Abstract: A gas-tight joint for pipe linings and risers inside a bore, consisting of a neck with an outside thread and of a matching collar with an inside thread, with a groove in the vicinity of the thread on the collar and/or of the thread on the neck to accommodate a deformable gasket that, when the joint is screwed tight, is demarcated and deformed by the base of the groove in the neck and/or in the collar and by the contour of the thread on the other component. The cross-sectional area demarcated by the base of the groove in the neck and/or collar and by the contour of the thread on the other component once the two components have been screwed together remains constant along the groove and is equal to or larger than the cross-sectional area of the deformable gasket before the components are screwed together.

Abstract: A method for production of a multi-layer gap-less steel pipe. An inner pipe and an outer pipe are formed from thermomechanically rolled steel strip with high notched bar impact strength by welding. The individual helical welding seam steel pipes of about the same lengths are matched with a difference of less than about one percent between the outer diameter of the inner pipe and the inner diameter of the outer pipe. The matched inner pipe is inserted into the outer pipe and the pipes are mechanically expanded with diameter control to a preset outer diameter of the multi-layer steel pipe. The resulting multi-layer steel pipe has the inner pipe disposed under compression and the outer pipe layer disposed under stress. The presence of a compression stress in the inner pipe provides a means opposed to hydrogen sulfide stress corrosion.

Abstract: For increasing the resistance of steel pipes or tubes against acidic medium, by a combination of a heat treatment and the use of an alloyed steel, a compressure stress is built up on the side of the tubes or pipes facing the acidic medium, of up to 30% of the yield limit.

Abstract: A method for production of a multi-layer gap-less steel pipe. An inner pipe and an outer pipe are formed from thermomechanically rolled steel strip with high notched bar impact strength by welding. The individual helical welding seam steel pipes of about the same lengths are matched with a difference of less than about one percent between the outer diameter of the inner pipe and the inner diameter of the outer pipe. The matched inner pipe is inserted into the outer pipe and the pipes are mechanically expanded with diameter control to a preset outer diameter of the multi-layer steel pipe. The resulting multi-layer steel pipe has the inner pipe disposed under compression and the outer pipe layer disposed under stress. The presence of a compression stress in the inner pipe provides a means opposed to hydrogen sulfide stress corrosion.