Quality Control

A walk through is performed every 30 minutes and QC tests are performed every 200 joints on a run of continuous size or with every change in order, wall thickness, or diameter. 

Cathotic Disbondment Test (CDT)
A 4" by 4" plate from each sample is used to test the coating for resistance to disbonding under electrical stress at elevated temperature. A 3% NaCl (salt water) solution and a potential of 3.5 DC volts (reference calomel electrode) is impressed through a 1/8” drilled holiday. Electrolyte solution temperature is maintained at 150°F for 24 hours. After the test period, radial cuts are made through the coating at a point 45° from the edge of the holiday. The radius of disbondment is measured by inserting the knife point under the coating to "flick" the coating until a definite resistance to this levering action can be noted.  The distance from the holidays center to the edge of the flaking will be measured and must be under 10 by NACE standards (we avg 2.5mm).
Moisture Permeation Test
One 4" by 4" plate from each sample is used to evaluate coating resistance to moisture permeation. Tap water maintained at 150°F for 24 hours is the solution. Certain specifications require higher temperatures and/or durations. After the test cycle, a 1"x1.5" rectangle is scribed through the coating (like tic tac toe). Evaluation is performed by testing the adhesion of the coating to the substrate. The procedure used is the same as with the CDT Test.
Bend Test
Three 1” x 8" straps are cut from each test sample and cooled to 32°F to test coating flexibility at low temperatures. This test is performed within 30 seconds of removal from the cooling unit and the sample is bent to the point of failure.  Evaluations of samples are performed using charts of known radius.  Passing standards according to NACE are 2.5° for FBE and 1.5° for ARO.
Interfacial Contamination
One 1”x 8" strap is bent sharply at low temperature to remove coating chips. The chips are examined under a microscope to determine contamination levels.  The contamination present at the coating's interfacial layer is evaluated and rated using a solution of copper-sulfate. The copper-sulfate will turn steel present on the coating chip a copper color. Oxides will have a black contrast.  Passing standards according to NACE are 30% (We are normally at 10%).
Cross Section Porosity Test
Using the same 1" by 8" strap that was used for interfacial contamination, a 1”x1/8” rectangular piece is removed for the cross section porosity test.  The foam present at the interface and cross-section is determined and rated against known standards such as NACE RPO394-94. The scale is 1 to 5, with 5 being 100 percent foam.   A score of 4 or 5 is failing according to NACE (We are around 2).
DSC Test
The DSC test is used to prove cure of the FBE.  The manufacturer of the FBE can supply this from their QC sample or a coated sample may be test to ensure glass transition.