High Longevity Oil-Well Tubing and Interlocks of Production Strings for Corrosive Media

The tubing complete with wear-resistant interlocks per this TU is meant for regular operation in corrosive hydrosulfide media with parameters specified in Table 5 "Safety Regulations for Petroleum and Gas Industries".

Besides, the tubing has enhanced corrosion resistance at well treating with hydrochloric acid and is cold-resistant up to temperature -50°C. The general corrosion rate for tubing metal is not more than 0.5 mm/year.

The range of tubes, subs and couplings is specified by Table 1.

Tube type	DN (nominal diam.), mm	Tube wall thickness, mm	Outside Diameter of coupling and sub, mm
Plain as per GOST 633-80	60 73 89 102 114	5.0 5.5 : 7.0 6.5 : 8.0 6.5 7.0	73.0 88.9 108.0 120.6 132.1

The tubes are manufactured in version A per GOST 633-80. In coordination with client, the tubes can be manufactured with the length up to 11 meters. The tubes are manufactured with strength groups Ks, Es, Ls from tube shell made from steel 40Kh, 40KhN, 40KhFBA and 40KhMFBA. Mechanical properties of tubes are specified by Table 1.1. Parameter description Nominal value of parameter for steel of strength group: Ks Es Ls Tensile strength, σt, N/mm2 (kgf/mm2), not less tha 647(66) 657(67) 755(77) Yield strength, σy, N/mm2 (kgf/mm2), not less than not more than 519(53) 627(64) 549(56) 657(67) 647(66) 784(80) Ratio σy/σt, not more than 0.8 0.85 0.85 Rockwell hardness, not more than 95 HRB 98 HRB 23 HRC Elongation, δ5, %, not less than 18 16 15 Impact strength at Charpy specimens, J/cm2 (kgf/mm2), at test temperature -50°C not less than KCV-50°C. 98(10) 98(10) 98(10) Share of ductile component (V) at test temperature -50°C, not less than 70 70 70 The tubing per this TU is completed with wear-resistant interlocks consisting of coupling and sub fabricated in accordance with TU 6846-109-07500303-01. The couplings and subs of wear-resistant interlocks are fabricated from steel 40Kh, 40KhN, 40KhFBA and 40KhMFBA and subjected to ionic nitride hardening procedure. Using of interlocks provides increased service life of threaded connections. Mechanical properties of couplings and subs are specified by Table 1.2. Parameter description Nominal value of parameter for steel of strength group: Ks Еs Ls Tensile strength, σt, N/mm2 (kgf/mm2), not less than 687 (70) 689 (70,3) 758 (77,3) Yield strength, σy, N/mm2 (kgf/mm2), not less than 491 (50) 552 (56,2) 654 (66,8) Elongation, δ5, %, not less than 12 13 13 Impact strength at Charpy specimens, J/cm2 (kgcm/mm2), at test temperature -50°C not less than KCV-50°C. 98 (10) 98 (10) 98 (10)

Steel seamless tubing as per this TU has enhanced corrosion resistance and is cold-resistant up to temperature -50°C.
The general corrosion rate for metal of tubing, couplings and strengthened connection parts is not more than 0.5 mm/year.

The tubing is made in two versions:

1. Plain tubes with couplings per GOST 633-80;

2. Tubes completed with strengthened connection parts.

The tubes are manufactured with strength groups Ks, Es, Ls with range as per GOST 633-80.

The range of tubing with couplings is specified by Table 1.1.

DN (nominal diam.) of pipe, mm	Tube wall thickness, mm	Tube type
		Plain, without thread	Plain, with triangular thread
60	5,0	Ks, Es, Ls	Ks, Es, Ls
73	5.5 : 7.0	Ks, Es, Ls	Ks, Es, Ls

The range of tubing with strengthened connection parts is specified by Table 1.2.

Tube type	DN (nominal diam.), mm	Tube wall thickness, mm	Outside Diameter of coupling and sub, mm
Plain as per GOST 633-80	60 73 89	5.0 5.5 : 7.0 6.5 : 8.0 6,5 7.0	73.0 88.9 108.0 120.6 132.1

The tubes are manufactured in version A per GOST 633-80.
In coordination with client the tubes can be manufactured with the length up to 11 meters.
The tubes and couplings are manufactured from tube shell made from steel 30 FB, 30 KhF and 30 KhMFBA.