Pipes and Pressure Vessels Welding: MATPV501

Pipes and Pressure Vessels Welding Overview

• Module name: Pipes and Pressure Vessels Welding, module code MATPV501.
• Focuses on performing pipes and pressure vessels welding
• RQF (Rwanda Qualification Framework) Level 5 competency with 10 credits
• Requires 100 learning hours.
• Falls under the Manufacturing and Mining sector along with Manufacturing Technology trade.
• It is a specific module within the MAMMAT5001 TVET Certificate V in Manufacturing Technology curriculum.
• Copyrighted by Rwanda TVET Board, 2024, issued in February 2024.

Introduction to Pipe and Pressure Vessels Welding

• Includes organizing the workplace, totaling 20 learning hours.
• PIPE is a device for transporting fluids or gases, made of materials like plastic or metal in various shapes/sizes (tees, elbows, flanges, reducers).
• Piping refers to a system of pipes used to convey fluids (liquids/gases) from one location to another.
• Pipe design is determined by:
• Fluid type
• Allowable pressure drop/energy loss
• Desired velocity
• Space limitations
• Process requirements (drainage or straight run)
• Stress analysis
• Temperature

Fittings

• Connect straight sections of pipe or tube, adapt to different sizes/shapes, and regulate fluid flow.
• Common fittings: tees, elbows, flanges, reducers
• Tees are T-shaped fittings with two outlets at 90 degrees, connecting pipelines at right angles.
• Elbows are bent fittings changing flow direction by 90 degrees, attach to various materials
• Flanges connect pipes, valves, pumps, provide access for cleaning/inspection, usually welded/screwed with bolted joints and gaskets to prevent leaks.
• Reducers decrease pipe size, reducing bore size from large to small.

Pressure Vessels

• Containers for liquids, gases, or materials under high pressure; come in various sizes/shapes (spheres, cylinders).

Shielding Gas

• Used to protect molten metal during welding or high-temperature, it provides a protective atmosphere around the weld to prevent metal and contaminants from contacting air/moisture which can cause oxidation, porosity, or weld defects.
• Examples include argon, helium, carbon dioxide.
• Choosing shielding gas depends on:
• Metal type
• Arc and metal transfer characteristics
• Gas availability/cost
• Mechanical property requirements
• Penetration and weld shape

Welding Methods

• MIG stands for Metal Inert Gas
• MAG stands for Metal Active Gas
• GMAW stands for Gas Metal Arc Welding
• MIG/MAG uses a continuous wire electrode and inert gas to join metal workpieces.
• An electric arc melts the wire, depositing it onto the workpiece for a strong weld.
• MIG welding uses inert shielding gas, MAG uses active shielding gas.
• MAG is actually more common in practice, but MIG term is often used accidentally to describe MAG welding.

MIG and MAG Welding Equipment

• Includes: power source, wire feeder, grounding cable, welding gun, liquid cooling unit (optional), and shielding gas tank or interface.
• The wire feeder feeds welding wire to the welding gun and start/stop the power source.
• It controls voltage with electronic power sources and shielding gas flow.
• Power source/wire feeder connect via cable.
• Advantages of MIG/MAG:
• Fast welding speed
• Maintained long arc time
• Minimal electrode changes
• Appropriate for difficult-to-weld materials
• Welding in all positions
• Clear welding arc and pool
• Minimal after-treatment
• High deposition rate
• No slag formation
• Simple arc ignition
• Well-suited to mechanized/automated welding
• High weld speeds
• Suitable for out-of-position welding and welding in difficult positions
• Low filler metal costs
• Disadvantages:
• GMAW equipment is expensive and complicated
• Wire/shielding gas costs are higher
• Shielding can be disrupted by winds above 5 mph
• Windshields/enclosures are needed
• High gas flow due to wind can cause turbulence
• GMAW requires greater work access
• The wire feeder must be close

FCAW

• Stands for Flux Cored Arc Welding.
• Uses a consumable wire electrode and flux to join metals.
• An electrode or core wire is a tubular metal sheath filled with flux/alloying ingredients.
• Types:
• Self-Shielded: Arc heat decomposes the electrode's flux core, protecting molten metal.
• Gas-Shielded: Uses protective gas like CO2 or argon/CO2 mixes along with flux core.

FCAW Core Wire

• FCAW flux selection depends on material, joint properties.
• Must identify the base metal type via tests if unknown: visual, magnetic, chisel, flame, fracture, spark, or chemistry
• Important factors for filler metal selection include:
• Base metal strength
• Composition
• Welding position
• Current
• Joint design/fit-up
• FCAW welding fluxes functions:
• Forms slag for chemical reactions and affects weld bead.
• Acts as a fluxing agent to reduce molten metal surface tension
• Stabilizes the arc
• Adds alloying elements for mechanical properties because of difference in properties
• Shielding gases protect from oxygen

FCAW Flux types

• Divided into Rutile-Based (T-1) and Lime-Based (T-5).
• T-1 fluxes generate a smooth arc, produce fine drop transfer, low fumes, and easy slag removal, does not produce the quality as the T-5 systems
• T-5 fluxes remove impurities, but fluid slag causes more spatter, fumes and more slag adhesion than T-1.
• Types of FCAW Welding Process include:
• Self-Shielded: Arc between flux-cored wire and work, flux provides gas shielding.
• Gas-Shielded: Hybrid of self-shielded and gas metal arc welding, uses fluxing/deoxidizing/alloying core ingredients instead of protective vapors

FCAW Equipment

• Similar to GMAW: power source, gas cylinder, controls, wire feeder, welding gun, cables.
• Gas-shielded wires need gas shielding system.
• Fume extractors used, with seam followers/motion devices for automatic welding.
• FCAW Welding Machine includes;
• Generator/Alternator Welding Machines are powered by electric motors or internal combustion engines.
• Transformer Welding Machines are rectifier-equipped- more efficient than motor-generators, provide quieter operation.
• Wire Feeders: Wire feed motor drives the electrode through the cable/gun.
• FCAW Welding Guns: The welding guns deliver wire, current and gas during the FCAW process.
• Fume Extractors: Reduces smoke from flux-cored electrodes.
• Flowmeter and Regulator: Regulator maintains constant gas pressure, flowmeter controls gas flow to the welding gun.

Accessories used

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

Advantages of FCAW Welding

• High metal deposition rates.
• Portable machines.
• Efficient filler metal use.
• It requires a narrow groove angle.
• Minimal pre-cleaning.
• Can be welded in all positions using special fluxes.
• Multi-pass welds.
• It gives high reliability for welding on boilers/pressure vessels/structural steel.
• It has excellent control.

Disadvantages and limitations of FCAW

• Applicable to ferrous metals and nickel-based alloys only.
• The FCAW equipment/electrodes are expensive.
• Slag must be removed
• Increase in smoke/fume generation.

TIG

• Stands for Tungsten Inert Gas welding, joining metals with a non-consumable tungsten electrode and inert gas (argon, helium).
• Generates an electric arc to melt/deposit metal.
• Tungsten is a rare metal.
• Inert gas possesses extremely low reactivity
• TIG Electrodes are made from tungsten with thorium/zirconium additions, improving arc striking and stability.
• Thoriated electrodes are for DC welding machines.
• Zirconiated electrodes are for AC welding, and are particularly suitable for welding.
• TIG Welding Equipment includes: power source, grounding cable, welding torch, and shielding gas tank/interface.
• Suitable for all carbon steels, low-alloy steels, alloyed stainless, nickel alloys, aluminum and its alloys, copper and its alloys, titanium, magnesium, and nonferrous alloys.

TIG Accessories

• Welding Nozzles
• Collet for TIG Torch
• Collet body for TIG-Torch
• Long back cap for TIG-torch
• TIG welding pedal control
• Ground Cable & Clamp Assembly
• Short back cap for TIG Torch
• TIG Torches
• TIG Parts Kits
• TIG Welding Glove

Advantages of TIG welding process

• It gives flawless joints because there is no need to stop for replacing the electrode
• Reduction of downtime in production because no flux is required
• High quality and strong welding
• Cleaner and more appealing joints
• The weldings are suitable for very thin sections, and can work with and without filler metal.
• Variety of metal can be welded.
• Non-corrosive and ductile joints.
• The amount of flames and spark is minimum.
• it can be done in both automatic and manual.

Disadvantage of TIG welding process

• It is a time-consuming process in comparison with other welding causing a lower filler deposition rate.
• More complicated which needs highly skilled and professional workers to perform TIG welding.
• Welders are exposed to high intensity of light which can cause eye damage and has high initial cost.
• Can not use in thicker sheets of metal.

Advantages and Disadvantages of Pipe and Pressure Vessels Welding

• Advantages:
• Provides strong, durable joints.
• More cost-effective
• Performed on various materials (carbon steel, stainless, alloy steel as well as various types of pipes and vessels).
• Helps prevent leaks/failures, improving industrial safety.
• Allows for the sufficiency and effective joining of pipes and pressure vessels.
• Allows for customization of pipes and pressure vessels to certain dimensions, shapes sizes, making it ideal for certain applications.
• Helps reduce waste and emissions, such as bolts/rivets.
• Disadvantages:
• Requires strict quality control.
• Needs specialized knowledge/experience.
• Safety risks if measures are not followed.
• It is time-consuming when working with large and complex components.
• Limitations on material.
• Can required addtional post-weld processing.
• Welds are disposed to defects, etc.

Application of Pipes and Pressure Vessels Welding

• Oil and gas: Joins pipes and pressure vessels in production, transportation, and refining.
• Chemical: Joins pipes and pressure vessels for storing, transporting, and processing hazardous chemicals.
• Power Generation: Joins pipes and pressure vessels in power plants for electricity generation, transmission and distribution.
• Aerospace: Joins pipes and pressure vessels for storing/transporting fuels, gases, fluids in aircraft/spacecraft.
• Automotive: Joins pipes and pressure vessels for storing/transporting fuel, brake fluids, and other fluids in vehicles.
• Pharmaceutical: Welding joins pipes/pressure vessels for storing/transporting medicines.

Preparing the Workplace

• Job Hazard Analysis focuses on identifying workplace hazards to minimize injuries.
• Step-by-step guide:
• Choose Procedure
• Break Job Into Steps
• Identify Hazards
• Implement Solutions
• Communicate Findings
• Review and Update
• Workplace Flexibility helps employees address their work and life needs.

Types of Hazards

• Physical Hazard;
• Agent/factor that can cause harm (ergonomic, radiation, heat/cold stress, vibration, noise).
• Chemical Hazard;
• Exposure to chemicals in the workplace.
• Biological Hazard;
• Biological substances pose threat to health of living organisms
• Electrical Hazard;
• Dangerous condition where worker can contact energized equipment/ conductor.
• Use Control methods for any hazard.

5S System

• 5S is to clean and an efficient working environment.
• Consists of 5 steps (5 pillars of a visual workplace):
• Sort: Eliminate unneeded items.
• Straighten: Put things in order
• Shine: Clean everything
• Standardize: Make cleaning and checking routine
• Sustain: Maintain control and self-discipline
• Machine Shop Safety Rules:
• Keep the Machine OFF.
• Keep the floor clean.
• Work with a supervisor.
• Follow all safety guidelines.
• Stop the machine to adjust.
• Do not wear loose ties, baggy clothes etc.
• Always wear a coat or apron.
• Make sure that the guards are in place.
• Know the machines operating instructions.
• Be familiar with all the stop buttons.
• Remove burrs and chips.
• Wash your hands after work.
• Report any injuries to the foreman.
• Keep your mind on the job.
• work where theres proper lighting.
• Workshop Arrangement:
• Have fire extinguishers and sand available.
• Remove all combustible material.
• Dont keep flammable materials nearby.
• Keep the area clean.
• Ventilation if needed.
• Safety Precautions for Pipe Welding Equipment (MIG/MAG, TIG, FCAW):
• Ensure equipment works properly.
• Wear protective clothing.
• Never weld with a hand torch.
• Do not operate flammable equipment.
• Do not weld in confined locations.
• Others can be affected by light.
• Never work on the equipment.
• Dont leave equipment running.
• Protect your hands.

Materials Required for Pipes and Pressure Vessels Welding

• Piping Material must suit operating conditions, as per ASME Code guidelines for:
• Power Piping
• Industrial Gas and Air Piping
• Refinery and Oil Piping
• Refrigeration Piping Systems
• Objective: Ensuring material is entirely safe under pressure, temperature, corrosion, and erosion
• Materials Commonly used in power plant piping include;
• Steel: Frequently used for piping, forged steel for fittings, cast steel for special applications in seamless/welded categories
• Cast Iron: Corrosion/abrasion-resistant, used for ash handling/sewage/underground water lines. Made in different grades such as gray cast iron, malleable cast iron and ductile cast iron.
• Brass and Copper: Non-ferrous, used in instrumentation/water services with limited water temperature.
• Commercial Pipe Sizes: In standard sizes with various wall thicknesses/weights.

Commercial Pipe Sizes

• Up to 304.8 mm (12 inch), the size is listed as nominal (approximate) inside diameter.
• Above 304.8 mm, size is listed as the actual outside diameter.
• Classes have the same outside diameter, with different inside weights due to weight.
• Two systems designate wall sizes: older method (standard, extra strong, double extra strong) and newer (schedule numbers).
• Schedule numbers: 10, 20, 30, 40, 60, 80, 100, 120, 140, 160 (schedule 40 = standard, schedule 80 = extra strong).

Types of Pipes

• Galvanized: Steel pipes dipped in a protective zinc coating. Commonly used in homes before 1960 providing a higher resistance to corrosion and helps to prevent the buildup of mineral deposits that can clog the water line.
• Stainless Steel: Used in piping system for transporting fluids or gases it contains nickel as well as chromium, which give its corrosion-resistant properties
• Carbon Steel is a durable material that can withstand stress which makes it commonly used among industries, a steel that is alloyed with iron and carbon.

Galvanized Steel Pipe vs Stainless Steel

• Galvanized steel contains an outer layer of anti-rust coating that wears off over time, stainless steel uses steel that is mixed with a minimum of 10% chromium
• Galvanized steel is cheaper and more readily available vs stainless steel is more stronger.
• Galvanized steel used for smaller-budget projects, stainless steel is used to manufacture equipment that requires lots of heavy lifting or thick components

Difference Between Pipe and Tubes

• Pipe is specified by Nominal Pipe Size (NPS) with constant Outside Diameter (OD) and Schedule (SCH) defining wall thickness. Tubes can be either specify the OD, ID or WT
• For NPS 1/8 to 12, NPS and OD are different, but NPS 14 and above has = NPS and OD.
• Tubes can be both rigid and flexible vs pipes are usually rigid and have no flexibility, tubes can also be used among smaller diameters.
• Tubes are normally used for structural purpose while Pipes are normally used to transport fluids.

Metal Specifications

• Metal specifications are defined by metal shapes and sizes in a precise way as well as reducing the amount of metal cutting into steel chips.
• Types of metal
• Ferrous Metals, mostly contain Iron. which are magnetic and give little resistance to corrosion such as carbon steel, mild steel, stainless steel, cast iron.
• Non-Ferrous metal include those that do not contain iron inappreciable amounts such as Aluminum, copper.
• Measuring tools
• Used for measuring the workpieces, those includes tape measure, steel ruler, setsquare, protractors, etc.
• Marking tools
• Used for marking on a workpiece after measurement and before cutting. Those include scribers, punches, markers, etc.
• Holding tools
• Used for holding or positioning the workpiece before cutting or perform welding process, example is bench vices.
• Cutting tools
• Serves the purpose of cutting-off the work-metal to into desired shape or sizes. Examples are hacksaw, angles grinder, files, etc. Apply handling techniques in order to reduce the change of degradation.

Tools Required In Pipe Fitting

• Chains, Steel cables and Heavy duty are used for lifting and holding them.
• C-clamps, Chain hoists and Cranes, Hammers of various size are to for heavy pipes and fittings tackles
• Crow bars and Pinch bars are needed occasionally to bend the pipe joint in order to align them
• Steel rulers, Steel tapes, Sprits levels, Protractors are tools to inspect for quality

Material handling

• Material handling is the movement, protection, storage and control of materials and products throughout manufacturing, warehousing, distribution, consumption and disposal.
• Types
• Handling and storing product involve diverse operations such as hoisting and carrying products from working place to the storage and must be Stored in dry place free from atmospheric contamination.
• Manual handling defined by exerting human effort, directly or indirectly to move or support a load as well using lifting.
• Lifting can either
• Manual Lifting
• And Individual lifting that make use of overhead cranes and their supporting runways, patient hoists, motor vehicle lifts, vehicle tail lifts and cranes fitted to vehicles, a building cleaning cradle and its suspension equipment, goods and passenger lifts, fork lifts, lifting accessories
• Use Team lifters when working where other solutions are inappropriate.
• Mechanical handling is the backbone of warehouse operations, optimising inventory management and order fulfilment in various commercial industries, specially retail
• A material handling system is designed to improve workplace safety and increase worker productivity in order to reduce to risk of injury.
• Conveyer handling is the use of in many Industries as a standard piece of mechanical handling equipment to move goods, products, raw goods, and other materials in area or building

Setting MIG/MAG, TIG AND FCAW Equipment

• Ensure its CONNECTING WELDING MACHINE COMPONENT

Control Units

• Consist of several controls
• Argon gas switch
• Wire feeder
• Arc self-control controls
• Wire Feed Unit speeds
• Push type: The wire is pushed forward by the wire drive unit through the wire guide liner to the torch,
• Pull type: The wire is pulled forward to the torch by a wire feed unit in the torch, figure and and are placed inside the welding torch,
• .Pull- push: The wire is pushed forward by a wire feed unit in the welding machine and at the same time it is pulled through the wire liner by a wire feed unit in the welding torch

Wire installation for MIG/MAG

1. Connect the gas cylinder to the regulator
2. Plug gun euro connection and control cable
3. Fit wire spool to the spool gun
4. Connect polarity for the type of wire needed 5.Plug the short mechanical connector, then plug the work return.
5. Tum the machine on, while confirming the light is turned on.
6. Confrim wire speed

The Welding Gun

• Directs the wire to the joint, it transfers welding current the wire, direct the shield gas towards the weld and are is air, Gas and water cooled. There are five major factors that influence choice of filler wire. Base plat chemical composition, as well Shielding gas, type of weld joint design and type of service applied. Make sure that, insertion is solid and in good working order.

Loose Connection

• Is defective so its important when out setting MIG/MAG equipment to check for the loose. and gas leakage will make setting MiG//MaG Equipment.

Adjusting wire and gear speeds

• Adjust wire drives and gear ratios with proper input and output guide Factors to Consider in adjusting wire feed rate consist of;
• voltage and amperage is regulated so that its is increased.
• Type of electrode.
• Diameter used
• Thickness of the work

Setup TIG welding equipment

• Knowledge of equipment setup, adjustment, and shutdown is necessary to make effective and efficient welds
• Referto the manufacturer's safety precautions and proper tip preparation, as well as also, wear safety glasses in the welding area and attach remote control to its source
• Confrim electrode is connected.

TIG Equipments include;

• Power Source: Constant current (cc) machines can produce AC or DC welding power.
• TIG welding, include tungsten electrode, collets and nozzle as well as being cooled or air cooled.
• Shielding gas supply use argon to protect weld oxidize.
• Foot Controller

Procedures for Assembling Tig Equipment

• Assembling.
• Install electrode and nozzle.
• Confrim that its finger tight.

Welding Regulators

• Argon.
• CO2 and Argon/CO2 and Helium.

TIG Electrodes Types

• Colour indicates electrode materials
• Electrode Tip Angle different tip angle of non-consumable tungsten electrodes is used, varies from 150 to 180o with affects Weld Size/Stability/penetration properties.
• Remember that always to look look for Spatter the removal area, as well potential safety problems

Procedures for equipment assembly

Follow manufactures guidelines when:

• Setting polarity
• Wire speed. -Gas levels.
• Clean the surface the welding.

Types Of Faults that Can occur

• Lose Connection ( hoses are improperly done.).
• Gas Leakage.
• Stoppage and malfucnions.
• Wire burns (too slow wirefeed).
• Knots.

Factors to consider in Selection of Electrode Flux

• Metal Strength Properties.
• Metal Composition
• Position Current and Design being used.
• Wire will also need fixing the proper procedures and guidelines of the manufacture
• Check the rollers and gear ratios with there specific input/output guides.

Setting current factors

• This should be adjusted based to types of materials: metals which enable high current setting and other which enable low current setting. while considering the setting of the work.

The Importance of Tack Welding

Importance of Track is can adjust measuring before full welding is: -Alignment and Gap as it helps adjust adjusting work pieces as well, the Backing. Is is key to note what position type of metal youre welding so that is can a considered and tacked. Is Important the machine will is visually functional, with a with electrode/ ground connection when testing

• Key Parameters like current and travels speeds
• Test weld, to avoid cracks and porosity.

Test

• the Non-destructive, by Visual Test MT. Magnetic MT (Flaws or defects on metal Using Magnetic flux leakage, for corrosion
• Liquid check for surface level defects.

Ultrasonic

• Wave. used for identification of defects
• Guided wave.
• Thermals.
• Radio Active for Materials.
• Acoustic wave.