(2) The 2)API specifies three lengths: R- 1 is 4.88~7.62m, R-2 is 7.62 ~ 10.36m, and R-3 is 10.36m or longer.
(3) Some imported goods are marked with the words LTC, that is, filament buckle sleeve.
(4) Apart from API standards, a few casings imported from Japan also have Japanese factory standards (such as Nippon Steel, Sumitomo and Kawasaki). ), steel grades are NC-55E, NC-80E, NC-L80, NC-80HE, etc.
(5) In the claim case, there are external defects such as black thread, thread damage, pipe folding, out-of-tolerance of fastening distance between broken wires and wires, out-of-tolerance of coupling J value, and internal quality problems such as brittle fracture and low yield strength of casing. (1) Domestic casing is specified in SY/T6 194-96, and the casing length is uncertain, ranging from 8- 13m. However, no less than 6m sleeves can be provided, and the number shall not exceed 20%.
(2) There should be no folding, hairline, delamination, crack, rolling and scarring on the inner and outer surfaces of the shell. These defects should be completely removed, and the removal depth should not exceed 12.5% of the nominal wall thickness.
(3) The outer surface of the coupling shall be free from defects such as folding, hairline, delamination, crack, rolling and scarring.
(4) The threaded surfaces of casing and coupling should be smooth, and there should be no defects such as burrs and tears that are enough to interrupt threads and affect strength and tight connection. (1) According to SY/T6 194-96. The casing and its coupling are made of the same steel. sulphur content
(2) Carry out chemical analysis sampling according to GB222-84. Chemical analysis was carried out according to the relevant regulations in GB223.
(3) api gravity: arispec5ct 1 version 9881. Chemical analysis shall be carried out according to the latest version of ASTME59 and ASTME350.
(4) The national standard steel grade of 4)J55 oil casing is 37Mn5. (1) According to SY/T6 194-96. Crushing test (GB246-97), tensile test (GB228-87) and hydrostatic test were carried out.
(2) Carry out hydrostatic test, flattening test, sulfide stress corrosion cracking test, hardness test (according to the latest version of ASTME 18 or E 10), tensile test and transverse impact test (according to the latest version of ASTMA370, ASTME23 and related standards) according to the provisions of API Gravity API Spec5ct1988. According to SY/T6 194-96, domestic casing shall be bound with steel wire or steel belt. The exposed part of each casing and coupling thread should be screwed with a protective ring to protect the thread.