Pipeline retard, support and protection method

A method for forming at least one foam retard transecting the void in a trench between a pipeline and the trench surface and for an incremental width distance in the void along the length of the pipeline, the retard serving to inhibit water from percolating longitudinally through an earthen backfill in the trench, the retard being fabricated in situ in the absence of forms and from a plurality of layers of a fast-setting, expandable, organic foam material wherein discrete cells in each foam layer are elongated along an axis generally perpendicular to the layer so as to impart a degree of lateral flexibility to the retard while maintaining the transverse compressive strength of the layer, comprising the steps of:

• excavating a trench for a pipeline;
• placing the pipeline in the trench in spaced relationship to the trench surfaces according to conventional techniques thereby forming a void between the pipeline and the trench surfaces;
• and
• forming the foam retard in the trench, comprising the steps of:
• obtaining the components for a fast-setting, expandable, organic foam material;
• separately conducting the components under pressure to a mixing chamber of a pressurized spray apparatus;
• rapidly mixing the components in the mixing chamber of the pressurized spray apparatus;
• spraying a layer of the mixed components into an incremental length of the void between pipeline and the trench, said incremental length corresponding to the width of the retard, the foam expanding and stiffening to form a layer of rigid foam;
• permitting an integral skin to form on each layer;
• and
• repeating the spraying and permitting successive layers on each previous layer until the foam retard structure has been fabricated.

A method for forming a retard for a pipeline in a trench, the trench having a width to accommodate a pipeline, the retard having a discrete thickness along the length of the axis of the pipeline, the retard also having a greater degree of flexibility in a lateral direction and a lesser degree of flexibility vertically, comprising the steps of:

• mixing the components of a fast-setting, expandable, organic foam in a mixing chamber of a spray apparatus, the components being introduced into the mixing chamber under an elevated pressure;
• expelling the mixed components as a spray from the spray apparatus;
• directing the spray of mixed components into a discrete length of the void between the pipeline and the trench until a layer of foam is obtained, the discrete length corresponding to the width of the layer, the foam layer expanding and setting during accretion;
• permitting the cells in each layer of foam to become elongated generally perpendicularly to the plane of the layer to impart a degree of vertical strength and a degree of lateral flexibility to the retard;
• permitting an integral skin to form on the layer;
• and
• building a retard by suitably repeating the directing and forming steps until a retard has been created in situ in the trench.

A method for supporting a pipeline above the bottom of a trench comprising the steps of:

• excavating a trench;
• obtaining the ingredients for a expandable, fast-setting, organic spray foam material;
• rapidly mixing the ingredients to form a foam material and expelling the foam material from a spray apparatus as a spray of foam material;
• building a plurality of support pads in the trench, each support pad spaced a discrete distance from the other, each support pad being formed by directing the spray into the bottom of the trench at spaced locations to form at least one layer of foam material as a band having a length transecting the bottom of the trench and a width corresponding to an incremental distance along the axis of the trench;
• allowing the foam material of the layer to rapidly expand into an expanded layer having vertically elongated cells;
• developing an integral skin on the surface of each layer before spraying a succeeding layer on the previous layer;
• and
• placing the pipeline in the trench on the support pads, the support pads supporting the pipeline above the bottom surface of the trench.

A method for protecting a pipeline in a trench comprising the steps of:

• excavating a trench;
• obtaining the ingredients for an expandable, fast-setting, organic spray foam material;
• transferring the foam ingredients to a foam spray apparatus;
• mixing and spraying the foam ingredients from the spray apparatus;
• directing the spray into a trench and forming a first layer of organic foam material in the trench;
• allowing the foam material to expand and at least partially cure;
• forming at least a second layer of foam on the first layer to build a support pad for the pipeline, the support pad having a length transecting the width of the bottom of the trench and having a width which is an incremental distance of the longitudinal axis of the trench;
• building a plurality of support pads at spaced locations in the trench with each support pad separated a discrete distance from the other by repeating the directing, allowing, and forming steps at said spaced locations along the trench;
• lowering the pipeline in the trench onto the support pads, the support pads supporting the pipeline above the bottom of the trench;
• fabricating a plurality of retards in the trench to impede the longitudinal percolation of water through an earthen backfill in the trench, each retard filling a discrete increment of the length of the void in the trench between the pipeline and the trench surface, each retard being prepared by spraying a plurality of layers of foam material into the trench while permitting each layer to at least partially cure thereby building each retard in situ in the trench in the absence of forming structures;
• and
• backfilling the remaining void between spaced retards in the trench with earth, each retard thereby being separated from each adjacent retard by an earthen backfill each retard thereby serving to inhibit water from percolating longitudinally through the earthen backfill along the length of the pipeline.

A method for inhibiting erosion of earthen backfill from around a pipeline in a trench wherein the pipeline has been previously assembled adjacent a trench excavated in a right of way according to conventional pipeline construction techniques, the method comprising the steps of:

• obtaining the ingredients for an expandable, fast-setting, organic spray foam material;
• delivering the ingredients to a mixing chamber of a spray apparatus;
• mixing the ingredients while expelling the mixed ingredients from the spray apparatus as a spray of organic foam material;
• building a plurality of support pads at spaced locations in the trench, each support pad having a length substantially corresponding to the width of the bottom of the trench and a width corresponding to an incremental distance of the longitudinal axis of the trench comprising the steps of:
• directing the spray into the trench at each location to form at least one layer of foam material transecting the bottom surface of the trench, the foam material in each layer rapidly expanding while forming generally elongated cells essentially perpendicular to the plane of each foam layer;
• and
• permitting an integral skin to form on the top surface of each layer by pausing momentarily before directing the spray thereon to form a next succeeding layer;
• placing the pipeline in the trench on the support pads, the vertically elongated cellular structure and membrane surfaces in the support pads imparting increased vertical strength to the support pads, the support pads supporting the pipeline above the bottom surface of the trench;
• retarding the erosion of backfill from around the pipeline in the trench by forming a plurality of spaced retards in situ in the trench, each retard having a width along the length of the pipeline an incremental length of the pipeline, forming each retard in situ comprising the steps of:
• directing the spray into the void between the pipeline and the trench surface thereby forming a layer of foam material, the foam material rapidly expanding while forming a cellular structure having cells elongated generally perpendicularly to the layer;
• permitting an integral skin to form on the outer surface of the layer by pausing momentarily before directing the spray thereon to form a next succeeding layer;
• and
• repeating the directing and skin forming steps until the retard has been formed in situ in the trench in the absence of form structures, the retard transecting the void in the trench between the pipeline and the trench between the pipeline and the trench surfaces and filling the transected portion of the trench to an incremental distance below the grade of the right of way for the trench;
• and
• separating each retard from an adjacent retard by backfilling the trench, the retards inhibiting the percolation of water through the backfill longitudinally along the trench.