Push-type coupling and conduit pipe assembly

A push-type coupling:

• a. said coupling, when viewed in transverse cross-section, defining a closed, convexly rounded figure with length to D ratio in the range of about 1 to about 2 and a wall thickness in the range of about 0.015 D to about 0.035 D, wherein D is the diameter in inches of the pipe for which the coupling is intended;
• b. said coupling having
• 1. an inner surface having a coefficient of friction, relative to the material of said pipe, of at least about 0.7,
• 2. a column expansibility in the range of about 2 .times. 10.sup..sup.-4 to about 20 .times. 10.sup..sup.-4 inches per pound,
• 3. a pull-out resistance of at least about 100 D pounds, and
• 4. a bending resistance of at least about 6,000 inch pounds;
• c. said coupling including a fiber-reinforced elastomer composite containing sufficient quantities of fiber and elastomer for providing the above-indicated column expansibility and pull-out resistance,
• 1. said composite including a liner layer of elastomeric material of substantially lower modulus than said fiber,
• 2. said fiber having a modulus of at least about 6 .times. 10.sup.6 psi, oriented around and bonded to said liner layer in an opposed, balanced helical pattern at a helix angle .theta. in the range of about 55.degree. to about 75.degree., measured from a reference line parallel to the coupling axis, which angle is substantially uniform throughout the length of the coupling in any given layer of said fiber, and
• 3. said elastomer being a binder of substantially lower modulus than said fiber having a modulus of at least about 50 psi at 100% elongation and at least about 100 psi at 300% elongation, a tensile strength of at least about 600 psi, and a Shore A durometer hardness in the range of about 15 to about 70, for mechanically interconnecting the opposed fiber pattern or patterns at the above-indicated helix angle, said binder being present in a weight percentage in the range of about 40 to about 60 percent, based on the total weight of fiber and binder,
• whereby said coupling will enlarge to receive the end of a rigid pipe which is pushed into it and generate pull-out resistance which is in response to and in proportion to pull-out force and which is substantially in excess of that which would be provided by the mere hoop-stress elasticity of the elastomeric material.

A pipe having a push-type coupling, comprising

• I. a flexible sleeve coupling,
• a. said coupling, when viewed in transverse cross-section, defining a closed, convexly rounded figure with a length to D ratio in the range of about 1/2 to about 2 and a wall thickness in the range of about 0.006 D to about 0.09 D, wherein D is the diameter in inches of the pipe for which the coupling is intended;
• b. said coupling having
• 1. an inner surface having a coefficient of friction, relative to the material of said pipe, of at least about 0.7,
• 2. a column expansibility of at least 1 .times. 10.sup..sup.-4 inches per pound, and
• 3. a pull-out resistance of at least about 100 D pounds;
• c. said coupling including a fiber-reinforced elastomer composite containing sufficient quantities of fiber and elastomer for providing the above-indicated column expansibility and pull-out resistance,
• 1. said fiber having a modulus of at least about 6 .times. 10.sup.6 psi, oriented and bonded in said elastomer in an opposed, balanced helical pattern or patterns at a helix angle .theta. in the range of about 45.degree. to about 75.degree. measured from a reference line parallel to the coupling axis, which angle is substantially uniform throughout the length of the coupling in any given layer of said fiber, and
• 2. said elastomer being a binder of substantially lower modulus than said fiber having a modulus of at least about 25 psi at 100% elongation and at least about 50 psi at 300% elongation, a tensile strength of at least about 300 psi, and a Shore A durometer hardness in the range of about 15 to about 90, for mechanically interconnecting the opposed fiber pattern or patterns at the above-indicated helix angle,
• Ii. a pipe section to which said flexible sleeve is connected in partially overlapping telescoping relationship whereby a free portion of said coupling extends free of said pipe section:
• A. said pipe section, when viewed in transverse cross-section, defining a closed, convexly rounded figure,
• B. said pipe section having sufficient circumferential rigidity so that its circumference will not change more than about 1% on application of 100 pounds per square inch radial pressure thereto, and
• C. said pipe section also having a circumference greater than the inside circumference of the coupling in the range of up to about 2%, to provide an interference fit with said coupling,
• whereby said coupling will enlarge to receive the end of a rigid pipe which is pushed into it and generate pull-out resistance which is in response to and in proportion to pull-out force and which is substantially in excess of that which would be provided by the mere hoop-stress elasticity of the elastomeric material.

A pipe having a push-type coupling, comprising

• I. a flexible sleeve coupling
• a. said coupling, when viewed in transverse cross-section, defining a closed, convexly rounded figure with a length to D ratio in the range of about 1 to about 2 and a wall thickness in the range of about 0.015 D to about 0.035 D, wherein D is the diameter in inches of the pipe for which the coupling is intended;
• b. said coupling having
• 1. an inner surface having a coefficient of friction, relative to the material of said pipe, of at least about 0.7,
• 2. a column expansibility in the range of about 2 .times. 10.sup.-.sup.4 to about 20 .times. 10.sup.-.sup.4 inches per pound,
• 3. a pull-out resistance of at least about 100 D pounds, and
• 4. a bending resistance of at least about 6,000 inch pounds;
• c. said coupling including a fiber-reinforced elastomer composite containing sufficient quantities of fiber and elastomer for providing the above-indicated column expansibility and pull-out resistance,
• 1. said composite including a liner layer of elastomeric material of substantially lower modulus than said fiber,
• 2. said fiber having a modulus of at least about 6 .times. 10.sup.6 psi, oriented around and bonded to said liner layer in an opposed, balanced helical pattern at a helix angle .theta. in the range of about 55.degree. to about 75.degree. measured from a reference line parallel to the coupling axis, which angle is substantially uniform throughout the length of the coupling in any given layer of said fiber, and
• 3. said elastomer being a binder of substantially lower modulus than said fiber having a modulus of at least about 50 psi at 100% elongation and at least about 100 psi at 300% elongation, a tensile strength of at least about 600 psi, and a Shore A durometer hardness in the range of about 15 to about 70 for mechanically interconnecting the opposed fiber pattern or patterns at the above-indicated helix angle, said binder being present in a weight percentage in the range of about 40 to about 60 percent, based on the total weight of fiber and binder,
• Ii. a pipe section to which said flexible sleeve is connected in partially overlapping telescoping relationship whereby a free portion of said coupling extends free of said pipe section:
• A. said pipe section, when viewed in transverse cross-section, defining a closed, convexly rounded figure,
• B. said pipe section having sufficient circumferential rigidity so that its circumference will not change more than about 1% on application of 100 pounds per square inch radial pressure thereto, and
• C. said pipe section also having a circumference greater than the inside circumference of the coupling in the range of up to about 2%, to provide an interference fit with said coupling
• whereby said coupling will enlarge to receive the end of a rigid pipe which is pushed into it and generate pull-out resistance which is in response to and in proportion to pull-out force and which is substantially in excess of that which would be provided by the mere hoop-stress elasticity of the elastomeric material.