MIL-STD-2199A
5.3.4.1.3 Fillers. Resin flow from the freshly applied GRP shall be minimized or eliminated by assuring the proper resin viscosity. Resin viscosity can be increased by the addition of a thixotropic filler material (see 5.2.1). The addition of thixotropic filler is typically required for shafts that are stationary during application of the GRP to keep the resin from dripping off of the GRP tape during both application and cure. The amount of filler added to the resin shall be determined based upon prior experience, trial, or the recommendation of the resin manufacturer. Particular care shall be taken to avoid beating air into the resin while mixing in the thixotropic filler. The addition
of the filler may obscure visual inspection for voids and trapped air. Fillers shall not be used on shafts which are rotated during application and cure.
5.3.4.2 Fiberglass tape. The length of fiberglass tape shall be calculated using the following equation:
3.5 x D x H
L=
W
L = Length of tape required for each ply (feet) D = Diameter of the shaft (inches)
H = Length of the section of straight run of shaft to be covered (feet)
W = Width of the fiberglass tape (inches)
NOTE: The factor 3.5 in the above equation is used instead of the extract factor (n = 3.14) to allow for some excess tape and some overwrap at terminations.
5.3.4.2.1 Example of calculation for fiberglass tape. Calculate the length of 6-inch wide glass tape required for each ply of a GRP for a 10-foot long section of shafting measuring 7 inches in diameter.
D = 7 inches
H = 10 feet
W = 6 inches
3.5 x D x H L= W
= 3.5ξ 7in ξ10 ft
6in
= 40.83 ft
The total length of tape required for the four plies is equal to four times the length of a single ply as calculated above.
5.3.4.2.2 Preparation of fiberglass tape. Determine the amount of tape on each roll furnished to be sure there is sufficient material for accomplishing the task. If the mass of the tape is used to determine the amount of resin required (see 5.3.4.1.1), determine the total weight of the GRP tape required to apply four layers of tape to the shaft.
NOTE: Care shall be taken to keep the tape free of dirt, dust and other contaminants. Tape that has been exposed to water, solvents, and lubricants is not useable and shall be discarded. The glass tape shall remain wrapped in plastic until such time that it is used.
5.4 Safety precautions.
5.4.1 General. Caution shall be observed when handling any chemicals or solvents. The application of the GRP shaft covering is no exception. When applying the covering, the following general precautions shall be observed:
a. The working area shall be properly and adequately ventilated to draw fumes away from the worker. b. Avoid direct contact with the solvents, resins, and associated hardeners and catalysts.
c. Keep chemical containers clearly labeled, tightly covered when not in use, and stored in a cool, dry area. d. Do not work near hot surfaces or open flames. Do not smoke on the job or when handling chemicals.
e. Review the manufacturer's MSDS for the specific resin system to be used.
f. For further guidance on related safety procedures and equipment, refer to S9086-VD-STM-010/631.
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