Method of solid phase welding for pipes

Claim 1

A method of solid phase welding adjacent ends of axially aligned pipes, comprising: respectively grasping the pipes only interiorly of said pipes closely adjacent and spaced from said ends with a pair of grasping elements using radial outward pressure substantially uniformly along the circumference of said pipes to cause said pipe ends to assume a circular configuration; maintaining coaxial alignment of the grasping elements to place and hold the pipe ends in axially aligned relationship; thereafter urging said grasped pipe ends into abutting relationship under pressure by urging the elements axially toward each other while maintaining said axial alignment and maintaining substantially the same radial outward grasping pressure; uniformly applying an exterior source of heat simultaneously around the entire periphery of the abutting pipe ends while said radial outward and axial pressures are maintained to heat the abutting pipe ends to an elevated temperature substantially below their fusion temperature; increasing the axial urging of the pipe ends into abutting relationship without increasing the radial outward grasping pressure after the pipe ends have assumed the subfusion welding temperature during heating and before the heat applying step is terminated to solid phase weld the pipe ends together under axial pressure and subfusion temperature only; and maintaining the external surfaces of said pipes adjacent their abutting ends free of clamping pressures during the steps of applying heat and increasing the axial urging.

Claim 2

A method of solid phase welding adjacent ends of axially aligned pipes, comprising: respectively grasping the pipes only interiorly of said pipes closely adjacent and spaced from said ends with a pair of grasping elements using radial outward pressure substantially uniformly along the circumference of said pipes to cause said pipe ends to assume a circular configuration; maintaining coaxial alignment of the grasping elements to place and hold the pipe ends in axially aligned relationship; thereafter urging said grasped pipe ends into abutting relationship under pressure by urging the elements axially toward each other while maintaining said axial alignment and maintaining substantially the same radial outward grasping pressure; uniformly applying an exterior source of heat simultaneously around the entire periphery of the abutting pipe ends while said radial outward and axial pressures are maintained to heat the abutting pipe ends to an elevated temperature substantially below their fusion temperature; increasing the axial urging of the pipe ends into abutting relationship without increasing the radial outward grasping pressure after the pipe ends have assumed the subfusion welding temperature during heating and before the heat applying step is terminated to solid phase weld the pipe ends together under axial pressure and subfusion temperature only; and maintaining the external surfaces of said pipes adjacent their abutting ends free of clamping pressures during the steps of applying heat and increasing the axial urging.