Technology of assembly and welding of tank roof coating panels 10000 m3.

Contents

Contents

P

INTRODUCTION

1. PROCESS SECTION

1.1 Description of the structure

1.2 Calculation of tank coating strength

1.3 Structural Materials

1.4 Requirements to welding technology

1.5 Selection of welding method, welding materials and

power supply

1.5.1 Welding Method

1.5.2 Welding materials

1.5.3 Selection of welding equipment

1.5.4 Selection of welding modes

1.5.4.1 Modes for mechanical welding

in the environment of active gases

1.5.5 Stress reduction measures

and deformations during welding

1.6. Technology of assembly and welding of coating boards

1.6.1 Assembly of flooring

1.6.2 Welding of the flooring

1.6.3 Assembly of the shield frame

1.6.4 Welding of the shield frame

1.6.5 Frame assembly with flooring

1.6.6 Welding of the coating board

1.6.7 Operational Control

1.6.8 Marking

1.7 Calculation of welding materials consumption

1.8 Quality control of welded joints

1.8.1 Visual and measuring inspection

1.8.2 Leak test of welds

1.8.3 Ultrasonic inspection (ultrasound test)

2. DESIGN SECTION

2.1Selection of process tooling for assembly

tank coatings

2.2 Development of assembly and welding section plan

3. ORGANIZATIONAL AND ECONOMIC DIVISION

3.1. Calculation for Basic Technology

3.2 Calculation for designed technology

4. SAFETY OF WORKS DURING ASSEMBLY AND WELDING

10000 M TANK COATINGS

4.1 Analysis of possible harmful factors arising during

welding works and ways of their elimination

4.1.1 Air medium and microclimate in welding shop

during welding operations

4.1.2 Possible damage by the rays of the electric arc of the eyes and

open skin surface during welding

works

4.1.3 Injuries of various mechanical nature

during assembly and transportation of heavy articles

to welding and during welding

4.1.4 Fire safety and measures to ensure it

4.1.5 Electrical safety during assembly and welding

tank coatings

4.1.6. Lighting of assembly and welding shop

4.2 Calculation of required air exchange at

general ventilation and calculation of general lighting

4.3 Environmental protection during

assembly and welding of tank coating

4.4 Output

Conclusion

LIST OF SOURCES USED

Appendix to the diploma project

Paper

The scope of the diploma project: pages - 94; Figures - 7; tables - 15;

drawings and posters 10 f. A1.

Keywords:

WELDING TECHNOLOGY, MECHANIZED WELDING WITH MELTING ELECTRODE IN ACTIVE GAS ENVIRONMENT, 10000 m3 TANK ROOF, PROCESS EQUIPMENT, WORKSHOP LAYOUT

The object of development is the technology of assembly and welding of the roof panels of the tank 10000 m3.

Purpose of development: Development of technology of assembly-welding of coating elements (panels) of the tank with pre-assembled coating sheets, selection of power sources and welding equipment, determination of cost-effectiveness of the selected technology.

To solve this problem, analysis of the tank coating design was carried out, analysis was carried out and welding methods were selected, design and process equipment for welding were selected, technological documentation was developed, welding operations were rationed, economic calculation of the welding technologies used was carried out, and safety issues of welding processes were considered.

The following results were obtained: The design of the coating panels has been developed, the technology of mechanized welding with a melting electrode in the medium of active gases has been developed. Welding equipment was selected and process equipment was designed. A comparative economic calculation was made showing the economy of the selected design technology compared to the basic one with annual savings of 688383 rubles.

Summary

Development object - 10000 m3 tank coating assembly and welding technology

The purpose of the development: Selection of technology for welding of coating boards, selection of technological equipment, determination of cost-effectiveness of selected solutions.

To solve the established problem, analysis of the coating design was carried out, analysis was carried out and methods of welding were selected, calculation of the coating strength was carried out, design of conductors for welding was selected, rationing of welding operations was carried out, economic calculation of the used welding technologies was carried out, safety issues of welding processes were considered.

The following results were obtained: Semiautomatic welding technology has been developed in the environment of active gases for the manufacture of a tank coating. Process tooling and welding equipment are selected. An assessment of economic indicators was carried out during, which revealed that the use of better equipment is a better option. The economic effect of the improved version is 688383 rubles/year.

Introduction

Tanks of various designs are widely used in almost all sectors of the national economy. They differ from each other in size, configuration, principles of action, method of manufacture.

The structures can be manufactured by various welding processes.

Welding is the technological process of producing an undisturbed compound by establishing interatomic and intermolecular bonds between welded parts of the product during their heating (local or general), and/or plastic deformation.

Before mass use in the metalworking of electric welding, non-detachable joints were most often made riveted, and some types of structures could not be made.

The basic principles of welding and cutting metals with an electric arc were developed in 1882 by N. N. Benardos and in 1890 by N. G. Slavyanov, but it took many years to develop and improve the process. As a progressive technological process, welding began to be used in the 20s of the last century. In the early 30s, welding began to be used as the main type of joints instead of riveting in the manufacture and installation of building metal structures.

The development of welding technologies entailed the development and use in the structures of alloyed steels of increased and high strength, as well as welded structures from non-ferrous metal alloys.

Today, welding joints are characterized by high mechanical properties, low metal consumption, low labor intensity and low cost. The reliability of joints made by welding allows it to be used in the assembly of the most critical structures.

The intensive development of the oil, gas and chemical industries required the commissioning of a large number of new storage facilities for their products. Such storage facilities are structures such as tanks, silos, spherical tanks, etc. They occupy a significant place in the total volume of installation work, accounting for about 20% of all steel structures.

The purpose of this diploma project is to develop the technology of assembly-welding of the coating of a vertical cylindrical tank for 10000 m3 for storage of oil products.

Process Section

Vertical cylindrical tanks for oil and oil products are responsible engineering structures, the accident of which can lead to economic and environmental damage, which is not commensurate with the cost of the structure itself.

That is why the issue of tank reliability is the subject of constant attention of Rostekhnadzor authorities in terms of industrial, fire and environmental safety.

Now the main normative document establishing the main technical requirements to a design, the device, production, installation, tests of vertical steel tanks (RVS) for oil and oil products is the PB 0360503 - "Rules of the device of vertical cylindrical steel tanks for oil and oil products".

It is also necessary to select and design the non-standard equipment, equipment and accessories used for the assembly and welding of the tank. During the development of the welding process, the processing, welding, assembly and inspection modes shall be presented (calculated). It is also necessary to select (with justification) all materials used for welding - welding wire, protective gas, etc.

In this industry (production of tank MKs), electric arc welding with a melting electrode is mainly used. To date, manual arc welding has been used in the construction of tanks. But automatic flux welding and semi-automatic welding in the environment of protective gas are increasingly used, since it is not inferior to manual welding in terms of availability of work, at the same time providing high productivity and quality of welding.

Reducing the cost of welding is one of the most important tasks of constructing steel vertical tanks of large capacity. For this purpose, a coating assembly is used from boards, which are welded to each other during installation.

The main advantages of such production of tank steel structures are:

- reduction of welding works on the installation site by 80% on average;

- high quality of welds due to the use of semi-automatic welding at the manufacturing plant.

1.4 Requirements to welding technology.

According to PB 0360503 welding methods, modes and techniques shall provide:

required uniformity and continuity of weld metal;

minimum stress concentration factor;

optimal cooling rate of welded joints (depends on steel grade, SEKV, metal thickness, linear energy, welded joint design, ambient temperature);

minimum value of welding deformations and movements of welded elements;

shape factor of each weld in the range of 1.3... 2.0.

Welding shall be performed in stable mode. Variations in welding current and voltage in the network to which welding equipment is connected shall not exceed ± 5%.

Welders certified according to requirements are allowed for welding of vertical cylindrical tank joints

PB 0327399 "Rules for certification of welders and welding specialists" and having the corresponding certificate.

Welding materials used in the construction and repair of steel vertical tanks shall be certified in accordance with the requirements of RD 0361303 "Procedure for the use of welding materials in the manufacture, installation, repair and reconstruction of technical devices for hazardous production facilities."

During the assembly and welding of each structural element of the tank, measures should be taken to reduce welding deformations and obtain the required geometric shape of the structure.

In double-sided butt joints, before making the seam from the back, it is necessary to grind the seam root with a reinforced abrasive circle to pure defective metal.

1.5. Select welding method, welding materials, and power supply

1.5.1 Welding method.

Considering the requirements, as well as for reasons of productivity and reduction of the cost of the built-up metal, the following welding methods will be used when welding the PBC coating:

manual arc welding (tacks).

mechanized welding in CO2 medium (welding of coating panels, defect correction);

Manual arc welding

In manual arc welding with coated metal electrodes, the welding arc burns from the electrode to the article, melting the edges of the welded article and melting the metal of the electrode rod and the electrode coating. The crystallization of the base metal and the electrode rod metal forms a weld.

Welding current (alternating or constant) is supplied to the electrode and welded article to form and maintain the electric arc.

If the positive pole of the power supply (anode) is connected to the product, it is said that manual arc welding is carried out at direct polarity. If the product has a negative pole, then the polarity is reverse.

Electrode consists of electrode rod and electrode coating. Electrode rod - welding wire; electrode coating is a multicomponent mixture of metals and their oxides. According to functional features, electrode coating components are separated:

1) Gas generating:

- protective gas;

- ionizing gas.

2) Slag-forming:

- for physical isolation of molten metal from active gases of atmospheric air;

- deoxidizers;

- refining elements;

- alloying elements;

3) Binders;

4) Plasticizers.

As a result of melting the electrode coating around the arc and above the welding bath, a gas atmosphere is formed that pushes air from the welding zone to prevent it from interacting with the molten metal. Pairs of alloying elements, base and electrode metals are also present in the gas atmosphere.

The slag, by covering the droplets of molten electrode metal and the surface of the welding bath, prevents their interaction with air, and also helps to clean the molten metal from impurities.

Advantages of the method:

- simplicity of equipment;

- possibility of welding in all spatial positions;

- possibility of welding in hard-to-reach places;

- Quick time transition from one material type to another

- a large range of welded metals.

Disadvantages of the method:

- large material and time costs for welder preparation;

- quality of welded joint and its properties are largely determined by subjective factor;

- low productivity (proportional to welding current, increased welding current leads to destruction of the electrode coating);

- harmful and difficult working conditions.

Manual arc welding is characterized by a relatively high level of specific heat deposition, leading to increased welding deformations, as well as low productivity, the use of this welding method in the manufacture of tanks should be limited.

The main method of welding in the manufacture of PBC coating is mechanized welding in the medium of active gases.

Mechanized welding in the environment of active gases.

When welding in the medium of protective gases, special gas is used to protect the welding arc and molten metal zone, which is supplied by jet to the melting zone using a torch, or welding is carried out in chambers filled with gas.

The most common is jet local protection by the gas flow flowing from the nozzle of the welding torch. The quality of the jet protection depends on the size and design of the nozzle, the distance from the nozzle cut to the surface of the material to be welded, and the flow rate of the protective gas. Various forms of the flow part of the nozzle are used: conical, cylindrical and shaped. To improve jet protection at the inlet of the nozzle, porous materials, fine grids and the like are installed in the burner, allowing further leveling of the gas flow at the outlet of the nozzle. Gas flow shall ensure laminar flow of the jet.

As protective gases, inert gases are used that do not interact with metal during welding (argon, helium, their mixtures), and active gases (CO2, N2, etc.) that interact with metal, as well as their mixtures. Protective gas determines physical, metallurgical and technological characteristics of welding method.

Welding in the environment of protective gases can be carried out by a non-consumable (usually tungsten), or melting electrode. In the first case, inert gases and mixtures thereof are used. The weld is formed by melting the edges of the article and, if necessary, the filler wire fed into the arc zone.

In the second case, welding wire is continuously fed into the arc zone, which melts and participates in the formation of the weld metal during welding. In order to increase the stability of the arc, increase the depth of penetration or change the shape of the seam or increase the welding efficiency of carbonaceous and alloyed steels, mixtures of inert gases with active gases are used, for example: argon mixture with 1... 5% O2, argon mixture c 10... 25% CO2, mixture of argon with CO2 (up to 20%) and addition of ≤5% O2.

Advantages of the method:

- production of quality weld;

- absence of slag crust, according to which no subsequent mechanical treatment is required;

- weld metal is less sensitive to corrosion;

- high labor productivity (1.5... 2.5 times higher than with manual electric arc welding);

- good conditions for visual observation of the welding process by the welder;

- slight warping of the part due to good gas cooling;

- possibility of using mechanical welding in different spatial positions;

- low fire of alloying elements during welding in inert gases.

Disadvantages of the method:

Disadvantages include:

- relatively large metal spattering;

- the need to apply protective measures against light and thermal radiation of the arc;

- possibility of gas protection violation during jet blowing.

Conclusion

In accordance with the initial data - the design drawing, the technical requirements for the welded structure, the production program, work was carried out on the technology of assembling and welding the coating of the tank, the main materials for welding were selected; to ensure the equal strength of welds with the main material, appropriate welding materials were selected, methods for producing an undisturbed joint were chosen, and the equipment necessary for welding the structure; welding modes are calculated, information on methods for inspection of welded joints is given.

The tooling for assembly and welding of the coating boards has been selected, as well as a plan of the assembly-welding section has been developed.

Issues related to safety of coating production are considered and measures to eliminate hazards are proposed.

Replacing equipment with a new one provides cost-effectiveness.

The economic effect is 6883830 rubles/year.