11 02/18 THRUST BLOCKS: Thrust blocks must be installed wherever the pipeline changes direction or size as at tees, elbows and reducers or at any point that develops thrust such as at a valve or similar equipment. The above situations may occur either where the fittings etc., are directly buried in the soil, or are in a manhole. Thrust blocks must be designed for maximum anticipated operating or test pressure. If it is anticipated that pressures higher than normal operating pressures will be used at some later date, thrust blocks to accommodate such pressures should be installed initially. Size and type of thrust blocks depend on pressure, pipe size, and the type of soil. The Design Engineer shall supply this information. Where a thrust block serves more than one line, the block must be designed to resist the sum of the thrusts of all the lines involved. Thrust blocks should be poured on and against undisturbed soil or soil tamped to 95% proctor density. Thrust blocks shall be installed using a concrete having a compressive strength of not less than 3,000 psi minimum ultimate 28 days compressive strength, air entrained, with water reducing admixture. Where the soil bearing value is less than 1,000 pounds per square foot, Thermal Pipe Systems, Inc. will make the necessary calculations and recommendations as to how the fitting should be thrusted. Where special thrust provisions are needed, Thermal Pipe Systems, Inc. will recommend the necessary design. The table below gives the thrust load at any fitting in lbs. at 100 psi* pressure. Size (in.) 90º Elbow 45º Elbow Tee 1 1/2 415 225 295 2 645 350 455 2 1/2 935 510 660 3 1,395 755 985 4 2,295 1,245 1,620 6 4,950 2,680 3,500 8 8,375 4,540 5,930 10 12,833 6,963 9,076 12 18,000 9,700 12,765 14 21,780 11,790 15,400 16 28,440 15,490 20,110 18 36,000 19,600 25,450 20 44,430 24,195 31,420 24 63,970 34,840 45,240 *For pressure other than 100 psi increase loads proportionately (example: for 150 psi multiply by 1.5; for 200 psi multiply by 2.0: etc.)