Joint fit up and alignment NCCER Unit 10

Intro Joint design and setup affect the safety and quality of a completed weldment. All of these are covered by codes and specifications that must be followed. Special tools for fit up and alignment will be discussed in this unit.

Code changes Codes are reviewed and updated as needed. When a code is updated, the code can be reissued with an updated year suffix or as an alternative, addendum sheets may be issued. Changes are typically highlighted to show changes. The asme updates the entire code every _______ years. An addendum is issued ________. The yearly addendum is identified by placing the letter ___ in front of the year on the cover of the code.

WPS A _____ is a written set of instructions for producing sound welds. All welding requires that acceptable industry standards be followed, but not all welds require a wps. The requirement for the use of a wps is often listed on the _____________ as a note or in the tail of the welding symbol.

Wps Each wps is written by an individual who knows welding codes, specs, and industry practices. It then becomes the responsibility of the contractor to test and qualify the wps before using it. The results of testing are recorded on a _______. The wps and pqr must be kept __________.

Fit up gauges and measuring devices Before making a weld, the joint must be fit up and checked to ensure it conforms to the WPS or site quality standards. The most common tools used to lay out and check joint fit ups are straightedges, squares, levels, and hi-lo gauges.

Straightedges Straightedges are used to scribe straight lines and check joint alignment. Always check a straightedge for ________________, heat can cause distortion and if this happens the straightedge is no longer good.

squares Two types are typically used….. Pipefitters squares- used to measure angles and check squareness. Combination squares- typically smaller, have attachments that slide and lock along a groove on the blade. The ________________ is used to measure round stock and to locate the center of shafts or other round objects.

levels Levels are used to check that layouts are level (horizontal) and plumb (vertical). Levels use a __________ in a glass vial to check level and plumb. The bubble must be centered in the vial to ensure the level is correct. Torpedo levels have three vials: one to check level, one to check plumb, and one to check 45 degree alighnment.

Hi lo gauges The main purpose of a hi lo gauge is to check for ______________________, although plate joint misalignment can also be checked. The name comes from the relationship between the alignment of one pipe to the other pipe, which is called high-low.

Fit up tools Many tools have been developed to aid plate and pipe fit up. Some are specialty tools and others are common hand tools. The following are common fit up tools….

Hydraulic jacks When using a hydraulic jack, never weld directly on the jack base or ram. Always protect the ram from weld splatter. If the ram is off the ground, secure it with rope or chain.

Chain hoists (chain falls) Chain hoists, also called falls, are used to lift or lower weldment parts. Always secure the chain hoists over the weldment with an _______________ wrapped around a secure structure. Never hang chain hoists from piping, ducts, conduit, or raceways.

Come-alongs Come-alongs can be used for vertical lifting and pulling at angles.

Plate alignment tools Special tools are manufactured for aligning plate. TYPICAL CONFIGURATION OF AN ALIGNMENT TOOL CONSISTS OF A YOKE, ADJUSTMENT ROD, GAP PLATE, AND ROOT BAR. THE ____________ CAN BE CHANGED TO MATCH THE SPECIFIED ROOT OPENING.

PIPE FIT UP TOOLS Pipe jacks and rollers are used to support pipe for fit up and welding. Jack stands and rollers are necessary tools in the pipeline welding industry.

Chain clamps _________________ are used to align and hold pipe for fit up and tacking. The chain is passed around the pipe and secured, the slack in the chain is then removed using a jack screw to pull the pipe tightly against the clamp. These clamps are ideal for jobs in which 100 percent ________ and _________ is required before the clamp can be released.

Weld distortion Distortion is the expansion and contraction of metal as it responds to changes in temperature. Distortion cant be prevented as long as the metal experiences changes in temps created in the welding process.

Distortion The degree of distortion is directly related to the ____________ generated during welding. Two of the biggest factors in distortion are coefficient of thermal expansion and the specific heat per unit volume. Metals with higher values for these two factors will experience a higher degree of distortion than those with lower values.

Controlling distortion Distortion can be controlled using various tools and techniques. It can also be controlled by using clamps and braces, tack welds, and controlling the amount of weld material. Excess face reinforcement actually reduces the strength of a weld and is therefore _______________ by welding codes.

Joint fit up Proper fit up and edge preparation also reduce the amount of weld required. Open root joints should have a root opening from _____ to ______ wide.

Welding sequence A welding sequence involves placing welds at different points on a weldment so that shrinkage in one area is counteracted by shrinkage in another area. Welding sequences are often performed by two individuals welding on ___________ sides of a joint at the same time. This is known as ___________ welding, which is one of the best ways at controlling distortion.