GB2185117A

GB2185117A - Bent sub gauge

Info

Publication number: GB2185117A
Application number: GB08700215A
Authority: GB
Inventors: Arthur Stewart
Original assignee: Stable Services Ltd
Current assignee: Stable Services Ltd
Priority date: 1986-01-07
Filing date: 1987-01-07
Publication date: 1987-07-08
Also published as: GB8600235D0; GB8700215D0

Abstract

A gauge (10) for measuring the angle by which the axles of one portion (38) of an article is inclined relative to the axis of another portion (36) where the surfaces of the portions are stepped apart (40) as in a bent-sub (34) used for rock drilling. Two members (12, 14) are arranged for relative angular displacement to traverse an angular scale (18), the edges (28, 32) of the members being offset to accommodate the step (40). A tapered pin connection (36) of a bent-sub is catered for by having an inclined edge (32) on member (14). The body member (14) has slots to allow lateral adjustment relative to member (12, 18), to enable the gauge to fit into the step (40). <IMAGE>

Description

SPECIFICATION Bentsubgauge This invention relates to a gauge more particularly a gauge, for measuring the angle between the axes of relatively inclined parts of a bent-sub.

When, during rock drilling, it is required to drill at an angle to the vertical, as is often the case from an oil rig, a so-calied "bent-sub" is introduced into the drill string. Such subs comprise an elongate cylindrical body having at a leading end thereof a tapered threaded pin connection by which the bent-sub is screwed tightly behind another sub in the string. The cylindrical body and threaded pin connection are separated by a step or shoulder.

The angle at which drilling effected is determined by the angular relationship between the axes of the pin connection portion and the cylindrical body and bent-subs of different angles (increasing in 0.5 degree increments from, say 1 degree to 3 degrees) are normally available to permit setting of a desired drilling angle. It is, however, difficult on site to distingu- ish between bent-subs having anglesthatdiffer by onlya small amount. Ifthe angle ofthe bent-sub isto be checked, it usually has to be sent ashore.

One object of the present invention is to provide a gauge which is relatively simple to use enabling a bent-subto bechecked on site.

In accordance with the present invention we propose a gauge for measuring the angle by which the axis of one portion of an article or assembly is inclined relative to the axis of another portion thereof where the surfaces of the portion are stepped apart, the gaugecomprising two memberswhicharere- latively angularly displaceableto transverse an angular scale and edges of which are offset to accommodate the step for contact, in use, along the respective surfaces, the gauge being adapted or adaptable to compensate for one or both of the surfaces being inclined relative to the axis of its respective portion. The extent of the offset is preferably adjustable.

For measuring articles or assemblies in which the surface of one portion is inclined relative to the axis thereof, the edge of one member may be inclined relative to the edge of the other member when the gauge is set to a position (conveniently zero degrees) on the angular scale intended to indicate alignment ofthe axes of the portions of the article or assembly.

If the surface of both portions are parallel with their respective axes or inclined at the same angle, then it will be understood that the edges are parallel when the gauge is set to the said position.

The threaded pin connection of a bent-subisusu- ally tapered for which purpose, one ofthe edges carries a taper complementary with that of the threaded pin connection. In practice, the taper is one ofthetwo specified by the American Petroleum Institute (API) and to enablethe gaugeto be used to measure subs in accordancewith eitherstandardtthe gauge preferably comprises a pointer having parallel side edges and pivotally mounted relative to a body bearing an angular scale transversed by the pointer, opposed side edges ofthe body being tapered by different amounts relative to the side edges of the pointer when set at zero degrees on the scale.In this way, either side edge of the body and painter can be used depending upon which standard API taper is carried by the bent-sub to be measured.

The body and pointer are also arranged to define between the two edges, a step corresponding to the step between the cylindrical body portion and the tapered threaded portion of the bent-sub to be measured.

In a preferred embodiment, the pointer is pivotally connected to a plate bearing the angular scale, the plate in turn having a slotted connection with the body affording relative lateral displacement of the pointer and the body which serves to adjust the height of the step as required to conform to apart icular bent-sub to be measured. Furtherthe gauge may be adjusted to compensate for non-standard tapered pin connections by providing interchangeable bodies having tapered edges at other angles.

An embodiment of the invention will now be des cribedwith referenceto the acconipanying drawings in which: Figure lisa plan view of the assembled gauge; Figures 2a, 2b and 2cshow respectively a body portion of the gauge, a pointer and a scaleforattach- mentto the body portion of Figure 2a; and Figure 3illustrates how the gauge is used to measure the relative inclination of the axes ofthe cylindrical part ofthe bent-sub and the pin connection.

The bent-sub marker gauge 10 shown assembled in Figure 1 comprises a pointer 12 and a body 14 between which is a plate 16 bearing an angular scale 18. The parts are connected together by a bolt 20 passing through holes in the pointer 12 and body 14and a slot 22 in the scale bearing plate 16 so thatthe point 12 is angularly displaceable relative to the body 14to transverse the angular scale 18. Aslotted connection formed by dowel pins 24 fitted in to the plate and running in slots 26 in the body 14, preventangular displacement of the plate 16 relative to the body 14 but allow relative lateral displacement to vary the distance between the parallel side edges 28 of the pointer 12 and the edges 30,32 of the body 14.

The side edges 30,32 of the body 14 carry different tapers, in this case 2 in. perft. and 3 in. perft. This enables the gaugeto be used for measuring a bentsub having a tapered pin connection in accordance with one oftheAPI standards.

In use, the gauge 10 is held againstthe bent-sub 34 as shown in Figure 3 with the appropriate side edge 30,32 of the body 14 in contact with the tapered pin connection 36 and the corresponding side edge 28 of the pointer 12 in contact along the cylindrical body portion 38 of the sub 34. Since the taper in the body 14 is complementarywith the taper ofthe pin con nection 36 the angular scale reading is equal to the angle A, being the angle between the axes ofthe cylindrical portion 38 and the tapered pin connection 36. The angle A is typically 1 1030J, 2', 2'30' or3".

Itwill be appreciated that tapered connections otherthan those in accordance with the API standard can be accommodated by replacing the body 14with another body having different tapers along the edges thereof. Also, due to the slotted connection between the plate and the body, the lateral position ofthe pointer and scale is automatically adjusted to suit the height of the step 40 between the cylindrical body portion 38 and the pin connection 36 ofthe bent-sub to be measured.

Claims

1. Agaugefor measuring the angle by which the axis of one portion of an article or assembly is incliend relative to the axis of another portion thereof where the surfaces of the portion are stepped apart, the gauge comprising two members which are relatively angularly displaceable to transverse an an gular scale and edges of which are offsetto accommodatethe step for contact, in use, along the respective surfaces, the gauge being adapted or adaptable to compensate for one or both ofthe surfaces being inclined relative to the axis of its respective portion.

2. A gauge according to claim 1 wherein the extent ofthe offset is adjustable to accommodate steps of different height.

3. Agauge according to claim 1 or claim 2, wherein one member is pivotally connected to a plate, the plate in turn having a slotted connection with the other member affording relative lateral displacement of the two members to adjust the extent of the offset.

4. A gauge according to any one of the claims 1 to 3 wherein the edge of one member is inclined relat ivetotheedge of the other member when the gauge is setto a position on the angular scale intended to indicate alignment of the axes of the portions ofthe article or assembly.

5. A gauge according to any one of the preceding claims comprising a pointer member having parallel side edges and pivotally mounted relative to a body member opposed side edges of which are tapered by different amounts relative to the side edges ofthe pointerwhen set to a position on the angular scale intended to indicate alignment ofthe axes of the portions ofthe article or assembly.

6. A gauge constructed and arranged substantially as herein described with reference to and as illustrated in the accompanying drawings.