How to design the welding process of boiler and boiler

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Boiler is a kind of heat exchange equipment that converts the chemical energy stored in coal, wood, bagasse, petroleum, combustible gas and other energy sources, as well as the waste heat or other energy sources in industrial production, into water or steam at a certain temperature and pressure.

The boiler equipment is composed of two parts: the boiler body and the auxiliary equipment.

The boiler body is composed of two parts: the "pinchang pot" (a heating system that receives heat from high-temperature flue gas and transmits it to the working fluid) and the "furnace" (a combustion system that converts the chemical energy of the fuel into thermal energy).

"Pot" refers to various components that bear internal or external action pressure and constitute a closed system, including pot shell, boiler barrel (steam drum), descending pipe, header (joint box), water wall, slag tube, boiler tube bundle, steam-water separation device, steam temperature regulating device, sewage discharge device, steam superheater, economizer, etc.

"Furnace" refers to the combustion equipment composed of various components that constitute the fuel combustion place, including the furnace (combustion chamber) and the coal hopper in front of the furnace, the coal gate, the grate (grate), the slag removal plate, and the distribution and distribution device.

Fuel** system equipment.

Fuel that meets the quality requirements to ensure the continuous operation of the boiler.

Ventilation and induction equipment.

The furnace is fed with the air required for combustion or the hot air desiccant is delivered to the coal grinding system, and the combustion product - flue gas is drawn out from the furnace to ensure the normal combustion of the boiler.

Steam and water system equipment.

It includes three major systems: steam, water supply, and sewage.

Boiler auxiliary equipment.

Ash removal equipment.

The ash slag, the combustion product of the boiler bucket, is continuously removed and transported to the ash yard.

Flue gas purification system equipment.

Remove the entrained solid particles - fly ash and sulfur dioxide, nitrogen oxides and other harmful substances in the boiler flue gas to improve the atmospheric environment. Including flue gas dust removal, desulfurization, denitrification equipment, instrumentation and automatic control system equipment.

Automatic detection, program control, automatic protection and automatic adjustment of the operating boiler.

Main furnace type. Laminar furnace A combustion device in which the fuel is burned in layers on a grate.

Chamber furnace is also known as suspension furnace, it has no grate, and all the fuel is suspended in the furnace room space for combustion. It can be burned with both solid fuel and liquid or gaseous fuel. Pulverized coal furnaces, oil-fired furnaces, gas furnaces, coal-water slurry boilers.

Semi-suspension furnace refers to a boiler in which part of the fuel is suspended in the furnace and the other part is burned on the grate. Coal throwing machine furnace, circulating fluidized bed furnace.

1. The concept of industrial furnace: industrial furnace.

Industrial furnace: It is divided into electric furnace and combustion furnace (industrial furnace in the narrow sense refers to combustion furnace).

2. The main products of boilers.

Seven categories: resistance furnace, induction furnace, vacuum furnace, electron beam furnace, heat treatment (or melting) unit, heat treatment auxiliary equipment, combustion furnace.

3. Resistance furnace: three major components: heater, furnace lining, and heat-resistant components.

1 It is divided into two categories: periodic and continuous.

2 Characteristics of Periodic Furnaces::

a. The charge is added and taken out at the same time.

b. The charge is basically unchanged when heating (except for special circumstances: such as drum furnace and roller hearth furnace).

c Strive for uniform temperature in the working area.

3 Classification of periodic resistance furnaces.

a Chamber furnace.

b Bogie furnace (self-propelled and trailed) is used for annealing, and the workpiece is cooled with the furnace after heating.

c Pit furnace.

d Bell furnace (mainly used for annealing, heating hood can be lifted).

e Bottom-lift bell furnace (fixed hood, lifting base, suitable for large furnaces).

f Drum furnace.

g Sealed chamber furnace (also known as multi-purpose furnace, which can carry out heat treatment processes such as carburizing, smooth quenching, carbonitriding, etc.) The radiant tube is heated by a resistive wire fixed by a refractory ceramic disc in a sealed heat-resistant steel tube, so that the atmosphere in the furnace will not affect the heating element).

4. Even hail or continuous resistance furnace.

a Push furnace.

b Conveyor belt type stove.

c Mesh belt furnace (suitable for annealing, sintering, brazing and solution treatment of thin and small parts. The structure is similar to that of a conveyor furnace).

d Continuous drum furnace.

e Roller hearth furnace (pan movement on rollers).

f Turnkey hearth thank you.

The edge deviation of the butt weld of the pot barrel should meet the following requirements.

1) For longitudinal seams, the centerlines of the steel plates on both sides of the weld should be consistent. When the thickness of the steel plate is the same, c(=e) sheet thickness, and 3mm. When the thickness of the steel plate is different, and its edge deviation is >, or 3mm, the two sides of the thick plate must be evenly thinned, so that a thin plate is smoothly connected, and the length of the thinned part is d 4c.

2) For annular seams, when the thickness of the steel plate is the same, the thickness of the C plate is 1mm, and 4mm. When the thickness of the steel plate is different, and c > or 4mm, the edge of the thick plate should be thinned, and the thinning length d 4c.

Article 32 When the boiler with a working pressure of 100kgf cm2 is connected with the pipe end or the pot or header for fillet welding, the groove must be made on the pipe end or the pot and the header.

There is no undercut on the welds of the pot barrel and the header. The undercut depth of the weld of the pipe does not exceed, and the total length (the sum of both sides of the weld) exceeds the circumference of the pipe by 1 4, and does not exceed 40mm. Liquid traces.

1. Tubular sheet manufacturing process.

2. The manufacturing process of the cylinder section.

Material acceptance, marking, material stamp, transplantation, blanking, splicing, welder's stamp, code rolling, longitudinal seam positioning welding, welding, welder's stamp, code rounding, processing end face and groove, measuring outer circle optional.

3. Manhole device manufacturing process.

1) Manhole cover.

Material acceptance, marking, blanking, drilling, turning, machining oval and sealing surface.

2) Bolts. Sawing and turning threads.

3) The two are assembled and welded to be installed.

4. The manufacturing process of the pot tube.

Positioning welding of the assembly of the cylinder and the cylinder section Welding Welding welder steel seal code Marking the center line of the cylinder and the position line of the pre-welded parts Positioning welding of the assembly of the cylinder and one end of the tube sheet Welding The welder steel seal code Pre-weldment positioning welding Welding The assembly of the cylinder and the other end of the tube sheet Welding The welder steel seal code Flaw detection Marking the position line of the pipe seat hole Processing the pipe seat hole Positioning welding Welding Flaw detection Marking the position line of the row hole Processing the row of holes Removing burrs and debris Internals assembly Closing the manhole cover To be assembled.

5. The first process flow of boiler pressure parts.

Supporting The left and right headers are fixed on the special tooling Assemble the positioning and welding header The pot barrel is located on the special tooling Assemble the positioning welding down pipe The descending pipe is welded with the left and right headers and the pot tube The water-cooled wall pipe and the rear sewage pipe are assembled and positioned The water-cooled wall pipe and the rear sewage pipe are welded through the smoke pipe and the tension brace and positioned The smoke pipe and the tension brace (expansion) are welded Flush the smoke pipe Remove the debris inside the pot and the header Close the manhole and hand hole, etc. Hydrostatic test Paint.

6. After each part of the boiler is packed, it is packed and put into storage or sent directly to the user.

There are several types of boilers, including steam boilers, hot water boilers, organic heat carrier furnaces, etc., each with a different process.

The repair methods are: cold top repair, hot top repair, and digging repair.

Dig repair repair: 1Before digging and repairing the pot, the repair unit should conduct welding process qualification. The welding specimen must be welded by the repair unit.

2.The material and thickness of the repair plate are generally consistent with the original plate, and should conform to the GB713-1997 boiler steel plate, and the welding material is consistent with the supplementary material.

3.The distance between the longitudinal weld of the repair weld and the longitudinal weld of the adjacent section of the original cylinder must be staggered by at least 100mm, and it is strictly forbidden to form a cross weld with the annular seam. When the cylinder is excavated and repaired, the spacing between the two longitudinal welds is at least 300mm.

4.According to the demarcation range, the model is made and the model is covered with a formal line at the excavation and repair.

5.The digging and cutting method generally adopts gas cutting, and the cutting line should be paid attention to the straight and smooth cutting line, and the 30-degree single-sided V-shaped groove should be done. The bevel surface should be polished smooth with a grinding wheel, and pay attention to leave a l-3mm gap with the repair plate.

Cut off the bulging part, roll the steel plate of the same thickness and the same material into the same arc, open the groove, assemble the butt and weld it, if it is a pressure boiler, go through the procedures, and detect the flaw and supervise the inspection.

If you don't consider the approval and inspection process, then:

1. Draw a marking line along the edge of the bulge and the normal part according to the regular figure.

2. Cut off the bulge along the marking.

3. Clean up the scum and beat the groove with a hand grinding wheel.

4. Buy a steel plate with the same size, material and thickness as the cutting part of the pot, press the patch plate according to the R arc of the pot, and beat the groove.

5. Put in the patch plate, spot weld and fix it first, adjust the gap, and use manual internal and external surfacing welding after confirming that it is correct.

6. Use the flaw detector to take pictures to ensure that there is no slag inclusion, undercut, and false welding.

7. Close the boiler manhole, hand hole, safety valve seat, and close the valve; Hit the water pressure test.

8. Install the safety valve and open the valve. --Start the furnace.

1. The medium is extremely or highly hazardous.

2. Containers requiring barometric pressure test or gas-liquid combined pressure test Class 3 and Class III pressure vessels.

4. Cryogenic pressure vessel.

5. Pressure vessel for fatigue analysis.

6. A pressure vessel directly heated by the flame.

Therefore, not all fillet welds of pressure vessels should be fully welded, and they should be used to save time and cost.

Abstract: Abstract: Abstract: In view of the full welding characteristics of the fillet weld of the steam drawn out pipe seat on the boiler barrel, this paper improves the welding groove design, optimizes the process and trains the skills of the operator, so that the one-time pass rate of ultrasonic flaw detection of the fillet weld of the boiler tube seat is significantly improved.

Innovatively developed the mechanical welding equipment suitable for fillet weld welding of the boiler tube seat, carried out a large number of tests and product trial production, its welding productivity is high, the quality is stable and reliable, greatly improves the operating environment of welders, and takes the lead in the industry to use new welding technology, to reach the domestic advanced level.

Just engaged in boiler design, first of all, on the boiler.

JB T1609 Technical conditions for the manufacture of boiler boilers and barrels JB T1610 Technical conditions for the manufacture of boiler headers.

JB T1611 Technical conditions for the manufacture of boiler tubes JB T1612 Technical conditions for boiler water pressure test.

JB T1613 Technical Specifications for Welding of Boiler Pressurized Elements JB T1615 Technical Conditions for Boiler Painting and Packaging.

JB T2191 - JB T2192 Boiler manhole and hand hole device, etc. Of course, for boiler designers, they should know more about the "Standard Method for Industrial Boiler Design and Calculation".

Now the general standard is the Japanese standard and the national standard, which is not the most important, the key is the principle design of each component. Then select the appropriate standard according to the customer's requirements.

Boiler design does not require separate qualifications, which is not the same as vessel design, but it is not independent. Even if.

It is not possible to use the drawings that have been reviewed by other manufacturers. Generally, the manufacturing of the manufacturing must have the corresponding level of qualification.

The qualifications for installation are separated, but boiler factories can install boilers of their own manufacture.

It is required as follows: The connection of the main pressure components Basic requirements (1) The main welds of the main pressure components of the boiler (including the boiler barrel (pot shell), header, furnace bladder, back-combustion chamber and the longitudinal and circumferential welds of the power station boiler starting (steam-water) separator, centralized descending pipe, steam pipe, head, tube sheet, furnace and foot ring, etc.) should be fully welded butt joints. (2) The tension braces of the boiler should not be spliced.

The connection of the T-joint is for the horizontal internal combustion boiler and the through-flow boiler with the rated working pressure not greater than that, and the pressure component connection of the flue gas temperature of the working environment is 6000C, and the butt connection of the T-joint can be used under the following conditions, but the lap connection can not be adopted: (1) the weld adopts the joint type of full welding, and the groove is machined; (2) The connection between the tube plate and the cylinder of the shell and the bile of the horizontal internal combustion boiler shall adopt a plug-in structure; (3) The thickness of the weld of the connection part of the T-joint shall not be less than the wall thickness of the tube sheet (pipe cover), and the parts of the back of the weld that can be sealed and welded shall be sealed and welded, and the parts that cannot be sealed and welded shall be made of argon arc welding to make the bottom and ensure the welding penetration; (4) The weld of the T-joint connection part shall be ultrasonic tested in accordance with the relevant requirements of NB T47013 (JB T4730) "Nondestructive Testing of Pressure Equipment". The connection between the pipe joint and the pot (pot shell), header and pipelineThe connection of the pipe joint with the pot tube (pot shell), header and pipeline shall be fully welded under the following circumstances

1) In the strength calculation, when the opening needs to be strengthened by the pipe joint; (2) When the outer diameter of the pipe joint of Class A high pressure and above boiler is greater than 76mm; (3) A-class boiler centralized descending pipe joint; (4) When the descending pipe or its pipe joint is connected with the header (except for the descending pipe with an outer diameter of 108mm and a plug-in structure). Thick-walled pipe joints should be used for the connection of exhaust, drainage, sewage and sampling pipes with 32 mm outer diameter of A-class boiler and the boiler (shell), header and pipe. For details, please refer to the boiler safety technical supervision regulations TSG G0001-2012