Abstract: A method of making tubing and pipes for conduction in the oil and gas industry or for use as drillpipes, wherein such tubing is connected at both ends with connector sleeves by means of welding, the welding seam being deburred thereafter. The steel used for the tubing, pipes or drill pipes as well as for the connector sleeves has the following composition, all percentages by weight, between 0.2 and 0.6% carbon, between 0.5 and 1.8% manganese, between 0.5 and 3.5% combined chromium and molybdenum, not more than 0.2% phosphorus and not more than 0.005% sulphur.

Abstract: Hot pipes are tempered in an oil bath contained in a tapered, covered pan; a flap is temporarily opened for feeding, but closed when oil vapor develops, to be sucked off without contaminating the environment. Pan and cover structure are supplemented to prevent uncontrolled escape of vapor during treatment. Different handling devices for pipes in the interior of the pan are described.

Abstract: A box member and a pin member each have a tapered thread, an abutment end face and a shoulder for engagement respectively with shoulder and end face of the other member, one coacting surface pair being conical, the other one being planar. Shoulder and end face are spaced differently in the two members such that upon engagement of a conical shoulder and end face, planar end face and shoulder have a gap of about 0.5 to 2.5 per cent of the spacing. Taper/bulge seals are provided adjacent the abutment surfaces to be effective before the planar surfaces abut as the joint is made up. The effective pitch diameter of the pin member remains consistently smaller than the pitch diameter of the box member, at least up to an insertion of the pin member so that the planar surfaces abut.