Thrust blocks are used at these locations to prevent damage to the pipe caused by unsupported pipe movement. Abrupt changes in pipeline grade, horizontal alignment, or reduction in pipe size normally require an anchor or thrust blocks to absorb any axial thrust of the pipeline. Thrust blocks pipelines, piping and fluid mechanics. Thrust blocks are required where fittings are used to change the direction i. Highperformance bearing solutions timken provides a variety of highperformance bearing. Bends, reducers, plugs, and the opposite side of tee branches all require thrust blocks. This is accomplished by transferring the unbalanced force generated by changes in direction and changes in diameter to soil bearing and frictional resistance.
The design involves consideration of undisturbed soil, soil bearing strength, test pressure, pipe size, fitting configuration, and trench depth to determine the bearing area of the thrust block. It is then a matter for the installer to form up and pour the proper block. Using the tables on the following page you can calculate the size of the thrust block for various pipe sizes. The size of the thrust block is determined by the working pressure, the. Tees, bends, plugs, hydrants, and other appurtenances and fittings require thrust. In efect, the thrust block transfers the load from the pipe to a wider load bearing surface. The thrust block should be designed knowing the intensity of the thrusts developed in the pipe and the load bearing strength of the soil. Thrust restraint in pvc piping systems when using any gasketed pressure piping system, proper thrust restraint at valves and fittings is extremely important to the long term performance of the installation. Thrust block design and rodding detail chesterfield. These parameters are pipe size, pipe type, test pressure, fitting type, trench type, depth of bury, soil type, and safety factor. The figure below the tables indicates methods required to calculate the thrust block area. This program is based on the equations and procedures found in the dipra brochure thrust restraint design for ductile iron pipe. The standard line of timken splitblock housings is constructed of cast iron and designed to protect bearings.
Guide to the design of thrust blocks for buried pressure. The table below lists the thrust force in newtons for an internal pressure of 690 kpa for various pipe sizes and fittings. The parameters involved in the design include pipe size, design pressure, angle of the bend or configuration of the fitting involved, and the horizontal bearing strength of the soil. Abrupt changes in pipeline grade, horizontal alignment, or reduction in pipe size normally require anchors or thrust blocks to absorb any axial thrust of the pipeline. Thrust blocks allow a narrow point force to be spread and distributed across larger areas of soil down to a pressure that the soil can bear. In design of thrust blocks, nfpa 2402 calls out the thrust equation under figure a. Determining size and type of thrust blocking size and type of the thrust block depends on maximum pressure, pipe size, kinds of soil and types of fittings. The design of a restrained piping system is both simple and proven. Our thrust block calculator can be helpful in sizing these blocks. Standard sewer detail drawings s1 standard bedding for rcp. In this manner, the pipeline itself acts as a thrust block. Types of thrust blocks bearing gravity bearing thrust block bearing area ft 2 safety factor thrust force lbs bearing capacity of undisturbed soil lbsft2 undisturbed soil bearing area 45 45 soil bearing strength sb soil sb lbft2 muck 0 soft clay 1,000 silt 1,500 sandy silt 3,000 sand 4,000 sandy clay 6,000 hard clay 9,000 bearing thrust block ht h. Thrust blocks take the point force created from the change in direction of the water static and dynamic and distribute that force to the soil. Thrust restraint can be accomplished by using properly sized thrust blocks 1.
Thrust restraint design of dead ends, valves, reducers and. Thrust restraint design for ductile iron pipe seventh edition dipra. Lbs thrust feet cross referencing the thrust with nfpa or 24s table shows discrepancy. Code to add this calci to your website just copy and paste the below code to your webpage where you want to display this calculator.
Pvc c905 largediameter transmission pipe waterworks products. Thrust block design calculator solving for area of thrust block required given thrust force and allowable soil bearing pressure. The size of the thrust block is determined by the working pressure, the size and type of fitting, and the soil conditions at the job site. Size and type of the thrust block depends on maximum pressure, pipe size, kinds of soil and types of fittings. Thrust forces, 161 hydrostatic thrust, 161 thrust resistance, 163 thrust blocks, 163 thrust restraint with welded or harnessed joints for pa horizontal thrust, 165 gasketed joints with small deflections, 166 thrust restraint with welded or harnessed joints for horizontal bends, 168 small vertical deflections with joints free to rotate, 170. Therefore, different scenarios for block dimension, soil density, pipe diameter and internal pressure are used to gained factor of safety to reach. Thrust control may also be needed at the end of the pipeline and at inline control valves. Design of thrust blocks consists of determining the appropriate bearing area of the block for a particular set of conditions. The guidance given in this report is principally for thrusts up to kn, limiting both the pressure range and pipe diameters and, more importantly, the thrust block sizes. Dimensions may be varied as required by field conditions where and as directed by the. The standard length of hdpe pipe is 50 feet, in sizes above 2 in diameter with. Sizing calculations of thrust blocks free download as excel spreadsheet. Well, the cool kids dont use thrust blocks anymore, thats for sure, unfortunately, here in central california, most engineers i know and many clients i have worked for insist on thrust blocks on their water mains. Snt metric plummer blocks and the saf inch pillow block line which include a wide range of sizes, housing designs, seals and accessories.
The next table lists the approximate soil bearing strengths. Also, nobody uses thrust blocks anymore, they use restrained joints. Get ebooks guide to the design of thrust blocks for buried pressure pipelines on pdf, epub, tuebl, mobi and audiobook for free. It includes guidelines for the design of thrust blocking using the standard details and special design requirements for nonstandard thrust blocks and restrained joint pipe. S40 oil and grease trap sizing s40a oil and water separator. Thrust blocks and restraints details boston water and sewer. T ru f where r, is the ultimate ground resistance, and f is the force applied to the thrust block. The use of portland cement concrete thrust blocks is not permissible except as shown on the plans or. Concrete thrust blocks if concrete thrust blocks are used, the size and type of thrust blocking must be based on the loadbearing capacity of the soil, pressure in the. A process for preliminary sizing proposed by loftin 1980 is shown in fig. Thrust blocks should be shown on the water main system plans and a cautionary note about digging in the area should be on the drawing. Provide poured concrete thrust blocks at all changes in size or direction. Thrustblock excel spreadsheet calculators engineers edge.
Thrust blocks and anchors must be large enough to withstand the forces tending to move the pipe, including those of momentum and pressure as well as forces due to expansion and contraction. This research investigate the economical dimensions that can be used against the. The positioning of the thrust blocks must consider whether connections adjacent to the thrust block are capable of movement, as well as the anticipated. Thrust blocking prevents main line from moving when the pressure load is applied. Always update books hourly, if not looking, search in the book search column. If thrusts due to high pressure are expected, anchor the valves as shown below. Their reliability may be compromised if future digging occurs near the thrust block. This book gives guidance on how to design blocks to restrain the forces from flow change in buried pressure pipelines. The size of the thrust block depends on the water pressure in th epipe, size of the pipe, type of fitting, and soil bearing strength. Hdpe pipe is corrosion and chemical resistant hdpe pipe will not corrode, tuberculate or. Conservative assumptions, along with an explicit safety factor, have been employed to assure a conservative design with an adequate overall safety factor.
Calculate thrust block size to resist downward forces at upturn bends. If thrusts due to high pressure are expected, anchor. Thrust block unless mechanically restrained, thrust blocks serve as a way to distribute the hydraulic force of the pipe network into the soil. In order to properly size thrust blocks or other devices to hold a pipe in place, the momentum equation is used to compute the necessary resistive force to hold the pipe stationary. Guide to the design of thrust blocks for buried pressure pipes. T2 pa sin q2 calculated volume calculated width required area t thrust. Thrust block forces on pipe bends anchor due to liquid velocity and internal pressure online resulting force calculator sponsored links in a piping structure without adequately support fluid flow velocities and internal pressures may create intolerable forces and tensions.
The table is conservative, giving thrust for two different types of pipe. There are more than 1 million books that have been enjoyed by people from all over the world. These are thrust bearings using tapered rollers, and the single type bearings have three types of housing washers. It provides a background knowledge to the underlying principles and theory involved with designing thrust blocks for buried pipelines. Thrust blocks take the point force created from the change in direction of the water static and dynamic. The sizing of thrust block for the horizontal component is calculated by the same formula used for horizontal bends, except the term t is replaced by t x 2pa sin 02 cos 0.