To make sure that high quality welds are produced and meet welding codes, base metals must be properly prepared prior to welding. Type of prep depends.

BASE METAL PREP

INTRO To make sure that high quality

welds are produced and meet welding codes, base metals must be properly prepared prior to welding.

Type of prep depends on code requirements and base metal type.

In this unit we will discuss different ways to prep metal.

BASE METAL CLEANING All metals should be __________ before welding. To ensure quality welds,

surface contaminants and oxides must be removed prior to welding. Do not assume metal is clean just because it is shiny, corrosion on stainless steel

and aluminum is silver and appears shiny.

All metal has surface corrosion. Corrosion occurs when metal is exposed to air. It basically forms a tight bond to the surface of metal that protects the metal. _________ corrosion cannot be removed by wire brushing.

A more recognizable form of corrosion that we deal with is rust. Rust is a coarse type of corrosion that tends to flake easy .

METAL DEFECTS- POROSITY The most common defect caused by surface contaminates is called

__________. This occurs when gas pockets or voids appear in the weld metal.

To keep contamination down, some metals must be stored separately from other metals and aluminum must always be stored indoors.

Large areas of contamination are best removed by _______________ and ____________.

TYPES OF WELD JOINTS There are 5 basic types of weld joints.

Butt joint, lap joint, corner joint, T-joint, and edge joint.

Each of these weld joints can be done using various types of welds.

Always try to position the weld to be completed in the ________ position.

SURFACE WELDS A surface weld is the only type of weld that is applied to just one base

metal surface.

It is used either to ______________ a metal surface or add material to a base metal to increase strength and stability.

For a proper weld, each layer of surfacing must be properly chipped, scraped and cleaned before applying additional layers of surfacing.

PLUG AND SLOT WELDS Plug and slot welds are used to

join metal pieces when the edges cannot be welded and are used with _________ joints

If the hole is round, the weld is called a plug weld. If it is slotted or elongated, then it is called a slot weld.

Typical way of doing one of these welds is to fill the hole with metal, then grind it back to a smooth surface.

V-GROVE WELDS These welds are typically applied to inside or outside corner joints, butt

joints, or edge joints.

A 45 degree angle must be cut on the ends to prepare this type of weld.

A double V- groove weld requires ________ the metal that a single V-groove requires.

GROOVE ANGLES The purpose of a groove angle is to allow access to the root of the weld.

Root penetration is sized to control melt-through.

For open root welds on plate, the groove angle should be _______ degrees and the max size of the root face is 1/8”.

Backing strips should always be _____ thick by ______ wide.

CODES AND WELDING SPECIFICATIONS A _________________ is a detailed

listing of the rules and principles that apply to specific welded products. Codes ensure that safety is first and helps keep everybody safe.

WELDING JOINT PREP There are many different ways to

prepare a joint for welding. Can be done mechanically with

nibblers, grinders, or cutters. Can be done thermally with a torch

or plasma cutter.

MECHANICAL JOINT PREPARATION Mechanical joint prep is used on

alloy steels, stainless steel, and nonferrous metal piping or plate.

Much _________ than using a torch or plasma cutter.

THERMAL JOINT PREP Preparing with the torch or

plasma cutter is known as ____________________________________________________.

Typically not as smooth and precise as using cutting tools.

PIPE BEVELING MACHINES Designed to cut pipe that is

_______ in diameter to ______ in diameter.

Anything larger than ____- inches requires special equipment.