the project.
(2) Preparation of total construction schedule
Calculation of the quantity of work, determination of the construction period of each unit of work, determination of the time of commencement and completion of each unit of work and the relationship between each other, and preparation of the total construction schedule.
(3) Preparation of labor force and main technical material requirement plan
Labor force and main technical material requirement plan includes labor force requirement plan, main material and prefabricated processed material requirement plan, main material and prefabricated processed material transportation plan, main construction machinery requirement plan, large temporary facilities plan.
(D) construction master plan design
Construction plan design includes the content of the construction master plan, the design basis of the construction master plan, the design principles of the construction master plan, the design steps of the construction master plan.
Six, single (unit) project construction organization design principles and methods
(a) single (unit) project construction program
Single (unit) project construction program includes determining the construction flow and construction procedures, division of construction sections, selection of construction methods and construction machinery, design of technical and organizational measures.
(2) the preparation of unit project construction schedule
it includes dividing the project, calculating the amount of work and determining the duration, determining the construction sequence, organizing the flow of work and drawing the construction schedule.
(3) construction preparation plan and resource guarantee plan
including construction preparation plan, unit project labor requirement plan, unit project main material requirement plan, unit project component requirement plan, unit project construction machinery requirement plan.
(4) unit construction plan design
Including unit construction plan design content, unit construction plan design requirements, unit construction plan design steps.
Chapter II Basic Knowledge of Construction Technology
This chapter introduces the basic knowledge of construction technology, including the basic content of welding, anticorrosion, heat preservation, heat insulation construction process and related specifications commonly used in installation projects, the role and methods of heat treatment, the role and methods of degreasing, pickling, passivation, and pre-film, the basic process of lifting the construction and quality inspection of construction works and the process flow;
Section I cutting and welding
I. Installation of commonly used cutting methods in the project, the characteristics of various cutting methods and the scope of application, the common cutting methods used in the project, including oxygen - gas cutting, plasma cutting, carbon arc gas planer and laser cutting.
(a) oxygen - gas cutting
1. Gas cutting metal should meet the conditions
(1) the melting point of metal oxides should be lower than the melting point of the metal.
(2 ) The burning of the metal with oxygen can release a lot of heat, and the thermal conductivity of the metal itself should be low.
2. Scope of application of gas cutting
Gas cutting is applicable to pure iron, low carbon steel, medium carbon steel and low alloy steel, and titanium.
3. Gas cutting process parameters
Gas cutting process parameters are preheating flame parameter, oxygen pressure, cutting speed, cutting torque distance from the surface of the workpiece and torch inclination.
(ii) plasma arc cutting
Plasma arc column temperature is high, and the cutting process is dependent on the completion of the melting, so it can cut most of the metal and non-metallic materials.
Plasma arc cutting commonly used gases for argon, nitrogen, helium and argon mixture, nitrogen and argon mixture. Plasma arc cutting process parameters are cutting current, no-load voltage, cutting speed, gas flow, nozzle height from the workpiece.
(C) carbon arc planer
Use of carbon rods or graphite rods as electrodes, and the workpiece generated between the arc will melt the metal, and compressed air will be blown out of the molten metal cutting method is called carbon arc planer. Carbon arc air planing characteristics, application scope, process parameters and possible defects can refer to the relevant information.
(D) laser cutting
It is a high energy density laser as a " cutting edge " of a method of cutting materials. There are laser gasification cutting, laser melting cutting, laser oxygen cutting, scribing and controlled fracture.
Two, the classification of welding methods, characteristics, selection and classification code
(a) the classification and characteristics of welding methods
(1) welding arc welding including hand arc welding, submerged arc welding, tungsten arc welding, gas shielded arc welding, plasma arc welding, melting and gas-shielded arc welding.
(2) resistance welding, including slag resistance heat as the energy source of electroslag welding and solid resistance heat as the energy source of resistance welding.
(3) high-energy beam welding including electron beam welding and laser welding.
(4) brazing is divided into flame brazing, induction brazing, furnace brazing, dip brazing, resistance brazing and so on.
The above are the characteristics and scope of application of each welding method.
(B) the choice of welding method and classification code
In the choice of welding method to consider the following factors:
(1) product characteristics. Including the structural characteristics of the welded product, the thickness of the workpiece, the form of joints, welding position and parent material properties.
(2) production conditions, welding production conditions, including the level of operation, welding equipment and welding materials.
(3) welding method code is a numerical or alphabetical representation of the welding method with the code.
Section II heat treatment
I, familiar with the basic concepts and meaning of heat treatment
The metal heated to a given temperature and maintained for a period of time, and then selected speed and method of cooling to get the required microstructure and properties of the operation process is called heat treatment.
Heat treatment of welded joints prevents brittle damage, delayed cracking, stress corrosion and hydrogen corrosion of welded parts. Correct heat treatment can make welding residual stress relaxation, softening of the hardened zone, but also to improve the organization, reduce the hydrogen content, improve corrosion resistance, impact toughness, creep limit, etc..
Two, familiar with pre-weld preheating, post-weld heat treatment overall heat treatment role and general requirements, familiar with its heating method
(a) pre-weld preheating
Preheating serves to reduce the temperature between the weld metal and the base metal, thereby reducing the shrinkage stresses (thermal stresses), reducing the cooling rate of the weld, controlling the organizational transformation of the steel to alleviate the localized hardening, and to improve the quality of the weld . It also reduces defects such as porosity and slag entrapment.
Usually, 35#, 45# steel preheating temperature can be selected 150 ~ 250 ℃, carbon content and then continue to increase or workpiece stiffness is very high, the preheating temperature can be increased to 250 ~ 400 ℃. Local preheating heating range of 150mm ~ 200mm on both sides of the weld.
(B) post-weld heat treatment
The role of post-weld heat treatment, the selection of heat treatment specifications, post-weld heat treatment of general requirements, post-weld heat treatment of heating methods and other content can be referred to the relevant information.
(C) the overall heat treatment
The overall heat treatment is to eliminate the stress produced by welding, stabilize the various geometric dimensions, change the welding phase
Organization, to improve the toughness of the metal and the ability to resist stress, to stop the cracks.
Section III degreasing, pickling, passivation
I, chemical production equipment, pipelines, etc., in the construction of the contrail system must be degreased as required. Carbon steel, stainless steel and copper pipes, fittings and valves should be industrial carbon tetrachloride, aluminum alloy pipes, fittings and valves should be industrial alcohol, non-metallic gaskets can only use carbon tetrachloride.
(a) degreasing method
Pipe and pipe degreasing, piping accessories and gaskets degreasing, carbon steel, stainless steel and copper pipes, fittings and valves should be industrial carbon tetrachloride, aluminum alloy pipes, fittings and valves should be industrial alcohol, non-metallic gaskets can only be carbon tetrachloride.
(B) degreasing test
Degreasing test is divided into two direct and indirect method.
Two, pickling requirements, scope of application and common methods
In construction, the equipment, pipeline wall has special cleaning requirements, should be pickled. Acid washing commonly used tank immersion method and system circulation method. Pickling work should be carried out in strict accordance with the requirements. After pickling pipeline and equipment, must be quickly passivated.
Three, passivation and passivation of common methods (omitted)
Section IV adiabatic, anticorrosion
One, adiabatic type, purpose, adiabatic range, adiabatic structure of the form and construction methods
Equipment, pipeline adiabatic, according to the use of heat preservation can be divided into heat preservation, heating heat preservation and cold preservation of the three kinds.
( A) insulation range
Equipment pipeline insulation, cold insulation temperature range of -196 ≤ ℃ ≤ 850.
(ii) adiabatic structure form
Adiabatic engineering, thermal insulation structure has a corrosion-resistant layer, thermal insulation and protective layer composition. Cold insulation structure should also increase the moisture barrier layer.
Adiabatic structure with mastic coated, filled, wrapped, composite, poured, spray method, prefabricated blocks and other structural forms and installation methods.