<p>The present invention relates to a pipe coupling comprising a pair of half members which have a half-ring shape on x-y plane and a thickness along z axis, wherein the half member includes a first end on which a circumferential groove is disposed, the circumferential groove comprising a first groove surface and a second groove surface which are inclined over the x-y plane; and a second end on which a is disposed, the circumferential protrusion comprising a first protrusion surface and a second protrusion surface which are inclined over the x-y plane, wherein the first groove surface and the second groove surface are inclined over the x-y plane in the same angle and direction as the first protrusion surface and the second protrusion surface.</p>
