Wear-Resistant Tool Joints for Tubing
TU 6846-109-07500303-01
This specification covers the wear-resistant tool joints (interlocks) for tubing per GOST 633-80 that are used in production and process strings.
During assembly, the wear-resistant coupling is screwed on the one end of the standard tubing, and the wear-resistant adapter on the other. When screwing the tool joint parts off the tubing, the maximal tightening torques are used in accordance with RD-39-136-95. The connection of tool joint parts with tubing is not to be disassembled later. In operation, the screwing-unscrewing of tubes with tool joints is executed upon connection coupling-adapter.
The wear-resistant tool joints are manufactured with strength groups K, E, L from the tube shell made from steel 40Kh, 40KhN, 40KhFA and 30KhMA.
The connection threads are made in accordance with GOST 633-80 and strengthened with ionic nitride hardening procedure up to hardness of 500-650 HV.
Usage of alloy steel and strengthening of the tool joint threads provides increased service life of tubing - up to 50 screw-unscrew cycles.
The wear-resistant tool joints are manufactured for plain and upset tubing.
The range of adapters and couplings is specified by Table 1.
| Tube type | DN (nominal diam.), mm | Length of coupling, mm | Length of adapter, mm | Outside Diameter of coupling and adapter, mm |
| Plain per GOST 633-80 |
60 73 89 | 110 132 146 | 165 165 165 | 73,0 88,9 108,0 |
| With upset ends per GOST 633-80 |
60 73 89 | 126 134 146 | 190 190 190 | 77,3 93,2 114,4 |
The usage of the tool joints allows keeping tightness of the threaded parts after multiple assembling-disassembling cycles at trip-in-hole/trip-out of string and prevents damaging of the tubing surface by anvils of wrench and spider.
It is advisable to use the tool joints combined with tubes of enhanced corrosion resistance.
The mounting of the tool joints can be accomplished at pipe shops on the new tubes as well as on the used ones, that have been rejected on account of the thread part, but are serviceable in respect to the tube body.
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.
