Assembly-welding of cementing tank

Contents

INTRODUCTION

1. MAJOR PART

1.1. Design Assignment and Description

2. PROCESS PART

2.1. Product Specification

2.2. Main Material Specification

2.3. Evaluation of steel weldability St3sp

2.4. Selecting a Welding Method

2.5. Selecting Welding Materials

2.6. Selection of welding equipment

2.8. Calculation of welding modes and normalization of assembly and welding per product

2.8.1. Calculation of welding modes

2.8.2. Calculation of weld metal mass for MP

2.8.3. Calculation of machine time

2.9. Development of welding structure manufacturing technology

2.10. Calculation of the chemical composition of the weld

2.11. Inspection of welded joints and structures

3. ORGANIZATIONAL PART

3.1. Development of measures to reduce welding deformations

3.2. Occupational safety and safety during welding

CONCLUSION

LIST OF LITERATURE

BBE

Introduction

Welding is the most efficient technology for creating permanent joints of structural materials and obtaining resource-saving blanks that are as close in geometry to the optimal shape of the finished part or structure.

In connection with the increase in demand, it is advisable to automate the technological processes for the manufacture of petrochemicals of construction.

The purpose of the course design is to design the process of assembly and welding of a cementing tank of a drilling rig from sheet steel of carbon structural steel of ordinary quality St3sp according to GOST 3802005.

To achieve this goal, the following tasks will be solved in the course project:

- Analysis and selection of welding method;

- Selection of welding equipment;

- Selection of welding materials;

- Development of assembly and welding technology;

- Calculation of optimal welding modes for a given product;

- Purpose of measures to combat deformation during welding;

- Safety requirements in the manufacture of welded structures

In the design version, it is proposed to perform welding in a mechanized or automatic way. This type of welding is very promising for welding products of building structures, has great advantages over existing welding processes.

Process Part

2.1. Product Specification

Product fabrication specification:

1. Chemical composition of steel as per GOST 3802005. hot-rolled sheet rolled stock as per GOST 1990374. Sheet rolled stock specification as per GOST 1463989.

2. All welds shall be tight.

3. Permissible defects according to RD 34.15.13296.

2.4. Selecting a Welding Method

The choice of welding method in each case shall be made taking into account a number of factors, the main of which are:

- properties of welded metal;

- thickness of the material from which the structure (article) is made;

- dimensions of the structure (article);

- economic efficiency.

In the manufacture of welded steel structures, various methods of arc welding are used.

Manual arc welding of low-carbon and low-alloyed steels is carried out mainly by electrodes with a main (fluoristocalcium) coating of type E42A, E-46, E50A, providing higher technological strength and improved plastic properties compared to electrodes of other types. In some cases, rutile coated electrodes such as ANO1 are used to weld low carbon steels (e.g., 09G2). The most widely used electrodes are grades UONIA 13/45A, SM11, ANO-8 (type E42A) and UONIA 13/55, DSK50, ANO-7 (type E50A), providing strength and ductility of the weld metal at the level of the properties of the base metal.

High strength of the weld metal during welding with electrodes of type E42A is achieved due to the transition of alloying elements into a weld of the base metal and an increased cooling rate of the weld metal.

Requirements for structural elements and geometric dimensions of welds are regulated by GOST 526480 and GOST 1553575.

Mechanized or automatic flux welding in most cases is carried out using the same welding materials as for welding low-carbon steels: fused fluxes AN348A, OSTS-45 (single-arc welding), AN60 (multi-arc welding), as well as welding wires Sv00GA, Sv-10G2. For welding microalloyed staly, for example 15G2AF, in some cases apply low-siliceous gumboil of AH22 in combination with provoloka of Sv08HM and Sv10NMA. However, the seams are less resistant to crystallization cracks, so that the welding should be preheated.

The metal of the fluxed welds, due to the significant share of the base metal and the sufficient content of alloying elements, has a higher corrosion resistance in seawater than the metal of the welds welded with coated electrodes of conventional composition.

Requirements for structural elements and geometric dimensions of welds are regulated by GOST 871379 and GOST 1553475.

Mechanized welding in protective gases is performed mainly in semi-automatic mode. The technology of welding low-alloy steels in carbon dioxide is practically no different from the technology of welding low-carbon steel. In practice, the same welding materials are used as for welding low-carbon steel. So, steel St3sp, St3ps, St3kp, 10. 20, 20L are welded with welding wire Sv00A. For single-layer welding and welding in not more than two or three layers, Sv12HA wire can be used.

Mechanized welding in CO2 is also performed with powder wires PPAN4 and PPAN8, at the same time seams are equal to the base metal and have increased plastic characteristics.

Thus, the use of mechanized welding in the carbon dioxide environment and automatic flux welding in the manufacture of the tank allows to reduce the cost of the product, as well as improve the working conditions of welders, increase the productivity of the process, however, it allows to obtain a product of high quality, which is especially important in the production of large-sized products for storing petroleum products.

Based on the dimensions of the article, the thickness of the sheet rolled stock, the length of the welding joints and the specified technical requirements for the finished design and quality of the joints, as well as the output volume of 750 pieces, the most acceptable option is mechanized (semi-automatic) welding in protective gases according to GOST 1477176.

The main advantages of welding in the environment of protective gases :

- Increased protection of metals from oxidation in the open air;

- ease of use of this type of welder when operating in different spatial positions;

- when argon is used as a protective gas, slag inclusions and oxides do not occur on the surface of the weld;

- when welding is used in the environment of protective gases, it is possible to monitor the process of forming the weld and adjust it;

Greater productivity and efficiency than arc welding;

- low cost when using carbon dioxide as a protective.

Disadvantages of this welding method are:

- scarcity and high cost of inert protective gases;

- the need to protect the welder from light and thermal radiation.

Organizational Part

3.1. Development of measures to reduce welding deformations

Welding deformations due to changes in the size and shape of structures significantly complicate their assembly, degrade their appearance and performance. Welding stresses reduce the resistance of welded structures to destruction, especially when exposed to cyclic loads and aggressive media. Therefore, various methods are used to reduce or eliminate welding strains and stresses.

Measures to reduce strains and stresses can be carried out at different stages of the design: before welding - at the design stage of the design and production technology, during and after welding.

The measures used mainly for the removal of welding stresses affect the deformations and, conversely, the measures used mainly for the reduction of deformations affect the magnitude of the stresses.

Methods of reducing residual stresses are divided into thermal, mechanical and thermomechanical. It is most efficient to remove residual stresses by methods carried out after welding.

Thermal methods include preheating and accompanying heating during welding and high tempering after welding.

Total high tempering is the most effective method of reducing residual stresses for our product, as it allows reducing stresses by 85-90% of the initial values ​ ​ and at the same time improving the plastic properties of welded joints. High tempering consists of heating (for steel to a temperature of about 650 ° C), holding (2-4 hours) and slow cooling.

Pre-welding activities.

1. Rational design of the welded product, which includes:

- reduction of the amount of weld metal and accordingly the amount of heat introduced during welding due to reduction of welds and their sections;

- avoidance of junctions and crossings of joints ;

- symmetrical arrangement of joints for balancing deformations;

- symmetric arrangement of stiffening ribs, straps, slashes, etc., and their minimal use.

2. At the stage of technology development, it is advisable to provide for :

- dimensions and shape of blanks taking into account the value of shrinkages occurring during welding;

pre-deformation of the workpieces, which would be opposite to the expected welding deformation;

- correct choice of welding type, considering that deformations in manual welding are usually more than in automatic welding, and deformations in flux welding are more than in carbon dioxide welding.

Welding Activities:

- reduction of linear energy at assignment of more economical modes;

- artificial cooling of the welding zone, for example with water, water-cooled copper linings, etc., to reduce the heating zone and, accordingly, welding deformations;

- fastening of welded items in rigid devices; use of multilayer seams instead of single-layer, forging seams after each pass;

- rational welding sequence for balancing deformations, application of back-step welding method, which consists in the fact that the whole length of the weld is disassembled into separate stages and welding of each stage is carried out in the direction opposite to the general direction of welding.

Post Welding Activities:

- mechanical straightening of welded articles to create plastic deformations reversed by welding, by stretching, bending, local deformation by forging, rolling with rollers, metal sediment in thickness under a press, etc.;

- heat correction by local heating. The metal expanding at local heating is deposited by the adjacent cold metal, therefore, after cooling, the dimensions of the heated section decrease, which leads to the elimination of local deformations (claps, bulges, etc.); - high tempering of parts in the fixtures.

Conclusion

In the first section of the course design, I reflected the description of the given design of the tank, the chemical composition and properties of the material used.

In the second section, the optimal welding method was chosen, which meets all the basic requirements of the design, welding materials, basic and auxiliary welding equipment were selected and the technology for manufacturing the welded structure "Detachable Vessel" was developed. Also in this section, I considered the feasibility of the process, such as:

- definition of weld joint types in the welded structure;

- determination of weld length and weld cross-sectional area;

- determination of the weight of the built-up metal;

- calculation of welding materials consumption;

- calculation of electric power consumption;

- appropriate methods of control of the given design are selected.

The third section of the project presented the main measures to combat deformation during welding, as well as safety during welding.

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