29 CFR 1910.251 & 1926.350Subpart Q & J

Prepared by County of Henrico Risk ManagementLoss Prevention

October 2nd 2013

Training Objectives Three Specific Types of Welding Modules Methods of Arc Welding Welding Hazards Safe Work Practices Fire Protection & Prevention Proper Ventilation for Welding Welding Operators Protection

In this Welding, Cutting, and Brazing module, three specific types of welding are covered. These are listed below: Oxygen-fuel gas welding and cutting Arc welding and cutting Resistance welding

The elements of Oxygen-fuel gas welding and cutting: General Requirements Cylinders Service Pipe Systems Pipe System Protection

General Requirements Focuses on using Acetylene Safely Flammable Unstable Cannot be adjusted above 15 psi

Safe Work Practices Blow out cylinder valve Turn on cylinder valve first and then

adjust the regulator pressure screw. Never stand in front or behind

a regulator when opening the cylinder valve Open cylinder valve slowly

• The pressure adjusting screw:– Turning clockwise allows the gas

to flow.– Turning counterclockwise

reduces or stop the gas flow.

General Requirements Cont.: Safe Work Practices Purge oxygen and acetylene passages Light the acetylene Never use oil or grease Do not use oxygen as a substitute for air Keep your work area clean

Before lighting the torch, remember to purge acetylene and oxygen passages.

Before opening the oxygen on the torch, light the acetylene. Never use oil or grease on regulators, tips, or any part that may

come into contact with oxygen. Do not use oxygen as a substitute for air. Always keep your work area free of items that could ignite.

Cylinders Cylinder approval and marking marked for the purpose of identifying the gas content,

with either the chemical or trade name of the gas

Storage of cylinders Storage area must be well ventilated Cylinders must be at least 20 feet from combustibles Valves must be closed Valve protection must be in place Inside storage must be limited to 2,000 cubic feet. Cylinders must be stored in upright position Oxygen must be at least 20 feet from fuel gas

or 5 feet with a 1/2 hour fire barrier Separate oxygen from fuel gas

Cylinders Cont.: Operating Procedures Operation must emphasize the absence of oily

or greasy substances. Follow these rules of operation: Cylinders, cylinder valves, couplings,

regulators, hose, and apparatus shall be kept free from oily or greasy substances.

Oxygen cylinders or apparatus shall not be handled with oily hands or gloves.

A jet of oxygen must never be permitted to strike an oily surface, greasy clothes, or enter a fuel oil or other storage tank.

Service Pipe Systems There are special requirements for service pipe

systems when using oxygen or acetylene. Oxygen Acetylene or Acetylene Compounds

Oxygen: When oxygen is supplied to a service piping system from a low pressure oxygen manifold without an intervening pressure regulating device, the piping system shall have a minimum design pressure of 250 psig.

A pressure regulating device shall be used at each station outlet when the connected equipment is for use at pressures less than 250 psig.Acetylene or Acetylene Compounds: Piping for acetylene or acetyleniccompounds shall be steel or wrought iron.

Pipe System Protection The entire service pipe system must be protected

against build-up of excessive pressure and leaks. This protection is accomplished with: Protective equipment Regulators Proper hose and hose connections.

Pipe System Protection Cont.: Protective equipment is divided into the two

categories listed here: Pressure Relief Devices The pressure relief device should discharge upwards to a

safe location. Pressure relief valves are required in fuel-gas piping

systems to prevent excessive pressure build up within the system.

Pressure Relief Devices: Relief valves will vent automatically at preset pressures or may be manually operated to relieve pressure in the system.

The three function: The protective equipment in fuel-gas piping systems shall be located either at the main supply line, at the head of each branch line, or at each location where fuel-gas is withdrawn

Definition: A fusion process wherein the coalescence of the

metals is achieved from the heat of an electric arc formed between an electrode and the work. Application Installation Operation & Maintenance

Application Applies to a large and varied group of processes that

use an electric arc as the source of heat to melt and join metals.

Installation Arc welding requires proper installation of

equipment. A critical part of installation is ensuring that proper

grounding is completed.

Operation & Maintenance All connections to the machine shall be checked to make

certain that they are properly made. The work lead shall be firmly attached to the work. Magnetic work clamps shall be free from adherent metal

particles of spatter on contact surfaces. Coiled welding cable shall be spread out before use to

avoid serious overheating and damage to insulation.

Operation and Maintenance Cont.: During welding operations, cables with splices

within 10 feet (3m) of the holder shall not be used. Welders should not coil or loop welding electrode

cable around parts of their body. Cables with damaged insulation or exposed bare

conductors shall be replaced. Joining lengths of work and electrode cables shall be

done by the use of connecting means specifically intended for that purpose.

The connecting means shall have insulation adequate for the service conditions.

Definition: This is a group of fusion welding processes that use

heat and pressure to make the coalescence. The heat comes from electrical resistance to current

flow at the site of the weld. The processes include: Spot Welding Projection Welding Seam Welding

.

Spot Welding A process typically used in high-volume, rapid

welding applications. The pieces to be joined are clamped between two electrodes

under force, and an electrical current is sent through them. The advantages of spot welding are many and

include the fact that it is: An economical process Adaptable to a wide variety of materials including low

carbon steel, coated steels, stainless steel, aluminum, nickel, titanium, and copper alloys

Applicable to a variety of thicknesses A process with short cycle times A robust process Tolerant to fit-up variations

Potential Hazards Fires may start by hot materials igniting nearby

combustibles. Burns to the operator may occur if unprotected skin

comes into contact with the extremely hot work.

– Magnetic fields could easily destroy/disrupt electronic components, stored data if not careful.

Potential Hazards Cont.: Metal fumes from vaporizing of the work with the

extremely hot arcs may be inhaled into the worker’s lungs.

Certain metals and metal oxide fumes, including zinc, cadmium and beryllium, produce serious illnesses when inhaled.

Fluxes used with welding to create inert atmospheres at the point of the weld also present inhalation hazards.

All welding and cutting must have adequate ventilation to protect the person doing the welding and those working around the welding area.

Three Types of Welding Methods: Tungsten Inert Gas Welding (TIG) Gas Metal Arc Welding (MIG) Shielded Metal Arc Welding (SMAW)/ Stick Welding

Definition: TIG welding is an arc that is formed

between a non-consumable tungsten electrode and the metal being welded.

Gas is fed through the torch to shield the electrode and molten weld pool.

Benefits: Welds with or without filler metal Precise control of welding

variables (heat) Low distortion

Shielding Gases: Argon 2 to 5% Hydrogen w/Helium

Applications Most commonly used for aluminum and

stainless steel For steel Slower and more costly than consumable

welding Except for thin sections or where very high

quality is needed

Definition: The heat source is formed by creating an electric arc

between the work piece and a wire, which is fed continuously into the weld pool.

• Benefits:– Long welds can be made

without starts and stops– Minimal skill required– Minimal cleaning of

surface before weld– Allows welding in all

positions

Shielding Gases: Inert Argon, Helium Used for aluminum alloys and stainless steels.

Active 1 to 5% Oxygen, 3 to 25% CO2 Used for low and medium carbon steels

Applications Gas Metal Arc Welding (MIG) is used to weld all

commercially important metals, including steel, aluminum, copper, and stainless steel.

Definition: Consumable electrode coated with chemicals that

provide flux and shielding The filler metal (here the consumable electrode)

is usually very close in composition to the metal being welded.

Benefits Simple, portable,& inexpensive Self flux provided by electrode Provides all position flexibility

Shielding Gases No shield gases added Lower sensitivity to Wind

Applications Construction, pipelines, shipbuilding,

fabrication job shops. Used for: Steels, stainless steels, cast irons. Not used for aluminum and its alloys, or

copper and its alloys (energy density is too high).

Definition: A stream of oxygen is directed against a piece of

heated metal, causing the metal to oxidize or burn away.

Making a Cut Mark a line as a guide. Turn on acetylene as for welding and light. Turn on oxygen adjusting flame to neutral. Make sure the oxygen lever flame remains neutral. Place metal on the cutting table so metal will fall

clear.

Definition: A process which a filler metal is placed at or between

the faying surfaces, the temperature is raised high enough to melt the filler metal but not the base metal. The molten metal fills the spaces by capillary attraction.

Torch Brazing Oxy-fuel torch with a carburizing flame First heat the joint then add the filler metal

Electric & Gas Welding Safety Check: Ensure electrical cord, electrode holder

and cables are free from defects No cable splices within 10 feet of electrode holder.

Ensure welding unit is properly grounded. This helps to avoid over heating. All defective equipment shall be repaired

or replaced before using.

Electric & Gas Welding Cont.: Safety Check: Remove all jewelry – rings, watches, bracelets, etc… Ensure PPE e.g.. welding hood, gloves, rubber boots or

safety shoes, apron are available and in good condition. Ensure fire extinguisher is charged and available. Ensure adequate ventilation and lighting is in place. Set Voltage Regulator to Manufacture’s specifications. Avoid electrical shock DON’T wrap cables around any

body part. Ensure fittings are tight.

Electric & Gas Welding Cont.: Safety Check: Inspect hoses for cuts and frayed areas. Set gauges to desired PSI. Ensure that sufficient PPE is made

available. Locate welding screens to protect

employee’s – DON’T block your exit. Ensure that adequate ventilation and

lighting are in place.

Fire hazards must be removed, or Guards installed, or Welding/cutting must NOT take place

Hot work permit should be used outside designated areas to ensure that all fire hazards are controlled

Use of fire watch 1/2 hour after operation ceases

Welding areas should meet the following requirements: Floors swept & cleared of combustibles 35 ft.

radius of work area. Flammable and combustible liquids kept 35 ft.

radius of work area. At least one fire extinguisher – on site Protective dividers to contain sparks andslag Welding curtains Non-combustible walls Fire resistant tarps & blankets

• Ventilation Proper ventilation can be obtained either naturally or

mechanically. Natural Ventilation is considered sufficient for welding and

brazing operations if the present work area meets these requirements: Space of more than 10,000 square feet is provided per welder A ceiling height of more than 16 feet.

Mechanical ventilation options generally fall into two basic categories. Low vacuum system which takes large volumes of air at low

velocities. High vacuum system that are captured and extracted fumes as near

to the work as possible.

Ensure protection from fumes and gases by one or a combination of the following: Good general ventilation. Use of a booth. Local exhaust ventilation

on the hand piece. Air supply to the helmet.

Welding involves specialized personal protection that must be worn every time you perform welding operations. The following is a list of basic PPE: Fire-resistant gloves Aprons Safety shoes Helmet Ultraviolet radiation filter plate (arc welding) Goggles with filter lenses

Summary Major hazards include: Fire Burns Shock Toxic Exposure

Follow proper procedures to prevent fires Use appropriate engineering controls Wear appropriate PPE

Any Questions

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