The connection of drill pipes
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Sizes of drill pipes, determining the way of their connection
GOST R 51510−99 defines the requirements that are imposed on drill pipes of domestic production. It applies to drill pipes designed for all types, methods and conditions of geological exploration drilling for solid minerals and water, for prospecting and exploration, engineering and geological surveys, seismic exploration, construction, etc. Using both domestic and foreign drilling equipment and tools.
Types of drill pipes, depending on the field of application are given in the table
|Application area||A type|
|Traditional core and non-coring drilling||Pipes for drilling universal||TBSU|
|Pipes boring light-alloy||TBL|
|Pipes drill heavier||TBU|
|Drilling with a removable core receiver||Pipe boring steel light series||TBSL|
|Pipes for drilling heavy steel series||TBTT|
|Pipe boring heavy-alloy series||TBTT|
|Drilling with hydraulic and pneumatic conveying of core||Double-walled drill pipes with external steel pipe||TBD|
|Double-drill pipe with external light alloy pipe||TBDL|
The main way of detachable connection of drill pipes is a locking joint, which includes a nipple and a coupling. On these parts of the valve there is a thread, by means of which the connection is made. Thread type — conical lock.
Buy drill pipes of domestic production in an extensive range and at economically favorable prices of the manufacturer offers the company Elektrovek-steel. The supplier guarantees immediate delivery of products to the address set by the customer.
Characteristics of the threaded connection of drill pipes
GOST 7918−75 sets the following parameters and dimensions of the lock connection:
Clutch and nipple configuration;
Registration of joints, unifying the use of a certain fitting tool (ring grooves or «turnkey» flats);
Right and left execution of locks;
Mean values of thread diameters in the main plane;
Profiles and sizes of pipe threads;
Limit values of thread pitch and taper (shown in the table):
|Elements of the thread profile||Limit deviation on length, mm|
|Step||± 0.05||± 0.10|
|Taper (for outer, middle and inner diameters)||± 0.08||± 0.16|
The technical requirements for the locking connection include the following items:
Locks should be made of steel 40HN according to GOST 4543, the mechanical properties of which after heat treatment should not be lower than the following:
|Tensile strength, kgf / mm 2… .||90|
|Tensile yield strength, kgf / mm 2 …||70|
|relative extension, %… …||15|
|Relative narrowing,%… …||50|
|Impact strength at 20 ° C, kgf / cm 2 …||12|
|Hardness, HRC e (HB)… …||28 (262)|
The outer surface of the couplings and nipples to be subjected to induction heat treatment to a depth of 1.5… 2.5 mm and hardness of at least 49,5 HRC e. In this case, sections of 50 to 65 mm in length from the end of the locking thread of the coupling and 30… 35 mm from the pipe thread of the pin and the coupling are not subject to induction heat treatment.
It is allowed to harden the outer surface of individual belts, the dimensions of which are indicated in the working drawings.
Note. The outer surface of the couplings and nipples of the left-hand locks is not subject to induction heat treatment.
Z-joint thread 50 of the pin and the box must be subjected to induction heat treatment to a depth of 3.3 to 5.0 mm from the crest to hardness 49 — 57 HRC in a zone e from the second to the tenth of turns counted from the filar coil. After induction heat treatment, to remove internal stresses, the parts must be subjected to low tempering or the operation replacing it.
The groove and cavities of the locking threads of the nipples (for smoothing micro cuts and unevennesses) must be rolled with rollers prior to induction heat treatment. Surface roughness after break-in is Ra 1.25 μm.
The deviation from the alignment of the threads of each part (nipple or coupling) must not exceed 0.1 mm per 100 mm of length.
The distance between the stop face of the coupling and the thrust shoulder of the lock nipple, which is screwed by hand (interference in the pair), should not be more than 0.5 mm.
The surfaces of the thrust shoulder of the lock nipple and the stop face of the coupling must be free of burrs, nicks and other defects that break the strength and tightness of the joint. Do not apply any marks on these surfaces.
Locks should not have cracks, hair, captivity, shells and bundles. Cutting, welding and sealing of defective places are not allowed.
Threads of the lock thread must be blunted to the full profile. It is possible to blunt the thread of the locking thread of the coupling in the form of a bevel at an angle of 30 ° — 35 ° to the thread axis.
Locks must be galvanized or phosphated. Zinc phosphate coating — according to GOST 9.306. The thickness of the zinc coating layer is 15… 24 μm.
The lock set should include a nipple and a coupling, tightly screwed by hand.
Average operating time of the lock thread to failure T cp — not less than 800 cycles of mechanized screwing-unscrewing.
The established trouble-free operating time of T y is not less than 500 cycles of mechanized screwing-unscrewing.
A sign of the failure of the lock thread is its wear, characterized by a decrease in the number of revolutions of the parts of the lock, which are necessary for its complete screwing up to 2.5 revolutions.
Buy at an affordable price drill pipe, designed for threaded connections, offers the company Elektrovek-steel. The supplier guarantees the timely delivery of products to any point specified by the consumer.