First, the architectural design of doors and windows
Doors and windows are building units, decorative symbols of facade effect, and finally reflect the characteristics of buildings. Although different buildings have different requirements for the design of doors and windows, and the details of doors and windows are ever-changing, we can still find some rules.
1. The facade of doors and windows shall conform to aesthetic characteristics, and the following factors shall be considered when designing door frames.
1) scale. As far as a single glass plate is concerned, its aspect ratio is close to that of a gold frame, which is beautiful, and it is not suitable for designing a square or a long and narrow rectangle with an aspect ratio above 1: 2.
2) The partition of the facade of doors and windows should not only have certain rules, but also reflect the changes, and seek the rules in the changes; The grid lines are dense; The division of equal distance and equal size shows rigor, solemnity and seriousness; Unequal free division shows rhythm, liveliness and movement.
3) At least the horizontal frame lines of doors and windows in the same room and wall should be on the same horizontal line as far as possible, and the vertical lines should be aligned as far as possible.
4) When designing the facade of doors and windows, we should consider the overall effect requirements of the building, such as the contrast between reality and reality, light and shadow effect, symmetry and so on.
2. Selection of door and window colors (including colors of glass and profiles)
The color selection of doors and windows is an important part that affects the final effect of buildings. When determining the color, we should reach an agreement with the architect, the owner and other parties, and finally the architect should sign it.
3. Personalized design of doors and windows
We can design unique door and window shapes according to customers' different hobbies and aesthetics.
4. Permeability of doors and windows
The facade of doors and windows is within the line-of-sight height of the subjective position (1. 5m~ 1 .8m), it is best not to set horizontal frames and vertical frames to avoid blocking the line of sight. Some doors and windows need to use high transmittance glass or require a wide field of vision, which is convenient for viewing outdoor scenery.
5. Lighting and ventilation of doors and windows
The ventilation area of doors and windows and the number of movable fans should meet the requirements of building ventilation; At the same time, the lighting area of doors and windows should also meet the requirements of "Architectural Lighting Design Standard" (GB/T50033-200 1) and architectural design drawings. Code for Design of Building Energy Efficiency (GB50 189-2005). 2。 Article 4 stipulates that the area ratio of window to wall of building exterior windows in all directions should not be greater than 0. 70。 When area ratio of window to wall is less than 0. At 40, the visible light transmittance of glass should not be less than 0. 4。
Second, the door and window safety design
1. wall thickness requirements of aluminum profiles for doors and windows
2. Safety design of door and window glass
(1) Selection of glass: the thickness of glass is determined by calculation, and it should not be less than 5 mm ... Safety glass (tempered glass or laminated glass) must be used for the doors and windows below the building;
(a) External windows of buildings with 7 floors and above;
(b) The area is greater than 1. 5m2 window glass;
(c) Floor-to-ceiling windows with the bottom edge of glass less than 500mm from the final decoration surface;
(d) Inclined windows, the included angle with the horizontal plane is less than 75 degrees, and the included angle with the indoor floor is more than 3 meters;
(e) The glass area is greater than 0. 5 m2 frame glass door;
(f) The frameless glass door shall be tempered glass with a thickness of not less than10mm. ..
(2) The lap joint between the glass and the notch and other matching dimensions shall comply with the provisions in Tables 5 and 6 of Aluminum Alloy Window (GB/T8479).
(3) The grooves of the glass and aluminum alloy frame should be in flexible contact with the rubber gasket.
(4) Glass shall be mechanically edged, and the number of grinding wheels shall be above 180 mesh.
3. Selection and design of hardware fittings.
4. The overlapping part between the sash of sliding door and window and the guide rail of upper and lower frames should be no less than 10mm, and safety measures such as anti-falling blocks and anti-collision blocks must be installed to prevent the sash from falling and colliding when it is opened.
5. The height of the lower frame of the movable sash of the external wall of the building from the indoor ground should not be less than 900 mm.. Under special circumstances, if it is less than 900mm, other protective safety measures should be taken (such as adding protective railings, etc.). ).
6. The screws and bolts used for connecting and fixing aluminum alloy doors and windows must be made of high-quality stainless steel products to prevent the screws from loosening due to electrochemical corrosion. Stainless steel screws should be threaded by machine as far as possible, and self-tapping nails should be avoided as far as possible. Threaded connections should be designed in shear state.
7. Doors and windows should be reliably connected and fixed with the wall.
The connection modes of doors and windows and walls mainly include steel frame connection, dovetail iron foot welding connection, dovetail iron foot connection with embedded parts, fixed steel plate nail connection, fixed steel plate metal expansion bolt connection and so on. The thickness of dovetail iron foot should be ≥3mm. Thickness of fixed steel plate ≥ 1. 5mm, width ≥ 15 mm, and the surfaces of all dovetail iron feet and fixed steel plates shall be hot-dipped galvanized. The distance between the fixed points of door and window connection is generally between 300 mm and 500mm, and cannot be greater than 500 mm.
(1) steel frame is suitable for connecting doors and windows with various walls, with high installation accuracy and reliable connection, but the cost is high.
(2) Doors, windows and steel structures can be welded with dovetail iron feet. The connection between the dovetail iron foot and the steel structure is adjusted by welding steel bars or angle codes.
(3) Doors and windows should be connected with light wall by welding dovetail iron feet and embedded parts. Swallowtail iron feet and embedded parts are welded and adjusted with steel bars or angle steel yards.
(4) Doors and windows can be connected with the reinforced concrete wall through fixed steel plate (or dovetail iron feet) nails or metal expansion bolts. When the fixed steel plate is used to connect the fixed doors and windows, the gap between the surrounding frames of the doors and windows and the wall should be filled with cement mortar. Cement mortar caulking can make the door and window frame firmly and reliably connected with the wall, which plays an important role in strengthening the door and window frame materials. When the gap is filled with polyurethane foam caulking agent or other flexible materials, dovetail iron feet are used instead of fixed steel plates to ensure the reliability of the connection and fixation of doors and windows with the wall.
(5) Doors, windows and brick walls can be connected by fixed steel plates (or dovetail iron feet) and metal expansion bolts. It is forbidden to use nails to fix doors and windows on brick walls. Like reinforced concrete walls, gaps should be plugged with cement mortar when steel sheets are fixed, and dovetail iron feet should be used to fix them when polyurethane foam caulking agent or other flexible materials are used.
3. Waterproof sealing design of aluminum alloy doors and windows
1. Minimum control index of water tightness of aluminum alloy doors and windows
The minimum water tightness index of aluminum alloy doors and windows can be determined by the following formula, and it should not be less than 250Pa (i.e. the water tightness index of aluminum alloy doors and windows should not be less than Grade 3):
P=k×μz×μs×W0
Where p: water tightness design value (PA);
W0: basic wind pressure (n/㎡);
μz: coefficient of variation of wind pressure height;
μs: shape coefficient, which can be 1. 2;
K: coefficient, the value of K in coastal tropical storm and typhoon area is 0. 3, take 0 elsewhere. 25。
2. Waterproof design of door and window structure
It is the most effective way to improve the waterproof and sealing performance of (1) aluminum alloy doors and windows by actively adopting the principle of equal pressure in structural design.
(2) The overlapping part between movable fan and window frame should not be too small. The lap joint between the casement sash and the window frame should not be less than 7 mm
(3) Try to use plane door and window structure, and use little or no push-pull door and window structure. Because there is a big gap between the movable sash and the upper and lower sliding rails of sliding doors and windows, and the two adjacent sashes are not on the same plane, there is no sealing pressure between the two sashes, but there is a gap between the tops, so the sealing effect is very weak, so the waterproof sealing performance of sliding doors and windows is very poor. There are 2 ~ 3 sealing strips between the sash and the window frame of flat doors and windows. After the sash is closed and locked, the sealing strip is pressed tightly, and the middle cavity is easy to form an isobaric cavity, so doors and windows with excellent sealing performance can be designed.
(4) The aluminum alloy glass pressing line for installing glass for doors and windows should be designed in the indoor direction to avoid water seepage from the tiny gap between the glass pressing line and the window frame.
(5) For sliding doors and windows, a high enough water baffle should be designed on the indoor side, otherwise when the outdoor rainwater has a certain pressure, it will cross the water baffle and flow into the room.
(6) The upper part of the movable door sash should be provided with a flashing plate, and the lower part should be provided with a drainage hole.
(7) The exposed flat-fell seam of combined doors and windows should be reduced as much as possible, because tiny gaps cannot be sealed with sealant, resulting in leakage. When the exposed flat-fell seam cannot be avoided due to structural reasons, the two contact surfaces of the profile at the flat-fell seam form 90 degrees, which is convenient for sealing with sealant.
Environmental protection and energy saving
In the past three years, China's construction industry has developed vigorously, and the demand and consumption of energy-saving aluminum alloy doors and windows have advanced by leaps and bounds. At the annual meeting of aluminum alloy and curtain wall in Guangzhou in 2000, the total number of domestic aluminum alloy thermal insulation profiles production lines did not exceed 10. In the past three years, under the guidance of national policies, the promotion of industry leaders and experts, and the demand of the market, there are currently more than 50 European-style aluminum alloy bridge-breaking (belt-piercing) production lines in China, which have been used by more than 20 manufacturers. In 2003, the consumption of heat insulation strips exceeded 30 million meters. The rapid development of the market is really gratifying! But we also notice the hidden crisis and turning point behind this great opportunity. Based on the development track of energy-saving aluminum alloy doors and windows in Europe, this paper discusses some special phenomena existing in China market at present, and how the industry will be in line with international standards and compete in the future.
1, development of energy-saving doors and windows in Europe
/kloc-in the 1970s, the Arab-Israeli war in the Middle East led to two oil crises, which made industrial countries, mainly Germany and Italy, short of energy and strengthened investment in new energy development and energy conservation. According to statistics, 40%-50% of the energy consumption of general families and public buildings is used for air conditioning or heating, and whether these doors and windows adopt energy-saving doors and windows is related to 30%-50% of the energy-saving effect (depending on K value). Therefore, vigorously promoting energy-saving doors and windows can not only have an immediate energy-saving effect, but also become an important energy policy of the government.
In the development of energy-saving doors and windows, it is divided into three major fields according to the range of materials, namely wooden doors and windows, plastic steel doors and windows and aluminum alloy broken bridge doors and windows. Among them, aluminum alloy thermal insulation windows are divided into two types: American glue injection and European nylon broken bridge. The following discussion focuses on European doors and windows and door and window systems.
After 30 years' development, European aluminum alloy energy-saving windows have developed from scratch to now. It is very important to have complete functions, perfect equipment, beautiful appearance, strict and standardized construction technology and well-trained and responsible construction personnel.
2. Reconstruction of thermal environment on the top floor of existing buildings.
Because the thermal insulation performance of ordinary residential roofs does not meet the requirements, the top floor residents often suffer from "hot in summer and cold in winter". In the projects of Constantine Villa and Mao Ye Villa, we pasted the inner wall insulation board on the top roof, and the summer temperature dropped from 50℃ to 365,438+090, which was unanimously recognized by residents. In addition, this product will also be widely used in the energy-saving transformation of east and west gables.
3. Insulation, heat insulation, sound insulation and moisture-proof of the floor.
In order to overcome the shortcomings of poor seismic performance and easy cracking and leakage of hollow precast slab used in ordinary residential buildings, it is replaced by cast-in-place solid floor slab with a thickness of only 80 mm-120 mm. Because the thickness of the latter is much lower than that of the hollow precast slab, its sound insulation effect becomes worse. Because the insulation board in the wall has excellent sound insulation performance, many families choose it as the bottom cushion when laying the floor, which has a unique effect in isolating the noise transmission upstairs and downstairs and the physical sound transmission of the building. At the same time, the product has excellent moisture-proof performance, and residents at the bottom can also lay it under the ground to prevent moisture.
4. Heat the floor
Low-temperature floor radiant heating is a kind of radiant heating method, in which the heat source is buried underground and the heated ground is used as the heat dissipation surface. With the continuous progress of various electric heating or hot water pipes, heating floors have great development prospects in energy-saving houses. When the insulation board in the wall is used as the bottom cushion material, its compression resistance, safety and thermal insulation performance are superior, which is of great popularization value.
With the promotion of national and local government regulations and standards on building energy efficiency, building energy efficiency in China is developing vigorously. As building energy conservation is a systematic project, involving many sciences such as thermal design, structural technology, material technology, construction technology, property management, etc., training professionals in all fields is the top priority at present, and it is also one of the keys to ensure the healthy development of building energy conservation in China.
The whole industry includes systems (such as Germany,-Shuke), aluminum materials (such as-Heidelu), glass, heat insulation strips, rubber strips, door and window hardware, equipment and other supporting companies. In the whole big industry, "system company" is in the leading position, and some powerful big aluminum companies have their own system departments. In the market, engineering users or general consumers must specify XX brand system doors and windows. Without systematic doors and windows, it can be said that it is difficult to move in Europe! Thus, the importance of the system can be imagined.
5. Design requirements of the system
The definition of doors and windows in the system is that good doors and windows must have good air tightness, water tightness, sound insulation, heat insulation and wind pressure resistance, and the following points must be considered when designing:
1) Minimize the side section.
Most profile wholesalers or door and window companies face the same problem. There are many kinds of profiles, which are easy to overstock, which affects the difficulty of capital flow and management. For example, in the design of non-insulated windows, if the availability of internal opening, external opening and movable shutters is considered, the types of profiles can be reduced.
2) The unification of accessories, corner codes and rubber strips.
3) unification and simplification of the process
General door and window design, mainly consider the profile section and hardware cooperation. Little consideration is given to the convenience of field workers' production and manufacturing. The higher the productivity of workers, the higher the qualified rate of quality and the lower the relative production cost.
4) Perfect contacts to cater to different opening modes.
When architects design projects, they often have different requirements for doors and windows for the beautiful modeling effect of buildings. Therefore, in order to cooperate with the project, a good system can meet the demand with only a few modifications, and there is no need to start a new stove. For doors and windows, the joints between sliding windows (doors) and casement windows (doors) should also be well designed to prevent several aluminum profiles from being connected together, which will affect the visual beauty. At the same time, it can meet different opening requirements, such as external opening, internal opening, internal opening and internal guiding, external turning, internal turning, push-pull and other functions.
5) Good overall tolerance and perfect production process.
The window structure consists of aluminum profile, glass, heat insulation strip, rubber strip, hardware and processing technology. Without good tolerance, it is difficult to produce qualified doors and windows, so the system company plays a leading role in this respect. Imagine what would happen if all the parts of the car we were driving didn't have good tolerances. For the manufacture and sale of doors and windows in Europe, it is required to pass the testing in the door and window laboratory (such as Rossem, Germany), and the testing standards are clear (see CENTC33 for details). In order to pass the inspection, good tolerance, continuous and perfect manufacturing technology are necessary. For example, in order to achieve "water tightness" and prevent "condensation" caused by indoor and outdoor temperature difference, the design of "drainage holes" and "ventilation holes" is very important.
6) Requirements for materials
A. Hardware: Cold (hot) rolled iron hardware is not suitable because there is potential difference between aluminum and iron hardware, which is easy to cause aluminum corrosion. On the premise of meeting the strength, the commonly used materials are mainly stainless steel, aluminum alloy, zinc alloy and engineering plastics.
B. Rubber strip: EPDM is the main rubber, and silicone rubber is needed in cold areas. European cars are made of EPDM rubber tape, and of course this material is also used for home doors and windows.
C. Heat insulation strip: the main materials are nylon 66 and 25% glass fiber. At present, there is no other material to replace it. If nylon 66 is replaced by PVC, the consequences will be reported in the laboratory.
7) Scalability of the system
A good door and window system, in addition to meeting the current requirements of push-pull and horizontal opening (internal opening, internal opening and external opening), needs to be upgraded to be combined with curtain wall system, indoor partition system and indoor door system on the existing basis before it can be called a complete system. "System development" can be summarized as follows: (a) Doors and windows must pass the testing requirements of the door and window testing laboratory and various related standards; (b) Meeting the existing demands of the market; (c) Support the effective management and cooperation of industries and companies; (d) Problems, mistakes and improvement experiences encountered in the development of the company. Many details of door and window systems, seemingly ordinary, are actually accumulated experience from many mistakes. Therefore, the system is regarded as the core competitiveness of European system companies and profile companies, and its value is immeasurable. Consumers recognize a brand of doors and windows, a system, because it represents the guarantee of quality and performance.
6. The special phenomenon of China market.
Domestic understanding of the system, from the early Reynolds, Xu Ge, Aruk to the systematic cooperation with Mr. Rokaidi. Generally speaking, China has a huge market and unlimited potential, but some concepts seem to be in line with international standards as soon as possible.
1) The window structure is mainly fixed and opened slightly.
In Greater China, including Chinese mainland, Taiwan Province Province and Hongkong, most doors and windows are like this. According to the opinions of door and window companies and real estate developers, this structure has the advantages of low cost, saving hardware, low cost of profiles, good lighting and beautiful vision. On the other hand, European-style windows are large in size and good in lighting, but they require higher strength of hardware. They can be easily opened and cleaned, unlike the doors and windows in China, which are not easy to clean and affect the city appearance.
2) Some doubts about the use of external windows.
A, traditional windows, using four-bar friction hinges and single-layer glass, such as most windows used in Hongkong, Taiwan Province and South China, have basically no shortcomings except energy saving and poor sound insulation. Once the requirements of energy-saving doors and windows in "hot summer and cold winter areas" and "hot summer and warm winter areas" are met, it is necessary to use insulating glass, and it is possible to use heat-insulating bridge-breaking aluminum, which will increase the weight of a single door and window. If the traditional friction hinge is still used, because the weight of doors and windows will increase by at least 30%, its supporting strength needs to be strictly demonstrated again, otherwise the danger will increase!
B, thermal insulation broken bridge window, if using hinges, hinges should cover all aluminum. If you still use non-insulated window hinges, because they are not wrapped in all-aluminum materials, the strength is not enough, which will definitely cause safety hazards.
C, the window is insulated, and the glass beads are placed outdoors, which has the following disadvantages: when it rains, the rain will leak indoors; Not conducive to theft; If silica gel is injected around the glass, it is not conducive to the replacement of glass, especially the doors and windows of high-rise buildings. Moreover, the glue injection process is not good, and the doors and windows will be like runny noses.
D basically, windows are rarely used in Europe, and there are even fewer windows with aluminum insulation. Its biggest disadvantage is that it can't clean doors and windows, and more consideration is given to the safety of doors and windows. In Europe, windows are mainly opened from the inside and guided from the inside, because this has a good effect on air tightness, water tightness, sound insulation and cleaning doors and windows. In addition, in southern European countries such as Italy, the use of sunshade blinds is extremely common in hot summer, which is easy to produce local heat insulation and anti-theft effects.
3) Use heat insulation strips and EPDM rubber strip.
At present, it is known that China's standards for heat insulation strips and national standard discussion drafts have been released, but they have not yet been promulgated and implemented. At present, the consumption of PVC strips in the market exceeds 66 nylon strips (including 25% glass fiber), which is actually a retrogression. Rubber strip or PVC strip, or fake EPDM. Among the air tightness, water tightness and sound insulation characteristics of doors and windows, EPDM tape is definitely the key factor. Take a look at rubber strip in the limousine. Do you use PVC strips or silicone? Since humans spend more time in the house than in the car, why not pay attention to their own quality of life?
4) Structure, characteristics and tolerance requirements of doors and windows
In the product catalogs and displayed samples of most profile companies, the structure is very simple. Do not understand the processing technology, condensation requirements, tolerance deepening and so on. I always think that what kind of windows sell well in the market, I try to buy one or two samples to imitate them, which is considered to be redundant for people to understand the structure of doors and windows. I would like to ask, if the doors and windows are not considered as a whole structure, good tolerance fit (including profiles, rubber strips, hardware, etc. ), how to produce qualified imitations of doors and windows, and how to understand tolerances. No door and window system is equivalent to a product without overall thinking, which will cause many problems and a lot of molds and waste time. In the 1970s and 1980s, there were many precedents for such companies in Italy. The tolerance of doors and windows should be considered comprehensively, and the standardization of processing technology should be coordinated. There is no need to buy any famous brand profiles or hardware, and doors and windows can be done. The price of doors and windows of European Systems Company is higher than that of ordinary doors and windows, because it sells quality, technology, performance and service.
5) Consider the wall thickness of profile and the requirements of accessories.
The new national standard requires the wall thickness of aluminum profiles to be 2.0mm for doors and 1.4mm for windows. There is no problem with the wall thickness of window profile 1.4mm, but I feel a little skeptical about the door material of 2.0 mm The wall thickness of doors and windows is mainly to resist wind pressure and increase strength. Different areas, different building heights and different orientations have different requirements. If we all use the lowest 2. Omm requirements are obviously a bit subjective. There are many doors in Europe whose design is less than 2.0 mm From the design point of view, reasonable structural design of different profiles such as stiffeners can be adopted, which can not only improve the structural strength, but also save a lot of aluminum. What's more, since the minimum wall thickness requirement of profiles has been put forward, the weight of doors has also increased relatively, and the corresponding hardware bearing regulations and testing standards should also be coordinated in time, otherwise the next safety problem will appear again.
7. China doors and windows should be in line with international standards as soon as possible.
The development law of any product is a stage from scratch to perfection. We are glad to see the prosperity of aluminum alloy energy-saving doors and windows in China. At present, the quality of products on the market is uneven. I hope more correct concepts can guide people to the market. Government departments and experts can formulate standards that meet international requirements and strictly implement them continuously.
On the design of aluminum alloy doors and windows curtain wall in buildings
This paper discusses the main components of design description of aluminum alloy curtain wall and aluminum alloy doors and windows.
[Keywords:] design description, project introduction, design basis, design parameters, design performance, material selection and construction technical requirements.
According to the "Provisions on the Depth of Compilation of Architectural Engineering Design Documents", the architectural engineering design description includes the overall design description and the professional design description. According to the experience of bidding in recent years and the questions raised by bid evaluation experts, the author thinks that the design description of aluminum alloy curtain wall and aluminum alloy doors and windows is different from the architectural design description, and generally consists of the following parts:
(1) Project Introduction
The project introduction includes:
I. Name of the project; B. project address; C. the name of the owner; D, engineering architectural design unit; E, engineering supervision unit; F, building profile (building structure type, maximum elevation of doors and windows or curtain wall, building height, etc.). ); G. Project area: the cross-sectional area of doors, windows and curtain walls with different structural forms and different panel materials; The total area of doors and windows curtain wall, etc.
(2) Design basis:
A, used for doors and windows, curtain wall engineering design is based on the current national standards, industry standards and local standards of the standard name and standard number, year number;
B. Names and document numbers of relevant regulations of local governments at all levels where doors, windows and curtain walls are designed;
C the drawing name, drawing date and version of the architectural design construction drawing of the project where the doors, windows and curtain walls are designed by the architectural design institute;
E, doors and windows, curtain wall project owner's specific requirements (if any) or the name and date of the project bidding documents.
note:
1, because the standards of raw materials are stipulated in the current national standards, industry standards and local standards. Therefore, in principle, there is no need to list the material standards in detail in the design description.
2. When this project adopts new materials not covered by current national standards, industrial standards and local standards, the standard name, standard number and year (or version) number of the selected materials must be listed in detail.
Relevant regulations of the local government of the project;
Other national and industrial standards and specifications related to the acceptance of raw materials, products and projects.
(Note: At present, China is at the peak of edition change and revision of standards and specifications. For standards and specifications without year number, the corresponding year number standard must be selected according to the specific situation of the project. )
⑶ Design parameters
A, the basic wind pressure of the project location once every 50 years;
B, gust coefficient at height z;
C, wind load shape coefficient;
D, ground roughness category and wind pressure height variation coefficient;
E, the annual temperature change of curtain wall;
F, curtain wall weight standard value;
G, whether the curtain wall engineering seismic design, if seismic design, the fortification intensity of curtain wall.
⑷ Design performance of aluminum alloy doors and windows and building curtain walls
A, wind pressure resistance;
B, water tightness;
C, air tightness;
D, in-plane deformation performance (only for building curtain walls);
E other performance required by the design: such as thermal performance, optical performance, impact resistance, sound insulation performance, etc.
5] Fire protection requirements
Explain the form of fire protection structure; Names, varieties, specifications and fire resistance limits of various materials used for fire prevention construction.
[6] Lightning protection requirements
Explain the form and connection mode of lightning protection structure, the names, varieties and specifications of various structural materials, as well as lightning protection categories and specified grounding resistance.
Once the exterior wall decoration modeling or selection instructions.
The modeling characteristics and types of facade of building curtain wall are briefly described, as well as the selection basis of material specifications of aluminum alloy profiles, columns and beams used in aluminum alloy doors and windows and building curtain wall.
Being selected materials
Explain the materials, varieties and specifications of various raw materials, connecting materials, sealing materials, welding materials, fasteners, hardware fittings and accessories directly used in the project, as well as the technical quality requirements of surface anticorrosion requirements of various materials.
Levies construction technical requirements (only for construction drawings)
A, explain the operation essentials, technical requirements, inspection standards and special inspection methods of key processes in the process of installation and construction;
B, explain the safety requirements in the installation process.
⑽ New materials and technologies
Extract someone else's and see if it works.