INTRODUCTION
In order to obtain the maximum benefit and service from fiberglass reinforced plastic (FRP) equipment, it is essential that the equipment be designed, fabricated, and installed correctly. Properly scheduled inspections of FRP equipment ensure the fabrication of a quality product and one that gives satisfactory service life. This paper suggests when to inspect FRP equipment, describes inspection procedures, and gives examples of common FRP defects that can occur. Some continuous monitoring techniques will also be discussed. The information should be beneficial in developing process safety management programs for FRP equipment.
There are generally six occasions when FRP equipment should be inspected, I) during fabrication, 2) when fabrication is completed, 3) when finished equipment is received, 4) when finished equipment is installed, ready for service, 5) after a specified period of use, and 6) when changing service. Proper inspection procedures and knowing what defects to look for greatly aid in obtaining a quality FRP product and ensures that it provides satisfactory service life. This paper describes a number of laminate flaws that can arise in new and in-service FRP composites and how to inspect for these flaws. A number of other quality related tests and considerations are discussed. In addition, some continuous monitoring methods are discussed.
Inspection During Fabrication
General. Many companies have written inspection guidelines which provide for an in-progress inspection upon completion of laminates or when any assembly is made. An efficient approach is to make each piece of laminate equipment just prior to the inspection: the equipment should be completely finished except for the final color coat. This includes allowing sufficient time for final resin work to reach required hardness and insuring that the specified resin has been used in the manner prescribed by the resin manufacturer.
In any case, all shop fabricated FRP components should be inspected prior to shipment. All mold release sheets, dust or coatings, that restrict visual laminate inspection must be removed. Also, at this time, inspection for compliance of overall dimensions and orientation of nozzles should be performed. The final inspection and acceptance of equipment should typically be made upon delivery at the plant site.
Inspection Tools. Listed below are some suggested personal inspection tools for use in evaluating fiberglass reinforced plastic equipment.
a. Magnifying glass
b. Small bottle of acetone
c. Flash light
d. Cotton balls
e. Small dental pick or pocket knife
f. Thickness gauge
g. Barcol hardness impressor 934-1(1) - for resin hardness values
Safety procedures and equipment used during inspection should conform to individual plant requirements.
Resin cure is a primary concern of any inspection of new FRP equipment. Resin hardness values should be obtained on both the inside and outside surface of the equipment and meet minimum resin hardness values specified. Critical measurement points are secondary bonds, such as flanges and internal connections. Hardness tests are made by taking 12 readings, rejecting the high and low readings, and averaging the remaining ten. The acetone cure test may be used in conjunction with the resin hardness test.
