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of installation and can also help prevent breaking of the lines or fittings where settling might cause excessive movement. However, due to the inherently flexible char- acteristics of fiberglass pipe from Smith Fiberglass Products, flexible connectors may not be required when connecting to tanks. API publication 1615 states, "FRP piping, which is inherently flexible, can be used to create its own flexible joint if at least 4 feet (1.2 m) of straight run is provided between any directional changes of more than 30 degrees." This statement can be misleading. The flexibility of FRP piping discussed in API 1615 is related to the bending properties. The straight run of pipe must be located in an area that will allow the pipe to bend over a 4 -ft. length. The bending of this "4 feet of straight run" will help pre- vent shear loads in the pipeline and not exceed the allow- able bending stresses if the movement is small (less than 1"). The movement must be perpendicular to the "straight run" so that the bending is similar to the bending of a div- ing board (a cantilever beam). These conditions can exist above tanks where the backfill and/or pipe above the tank will settle or rise with slight movement of the tank. If there is a chance that the pipe will not be free to bend, a commercial flexible hose connector is recommended (see Fig. 1.6.26). Note: The use of swing joints is not recommended. Greater than 30° 4 Ft. Minimum FIGURE 1.6.26 SECTION 6 ♦ Installation smaller gap or no gap. Misalignment is easier to detect if one sights down the line and views the joint from a distance. NOTE: When using heat assist, the pipe may bend if it is under stress while curing. In this case, it is extreme- ly difficult to determine if the pipe is bent because of heating or if it is a cocked joint. Avoid making up pipe and fitting joints when pipe is under stress. Improperly cured joint --If the adhesive bead is soft or flexible, the adhesive is not sufficiently cured. If the bead is cured, it is hard and brittle when checked with a knife. When the bead is not hard after exposure to the recommended temperature and time cycle, the ad- hesive was not mixed properly. In some cases, the sur- face layer of the bead will be white and may actually be tacky and soft on the surface. This is caused by wa- ter absorption on the surface of the adhesive bead. Use a knife to remove a section of the adhesive bead and check the bottom side for the color change (i.e. white color). If the entire bead is white and tacky throughout, then the adhesive was contaminated with water before it was applied to the joint. This will also produce an improperly cured joint. Caution: The ad- hesive bead will cure faster than the adhesive in the joint. It is important that the joint not be pressurized until it has been subjected to the proper time -tempera- ture cure cycle. A temperature vs. time -to -pressure chart is included in the instructions packed with each adhesive kit. Although not all-inclusive, the conditions mentioned above are the most common indications of failure to achieve a properly assembled joint. All damaged or improperly assembled joints must be re- placed. See Section 8. SECTION 7 • TESTING RECOMMENDATIONS READ THIS CAREFULLY 1.6.8 Inspecting for Potential Causes of joint Failure 1.7.1 Safety Precautions Joint backout—When assembling a bell and spigot joint, a bead of adhesive is normally formed at the edge of the bell. If the joint is not locked up, and backs out before the adhesive cures, the bead will no longer be next to the edge of the bell. NOTE: To form a good adhesive bead, it is best to apply an excess of adhesive at the edge of the unmachined surface of the spigot. Excess adhesive in this area forms a good bead at the edge of the bell, but will not hinder joint make- up. 2. Cocked joint -If a joint is cocked or misaligned, there will usually be a large gap between the bell and spigot on one side. The opposite side will usually have a SMITH FIBERGLASS PRODUCTS SHALL NOT BE LIABLE UNDER ANY WARRANTY, CONTRACT, OR IN TORT, FOR ANY RESULTING INJURY TO PERSONNEL OR DAMAGE TO EQUIPMENT, PIPE, OR OTHER PERSONAL PROPERTY FOR FAILURE TO FOLLOW THE PROCEDURES AND COMPLY WITH THE PRECAUTIONS SET FORTH. As in any system where pressure is employed, ade- Aquate safety precautions should be exercised. EXER- CISE DUE CARE IN INSTALLING AND TESTING THE PIPING SYSTEM. DO NOT ASSUME THE RISK OF INJURY OR PROPERTY DAMAGE. RED THREAD IIA Pipe Sr Fittings so 17