workmanship standards
EVALUATION CRITERIA FOR PIPING PROJECTS
The following criteria will be applied to all projects in the Pipe Fabrication Concentration.
Deductions for field fabricated fittings:
Patterns and drawings:
Deductions will result from variations of parallel lines, line termination, inside and outside diameter measurements, and satisfy criteria listed on assignment sheet. Deduction values will be one point per defect on pattern drawings. Tolerances of plus/minus 0” will be imposed on patterns.
Fittings and pipe runs:
Deductions of plus/minus 1/16” will be imposed on fitting. Deduction values will be one point per defect within tolerances and one additional point for every 1/16” over tolerance.
Deduction values will be one point per defect for tacking standards. A five-point deduction will be imposed for each arc strike. Arc strikes can be repaired with a file to show that you acknowledge the arc strike. This in not an acceptable repair in reality, but will show that you are aware it occurred.
Root openings in all connecting pipe joints must be a minimum of 1/16” and a maximum of 1/8” in each quadrant. A 1-point deduction will be imposed for the fit-up configuration outside of these parameters.
Example: if the fit-up shows the two pipe ends comprising the joint are touching in all four quadrants, it will be considered a 4-point deduction.
A tolerance of plus/minus 1o will be allowed for intersecting branches. A one point deduction will be imposed for every 1o over or under the assigned angle.
Pipe ends will be checked for square cuts. A tolerance of plus/minus 1/16” will be applied in each quadrant of each prepared pipe end. Pipe ends will also be evaluated for chamfered edges. One point deductions will result from inconsistence in chamfer angle, gouges, serrations, or omission of chamfer at any point on the pipe edge surface.
All inside and outside diameters must be free of any burrs, jagged edges, or slag. The resulting penalty will score your project as 40.
Deductions for pipe runs:
Deductions will result from evaluating runs at each joint. All tacking standards will apply. A one point deduction will result from failure to comply with tacking standards.
Deductions will result for pipe runs that are not level. If the bubble on the level touches the line, there will be no deduction. If the bubble is beyond the line 1/4 bubble, a one point deduction will be imposed. If the bubble is beyond the line 1/2 bubble, a 2 point deduction will be imposed. If the bubble is beyond the line 1 bubble or more, a five point deduction will be imposed.
Pipe hangers will be evaluated. Deductions will result as one point each for loose nuts, improperly configured hardware and improper attachment to support structure.
Five Point Deductions:
Welding smoke, slag, and arc strikes will all be deducted at a value of five points per occurrence. The reason for this high point value is because it is the easiest thing to address and correct.
All tacks must have slag removed and be feathered to tacking standards. Brushing tack welds in mandatory.
All welding smoke must be removed from projects. Brush ALL smoke from joints to remove risk of deductions.
Arc strikes are critical in some applications because each one creates a point of stress by changing the material characteristics of the metal and can cause a failure. Complicated procedures for making repairs might include replacement of the pipe joint in some specialized applications. To acknowledge that we recognize the seriousness of an arc strike in a system, a file can be used to superficially repair the strike. When students follow this procedure, no points will be deducted. Always be sure to know the job specifications so you’ll know how to deal with arc strikes in piping systems.