Application of Plastic Patches

Figure 2-24.—Resin temperature vs kick-over time. Application of Plastic Patches In the following discussion on applying different types of plastic patches (simple, elbow, severed, and others) you can readily see that as the individual patch materials are applied, the patch becomes progressively wider. The sketch in figure 2-25 shows the relative positions of the patch materials to one another. The buildup in the patch length during application must be considered in initially determining the length of the patch to be applied. Where suitable, allow the patch to extend at least 4 to 5 inches on either side of the rupture. In addition to the size of the rupture, the width of the patch also may depend upon the location of the rupture in the pipe system. For example, an elbow rupture may require a patch of greater width than the same size rupture would require in a straight section of pipe. Complete application instructions are in- cluded in each kit. Figure 2-25.—Sequence of applied patch materials. PREPARATION.— Before you actually apply the plastic patch, you must make the following prepa- rations: 1. Secure or isolate the ruptured area in the piping system. 2. Remove all lagging. 3. Clean the area around the rupture and remove all grease, oil, dirt, paint, and other foreign matter. If grease or oil is present, use an approved solvent to clean around the rupture. If no approved solvent is available, scrape and wipe the surface until it is clean. When a clean surface is obtained, the surface may be further abraded for better adhesion. An abrasive cloth is fur- nished with the kit. 4. Ensure that all moisture and fuel are removed from the inside of the piping and the entire pipe surface is dry. 5. Where practical, the rupture should be simpli- fied by bending or removing irregular projections. This may be done by cutting or burring. CAUTION Ensure no explosive conditions exist be- fore you use spark-producing tools or burring equipment. 6. Determine the amount of materials required, such as the amount of woven roving cloth as well as the 2-17