Gas welding of medium complexity and complex components. Types of welding work in practice. Independent work of the student

§ 55. Electric welder for manual welding (2nd category)

Characteristics of work

Tacking parts, products and structures in all spatial positions of the weld.
Manual arc and plasma welding of simple parts in the lower and vertical position of the weld, deposition of simple parts.
Preparation of products and assemblies for welding and cleaning of seams after welding.
Ensuring protection of the reverse side of the weld during welding in shielding gas.
Heating of products and parts before welding.
Reading simple drawings.

Must know:

device and principle of operation of electric welding machines and devices for arc welding in the conditions of using alternating and direct current;
methods and basic techniques of tack welding;
shapes of the section of seams for welding;
device of cylinders;
colors, paints and rules for handling them;
rules for welding in shielding gas and rules for ensuring protection during welding;
rules for servicing electric welding machines;
types of welded joints and seams;
rules for preparing the edges of products for welding;
types of grooves and designation of welds in the drawings;
basic properties of the electrodes used and the metal and alloys being welded;
purpose and conditions of use of instrumentation;
causes of defects during welding and ways to prevent them;
device of torches for welding with a non-consumable electrode in shielding gas.

Work examples

1. Transformer tanks - welding the walls for automatic welding.
2. Cradle beams, suspension bars and bolsters of all-metal cars and cars of power plants - welding of reinforcing squares, guides and centering rings.
3. Rolling beams - welding of points and gripping wheels according to the markings.
4. Strikers, cylinders of steam hammers - fusion.
5. Diaphragms of frames of platforms and metal gondola cars and window frames of passenger cars - welding.
6. Frames of children's chairs, stools, greenhouses - welding.
7. Fence covers and other lightly loaded units of agricultural machines - welding.
8. Header brackets, brake control rollers - welding.
9. Brackets for dump truck subframes - welding.
10. Spring pads and linings - welding.
11. Steel flasks - welding.
12. Frames of transformer tanks - welding.
13. Bed mattress frames, armored and rhombic mesh - welding.
14. Simple cutters - fusing of quick cutter and hard alloy.
15. Steel and cast iron small castings - fusing shells in untreated areas.

Electric arc welding:

1. Lugs, bushings, cups - tack.
2. Structures not subject to testing - welding of the set on a stand and in the lower position.
3. Plates, racks, angles, corners, frames, simple flanges made of metal with a thickness of over 3 mm - tack.
4. Platforms and ladders - fusion of rollers (corrugation).
5. Racks, boxes, shields, frames made of squares and strips - potholders.
6. T-joints and cleaning of foundations for auxiliary mechanisms - welding.
7. Set to light partitions and baffles in the lower position - welding at the pre-assembly site.
8. Equipment fastening parts, insulation, technological ends, combs, temporary strips, bosses - welding to structures made of carbon and low-alloy steels.

Gas shielded welding:

1. Welded joints of critical structures - protection of the weld during the welding process.

§ 56. Electric welder for manual welding (3rd category)

Characteristics of work

Manual arc and plasma welding of medium complexity parts, assemblies and structures made of carbon steels and simple parts made of structural steels, non-ferrous metals and alloys in all spatial positions of the weld, except for the ceiling.
Manual oxygen arc cutting, planing of medium-complexity parts from low-carbon, alloy, special steels, cast iron and non-ferrous metals in various positions.
Welding of worn-out simple tools, parts made of carbon and structural steels.

Must know:

design of used electric welding machines and welding chambers;
requirements for the weld seam and surfaces after oxygen cutting (planing);
properties and significance of electrode coatings;
main types of weld inspection;
methods for selecting electrode grades depending on steel grades;
causes of internal stresses and deformations in welded products and measures to prevent them.

Work examples

1. Beater and cutting drums, front and rear axles of a tractor trailer, drawbar and frame of a combine and header, augers and headers, rake and reel - welding.
2. Sidewalls, transition platforms, footboards, casing of railway cars - welding.
3. Raid buoys and barrels, artillery shields and pontoons - welding.
4. Electrical machine shafts - welding of journals.
5. Parts of the body frame of freight cars - welding.
6. Details of the rocker mechanism - fusing of holes.
7. Frames for switchboards and control panels - welding.
8. Support rollers - welding.
9. Keel blocks - welding.
10. Assembled casings, heating boilers - welding.
11. Truck brake pads, casings, rear axle axle shafts - welding.
12. Structures, components, parts of the gun mount - welding.
13. Housings of electrical explosive equipment - welding.
14. Lifting cranes - fusing of slopes.
15. Car dealership bodies - welding.
16. Diesel locomotive frames - welding of conductors, flooring sheets, parts.
17. Shaped cutters and simple dies - welding and surfacing of high-speed cutters and hard alloys.
18. Small machine beds - welding.
19. Racks, bunker grates, transition platforms, stairs, railings, decking, boiler casing - welding.
20. Smoke pipes up to 30 m high and ventilation pipes made of sheet metal carbon steel- welding.
21. Connected smoke pipes in boilers and steam superheater pipes - welding.
22. Heated pipes - welding of beads.
23. Non-pressure pipelines for water (except main ones) - welding.
24. Pipelines of external and internal water supply and heating networks - welding in stationary conditions.
25. Gears - fusing of teeth.

Electric arc welding:

1. Expansion tanks - welding, pipe welding.
2. Tanks, pipelines, vessels, containers made of carbon and low-alloy steels for filling with water - welding.
3. Buoys, raid barrels, artillery shields and pontoons - welding.
4. Rollers, bushings - fusing in the lower position.
5. Shafts and frames of electric motors - welding of shells and cracks.
6. Light barriers - welding on the slipway to each other and to internal structures.
7. Bushings on the front panels of the main distribution boards are welded to the conductor.
8. Doors and hatch covers are permeable - welding.
9. Doors are permeable, hatch covers are welded.
10. Parts of distribution boards: caps, substitutes, grooves, hinges, barrels, racks, welds, studs - welding to the body, frame or cover.
11. Parts of ship mechanisms - fusing the edges of sheets and other parts during assembly work.
12. Details of units, foundations, small metal thickness of 3 mm and higher, made of carbon steel - welding.
13. Diffusers of compensators of gas turbine installations, fundamental frames - tacking of parts.
14. Chimneys and chimneys of the main and auxiliary boilers - welding of vertical and horizontal seams, welding of stiffeners.
15. Straight and angled gutters for laying cables - welding along the remote control route.
16. Round blanks for dies - welding.
17. Locks: wing, rack, lever, latch - welding of butt and overlap joints.
18. Sewing when installing equipment - welding in the lower position.
19. Lightweight portholes - welding.
20. Water chambers, compensator casings, frames, power units - welding.
21. Chambers for shot blasting machines, armor protection for shot blasting machines - welding.
22. Frames, brackets, beams and instrument frames of simple design - welding.
23. Frame and casing of auxiliary water-tube recovery boilers and air heaters - welding.
24. Frames, beds and other equipment for assembling large units - welding into volumetric units.
25. Pockets for photo circuits, pencil cases, spare fuses, fuse links - welding in power distribution devices.
26. Welded body structures made of carbon and low-alloy steels - air-arc planing in all spatial positions (removing temporary elements, melting defective areas of welds, cutting edges).
27. Fastening the ballast - welding on the slipway.
28. Covers of hermetic boxes - welding of shells, grooves.
29. Frames and lining of doors of power distribution devices - welding.
30. Frames of cabins, beds - welding into volumetric units.
31. Electric bridge crane rollers - welding.
32. Keel blocks and cages for slipways - welding.
33. Main body structures made of AK and YuZ steels - electric tack (removable) along the installation joints.
34. Casings, gutters, panels, pallets made of carbon and low-alloy steels with a metal thickness of over 2 mm - welding.
35. High pressure turbine casings - tack.
36. Bodies, frames of mobile diesel power plants, frames, levers, angles - welding.
37. Fastening special coatings: studs, staples, combs - welding.
38. Spacer rings, counterweights, spacer beams - welding to OK with technological non-measurement.
39. Waterproof covers - welding under pressure from 0.1 to 1.5 MPa (1 -15 kgf/sq. cm).
40. Coamings of covers, doors, hatches, necks, grilles - welding.
41. Folding sheets, fairings, ship devices - welding in the workshop.
42. Light hatch - welding the body and welding the covers.
43. Superstructures - set welding, welding and welding to decks.
44. Superstructures - set welding, welding and welding to decks in lower and vertical positions.
45. Saturation of the metalwork building - welding.
46. Outer casing - welding of technological seals that are not subject to control.
47. Simple hull structures - electric air gouging (surfacing of the weld root and removal of temporary fasteners).
48. Insulation purlins on sides and bulkheads - welding on the slipway and afloat.
49. Sheathing - welding in the ceiling position.
50. Butts and lifting products up to 5 tons - welding of the pre-assembly section.
51. Sheathing of frames, front panels - welding to structures.
52. Platform fencing, fan railings (storm railings, handrails for ladders) - welding to structures.
53. Supports, covers for distribution boards - welding.
54. Deck pipes - welding.
55. Suspensions of pipes, cables, fastenings of electrical appliances, brackets made of carbon and low-alloy steels - welding.
56. Support stands, pedestals, beams without cutting edges - welding.
57. Special devices for filling cable boxes - welding the bushing to the shaft.
58. Light bulkheads, baffles - welding of stiffeners in the lower position.
59. Rudder blade made of low-carbon steel - welding.
60. Transverse and longitudinal bulkheads, deck partitions - welding of units, panels along joints and grooves in the lower position in the pre-assembly area.
61. Planks, brackets, brackets, racks, suspension of pipes, cables, fastening of electrical appliances - welding on a slipway.
62. Protectors - welding.
63. Instrument frames and frames of complex configuration - welding.
64. Spacer beams, rings, crosspieces - welding to the main body.
65. Grilles made of tubes with a diameter of 10 to 15 mm - welding.
66. Rollers, hubs, couplings - welding and fusing of teeth.
67. Rudders - welding the flat part of the feathers.
68. Gas cutting tables, boxes for transporting parts and charge - welding.
69. Trawl brackets, transition bridges, platforms, bulwarks, numbers, letters - welding on the slipway.
70. Staples, fastening bags, pliers, panels - welding.
71. Gas cutting tables, boxes for transporting parts and couplings - welding.
72. Racks for storing documentation - welding.
73. Walls made of sheet metal with a thickness of 3 mm and above - welding in the lower and vertical position.
74. Vertical and inclined ladders (steel), gangways - welding.
75. Galley chimney pipes - welding.
76. Ship ventilation pipes made of carbon and low-alloy steels with a thickness of over 2 mm - welding.
77. Air guide device, air heaters for water tube boilers - welding.
78. Railing, loading, winches, views - welding.
79. Ventilation flanges - welding.
80. Foundations made of carbon and low-alloy steels: for auxiliary mechanisms, cylinders, boat and mooring devices, equipment fastenings - welding.
81. Shanks of oil seals, punches, dies - welding to metal structures.
82. Cylinders, pipes, glasses that do not require leak testing - welding of longitudinal and circumferential seams.
83. Cabinets and safes with locks - welding.
84. Frames made of carbon and low-alloy steels - welding and welding to the skin at the pre-assembly site.
85. Medium complexity dies with pressure up to 400 tons - welding.
86. Anchors, sternposts, stems - welding of defects.

Gas shielded welding:

1. Bosses, bottoms, crosses, partitions, strips, ribs, cups, angles, flanges, fittings in assembled welded assemblies made of aluminum, copper and other alloys - tack.
2. Light fences, platforms made of alloys - welded to each other and welded on a slipway to internal structures.
3. Sleeves for support made of copper and copper-nickel alloys - welding of bosses and extensions.
4. Insulation details of water tube boilers - welding.
5. Parts made of aluminum alloys, metal thickness over 3 mm - tack.
6. Frame parts made of aluminum alloys 6 mm thick - welding.
7. Parts for fastening furniture and products made of non-ferrous alloys - welding.
8. Products working under pressure - seam protection during the welding process.
9. Products made of aluminum alloys with a metal thickness of over 3 mm (casings, gutters, panels, screens, pallets, boxes, housings, covers, frames, brackets, various assemblies) - welding.
10. Products made of brass with metal thickness up to 1.5 mm - welding for chrome plating.
11. Frames, brackets, frames made of profile metal, alloys - welding.
12. Casings on the route of steam heating and electrical cables made of non-ferrous alloys - welding.
13. Boxes measuring 300x300x100 mm - tack welding.
14. Metal furniture - welding.
15. Set in sections made of aluminum alloys - tack during installation.
16. Castings from non-ferrous alloys, simple structures - welding of shells and cracks.
17. Non-ferrous castings - welding of defects.
18. Planks, cassettes, bracket-bridges, pendants, shanks and other saturation from alloys - welding.
19. Suspensions, foundations for electrical equipment - welding at the pre-assembly site.
20. Simple parts made of titanium and its alloys - welding.
21. Tanks made of alloys that do not require hydrotesting for tightness - welding.
22. Tanks that do not require hydrotesting for tightness - welding.
23. Railing devices (stands, railings, casings, grounding hooks) made of non-ferrous alloys - welding.
24. Main foundations, frames, deckhouses, tanks - protection of the weld during the welding process.
25. Studs, brackets made of alloys - welding to ship structures.

§ 57. Electric welder for manual welding (4th category)

Characteristics of work

Manual arc and plasma welding of medium complexity of machine parts, assemblies, structures and pipelines made of structural steels, cast iron, non-ferrous metals and alloys and complex parts, assemblies, structures and pipelines made of carbon steels in all spatial positions of the weld.
Manual oxygen cutting (planing) of complex parts made of high-carbon, special steels, cast iron and non-ferrous metals, welding of cast iron structures.
Fusion of heated cylinders and pipes, defects in machine parts, mechanisms and structures.
Welding of complex parts, assemblies and complex tools.
Reading drawings of complex welded metal structures.

Must know:

installation of various electric welding equipment;
features of welding and arc cutting on alternating and direct current;
technology for welding products in chambers with a controlled atmosphere;
basics of electrical engineering within the scope of the work performed;
methods for testing welds;
types of defects in welds and methods for their prevention and elimination;
principles for selecting welding modes based on instruments;
brands and types of electrodes;
mechanical properties of welded metals.

Work examples

1. Devices, vessels, tanks made of carbon steel, operating without pressure - welding.
2. Bearing reinforcement reinforced concrete structures- welding.
3. Transformer tanks - welding of branch pipes, welding of boxes for terminals, cooler boxes, current settings and tank covers.
4. Rudder stocks, propeller shaft brackets - welding.
5. Fittings and boiler burner bodies - welding.
6. Cast iron parts - welding, fusion with and without heating.
7. Chambers of hydraulic turbine impellers - welding and surfacing.
8. Frames of industrial furnaces and boilers DKVR - welding.
9. Engine crankcases - welding.
10. Gas exhaust manifolds and pipes - welding and welding.
11. Hydraulic turbine control rings - welding and surfacing.
12. Housings and axles of the header drive wheels - welding.
13. Compressor casings, low and high pressure cylinders of air compressors - cracking.
14. Rotor housings with a diameter of up to 3500 mm - welding.
15. Stop valve housings for turbines with power up to 25,000 kW - welding.
16. Fastenings and supports for pipelines - welding.
17. Brackets and pivot fastenings of the diesel locomotive bogie - welding.
18. Sheets of large thicknesses (armor) - welding.
19. Masts, drilling and production rigs - welding in workshop conditions.
20. Struts, axle shafts of aircraft landing gear - welding.
21. Foundation slabs for large electrical machines - welding.
22. Dust-gas-air ducts, fuel return units and electric precipitators - welding.
23. Transformer frames - welding.
24. Bed frames - welding in a rotary jig in all spatial positions, except for the ceiling.
25. Tanks for petroleum products with a capacity of less than 1000 cubic meters - welding.
26. Rails and prefabricated crosspieces - fusing ends.
27. Stators of air-cooled turbogenerators - welding.
28. Crusher beds - welding.
29. Welded-cast frames and housings of electrical machines - welding.
30. Beds of large-sized cast iron machines - welding.
31. Beds of working stands of rolling mills - surfacing.
32. Pipelines of external and internal water supply and heating networks - welding during installation.
33. Pipelines of external and internal low-pressure gas supply networks - welding in stationary conditions.
34. Technological pipelines (V category) - welding.
35. Complex cutters and dies - welding and surfacing of high-speed cutters and hard alloys.
36. Fachwerks, connections, lanterns, purlins, monorails - welding.
37. Car block cylinders - fusing of shells.
38. Car tanks - welding.

Electric arc welding:

1. Fittings, pipelines, branches, flanges, fittings, cylinders, tanks, tanks made of carbon steel, operating under a pressure of 1.5 to 4.0 MPa (from 15 to 40 kgf/sq.cm) - welding.
2. Beams and traverses of crane trolleys and mechanisms - welding.
3. Lugs, flanges, welds, fittings for high-pressure compressor cylinders - welding.
4. Cylinders, tanks, reservoirs, tanks, separators, filters, evaporators made of carbon steel - welding under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm).
5. Reflective tanks made of low-carbon steel with a thickness of 1.0 to 1.5 mm - welding in the lower position.
6. Banquettes, shaft housings, winch housings, winch gearbox housings, deck glasses - welding under pressure from 0.1 to 1.0 MPa (from 1 to 10 kgf/sq. cm) in the lower position.
7. Block sections - welding of baffles, saturation to the body.
8. Waterline beads - surfacing along the ship’s hull.
9. Medium-sized crankshafts - welding and fusing of worn parts.
10. Propellers, blades, hubs of normal accuracy class of all sizes and designs - air-arc planing of all surfaces.
11. Enclosures, bulkheads and cabins - welding and welding in various spatial positions.
12. Gas exhausts, air distributors, ventilation pipes in the superstructure - welding.
13. Silencers of high pressure compensators, steel, metal thickness 1.5 mm and diameter up to 100 mm - welding.
14. Doors and hatch covers are water-gas-tight - welding.
15. Bottom, side, upper and lower decks, platforms, three-dimensional sections of the extremities, transverse and longitudinal bulkheads - welding of the joints of the set on the slipway.
16. Metalwork details for the main body and lining of the main tanks - welding.
17. Shelf parts - welding to intercompartment transverse bulkheads.
18. Doors, panels, angles, sheets, bushings with a metal thickness of 1.4 to 1.6 mm - welding.
19. Parts of complex configuration, intended for work under dynamic and vibration loads, material thickness from 10 to 16 mm - welding.
20. MSCh products - anti-corrosion deposits of AK type steels on surfaces for machining.
21. Casings, gutters, panels, pallets made of carbon and low-alloy steel with a thickness of up to 2 mm, of alloy steel with a thickness of over 2 mm - welding.
22. Cable boxes - welding under pressure testing from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm) during unit assembly.
23. Casings, gutters, panels, pallets made of carbon and low-alloy steels up to 2 mm thick, alloy steel over 2 mm thick - welding.
24. Ship ventilation ducts - welded to bulkheads on the slipway.
25. Anchor fairleads - welding.
26. Casings, gutters, panels, pallets made of alloy steel up to 2 mm thick - welding.
27. Ventilation valves - welding.
28. Cargo hold coamings - welding the set together.
29. Body structures made of carbon, low-alloy and high-alloy steels - air-arc gouging in hard-to-reach places (melting the weld root, removing temporary elements, smelting defective areas).
30. Ship-carrying train structures - welding.
31. Hull of a surface vessel: outer deck plating - welding of joints and grooves on the slipway in all positions.
32. Hulls of heavy portholes - welding and welding into the ship’s hull.
33. Hull structures and assemblies, up to 20% of the welds of which are subjected to ultrasonic or gammagraphic control - welding.
34. Brackets, edges, screens made of sheet and profile metal up to 2 mm thick - welding.
35. Caps and bearing housings made of castings - welded for tightness testing.
36. Removable sheets of carbon and low-alloy steels - welding.
37. Recess marks, cargo welding - welding to the ship's hull.
38. Masts, cargo booms, cargo columns - welding of assembly joints and face sheets on the slipway.
39. Signal masts - welding during assembly.
40. Metal structures of ships - welding of defective areas of seams when tested on a slipway and afloat in all positions.
41. Intercompartment transverse bulkheads - welding.
42. Saturation of fittings and hulls - welding on the transverse and longitudinal bulkheads of the superstructure.
43. A set of longitudinal and transverse bottom, side and deck (calculation) sections made of structural steel - welding to each other and welding to the outer plating and deck flooring on pre-stacking assembly.
44. Set with grooved edges, joints and grooves of steel bulkheads - assembly and welding at the pre-assembly site.
45. A set of bottom sections with a height of 0.8 to 1.5 m - welding in the bow, to the bottom deck and welding between them.
46. Superstructures, cabins made of alloy steels - welding and welding to the main body.
47. Double bottom decking - welding joints and grooves on the slipway.
48. Saturation of cargo masts, booms (heads, foundations, control platforms with railings) - welding to structures.
49. Butts for transporting sections with a carrying capacity of up to 20 tons - welding and welding to sections.
50. Butts with a lifting capacity of over 20 tons - welding and welding.
51. Steel rudder blade - welding of the flat part.
52. Transverse and longitudinal bulkheads, outer walls of superstructures - welding of joints and grooves of panels in all positions on the slipway.
53. Reinforcements for foundations, building device stops, side keels, outer walls of tanks, outer walls chimney- welding on the slipway.
54. Other tanks - welding of seams with cutting edges and structural lack of fusion on a sectional assembly.
55. Rails of workshop electric trolleys - welding.
56. Joints and grooves of the aft end skin, brackets and stabilizers - welding.
57. Joints of sheets of walls, roofs and a set of internal tanks - welding and welding to the plating, bulkheads and to each other.
58. Assembly joints of reinforced concrete vaults - welding.
59. Tambour, airlock, bathrooms - welding and welds.
60. Ship ventilation pipes made of carbon and low-alloy steels up to 2 mm thick - welding and welding of flanges to them.
61. Carbon steel pipelines operating under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf / sq. cm) with a pipe wall thickness of more than 2 mm - welding.
62. Pipelines - welding of joints on backing rings with quality control of seams by radiography.
63. Pipelines - welding of pressurized joints with quality control of seams by radiography.
64. Anchor, towing, launching and mooring devices, construction device stops - welding.
65. Flanges, pipes, fittings, welds, nozzles, nipples - welding to the pipeline under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm).
66. Foundations made of alloy steel for auxiliary mechanisms, cylinders, boat and mooring devices - welding.
67. Frames - welding of joints during heat treatment on a HDTV installation.
68. Dies for presses with pressure over 400 tons - welding.

Gas shielded welding:

1. Tin bronze fittings under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm) - fusing of exposed casting defects after machining.
2. Fittings, casting, parts made of aluminum-magnesium alloys - welding, welding of defects.
3. Fans - welding of disks with a brush made of aluminum alloys.
4. Views made of non-ferrous alloys - welding.
5. Flame pipe heads, aluminum alloy flame pipe - welding.
6. Gas exhausts, mufflers made of stainless steel, copper-nickel alloys - welding.
7. Silencers for high-pressure compressors made of aluminum alloys with a metal thickness of 2 to 3 mm - welding.
8. Details of saturation of the body made of aluminum alloys - welding in the ceiling position.
9. Parts and assemblies made of aluminum-magnesium alloys of medium complexity, operating under pressure from 0.1 to 1.0 MPa (from 1 to 10 kgf/sq.cm) - welding.
10. Parts and assemblies of current distribution devices made of aluminum alloys: hermetic boxes, shells, angles, hinges, cans, brackets, racks, frames, shoulders, welds, gaskets, grooves - welding to the body and welding.
11. Hull structures after hydraulic tests - tacking, welding, correction of seam defects; binding of temporary fastenings.
12. Rings and branches of pipe sections made of non-ferrous alloys under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm) - welding.
13. Structures made of aluminum, titanium and non-ferrous alloys - welding of holes, tack welding in vertical and ceiling positions.
14. Impellers, flanges, covers of electrical appliances made of aluminum alloys - welding cracks, attaching broken parts.
15. Alloy structures - tack in all spatial positions.
16. Structures made of aluminum and titanium alloys - straightening using the method of applying blank rollers.
17. Composite structures (steel - aluminum alloy) - welding using bimetallic inserts.
18. Masts made of aluminum alloys - welding of joints and grooves of the mast barrel and welding of components.
19. Superstructures, deckhouses made of aluminum alloys - welding of volumetric units, set joints at intersections.
20. Castings with a wall thickness of up to 10 mm - welding of shells and cracks under pressure testing of 0.1 to 1.0 MPa (from 1 to 10 kgf/sq.cm).
21. Castings from aluminum alloys - welding of defects.
22. Castings with a wall thickness of over 10 mm, operating under pressure over 1.0 MPa (10 kgf/sq.cm) - welding of defects.
23. Hydraulic cylinder pistons and other products (hooks of anchor devices, winch seals) - cladding with copper alloys.
24. Frames, sashes made of non-ferrous metal - welding of incoming parts.
25. T-joints - with full penetration of the outer skin sheet made of aluminum alloys.
26. Joints of pipes not working under pressure, made of aluminum and non-ferrous alloys - welding of rotary joints.
27. Vertical and inclined ladders made of aluminum alloys - welding.
28. Reinforcement units made of non-ferrous metals - welding of parts, welding of parts under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm).
29. Flanges, rollers, housings, boxes, covers, blocks - fusing and welding with bronze, alloys, corrosion-resistant steels.
30. Foundations for mechanisms and devices - editing.
31. Seams after automatic welding in shielding gases - making fillets and finishing rollers.
32. Alloy scuppers - welding.
33. Copper busbar with a metal thickness of 12 mm - welding with preheating of the metal.

§ 58. Electric welder of manual welding (5th category)

Characteristics of work

Manual arc and plasma welding of complex building and technological structures operating in difficult conditions.
Manual arc oxygen cutting (planing) of complex parts made of high-carbon, alloyed and special steels and cast iron.
Fusion of defects in various machine parts, mechanisms and structures.
Welding of complex parts and assemblies.

Must know:

electrical circuits and designs of various types of welding machines;
technological properties of welded metals, metal deposited with electrodes of various brands and castings subjected to planing;
technology for welding critical products in chambers with a controlled atmosphere;
selection of the technological sequence of suturing and welding modes;
methods of control and testing of critical welds;
rules for reading drawings of complex welded spatial metal structures.

Work examples

1. Apparatuses and vessels made of carbon steels operating under pressure and alloy steels operating without pressure - welding.
2. Fittings for open hearth furnaces - welding during repair of existing equipment.
3. Reinforcement of load-bearing and critical reinforced concrete structures: foundations, columns, floors, etc. - welding.
4. Tanks of unique powerful transformers - welding, including welding of lifting hooks, jacking brackets, stainless steel plates operating under dynamic loads.
5. Center beams, buffer beams, pivot beams, locomotive and wagon bogie frames, wagon body trusses - welding.
6. Beams and traverses of crane trucks and balancers - welding.
7. Span beams of overhead cranes with a lifting capacity of less than 30 tons - welding.
8. Drums of boilers with pressure up to 4.0 MPa (38.7 atm) - welding.
9. Blocks of building and technological structures made of sheet metal (air heaters, scrubbers, blast furnace casings, separators, reactors, blast furnace flues, etc.) - welding.
10. Cylinder blocks and water manifolds of diesel engines - welding.
11. Large crankshafts - welding.
12. Gas tanks and tanks for petroleum products with a volume of 5000 cubic meters and more - welding in stationary conditions.
13. Gas and oil product pipelines - welding on a rack.
14. Parts of machines and mechanisms (charging devices of blast furnaces, propellers, turbine blades, rolls of rolling mills, etc.) - for melting with special, hard, wear-resistant and corrosion-resistant materials.
15. Parts of machines, mechanisms and structures forged, stamped and cast (propellers, turbine blades, cylinder blocks of parts, etc.) - fusing of defects.
16. Caissons for open-hearth furnaces operating at high temperatures - welding.
17. Columns, bunkers, trusses and sub-trusses, beams, trestles, etc. - welding.
18. Structures of radio masts, television towers and power line supports - welding in stationary conditions.
19. Head housings, traverses, bases and other complex components of presses and hammers - welding.
20. Rotor housings with a diameter of over 3500 mm - welding.
21. Stop valve housings for turbines with power over 25,000 kW - welding.
22. Housings of cutters, loading machines, coal combines and mine electric locomotives - welding.
23. Covers, stators and lining of blades and hydraulic turbines - welding.
24. Masts, drilling and production derricks - welding during installation.
25. Bases made of high-alloy drill pipes for drilling rigs and three-diesel drives - welding.
26. Foundation slabs for a walking excavator unit - welding.
27. Frames and components of cars and diesel engines - welding.
28. Pivot and diesel locomotive frames - welding.
29. Reservoirs for oil products with a capacity of 1000 to 5000 cubic meters. - welding during installation.
30. Rods for cold rolling mills, pipes and pipe drawing mills - welding of individual elements.
31. Joints of reinforcement outlets of elements of load-bearing prefabricated reinforced concrete structures - welding.
32. Pipe elements of steam boilers with pressure up to 4.0 MPa (38.7 atm.) - welding.
33. Pipelines of external and internal low-pressure gas supply networks - welding during installation.
34. Pipelines of external and internal gas supply networks of medium and high pressure - welding in stationary conditions.
35. Technological pipelines of III and IV categories (groups), steam and water pipelines of III and IV categories - welding.
36. Units of under-engine frames and cylinders of shock absorbers for aircraft landing gear - welding.
37. Tires, compensator tapes for them from non-ferrous metals - welding.

Electric arc welding:

1. Fittings, pipelines, branches, flanges, fittings, cylinders, tanks, tanks made of corrosion-resistant steels operating under pressure from 1.5 to 4 MPa (from 15 to 40 kgf/sq.cm.) - welding.
2. Sternposts, stems - welding of joints and welding of outer skin.
3. Intermediate shafts, propeller and stern tubes - welding.
4. Propellers - welding steel, cast or forged blades.
5. Propellers, hub blades of medium, high and special accuracy classes of all sizes and designs - air-arc planing of all surfaces of the propeller, blades and hubs.
6. Vertical keels and impermeable stringers - welding of installation joints.
7. Gas-tight steel decking - welding and welding to the main body.
8. Metalwork details for the main body and lining of the main tanks - welding.
9. Shelf parts - welding to the main hull and to the end transverse bulkheads.
10. Steel parts - air-arc gouging (melting the root of the weld and removing temporary fasteners).
11. Parts operating under vibration loads - welding of sections.
12. Ship hulls made of carbon and low-alloy steels - welding of joints and grooves of the outer plating in all spatial positions.
13. Boat hulls (repair) - welding.
14. Brackets, mortars and propeller shaft fillets - welding, welding of joints, welding to the hull.
15. Stabilizing columns, braces, connections of tubular and box-shaped forms of floating drilling rigs - welding during installation afloat.
16. Structures made of low-magnetic steel with a metal thickness of 1.5 to 3 mm, planned steels - welding.
17. Ship pump housings, nozzle segments with milling blades, ship steering gears (cylinders, plungers, valve boxes) - welding.
18. Brackets, mortars, propeller cores - welding and welding on type vessels.
19. Hatch coamings made of alloy steel - welded to the hull skin (under the supervision of a technologist).
20. Steel structures SW - welding of joints and grooves.
21. End and intercompartment bulkheads - welded to the main body.
22. Stern and bow extremities in confined spaces in workshop conditions - welding of the set to each other and to the skin of the extremities.
23. Set with grooved edges, joints and grooves of steel bulkheads - assembly and welding at the pre-assembly site.
24. Anchor fairlead niches - welded to the outer skin on the slipway.
25. Butts, traverses, beams of overhead bridge cranes with a lifting capacity of up to 30 tons - welding and welding.
26. Sheathing and set of ORs, superstructure of fairings and ends of the NK - welding to OK.
27. Supporting parts of the foundations for opening the shields - welding to each other and welding to the structures of the bow end.
28. Sheathing and set of stabilizers - welding to mortars.
29. Main tanks - welding and tacking them to the main body.
30. Sheathing of the outer casing made of steel - welding of installation joints.
31. Decks and platforms - welding of joints and grooves in the ceiling position on the slipway.
32. Welded joints, welded joints made of alloy steel, container cups - welding on a slipway.
33. Sheets and sets of bulkheads and tanks located inside the vessel and of unequal strength to it - welding.
34. Spacer platform sheets - welding to bulkheads.
35. Transverse and longitudinal brackets of stabilizers - welding to each other.
36. Foundation frames of high pressure compressors - welding.
37. Joints and grooves of the outer plating of technological structures of the ship's hull - welding on a welding assembly.
38. Sections of the stern and main ends at the pre-assembly site and slipway - welding of joints and grooves.
39. Welding and set of impermeable bulkheads and stringers, stabilizers, rudders, nozzles, nacelles - welding on site.
40. Joints and grooves of the shells of the main body - welding.
41. Joints and grooves of the outer skin made of AK and YUZ type steels, stringers, vertical keel, frames - welding of the seam in all spatial positions with a through wire.
42. Pipelines made of low-alloy and corrosion-resistant steels operating under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm) with a pipe wall thickness of over 2 mm - welding.
43. Foundations for main mechanisms, reinforcements for intercompartment bulkheads, internal tanks - welding.
44. foundations for retractable devices - welding to base plates, platforms and impulse tank.
45. Shafts, other deckhouses, coamings of entrance and loading hatches - welding to the main hull.
46. Frames - welding joints and welding to the main body.
47. Mines, other cuttings - welding of joints and grooves.
48. Dies - hard alloy deposition.
49. Dies of complex configuration, plates, rods, tips, spindles - fusing edges with hard alloys.

Gas shielded welding:

1. Heat exchangers and other coils made of light and non-ferrous alloys, as well as tanks, reservoirs and vessels made of aluminum alloys under hydraulic pressure from 1.5 to 4.0 MPa (from 15 to 40 kgf/sq.cm) - welding.
2. Fittings made of alloys, pipelines and fittings made of aluminum alloys - welding of flanges, fittings, nozzles, nipples.
3. Fittings for bellows expansion joints made of corrosion-resistant steels and titanium alloys - welding with 100% gammagraphy.
4. Blocks, frames, boxes, covers, panels made of non-ferrous metal - welding under pressure testing from 0.1 to 1.0 MPa (from 1 to 10 kgf/sq.cm).
5. Propellers made of non-ferrous alloys - fusing, welding of cracks, welding of fittings.
6. Doors and components with metal thickness up to 1.5 mm from homogeneous and dissimilar aluminum alloys - welding.
7. Parts of complex configuration made of dissimilar aluminum alloys and corrosion-resistant steels with a wall thickness of up to 2 mm - welding.
8. Casings, fairings made of alloys - welding under pressure testing up to 4.0 MPa (40 kgf/sq.cm).
9. Compensators and other critical components of water tube boilers made of alloys - welding.
10. Housings made of corrosion-resistant steels operating under pressure from 1.5 to 4.0 MPa (from 15 to 40 kgf/sq.cm) - welding.
11. Alloy superstructures - welded to the hull.
12. Saturation of the hull and end bulkheads from alloys - welding.
13. Pipelines made of copper-nickel and aluminum alloys operating under pressure from 0.1 to 1.5 MPa (from 1 to 15 kgf/sq.cm) - welding.
14. Pipes made of copper, copper-nickel, aluminum alloys, corrosion-resistant steels and alloys - welding of joints, welding of flanges, pipes, fittings, welds under pressure from 1.5 to 4.0 MPa (from 15 to 40 kgf/ sq. cm).
15. Stern tubes, propeller shafts, sealed closure covers - cladding with non-ferrous alloys and corrosion-resistant steels.
16. Units of aggregates made of alloys with a metal thickness of 0.3 mm - welding.

§ 59. Electric welder of manual welding (6th category)

Characteristics of work

Manual arc and plasma welding of complex devices, components, structures and pipelines made of various steels, non-ferrous metals and alloys.
Manual arc and gas-electric welding of complex building and technological structures operating under dynamic and vibration loads, and structures of complex configuration.
Welding of experimental structures made of metals and alloys with limited weldability, as well as titanium and titanium alloys.
Welding of complex structures in block design in all spatial positions of the weld.

Must know:

the design of the serviced equipment;
varieties of titanium alloys, their welding and mechanical properties;
types of corrosion and factors causing it;
methods of special tests of welded products and the purpose of each of them;
diagrams of evacuation systems of chambers with controlled atmosphere;
main types of heat treatment of welded joints;
fundamentals of weld metallography.

Work examples

1. Beams of working platforms of open-hearth shops, structures of bunkers and unloading platforms of metallurgical enterprises, crane beams for heavy-duty cranes, booms of walking excavators - welding.
2. Span beams of bridge cranes with a lifting capacity of 30 tons and above - welding.
3. Boiler drums with pressure over 4.0 MPa (38.7 atm.) - welding.
4. Gas tanks and tanks for petroleum products with a volume of 5000 cubic meters and more - welding during installation.
5. Main gas and oil product pipelines - welding during installation.
6. Vacuum and cryogenic containers, caps, spheres and pipelines - welding.
7. Spherical and drop-shaped containers and coatings - welding.
8. Locks of drill pipes and couplings - double seam welding.
9. Working wheels of gas turbine compressors, steam turbines, powerful blowers - welding of blades and blades.
10. Ammonia synthesis columns - welding.
11. Structures of radio masts, television towers and power line supports - welding during installation.
12. Steam turbine boxes - welding and fusing of shells.
13. Stator housings of large turbogenerators with hydrogen and hydrogen-water cooling - welding.
14. Heavy hulls diesel engines and presses - welding.
15. Ship steam boilers - welding of bottoms, welding of critical components with a one-sided butt weld.
16. Structures made of light aluminum-magnesium alloys - welding.
17. Feet and rustles of drill bits, drilling steam conductors - welding.
18. Oil and gas pipelines - welding to eliminate gaps.
19. Pipeline piping of oil and gas wells and edge flooding wells - welding.
20. Tanks and structures made of two-layer steel and other bimetals - welding.
21. Reinforcement bars of reinforced concrete structures in split forms - welding using the hot tub method.
22. Span structures of metal and reinforced concrete bridges - welding.
23. Pipe elements of steam boilers with pressure over 4.0 MPa (38.7 atm.) - welding.
24. Pressure pipelines; spiral chambers and impeller chambers of hydroelectric turbines - welding.
25. Pipelines for external gas supply networks of medium and high pressure - welding during installation.
26. Technological pipelines of I and II categories (groups), steam and water pipelines of I and II categories - welding.

Electric arc welding:

1. Heat exchangers and other vessels made of special steels under test pressure over 20.0 MPa (over 200 kgf/sq.cm) - welding.
2. PC brackets - welding to the casing.
3. Necks made of alloy steel - welding with a sealed seam under pressure over 4.0 MPa (over 40 kgf/sq.cm).
4. Doors and entrance hatch collars with bulkhead panels - welded.
5. Buffer tanks for air pressure of 40.0 MPa (400 kgf/sq.cm) - welding.
6. Plugs for hydraulic testing of the block - welding.
7. Collectors, chambers, pipes, cylinders, tanks, tanks made of carbon and low-alloy steels under pressure over 4.0 MPa (over 40 kgf/sq.cm) - welding.
8. Cable boxes - welding under pressure testing over 4.0 MPa (over 40 kgf/sq.cm).
9. Housings of flaps and TA pipes - welding to the main body, item 21.
10. Special purpose tank bodies (bottom sheets, transverse bulkheads, roof) - welding.
11. Support columns of floating drilling rigs - welding during installation.
12. Structures made of high-strength special steels - welding of installation joints OK in vertical and ceiling positions.
13. Hull structures and assemblies, 100% of the welds of which are subjected to ultrasonic or gammagraphic control - welding.
14. Sheets of removable housing made of high-strength steel - welding after hydraulic tests.
15. Interhull transitions, coaming platforms, TA and stern tubes - welding and straightening.
16. Mortars, necks, fillets, chairs, glasses and others - welding and welding.
17. Butts, traverses, beams of overhead cranes with a lifting capacity of over 30 tons - welding.
18. Sheathing OK, PR - welding of joints and grooves.
19. Sheathing of external durable tanks and enclosures - welding and sealing.
20. Sheathing and frames of rescue devices, as well as coamings welded into them, rod devices - welding and welding.
21. Sheathing and frames of containers - welding.
22. Sheathing of internal durable tanks, recesses, partitions and sheets of impenetrable bulkheads (stringers) - welding together and welding.
23. Other capsules, chambers, gondolas, etc., operating at full outboard pressure - welding.
24. Shelf panels and a set of end strong bulkheads - welding and welding.
25. Fabrics and a set of inter-hull connections OK and equal-strength structures - welding and welding to OK.
26. Sheets and sets of spacer platforms and impermeable bulkheads - welding and sealing.
27. Walls and stiffeners of the PTU frame, foundations of the main mechanisms - welding and welding.
28. Removable sheets and seals of the main body ed. 21 - welding.
29. The ends of a set of end bulkheads, external and internal tanks - welding to the OK and PTs casing.
30. Main and auxiliary steam pipelines - welding of fittings and jets under pressure over 4.0 MPa (over 40 kgf/sq.cm).
31. Boiler pipes under test pressure over 4.0 MPa (over 40 kgf/sq.cm), fixed joints under solid pressure over 2.5 MPa (over 25 kgf/sq.cm) - welding.
32. Pipelines - welding in hard-to-reach places with quality control of seams by radiography.
33. High-pressure pipelines with a working pressure of 40.0 MPa (400 kgf/sq.cm) and higher on floating drilling rigs - welding.
34. Bimetallic pipes under pressure over 20.0 MPa (over 200 kgf/sq.cm) - straightening flanges and welding.
35. Welded seams - welding in hard-to-reach places using a mirror.

Gas shielded welding:

1. Heat exchangers made of aluminum and copper alloys under hydraulic pressure over 4.0 MPa (over 40 kgf/sq.cm) - welding.
2. Fittings made of tin bronze and silicon brass - welding of defects under pressure over 4.0 MPa (over 40 kgf/sq.cm).
3. Cylinders made of titanium alloys and corrosion-resistant steels under pressure over 4.0 MPa (over 40 kgf/sq.cm) - welding.
4. Portholes made of special alloys and steels under pressure over 20.0 MPa (over 200 kgf/sq.cm) - preliminary welding and welding into the body.
5. Caps, shells, housings, covers, pipes made of non-ferrous metals - welding under pressure testing over 4.0 MPa (over 40 kgf/sq.cm).
6. Structures made of alloys and corrosion-resistant steels operating under pressure over 20.0 MPa (over 200 kgf/sq.cm) - welding.
7. Special structures made of corrosion-resistant steels up to 2 mm thick, subjected to x-ray gammagraphy, hydro- and pneumatic tests under pressure over 5.0 MPa (over 50 kgf/sq.cm) - welding.
8. Containers, housings made of corrosion-resistant steels - welding under pressure testing over 5.0 MPa (over 50 kgf/sq.cm).
9. Pipes made of corrosion-resistant steels - welding of fixed joints.
10. Joints of pipes made of copper-nickel, copper, aluminum, titanium alloys, corrosion-resistant steels in systems with pressure over 4.0 MPa (over 40 kgf/sq.cm) - welding, welding of fittings.
11. Joints of mounting housings made of special steels and alloys - welding in hard-to-reach places.
12. Pipelines made of corrosion-resistant steels under pressure over 5.0 MPa (over 50 kgf/sq.cm) - welding in hard-to-reach places using a mirror.
13. Copper water desalination plants - welding under pressure 0.6 MPa (6 kgf/sq.cm).

Gas welding is relatively simple and does not require complex, expensive equipment or a source of electricity.

Disadvantage gas welding is a lower metal heating rate compared to an arc and a larger zone of thermal influence on the metal. When gas welding, the heat concentration is less, and the warping of the parts being welded is greater.

Due to the relatively slow heating of the metal by the flame and the low heat concentration, the productivity of gas welding decreases with increasing thickness of the metal being welded. For example, with a steel thickness of 1 mm, the gas welding speed is about 10 m/h, with a thickness of 10 mm - only 2 m/h. Therefore, gas welding of steel with a thickness of over 6 mm is less productive than arc welding.

The cost of acetylene and oxygen is higher than the cost of electricity, so gas welding is more expensive than electric welding. Disadvantages of gas welding also include explosion and fire hazards if the rules for handling calcium carbide, flammable gases and liquids, oxygen, cylinders with compressed gases and acetylene generators are violated. Gas welding is used for the following work: manufacturing and repairing steel products with a thickness of 1-3 mm; welding of vessels and small tanks, welding of cracks, welding of patches, etc.; repair of cast products made of cast iron, bronze, silumin; welding joints of pipes of small and medium diameters; manufacturing products from aluminum and its alloys, copper, brass and lead; production of structural units from thin-walled pipes; surfacing of brass on parts made of steel and cast iron; joining ductile and high-strength cast iron using filler rods made of brass and bronze, low-temperature welding of cast iron.

Gas welding can be used to join almost all metals used in technology. Cast iron, copper, brass, and lead are easier to gas weld than arc welding.

GAS WELDING TECHNIQUE

Gas welding can be used to perform bottom, horizontal, vertical and ceiling seams. Ceiling seams are the most difficult to make, since in this case the welder must maintain and distribute liquid metal along the seam using the pressure of the flame gases. Most often gas welding is used to make butt joints, less often corner and end joints. It is not recommended to make lap and T-joints using gas welding, since they require intense heating of the metal and are accompanied by increased warping of the product.

Beaded joints of thin metal are welded without filler wire. Intermittent and continuous seams are used, as well as single-layer and multi-layer seams. Before welding, the edges are thoroughly cleaned of traces of oil, paint, rust, scale, moisture and other contaminants.

In table Figure 10 shows the preparation of edges when gas welding carbon steels with butt welds.

MOVEMENT OF THE TORCH DURING WELDING

The burner flame is directed at the metal being welded so that the edges of the metal are in the reduction zone, at a distance of 2-6 mm from the end of the core. It is impossible to touch the molten metal with the end of the core, as this will cause carburization of the metal of the bath. The end of the filler wire must also be in the reduction zone or immersed in the molten metal pool. In the place where the end of the flame core is directed, the liquid metal is slightly inflated to the sides by gas pressure, forming a depression in the weld pool.

The rate of heating of metal during gas welding can be adjusted by changing the angle of inclination of the mouthpiece to the metal surface. The larger this angle, the more heat is transferred from the flame to the metal and the faster it will heat up. When welding thick or good heat-conducting metal (for example, red copper), the angle of inclination of the nozzle a is taken greater than when welding thin or low thermal conductivity. In Fig. 86, and shows the angles of inclination of the mouthpiece recommended for left-handed (see § 4 of this chapter) welding of steel of various thicknesses.

In Fig. 86, b shows ways to move the mouthpiece along the seam. The main thing is to move the mouthpiece along the seam. Transverse and circular movements are auxiliary and serve to regulate the rate of heating and melting of the edges, and also contribute to the formation of the desired shape of the weld.

Method 4 (see Fig. 86, b) is used when welding thin metal, methods 2 and 3 - when welding metal of medium thickness. During welding, you must strive to ensure that the metal of the pool is always protected from the surrounding air by the gases of the reduction zone of the flame. Therefore, method 1, in which the flame is periodically drawn to the side, is not recommended, since it may oxidize the metal with atmospheric oxygen.

BASIC GAS WELDING METHODS

Left welding (Fig. 87, a). This method is the most common. It is used when welding thin and low-melting metals. The torch is moved from right to left, and the filler wire is led in front of the flame, which is directed to the unwelded section of the seam. In Fig. 87, and below shows a diagram of the movement of the mouthpiece and wire during the left-hand welding method. The flame power for left-hand welding is taken from 100 to 130 dm 3 acetylene per hour per 1 mm of metal (steel) thickness.

Right welding (Fig. 87, b). The burner is driven from left to right, the filler wire is moved after the burner. The flame is directed to the end of the wire and the welded area of the seam. Transverse oscillatory movements are not produced as often as with left welding. The mouthpiece makes slight transverse vibrations; when welding metal with a thickness of less than 8 mm, the mouthpiece is moved along the axis of the weld without transverse movements. The end of the wire is kept immersed in the weld pool and the liquid metal is mixed with it, which makes it easier to remove oxides and slags. The heat of the flame is dissipated to a lesser extent and is better utilized than in left-hand welding. Therefore, during right-hand welding, the opening angle of the seam is made not 90°, but 60-70°, which reduces the amount of deposited metal, wire consumption and warping of the product due to shrinkage of the weld metal.

It is advisable to use right-hand welding to connect metal with a thickness of more than 3 mm, as well as metal with high thermal conductivity with grooved edges, such as red copper. The quality of the seam in right-hand welding is higher than in left-hand welding because the molten metal is better protected by the flame, which simultaneously anneals the deposited metal and slows down its cooling. Due to best use heat, right-hand welding of metal of large thicknesses is more economical and more productive than left-hand welding - the speed of right-hand welding is 10-20% higher, and gas savings are 10-15%.

Right-hand welding connects steel up to 6 mm thick without bevel of edges, with full penetration, without welding on the reverse side. The flame power for right-hand welding is taken from 120 to 150 dm 3 acetylene per hour per 1 mm of metal (steel) thickness. The mouthpiece must be inclined to the metal being welded at an angle of at least 40°.

When right-hand welding, it is recommended to use filler wire with a diameter equal to half the thickness of the metal being welded. When left welding, use a wire with a diameter 1 mm larger than when welding right. Wire with a diameter of more than 6-8 mm is not used for gas welding.

Welding with a through bead (Fig. 88). The sheets are installed vertically with a gap equal to half the thickness of the sheet. The burner flame melts the edges, forming a round hole, the lower part of which is smelted with filler metal over the entire thickness of the metal being welded. Then the flame is moved higher, melting the top edge of the hole and applying the next layer of metal to the bottom side of the hole, and so on until the entire seam is welded. The seam is obtained in the form of a through bead connecting the sheets to be welded. The weld metal is dense, without pores, cavities and slag inclusions.

Welding with baths. In this way, butt and corner joints of metal of small thickness (less than 3 mm) are welded with a filler wire. When a bath with a diameter of 4-5 mm is formed on the seam, the welder inserts the end of the wire into it and, having melted a small amount of it, moves the end of the wire into the dark, reducing part of the flame. At the same time, he makes a circular motion with the mouthpiece, moving it to the next section of the seam. The new bath should overlap the previous one by 1/3 of the diameter. To avoid oxidation, the end of the wire must be kept in the reduction zone of the flame, and the core of the flame must not be immersed in the bath in order to avoid carburization of the weld metal. Welded in this way (lightweight seams) thin sheets and pipes made of mild and low alloy steel give excellent quality joints.

Multilayer gas welding. This method of welding has a number of advantages compared to a single-layer one: a smaller metal heating zone is provided; annealing of underlying layers is achieved when surfacing subsequent ones; it is possible to forge each layer of the seam before applying the next one. All this improves the quality of the weld metal. However, multi-layer welding is less productive and requires more gases than single-layer welding, so it is used only in the manufacture of critical products. Welding is carried out in short sections. When applying layers, care must be taken to ensure that the joints of the seams in different layers do not coincide. Before applying a new layer, it is necessary to carefully clean the surface of the previous one from scale and slag with a wire brush.

Oxidizing flame welding. Low carbon steels are welded using this method. Welding is carried out with an oxidizing flame having the composition

To deoxidize the iron oxides formed in the weld pool, wires of the Sv-12GS, Sv-08G and Sv-08G2S grades according to GOST 2246-60 are used, containing increased amounts of manganese and silicon, which are deoxidizers. This method increases productivity by 10-15%.

Welding with propane - butane-oxygen flame. Welding is carried out with an increased oxygen content in the mixture

in order to increase the temperature of the flame and increase the penetration and fluidity of the bath. To deoxidize the weld metal, wires Sv-12GS, Sv-08G, Sv-08G2S, as well as wire Sv-15GU (0.5-0.8% aluminum and 1-1.4% manganese) according to GOST are used.

Research by A. I. Shashkov, Yu. I. Nekrasov and S. S. Vaksman established the possibility of using in this case conventional low-carbon filler wire Sv-08 with a deoxidizing coating containing 50% ferromanganese and 50% ferrosilicon diluted on liquid glass. Coating weight (excluding weight liquid glass) is 2.8–3.5% by weight of the wire. Coating thickness: 0.4-0.6 mm when using wire with a diameter of 3 mm and 0.5-0.8 mm when using a wire with a diameter of 4 mm. Propane consumption is 60-80 l/h per 1 mm of steel thickness, b = 3.5, the angle of inclination of the rod to the metal plane is 30-45°, the cutting angle of the edges is 90°, the distance from the core to the rod is 1.5-2 mm, to metal 6-8 mm. This method can weld steel up to 12 mm thick. The best results were obtained when welding steel with a thickness of 3-4 mm. Wire Sv-08 with the specified coating is a full-fledged substitute for more scarce grades of wire with manganese and silicon when welding with propane-butane.

Features of welding various seams. Horizontal seams are welded in the right way (Fig. 89, a). Sometimes welding is done from right to left, holding the end of the wire at the top and the mouthpiece at the bottom of the bath. The weld pool is placed at a certain angle to the weld axis. This makes it easier to form a seam, and keeps the bath metal from dripping.

Vertical and inclined seams are welded from bottom to top in the left way (Fig. 89, b). With a metal thickness of more than 5 mm, the seam is welded with a double roller.

When welding ceiling seams (Fig. 89, c), the edges are heated until melting (fogging) begins, and at this moment a filler wire is introduced into the bath, the end of which is quickly melted. The metal of the bath is kept from flowing down by a rod and the pressure of the flame gases, which reaches 100-120 gf/cm2. The rod is held at a slight angle to the metal to be welded. Welding is carried out in the right way. It is recommended to use multi-layer seams welded in several passes.

Welding of metal less than 3 mm thick with flanged edges without filler metal is carried out using spiral (Fig. 89, d) or zigzag (Fig. 89, e) movements of the nozzle.

Administration Overall rating of the article: Published: 2011.05.31

§ 47. Electric and gas welder 4th category

Attention! This qualification characteristic is excluded by order of the Ministry of Labor of Russia dated April 9, 2018 N 215

Characteristics of the work. Manual arc, plasma and gas welding of medium complexity parts, assemblies, structures and pipelines made of structural steels, cast iron, non-ferrous metals and alloys and complex parts of assemblies, structures and pipelines made of carbon steels in all spatial positions of the weld. Manual oxygen, plasma and gas straight and shaped cutting and cutting with petrol and kerosene cutting devices on portable, stationary and plasma cutting machines, in various positions of complex parts from various steels, non-ferrous metals and alloys according to markings. Oxygen flux cutting of parts made of high chromium and chromium-nickel steels and cast iron. Oxygen cutting of ship objects afloat. Automatic and mechanical welding of medium complexity and complex devices, components, pipeline structures made of various steels, cast iron, non-ferrous metals and alloys. Automatic welding of critical complex building and technological structures operating in difficult conditions. Manual electric arc air planing of complex parts made of various steels, cast iron, non-ferrous metals and alloys in various positions. Welding of cast iron structures. Surfacing of defects in complex machine parts, mechanisms, structures and castings for machining and test pressure. Hot straightening of complex structures. Reading drawings of various complex welded metal structures.
Must know: installation of various electric welding and gas-cutting equipment, automatic and semi-automatic devices, features of welding and electric arc planing on alternating and direct current; basics of electrical engineering within the scope of the work performed; types of defects in welds and methods for their prevention and elimination; basics of metal welding; mechanical properties of welded metals; principles for selecting welding modes based on instruments; brands and types of electrodes; methods for producing and storing the most common gases: acetylene, hydrogen, oxygen, propane-butane, used in gas welding; gas cutting process for alloy steel.
Work examples
1. Equipment, vessels and containers made of carbon steel, operating without pressure - welding.
2. Equipment and vessels for chemical and petrochemical industries: tanks, separators, vessels, etc. - cutting holes with beveled edges.
3. Pipeline shut-off valves made of non-ferrous metals and alloys under test pressure over 1.6 to 5.0 MPa (over 15.5 to 48.4 atm) - fusing of defects.
4. Transformer tanks - welding of pipes, welding of terminal boxes, cooler boxes, current installations and tank covers.
5. Rudder stocks, propeller shaft brackets - hardfacing.
6. Cylinder blocks of car engines - surfacing of shells in castings.
7. Crankshafts - surfacing of necks.
8. Bronze and brass inserts - surfacing on steel bearings.
9. Headset and bodies of burners of boilers - welding.
10. Parts made of stainless steel sheets, aluminum or copper alloys - gas-electric cutting with beveled edges.
11. Parts made of cast iron - welding, surfacing with and without heating.
12. Parts made of sheet steel with a thickness of more than 60 mm - manual cutting according to the markup.
13. Parts and assemblies made of non-ferrous metals - welding followed by pressure testing.
14. Car retarders - welding and surfacing of components under operating conditions.
15. Cast iron gear teeth - hardfacing.
16. Thin-walled products made of non-ferrous alloys (air cooler covers, bearing shields, turbogenerator fans) - welding with brass or silumin.
17. Large cast iron products: frames, pulleys, flywheels, gears - fusing of shells and cracks.
18. Chambers of hydraulic turbine impellers - welding and surfacing.
19. Blast furnace structures (casings, air heaters, gas pipelines) - cutting with beveled edges.
20. Frames of industrial furnaces and boilers - welding.
21. Crankcases of large engines and mechanical transmission housings of diesel locomotives - welding.
22. Lower engine crankcases - welding.
23. Pole coils of electric machines made of strip copper - welding and welding of jumpers.
24. Gas exhaust manifolds and pipes - welding.
25. Hydraulic turbine control rings - welding and surfacing.
26. Housings and axles of the header drive wheels - welding.
27. Compressor housings, low and high pressure cylinders of air compressors - crack fusion.
28. Rotor housings with a diameter of up to 3500 mm - welding.
29. Stop valve housings for turbines with power up to 25,000 kW - welding.
30. Brush holder housings, reverse segments, electric motor rotors - welding.
31. Fastening and supports for pipelines - welding.
32. Brackets and fastenings for diesel locomotive pivot bogies - welding.
33. Sheets of large thicknesses (armor) - welding.
34. Masts, drilling and production rigs - welding in workshop conditions.
35. Aluminum furniture - welding.
36. Fundamental plates of large electrical machines - welding.
37. Struts, axle shafts of aircraft landing gear - welding.
38. Heaters - welding of a cage, a water-heating pipe with a cage, cone, rings and flanges.
39. Bearings and liners for axle boxes, drawbars - fusion along the frame and fusion of cracks.
40. Pistons of pneumatic hammers - fusing of shells and cracks.
41. Dust-gas-air ducts, fuel supply units and electric precipitators - welding.
42. Spool frames, pendulums - welding.
43. Porthole frames made of aluminum alloys - welding.
44. Conveyor frames - welding.
45. Air tanks for trolleybuses - welding.
46. Tanks for petroleum products with a capacity of less than 1000 cubic meters. m - welding.
47. Rail butt joints - welding under operational conditions.
48. Rails and prefabricated crosspieces - fusing ends.
49. Single and twisted metal mesh for pulp and paper production - soldering of ends with silver solder.
50. Crusher beds - welding.
51. Welded-cast frames and housings of electrical machines - welding.
52. Cast iron beds of large machine tools - welding.
53. Beds of working stands of rolling mills - surfacing.
54. Stators of air-cooled turbogenerators - welding.
55. Tubes for sensors with a radioactive isotope - fusing.
56. Pipe elements of boilers, armor plates, etc. - hot edit.
57. Pipelines of external and internal water supply and heating networks - welding during installation.
58. Pipelines of external and internal low-pressure gas supply networks - welding in workshop conditions.
59. Drill pipes - welding of couplings.
60. Technological pipelines of category 5 - welding.
61. Frameworks, connections, lanterns, purlins, monorails - welding.
62. Complex cutters and dies - welding and deposition of high-speed cutters and hard alloys.
63. Brass refrigerators - welding of seams for hydrotesting at pressures up to 2.5 MPa (24.2 atm.).
64. Cylinders of car blocks - fusing of shells.
65. Car tanks - welding.
66. Balls, floats and tanks made of special aluminum alloys - welding.

From July 1, 2016, employers are required to apply professional standards, if the requirements for the qualifications that an employee needs to perform a certain job function are established by the Labor Code, federal laws or other regulations ( the federal law dated May 2, 2015 No. 122-FZ).
To search for approved professional standards of the Ministry of Labor of the Russian Federation, use

Gas welding technique

Gas welding is a universal method, but when performing it, you must remember that a fairly large area around the welded joint is exposed to heat. Therefore, it is impossible to exclude the occurrence of warping and the development of internal stresses in structures, and they are more significant than with other welding methods. In this regard, gas welding is more suitable for such joints for which a small amount of deposited metal and low heating of the base metal are sufficient. First of all, we are talking about butt, corner and end connections (regardless of their spatial position - bottom, horizontal, vertical or ceiling), while T-joints and overlaps should be avoided (although they can also be carried out).

In order for the weld to have high mechanical properties, the following steps must be performed:

– prepare the edges of the metal;

– select the appropriate burner power;

– adjust the burner flame;

– take the necessary filler material;

– correctly orient the torch and determine the trajectory of its movement along the seam being performed.

As with arc welding, with gas, the edge of the metal being welded must be prepared. They are cleaned (20–30 mm on each side) of rust, moisture, oil, etc. To do this, just warm the edges. In the case of welding non-ferrous metals, mechanical and chemical cleaning methods are used.

When making butt joints (Table 42), you should remember some rules for cutting edges:

– when welding thin sheet metal (up to 2 mm), no additives are used - it is enough to flange the edges, which then melt and form a weld bead. This option is also possible: butt weld the edges without cutting or gap, but using filler material;

– when welding metal with a thickness of less than 5 mm, you can do without bevel of edges and carry out one-sided gas welding;

– when joining metal with a thickness of more than 5 mm, the edges are beveled at an angle of 35–40° so that the total opening angle of the seam is 70–90°. This will allow the metal to be welded to its full thickness.

Table 42. PRELIMINARY PREPARATION OF THE EDGES OF THE METAL TO BE WELD WHEN MAKING BUTT JOINTS

Note: a – gap size; a1 – magnitude of dullness; S and S1 – metal thickness.

When making corner joints, filler material is not used, and the seam is formed by melting the edges of the metal.

Lap and T-joints are allowed only when welding metal up to 3 mm thick, since with greater thickness the local heating of the metal is uneven, which leads to the development of significant internal stresses and deformations, as well as the appearance of cracks in both the weld metal and the base metal.

So that during the welding process the parts do not move and the gap between them does not change, they are fixed either with special devices or tacks. The length, number and gap between the latter depend on the thickness of the metal, the length and configuration of the seam:

– if the metal is thin and the seams are short, the length of the tacks is 5–7 mm with an interval between them of 70–100 mm;

– if the metal is thick and the seams are long, then the length of the tacks is increased to 20–30 mm, and the distance between them is increased to 300–500 mm.

During the welding process, the torch flame is directed at the metal so that it falls into the reduction zone and is 2–6 mm from the core. When welding low-melting metals, the torch flame is mainly oriented towards the filler material, and the core zone is moved to an even greater distance from the weld pool.

When welding, it is necessary to regulate the rate of heating and melting of the metal. To do this, resort to the following actions (Fig. 91):

– change the angle of the mouthpiece;

– manipulate the mouthpiece itself.

Rice. 91. Methods for adjusting the rate of heating and melting of metal by changing: a – the angle of inclination of the mouthpiece; b – trajectories of movement of the mouthpiece and wire; 1 – when welding thin sheet metal; 2, 3 – when welding thick sheet metal

When welding, you must ensure that:

– the flame core was not in contact with the molten metal, since the latter could become carbonized as a result;

– the weld pool was protected by a torch zone and a reduction zone, otherwise the metal would be oxidized by atmospheric oxygen.

When using a gas burner, you must follow the rules for handling it:

1. If the burner is in good condition, then the flame it produces is stable. If any deviations are observed (the combustion is unstable, the flame comes off or goes out, backfires occur), you need to pay special attention to the burner components and adjust it.

2. To check the injection burner, connect the oxygen hose and attach the tip to the body. After tightening the union nut, carefully unscrew the acetylene valve, set the appropriate oxygen pressure using the oxygen reducer, and then open the oxygen valve.

3. If a finger attached to the acetylene nipple is stuck, this means that oxygen is creating a vacuum. If this does not happen, the injector, mixing chamber or mouthpiece may be clogged. They should be cleaned.

4. Repeat the vacuum (suction) check. Its value is determined by the gap between the end of the injector and the entrance to the mixing chamber. By unscrewing the injector, the gap is adjusted.

There are two methods of gas welding (Fig. 92):

Rice. 92. Methods of gas welding (the arrow indicates the direction of welding): a – left; b – right; 1 – filler wire; 2 – welding torch

– left-hand welding, in which the torch is moved from right to left and held behind the filler wire. In this case, the welding flame is oriented towards the seam that has not yet been welded. This method does not allow sufficient protection of the metal from oxidation, is accompanied by a partial loss of heat and gives low welding performance;

- right hand welding, in which the torch is moved from left to right and held in front of the filler wire. In this case, the flame is oriented towards the finished seam and the end of the filler wire. This method makes it possible to direct a greater amount of heat to the melting of the metal of the weld pool, and the oscillatory transverse movements of the mouthpiece and wire are carried out less frequently than with the left method. In addition, the end of the filler wire is constantly immersed in the weld pool, so it can mix it, which contributes to the transition of oxides into slag.

The right method is usually used if the thickness of the metal to be welded exceeds 5 mm, especially since the welding flame is limited on the sides by the edges of the product, and behind - by the weld metal bead. As a result, heat loss is reduced and it is used more efficiently.

The left method has its advantages, since, firstly, the weld is always in the welder’s field of vision and he can adjust its height and width, which is of particular importance when welding thin sheet metal; secondly, when welding, the flame can spread over the surface of the metal, reducing the risk of burnout.

When choosing one or another welding method, you must also be guided by the spatial position of the weld:

– when making the bottom seam, the thickness of the metal should be taken into account. It can be applied both right and left. This weld is the easiest because the welder can observe the process. In addition, the liquid filler material flows into the crater and does not pour out of the weld pool;

– for a horizontal seam, the right method is preferable. To prevent liquid metal from leaking out, the walls of the weld pool are made with some distortion;

- For vertical seam for ascent - both left and right, and for a vertical seam for descent - only the right method;

– it is easier to apply a ceiling weld in the right way, since the flame flow is directed towards the seam and prevents liquid metal from flowing out of the weld pool.

A method that guarantees the high quality of the weld is bath welding (Fig. 93).

Rice. 93. Welding with pools: 1 – welding direction; 2 – trajectory of movement of the filler wire; 3 – trajectory of the mouthpiece

This method is used for welding thin sheet metal and pipes made of low-carbon and low-alloy steels with lightweight seams. It can also be used when welding butt and corner joints with a metal thickness of up to 3 mm.

The pool welding process proceeds as follows:

1. Having melted metal with a diameter of 4–5 mm, the welder places the end of the filler wire into it. When its end is melted, he introduces it into the reducing zone of the flame.

2. At the same time, the welder, slightly moving the mouthpiece, makes circular movements with it to form the next bath, which should slightly (by about a third of the diameter) overlap the previous one. In this case, the wire must continue to be kept in the reducing zone to prevent its oxidation. The flame core must not be immersed in the weld pool, otherwise carburization of the weld metal will occur.

When gas welding, seams can be single or multi-layer. If the metal thickness is 8-10 mm, the seams are welded in two layers, with a thickness of more than 10 mm - three layers or more, and each previous seam is first cleaned of slag and scale.

Multi-pass welds are not used in gas welding, since it is very difficult to apply narrow beads.

During gas welding, internal stresses and deformations arise, since the heating area is more extensive than, for example, during arc welding. To reduce deformations, appropriate measures must be taken. For this we recommend:

– heat the product evenly;

– select an adequate welding mode;

– evenly distribute the deposited metal over the surface;

– adhere to a certain order of sutures;

– do not get carried away with doing tacks.

Various methods are used to combat deformation:

1. When making butt joints, the weld is applied using a reverse-step or combined method, dividing it into sections 100–250 mm long (Fig. 94). Since the heat is evenly distributed over the surface of the weld, the base metal is practically not subject to warping.

Rice. 94. The sequence of applying a seam when welding butt joints: a – from the edge; b – from the middle of the seam

2. Reduction of deformations is facilitated by their balancing when the subsequent seam causes deformations opposite to those caused by the previous seam.

3. The method of reverse deformation is also used, when before welding the parts are laid so that after welding, as a result of the action of deformation, they take the desired position.

4. Preheating the products being joined also helps combat deformation, resulting in a smaller temperature difference between the weld pool and the product. This method works well when repairing cast iron, bronze and aluminum products, as well as if they are made of high-carbon and alloy steels.

5. In some cases, they resort to forging the weld (in a cold or hot state), which improves the mechanical characteristics of the seam and reduces shrinkage.

6. Heat treatment is another way to eliminate developed stresses. It can be preliminary, carried out simultaneously with welding, or the finished product is subjected to it. The heat treatment mode is determined by the shape of the parts, the properties of the metals being welded, conditions, etc.

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