3-Intermittent pipe supports should be spaced properly using the design parameters
discussed in the preceding pages. Anywhere unusual loadings or excessive
temperatures are encountered, continuous support should be considered.
discussed in the preceding pages. Anywhere unusual loadings or excessive
temperatures are encountered, continuous support should be considered.
4-Supports that simply cradle the pipe, rather than grip or clamp the pipe, should be
from one half to one pipe diameter in length and should support at least 120 degrees
or one third of the pipe perimeter. All supports should be free from sharp edges.
from one half to one pipe diameter in length and should support at least 120 degrees
or one third of the pipe perimeter. All supports should be free from sharp edges.
5-The supports should have adequate strength to restrain the pipe from lateral or
longitudinal deflection given the anticipated service conditions. If the design allows
free movement during expansion, the sliding supports should provide a guide without
restraint in the direction of movement. If, on the other hand, the support is designed
to grip the pipe firmly, the support must either be mounted flexibly or have adequate
strength to withstand the anticipated stresses.
longitudinal deflection given the anticipated service conditions. If the design allows
free movement during expansion, the sliding supports should provide a guide without
restraint in the direction of movement. If, on the other hand, the support is designed
to grip the pipe firmly, the support must either be mounted flexibly or have adequate
strength to withstand the anticipated stresses.
6-Heavy fittings or flanges should be fully supported and restrained for a minimum
distance of one full pipe diameter on both sides of the PE pipe. This supported fitting
represents a rigid structure within the flexible pipe system and should be fully
isolated from bending stresses associated with beam sag or thermal deflection.
distance of one full pipe diameter on both sides of the PE pipe. This supported fitting
represents a rigid structure within the flexible pipe system and should be fully
isolated from bending stresses associated with beam sag or thermal deflection.
Flange analysis is done based on the Kellogg equivalent pressure method. In addition to internal and external pressure, axial force and bending moment can act on flanges as equivalent pressure. The values of axial force and bending moment are determined from analysis without pressure thrust effect.
These internal forces are used to determine the equivalent design pressure of flange pair by formula
Now enter PN into the ASME B 16.5 pressure-temperature rating table associated with flange material. If PN is less than the allowed pressure on the rating table corresponding to the associated temperature then flange will not leak. If flange leak, then reduce bending moment and axial force acting on the flange or select the greater class flange.
1) This section presents the design methodology to be used when providing thrust restraint for
buried pressurized piping. It includes guidelines for the design of thrust blocking using the
standard details and special design requirements for non-standard thrust blocks and restrained
joint pipe.
buried pressurized piping. It includes guidelines for the design of thrust blocking using the
standard details and special design requirements for non-standard thrust blocks and restrained
joint pipe.
2) For pipe sizes larger than 24-inch, consider the cost of using one of the approved restrained joints or providing concrete thrust blocking to restrain the pipe or fitting. If the cost is approximately equal, design for concrete thrust blocks and if the restrained joints are considerably less expensive, then design for restrained joints unless otherwise directed.
3) In a pressurized buried pipeline such as a water main or sewage force main, thrust forces act on the pipe where changes in fluid velocity, changes in pipe size or changes in pipeline direction occur. This is generally at fittings such as plugs, caps, valves, tees, bends or reducers.