The steel pipe according to the present disclosure contains a chemical composition consisting of, in mass %, C: more than 0.50 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr: 0.30 to 1.50%, Mo: 0.25 to 3.00%, Ti: 0.002 to 0.050%, N: 0.0010 to 0.0100% and O: 0.0030% or less, with the balance being Fe and impurities. The steel pipe contains an amount of dissolved C within a range of 0.010 to 0.060 mass %. The tensile yield strength in the axial direction and the circumferential direction is 862 to 1069 MPa, and the yield ratio in the axial direction is 90% or more. The tensile yield strength in the circumferential direction is 30 to 80 MPa higher than the compressive yield strength in the circumferential direction.

This disclosure relates generally to corrugated pipe, and more particularly to corrugated pipe with an outer wrap. In one embodiment, a pipe includes an axially extended bore defined by a corrugated outer wall having axially adjacent, outwardly-extending corrugation crests, separated by corrugation valleys. The pipe also includes an outer wrap applied to the outer wall. The outer wrap may include fibers and plastic. The outer wrap may span the corrugation crests producing a smooth outer surface.

A steel pipe for pressure piping can be subjected to autofrettage. When an outer diameter of the pipe is D, an inner diameter is d, and a yield stress is σ.sub.y, and when a measured value of an outer surface residual stress is σ.sub.o1, a measured value of an outer surface residual stress after halving is σ.sub.o2, and a measured value of an inner surface residual stress after the halving is σ.sub.i2, D/d is 1.2 or more, an estimated value σ.sub.i1 of inner surface residual stress is [σ.sub.i1=(−σ.sub.i2)/(A×(t/T).sup.2−1)], where [t/T=((σ.sub.o2−σ.sub.o1)/(A×(σ.sub.o2−σ.sub.o1)−C×σ.sub.i2)).sup.1/2], [A=3.9829×exp(0.1071×(D/d).sup.2)], and [C=−3.3966×Exp(0.0452×(D/d).sup.2)] satisfies [1.1×F×σ.sub.y≤α.sub.i1≤0.8×F×σ.sub.y], and (F=(0.3×(3−D/d).sup.2−1) when 1.2≤D/d≤3.0, and F=−1 when D/d>3.0).

A steel pipe for pressure piping can be subjected to autofrettage. When an outer diameter of the pipe is D, an inner diameter is d, and a yield stress is σ.sub.y, and when a measured value of an outer surface residual stress is σ.sub.o1, a measured value of an outer surface residual stress after halving is σ.sub.o2, and a measured value of an inner surface residual stress after the halving is σ.sub.i2, D/d is 1.2 or more, an estimated value σ.sub.i1 of inner surface residual stress is [σ.sub.i1=(−σ.sub.i2)/(A×(t/T).sup.2−1)], where [t/T=((σ.sub.o2−σ.sub.o1)/(A×(σ.sub.o2−σ.sub.o1)−C×σ.sub.i2)).sup.1/2], [A=3.9829×exp(0.1071×(D/d).sup.2)], and [C=−3.3966×Exp(0.0452×(D/d).sup.2)] satisfies [1.1×F×σ.sub.y≤α.sub.i1≤0.8×F×σ.sub.y], and (F=(0.3×(3−D/d).sup.2−1) when 1.2≤D/d≤3.0, and F=−1 when D/d>3.0).

A method of manufacturing a seamless stainless steel pipe for Oil Country Tubular Goods by heating a billet having a specified chemical composition including forming the billet into a seamless steel pipe by applying hot working to the billet, cooling the seamless steel pipe to a room temperature at a cooling rate of air cooling or more, thereafter, performing quenching by heating the seamless steel pipe to a temperature of 850° C. or above, subsequently, cooling the seamless steel pipe to a temperature of 100° C. or below at a cooling rate of air cooling or more, and subsequently, applying tempering to the seamless steel pipe at a temperature of 700° C. or below for a specific holding time.

Special usage steels, particularly those intended to be in contact with combustion fumes, are described. Tubular components produced based on such steels are also described. The steel both is resistant to the coking phenomenon and has improved mechanical performances. The steel contains in percentage by weight from 0.08 to 0.15% carbon, from 0.4 to 0.8% manganese, from 1.5 to 2.5% silicon, from 0.5 to 2% copper, from 8 to 10% chrome, from 0.5 to 3% nickel, from 0.01 to 0.07% nitrogen, from 0.8 to 1.1% molybdenum, with the remainder being iron and impurities.

A carrier pipe is protected from corrosion by being received inside a casing at a location above ground. The casing, which can be formed from a polymer, defines a gap extending around an exterior surface of the carrier pipe. In one embodiment, the gap is substantially filled with a potting material having a corrosion-resistant property. In another embodiment, a self-contained impressed current cathodic protection system is received in the gap. A pull head is installed on the carrier pipe and/or casing for pulling the pipe assembly, including carrier pipe, casing, and elements received in the gap, into an underground bore as a single unit. In some embodiments multiple pipe assemblies are pulled together into the same bore.

A carrier pipe is protected from corrosion by being received inside a casing at a location above ground. The casing, which can be formed from a polymer, defines a gap extending around an exterior surface of the carrier pipe. In one embodiment, the gap is substantially filled with a potting material having a corrosion-resistant property. In another embodiment, a self-contained impressed current cathodic protection system is received in the gap. A pull head is installed on the carrier pipe and/or casing for pulling the pipe assembly, including carrier pipe, casing, and elements received in the gap, into an underground bore as a single unit. In some embodiments multiple pipe assemblies are pulled together into the same bore.

A high-strength thick-walled electric resistance welded steel pipe has excellent low-temperature toughness and excellent HIC resistance and a yield strength of 400 MPa or more. The steel has a chemical composition consisting of C: 0.025% to 0.084%, Si: 0.10% to 0.30%, Mn: 0.70% to 1.80%, controlled amounts of P, S, Al, N, and O, Nb: 0.001% to 0.065%, V: 0.001% to 0.065%, Ti: 0.001% to 0.033%, and Ca: 0.0001% to 0.0035% on a mass percent basis and the remainder being Fe and incidental impurities, and satisfies Pcm of 0.20 or less.

A high-strength thick-walled electric resistance welded steel pipe has excellent low-temperature toughness and excellent HIC resistance and a yield strength of 400 MPa or more. The steel has a chemical composition consisting of C: 0.025% to 0.084%, Si: 0.10% to 0.30%, Mn: 0.70% to 1.80%, controlled amounts of P, S, Al, N, and O, Nb: 0.001% to 0.065%, V: 0.001% to 0.065%, Ti: 0.001% to 0.033%, and Ca: 0.0001% to 0.0035% on a mass percent basis and the remainder being Fe and incidental impurities, and satisfies Pcm of 0.20 or less.