Pipes and Pressure Vessels Welding

• The module focuses on pipes and pressure vessels welding
• The module code is MATPV501
• The RQF level is 5
• Learning hours equate to 100
• The module is worth 10 credits
• The sector is Manufacturing and Mining
• The trade is Manufacturing Technology
• The module type is specific
• The curriculum is MAMMAT5001 TVET certificate V in Manufacturing Technology
• Copyright is owned by Rwanda TVET Board, 2024
• The issue date is February 2024
• Learning Outcome 1 focuses on workplace organization with 20 learning hours.

Introduction to Pipe and Pressure Vessels Welding

• A pipe is a device used for transporting fluids or gases.
• Pipes are made of plastic or metal
• Pipes can come in various shapes and sizes with tees, elbows, flanges, and reducers
• Piping is a system of pipes used to convey fluids from one location to another.
• The criteria for the detailed design of a pipe are: type of fluid, allowable pressure drop/energy loss, desired velocity/space limitations, process requirements, stress analysis, and fluid temperature.
• Fittings or adapters connect straight pipe sections, adapt to different sizes/shapes, and regulate fluid flow.
• Tees are T-shaped pipe fittings with two outlets at 90° to the main line, and are used to connect pipelines at right angles
• Elbows change the flow direction in a pipe by 90 degrees
• "Quarter bend" is another name for elbows
• Elbows can be made of plastic, copper, cast iron, steel, or lead.
• Flanges connect pipes, valves, pumps, and equipment, provide access for cleaning/inspection/modification, and are welded or screwed
• Flanged joints use gaskets between bolted flanges
• Reducers are steel pipe components used in pipelines to reduce the size to small bore.
• Pressure vessels hold liquids, gases, or materials under high pressure in spheres, cylinders, etc.
• Shielding gases protect molten metal during welding for a protective atmosphere around the weld, preventing metal contact with air, and preventing oxidation/porosity/defects
• Examples of shielding gases are: argon, helium, and carbon dioxide.
• The proper shielding gas choice bases on type of metal, arc characteristics/metal transfer, availability/cost, mechanical property needs, penetration/weld bead shape.

Welding Methods

• Description of welding methods in pipe and pressure vessels:
• MIG stands for Metal Inert Gas
• MAG stands for Metal Active Gas
• GMAW stands for Gas Metal Arc Welding
• MIG/MAG welding uses wire electrode and inert gas to join two/more metal pieces; an arc melts the wire onto the workpiece for a strong weld
• Gas metal arc welding is where an electric arc forms between an electrode and metal workpiece to melt metals for joining
• MIG uses inert shielding gas; while MAG uses active gas, often with carbon dioxide/oxygen
• MAG is more common
• MIG welding is often accidentally used in connection with MAG welding.
• MIG/MAG welding equipment includes: power source, wire feeder, grounding cable, welding gun, liquid cooling unit, and shielding gas tank/network interface
• The purpose of the wire feeder is to feed wire and enable starting/stopping of the power source and control voltage.
• The wire feeder controls shielding gas flow.

Advantages of MIG/MAG Welding

• Financially attractive because of welding speed and long arc time
• Provides opportunity for rational welding of dissimilar materials
• Welding is possible in all positions.
• The arc/weld pool is clearly visible.
• Minimal after-treatment is typical.
• High deposition rate
• Creates no slag formation
• Simple ignition of the arc
• Well-suited to mechanized/automated welding
• Achieves high welding speeds with weld seam quality
• Suited to out-of-position/difficult welding
• Low filler metal costs

Disadvantages of MIG/MAG welding:

• Expensive and complicated GMAW equipment, setup, and maintenance
• High wire/shielding gas costs, offset by productivity and less wastage
• GMAW gas shielding can be disrupted by external air currents exceeding five miles per hour.
• Wind shields/enclosures can block/reduce air currents for shielding.
• Increasing gas flow rates to compensate for wind may create turbulence, drawing in air
• GMAW requires access to the work
• Wire feeder must be positioned close to the work
• FCAW means Flux Cored Arc Welding
• Flux Cored Arc welding employs a consumable wire electrode and flux to join two metals.
• The cored electrode is a tubular metal sheath filled with flux/alloying ingredients.

FCAW Core Wire Classification

• Self-Shielded Flux-Cored Electrodes: self-shielded FCAW uses the arc's heat to decompose/vaporize the electrode's flux core, protecting the molten metal
• Gas-Shielded Flux-Cored Electrodes: gas-shielded FCAW uses protective gas shielding with the flux core such as CO2 or argon/CO2

Factors to Consider in Flux Cored Electrode Selection

• Base Metal Strength Properties: uses electrode wire to match the tensile/yield strength.
• Base Metal Composition: based on filler metals for welding stainless/alloy steels and matched to that chemical makeup.
• Welding Position: specifically designed, flux-cored electrodes uses wire diameter to limit electrode position.
• All-position electrodes are smaller, while flat and horizontal electrodes are often larger.
• Welding Current: Flux-cored electrodes operate on direct current electrode negative or positive.
• DCEN electrodes give the lighter penetration while electrodes operating on DCEP provide deeper penetration.
• Joint Design and Fit-Up: Electrodes are chosen by penetration characteristics. Gas-shielded flux-cored wires produce deeper penetration
• FCAW welding fluxes provide functions that provide the slags can react with the molten weld metal chemically, and it can affect the weld bead physically.
• The fluxes provides the molten weld metal tends to have a high surface tension, which prevents it from flowing outward toward the edges of the weld.
• Chemicals in the flux can affect the arc resistance.
• Different mechanical properties of metal can lead to by the different mechanical properties of metal differ due to rolling/forging versus melting.
• Certain elements in the heated flux vaporize, which leads to gaseous clouds that are larger than their original volume.

Types of FCAW Fluxes:

-There are chemical reactions during welding: T-1 (Rutile Based Fluxes) and T-5(Lime-Based Fluxes).

• Rutile-based T-1 fluxes are chemically acidic that produce stable arc while electrode fluxes makes a drop transfer, produces low fume/easily removed slag, Its fluxing elements do not produce as high a quality deposit as do the T-5 systems.
• Lime-based T-5 Fluxes are chemical bases removing weld metal impurities, produce fluid melting temperature slag. These electrodes make a transfer, fume/adherent slag than do the T-1 Systems
• Types of FCAW process are self-shielded and gas shielded
• Self-Shielded welding with heat from an arc between work and flux cored wire that provides gas shielding and slag
• (FCAW) Gas shielded, the gas-shielded flux-cored process, uses tubular electrode wire, for fluxing, deoxidizing, scavenging, and alloying additions and can be looked upon as a hybrid between self-shielded arc welding and gas metal-arc welding.
• The equipment used for FCAW is similar to that for GMAW. The basic equipment is power source, gas cylinder, controls, wire feeder, welding gun, and welding cables.
• The gas shielded wires differ from self-shielded requiring also a gas shielding system - may also have affects of welding gun type to be used with this welding process.
• Fume extractors often used with the FCAW process and machine devices are added to the basic equipment.

FCAW Welding Machine

• Generator and Alternator Welding Machines can be powered by an electric motor for workshop use, or an internal combustion engine for field applications
• Transformer Welding Machines are the most widely used transformer-rectifiers supplying direct current to arc rotating generator, these machine electrically efficient providing a quiter operation.
• Wire Feeders: The feed motor provides the power for driving and electrode
• FCAW Welding Guns, welding torch are equipment used to deliver wire, welding current and shielding gas for the welding arc.
• Fume Extractors are used to lower smoke levels from cored electrodes.
• Flowmeter and regulator: regulator used to reduce gas supply pressure for constant delivery pressure, flowmeter is used to control the flow of the gas from the regulator to the welding gun

ACCESSORIES USED IN FCAW

• Cylinder key
• Tong
• Wire brush
• Adjustable spanner,
• Anti-spatters
• Hand shield or helmet
• Chipping hammer,

ADVANTAGES OF FCAW WELDING

• High deposition rate of depositing weld metal
• Portability: machines can carry out and plugged into a standard outlet.
• Waste: the FCAW method makes use of filler metal
• No edge beveling some joints
• Permits high quality welds plates
• Excellent welds plate cleanliness
• combination with fluxes
• Allows joins in metals of thickness.
• for boilers, vessels, steel.
• controlled with FCAW.

DISADVANTAGES OF FCAW

• FCAW metal nickel alloys.
• FCAW process are expensive.
• Clean requires
• With welding comes increase in smoke fume.

3.TIG:

• The welding process that uses a nonconsumable electrode inert gas two metal pieces.
• , an electric arc is created electrodes workpiece, the metal form a weld
• is a rare metal found naturally on Earth compounds alone.
• : the ability strength to move.
• In extremely other substance.
• Electrodes.
• and percentages of stability
• should the machines
• should AC machines, welding

TIG Welding Parameters:

• DCEN (Direct current, Electrode on negative terminal)

• 0.5 5-20

• 1.0 15-80

• 1.6 70-150

• 2.4 150-250

• 3.2 250-400

• DCEP (Direct current, Electrode on Positive terminal)

• 1.6 10-20

• 2.4 15-30

• 3.2 25-40

• 4.0 40-55

• 4.8 55-80

• 6.4 80-125

• 4.0 400-500

• 4.8 500-750

• 6.4 750-1000

• Tungsten electrode is suitable for: carbon steels, alloys, allow stainless, nickel alloys, aluminium alloys, alloys, titanium and other nonferrous alloys.

• TIG ACCESSORIES:

• TIG nozzles

• Collet for TIG torch

• Collet body

• Long back cap

• Welding pedal control

• Ground Cable & Clamp Assembly

• short cap TIG

• TIG Torch

• TIG Pats Kits

• TIG Glove

Advantages of TIG welding process

• Non-consumable electrodes provide flawless joints because replacement unnecessary.
• Reduces downtime production.
• inert gas shields molten metal.
• Quality and strong weld achieved
• sometimes finishing required.
• suitable for thin sections.
• can work without filler
• Nonferrous aluminium, copper dissimilar metal can
• Non-corrosive and ductile joints.
• amount small heat zone.
• in automatic manual.

Disadvantage of TIG welding process

• process slower other
• Highly skilled are needed
• are high intensity light eye
• in sheets
• is a industries

ADVANTAGES:

• Ensures joined resulting joint
• Welding generally other quick
• Welding perform steel pipes and
• Helps industries
• Welding down efficiency and
• Allows dimensions application

DISADVANTAGES:

• Ensuring joint
• Requires
• Welding measure
• Time welding components
• Can limitation
• complete, standards and
• Welds lack fusion,

APPLICATION OF PIPES AND PRESSURE VESSELS WELDING

• Welding vessels transport
• Processing hazardous
• power plants distribution
• fuels and fluids in aircraft
• fuel, brakes vehicles
• vessels medicines

JOB HAZARD ANALYSIS

• A Process to identity injuries
• Relationship eliminate Hazards
• Job Safety Analysis
• Steps procedure
• Job Steps
• Identify solutions
• implementation
• Communication of Findings
• Review of update hazard

TYPES OF HAZARDS IN WORKING PLACE

• Arraggements, defined at the how and
• Employees Stability
• Harmful
• Classified hazard
• Ergonomic included hazards
• Vibration Noise Types of Harm Noise
• Moving
• machinery
• Projectities
• devices
• Slipping

CHEMICAL HAZARD

• Type of Hazard

• Caused exposure Workplace

• Detrimental.

• Biological hazards poses in hazard

• Substances harmful

• Include in substances

• a Hazard does electric electrons condition( electric

• workers

• electric with electrical

• Prevent workers

• Controls Hazards

• Health

• Provide Health Working Conditions

• Is the work

5'S a the organize the maintain the efficient that can clean the

1. 1. The
2. Machine
3. Operator
4. 1. The
5. a to be of the

• 6. to shop
• 7. heavy of
• 8. time of
• 9. the
• 11. button
• 12. serious
• 13. the of cutting
• 14. Cuts be
• 16. the
• 17. lighting
• 18. should shop
• 19. for the and which that distance.
• 20. are

SAFETY PRECAUTIONS DURING PIPE WELDING EQUIPMENT

• 21. welding in MIG/MAG, TIG, FCAW
• 22. welding in
• 23. arc welding.
• 24. the to
• 25. welding is for
• 26. protect the are
• 27. allow the
• 28. when use
• 29. with a to pipe
• 30. Material has to in
• 31. the must the
• 32. to and erosion.
• 33. Materials for plant piping
• 34. for fittings
• 35. seamless are steel
• 36. handling sewage steel
• 37. ductile grades.
• 38. materials and power
• 39. COMMERCIAL SIZES

COMMERCIAL PIPE SIZES

• Commercial is sizes thicknesses.
• size approximate
• The the outside
• size with outside designated mm
• size inside 152.4
• designate thickness pipe.
• and number
• The OF

TYPES OF PIPES

• 40. Zinc
• 41. steel
• 42. steel pipes
• 43. that and was a water
• 44. corrosion to primary lines.

• Galvanized is to the is from businesses

• 45. to

Stainless steel And galvanised steel

• steel in chromium againsed and and technical

• contains

• Galvanized steel Galvanized Galvanized corrosion or Galvanized extensive in the equipment, metal

• steel products

DIFFERENCE BETWEEN PIPE AND TUBE

• Pipe Nominal Outer Diameter Schedule the wall size Tubing Diameter outer diameter wall but OD Tubing is the tolerences diameter

• Rigid

• generally or

• the surfaces pipes

• or

• has structural

• Measured

• is the for

• diameter and sizing

• the

STAINLESS STEEL:

• oxygen the steel

• in that the oxidation also the As

• cover therefore that

• that the to for corrosion this from

4. that use:

• equipment
• equipment
• components fasteners where small amounts in steel and with are be include:
• Air components fasteners beams cabinetry
• Rolling
• poles

5. to shapes and with to

6. and to

7. This are the steel of the and to long. 2

8. are which

These are others are There and Cutting

7. are are used for the setsquare,

• to the

8. perform the

• is materials ware

• such wear

• and handling Health to

• the

• that carrying less

HANDLING EQUIPMENT

• Conveyor system
• goods another

SETTING EQUIPMENT

• machine compenent

• Several feed are

• wire feed wire a and is with for there

• through the liner

• The the in is two the shield guns'

• are MIG that

• solid

• is wire roller

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• which fault

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• depends

• has

• 25.4mm small

• .

CURRENT SETTING FACTORS

• the range by
• is the welding wire gas given shielding
• used the into
• for the

TIG welding equipment

• shutdown of sector the preparation
• to the
• the
• the
• electrode the

TIG welding Torch

• machine ac machines
• In inverter machines it
• the Torch: or Torch.
• varying can gases gases has

Procedures and assemble welding torch

• head

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• foot is and the

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• Regulators the

and and

• 30. Is used be how

• bead with

SET UP FCAW

• the the fire
• must area
• power are is
• the the
• the Source
• to needs source
• to the