US2981347A

US2981347A - Underwater inspection apparatus

Info

Publication number: US2981347A
Application number: US622665A
Authority: US
Inventors: Robert F Bauer; Stratton Hal
Original assignee: Shell Oil Co; Continental Oil Co
Current assignee: ConocoPhillips Co; Shell USA Inc
Priority date: 1956-11-16
Filing date: 1956-11-16
Publication date: 1961-04-25
Anticipated expiration: 1978-04-25

Description

April 25, 1961 R. F. BAUER ET AL 2,981,347

UNDERWATER INSPECTION APPARATUS Filed Nov. 16, 1956 4 Sheets-Sheet l IN V EN TORS. ROBERT F. BAUER HAL STRATTON MJM$M A T TORNEVS April 25, 1961 R. F. BAUER ET AL 2,981,347

UNDERWATER INSPECTION APPARATUS Filed Nov. 16, 1956 4 et 2 IN VEN TOR-5.

ROBERT F. BAUER HAL STRATTON BY W Maw A T TORNE VS April 25, 1961 R. F. BAUER ETAL 2,981,347

( UNDERWATER INSPECTION APPARATUS Filed Nov. 16, 1956 4 Sheets-Sheet 3 FIG. 6.

INVENTORZ ROBERT F. BAUER HAL STRATTON m,mw

ATTORNEYS April 25, 196] R. F. BAUER ET AL UNDERWATER INSPECTION APPARATUS 4 Sheets-Sheet 4 Filed Nov. 16, 1956 .II "n MIM IN VEANJEQgS. R0 ERT F. 8 HA? STRATTON ATTORNEYS Stt 2,981,347 UNDERWATER INSPECTION APPARATUS Filed Nov. 16, 1956, Ser. No. 622,665

8 Claims. (Cl. 175-7) This invention relates to apparatus for visual observation of underwater locations.

One of the most important uses of this invention is in the observation of underwater wells such as the oft-shore wells which are drilled in the ocean floor for geological information and the production of oil and gas.

At the present time, underwater or off-shore well drilling is usually accomplished from stationary structures rigidly anchored to the underwater formation. These structures provide static bases for the drilling equipment and are satisfactory for shallow water, for example, depths of 50 feet or less. However, for deeper water stationary structures are not always economically practical. Furthermore, these structures are sometimes permanent installations which may be navigation hazards.

To avoid the disadvantages of stationary bases for ofi-shore drilling, such drilling is now sometimes conducted from a floating vessel anchored over the well site. The advantage of this arrangement is that the floating vessel can readily be moved from one location to another, and can be used in waters of practically unlimited depth.

The principal difliculty in drilling or working on an underwater well from a floating vessel is in making trips to and from the well, for example, withdrawing drilling or other equipment from the well and subsequently reentering the well with such equipment. The movement of a floating vessel due to wind and wave action, which are almost invariably present, makes it difiicult to relocate the well once equipment is removed from it.

Various types of guide means have been developed and used in guiding equipment to and from the well, but such equipment is not infallible and it is often desirable to be able to make visual observations of the condition of the well and the equipment being used to work in or around it. For example, the guide means may become damaged or fouled, making access to the well diflicult or impossible. This invention provides means for making a remote visual inspection of the area of trouble. By such an inspection it is often possible to diagnose the difi'iculty and take appropriate remedial action at a minimum cost and danger to operating personnel.

Briefly, the invention provides apparatus for observing an underwater location whichv includes a watertight camera and guide means disposed adjacent the underwater location. A bracket is attached to the camera and adapted to move up and down on the guide means and carry the camera between an upper position and a lower position adjacent the underwater location. Means are also provided for lowering and raising the bracket and camera.

In the preferred form of the invention, the camera is a television camera to provide instantaneous information concerning conditions around underwater locations, and means are included for panning the television camera by remote control when it is in its lower position adjacent the underwater location.

These, and other aspects of the invention, will be more fully understood from the following detailed description Patented Apr. 25, 1961 4 form of the invention;

Fig. 3 is a fragmentary sectional view partially broken away detailing a portion of the camera control means of Fig. 2; v

Fig. 4 is an enlarged view taken on line 4-4 of Fig. 2;

Fig. 5 is a schematic fragmentary elevation, partly in section and partly broken away, of an alternate embodiment of the invention;

Fig. 6 is a sectional view taken on line 6-6 of Fig. 5; and

Fig. 7 is a schematic fragmentary elevation, partly in section and partly broken away, of another embodiment of this invention.

Referring to Fig. 1, a wellhead base 15 is lowered by a plurality of supporting lines 16 in a body of water 17 from a well-drilling platform, for example a floating barge 18, toward a well 19 being drilled from the barge in an underwater formation 20. Each line 16 is looped around a respective sheave 21 attached to the top of the wellhead base. One end of each line is connected to the barge, and the other is connected to a separate respective winch 22 on the barge, which is anchored over the well by a plurality of suitable anchor lines 24 extending in opposite directions from the barge and connected to anchors (not shown). A draw works 25 and a power unit 26, which may be of conventional type, are mounted on the barge to operate a hoisting cable 27 carried over a crown block 28 located at the upper end of a drilling mast 29, which is also mounted on the barge. The traveling end of the hoisting cable carries a traveling block 30 and a hook 31 which supports a swivel joint 32. A kelly joint 33 extends downwardly from the swivel through a kelly bushing 34 in the center of a rotary table 36 mounted on gimbals (not shown), as for example in a manner similar to that described in U.S. Patent No.

The rotary table is supported on a platform 37 directly over a cellar 38 in the barge, and is open at its bottom. Power is supplied to the rotary table through a shaft 39 turned by a rotary table power unit 40.

A string of drill pipe 41 is connected to the lower end of the kelly and extends down through the cellar, the water, a vertical conductor pipe 42 mounted in the Wellhead base, and down into the well. A drill collar 43 and an under reamer drill bit 44 are attached to the lower end of the drill pipe for boring the well to a diameter slightly larger than the outside diameter of the conductor pipe 42 which is welded to the wellhead base to project upwardly a relatively short distance above, and downwardly a relatively great distance from the wellhead base.

' The wellhead base may be positioned in the well by any one of several suitable means, for example, it may be suspended by lines 16 underneath the cellar of the barge while the drill pipe is extended down through the well conduit to drill the well in the formation.

After the well is drilled to a suflicient depth to receive the conductor pipe, the wellhead base is lowered from the barge so that the conductor pipe slides down the drill pipe and into the well, the bottom of the wellhead base resting on the earth formation around the upper end of the well as shown in Fig. 2. The lines 16 are then disconnected from the barge and withdrawn from the sheaves on the wellhead base. If desired, the conductor pipe may be firmly anchored in the well by pumping cement down the drill pipe to fill the annular spacebetween 3 the conductor pipe and the well. The under reamer may then be retracted and the drill pipe, drill collar and drill bit removed from the well bore, or drilling may be continued without removing the drill bit from the well until some later period of the drilling operation.

The wellhead base may take many forms, and the details of a suitable base are shown most clearly in Figs. 2 and 3. The base is a relatively flat and wide structure which is hexagonal in shape as viewed in plan. The periphery of the bottom of the base is made up of six sections 46 of I-beams of equal length welded together end to end to form a hexagon. A separate vertical brace 47 is welded to the junctions of the ends of each of the I-bcam sections 46 and connects the bottom of the base to the top of the base, which is also formed in six sections 48 of I-beams welded together end to end to form a hexagon identical in size and shape to the base bottom.

The upper end 49 of the conductor pipe 42 extends a short distance, about two or three feet, above the upper surface of the base. The conductor pipe extends below the bottom of the base for any suitable length, say twenty to a hundred feet. An upper set of horizontal and radially extending braces 50 (see Fig. 3) are welded at their outer ends to respective joints of the ends of the peripheral sections of the top of the base, and are welded at their inner ends to the outside of the conductor pipe. A lower set of horizontal radially extending braces 51 are welded at their outer ends to the joints of the ends of the peripheral sections of the bottom of the base and are welded at their inner ends to the conductor pipe.

Referring to Fig. 2, a set of six diagonal braces 52 extending upwardly and inwardly from the joints of the ends of the peripheral sections of the bottom of the wellhead base are welded at their lower ends to the base bottom and at their upper ends to the conductor pipe just below the inner ends of respective upper radial braces 50.

A plurality of separate watertight compartments 53 are attached to the interior of the wellhead base so that it may be floated and towed to any desired location.

An annular circular plate 55 having a central opening 56 equal in diameter to the outside diameter of the upper end of the conductor pipe is welded to the top surfaces of the radially extending braces in the top of the wellhead base. The outer diameter of the plate is approximately one half the maximum dimension of the wellhead base top.

The lower end of an upwardly extending tubular guide member 57 is disposed around a vertical anchor post 58 rigidly attached, e.g., by welding, at its lower end to the periphery of the plate. The internal diameter of the lower end of the tubular guide member is stepped down to form a portion 59 which makes a snug slip fit around the lower end of the anchor post. A retaining plate 60 is secured by bolts 61 to the upper end of the anchor post and has a diameter which makes a snug sliding fit with the larger internal diameter of the tubular guide member. Thus, the tubular guide member is rotatable about the anchor post and also may slide for a limited distance up and down the anchor post, the retaining plate on the anchor post and the shoulder in the lower end of the guide member preventing the guide member from sliding oil the anchor post.

The guide member is made up of a plurality of joints 62 of pipe, each joint being threaded at each end to permit it to be coupled to another joint. The threaded joints are made so that when coupled together, they present smooth external and internal surfaces. The guide member is of suificient length to extend above the water surface and into the cellar of the barge when the wellhead base is landed on the ocean floor as shown in Fig. 2.

Because of the length of the guide member, it is flexible enough to accommodate, without breaking or permanent deformation, any normal movement imparted to it at the surface by the floating barge, wave, current and wind action, etc.

A longitudinal key 63 is attached to the outer portion of the guide member and extends from a point several feet above the wellhead base to the upper end of the guide member. The key is made up of a plurality of collinear key sections 64, each section being attached to a respective joint of pipe in the guide member.

With the exception of the bottom joints in the guide member, all of the joints have right hand threads at each end. The joint of pipe disposed around the anchor post has a left hand thread at its upper end to form a back-oft" joint with the next joint, which has a left hand thread at its lower end and a right hand thread at its upper end. The back-off joint permits the guide member to be uncoupled near the wellhead base during a later state of the drilling operation, if desired.

An outwardly extending horizontal foot 65 is welded to the lower end of the guide member and is adapted to engage an upright stop 66 welded to the plate on the wellhead base. Thus, when the guide member is in its lower position, its rotation is limited by the stop and foot.

A drilling operation as illustrated in Fig. l is conducted as follows:

The wellhead base is towed to the desired location, and the drilling barge is firmly anchored over the well site. The supporting lines 16 are connected to the wellhead base, only the bottom joint of the guide member being in place at this time, and the tow line is disconnected. The buoyant compartments in the wellhead base are then flooded either by puncturing the wall of the compartments or by opening valves (not shown).

The upper ends of the supporting lines being controlled from the drilling barge, the wellhead base is allowed to sink and swing under the cellar in the barge, where it is held by the lines at a shallow depth below the cellar. The drill bit, drill collar and drill pipe are then made up on the barge and lowered through the conductor pipe in the wellhead base to the ocean floor.

A pump 67 on the barge picks up sea water from an inlet (not shown) and forces it through a flexible drilling mud hose 68 into the swivel, down through the kelly, drill pipe and out the under reamer bit. The pressure of the water forces the under reamer blades out into the position shown in Fig. 1, and the drill pipe is rotated by the rotary table turning the kelly joint so that the well is drilled. The bit is lowered by controlling the hoisting cable, and cuttings are washed out of the well by the sea water flowing from the bit up the annular space between the drill pipe and the well bore, no attempt being made to obtain return circulation of a drilling fluid at this time.

The drilling operation proceeds as described above until a suificient depth is reached to permit the conductor pipe to be lowered into the well and allow the bottom of the wellhead base to rest on the ocean floor. Before the base is lowered, the guide member joint with the left hand thread at its lower end is screwed into the joint disposed around the anchor post, and additional joints with right hand threads are then coupled to the guide member until it extends up into the cellar above the water line. The base is then lowered with the winches 22 to the position shown in Fig. 2, additional guide member joints being coupled during the lowering operation so that the guide member projects above water level when the base rests firmly on the ocean bottom. Each joint may already have its respective section of the key attached to it, or each key section may be attached, e.g. by welding, as the guide member is assembled. The ends of the lines attached to the barge are then released and the lines are withdrawn from their respective sheaves.

The drill bit and drill pipe are left in the well while the base is lowered so that the conductor pipe is readily guided into the well. The conductor pipe is cemented in place, or formation is allowed to settle around the conductor pipe to seal it in the well. The drill bit may then be either removed immediately or drilling may proceed to whatever depth it becomes necessary to replace the bit or provide for return circulation of drilling mud.

At this point it is desirable to have apparatus which will permit the remote observation of the underwater location adjacent the upper end of the well. The presently preferred form of such apparatus is shown in Fig. 2. A camera guide assembly 70 is adapted to slide up and down the guide member. The guide assembly includes a guide sleeve 71 disposed around and adapted to slide up and down the guide member. The guide sleeve. has a longitudinal slot 72 which slides onthe key and prevents the sleeve from rotating with respect to the guide member. A radially extending bracket 73 is welded at one end to the guide sleeve and at its other end to an upright camera boom sleeve 74. A rotatable and longitudinally slidable tubular camera boom 76 is disposed through the boom sleeve, and a television camera 78 enclosed in a watertight case 79 is attached by a horizontal pivot 80 to the lower end of the boom sleeve. The boom is made upof a plurality of pipe joints 81 threaded at each end and coupled together in a manner similar to that described for the guide member to be watertight. An outwardly extending stop ring 81A is welded to the camera boom at a point spaced from its lower end and prevents the camera case from being struck by the lower end of the boom sleeve. An electrical power cable 82 is connected to the camera and extends through a packing gland 83 (see Fig. 3) into the camera boom and up to the floating barge. The packing gland includes a packing gland nut 84 threaded into a stepped bore 85 in the wall of the boom sleeve. A packing ring 86 is squeezed between the inner end of the packing gland nut and a shoulder 87 in the bore 85 so that a watertight seal is formed around the electrical cable. The electrical cable is a multi-conductor so that the camera can be supplied the necessary electrical power from the barge and so that the signal from the camera can be transmitted to the b rge for the production of a television picture on a suitable receiver (not shown). which may be of a conventional tvpe. The camera housing is w tertight. but as a precautionary measure, an air line 87A is in the multi-conductor cable to supply compressed air from the barge to the camera housing interior to counterbalance the external water pressure.

One end of a cylinder 88 is connected by a horizontal pivot 89 to the upper and rear end of the camera case. A piston 90 is disposed within the cvlinder and a piston rod 91 attached to the piston is sealed through the other end of the cylinder and attached bv a horizontal pivot 92 to the camera boom; A first flexible and hollow line 93 is connected to one end of the cylinder on one side of the piston and a second flexible and hollow line 94 is connected to the other end of the cylinder on the other side of the piston. The

lines

93 and 94 extend into the boom through respective packing glands similar to that shown in Fig. 3 and extend to the surface where they are adapted to receive fluid pressure from the barge to move thecamera about its horizontal pivot.

A horizontal support arm 96 is attached at one end to the upper and forward end of thecamera case and projects longitudinally in fornt of the camera. A horizontal spirit level 98 is attached to the outer end of the support rod to be in the field of view of the camera. A budble 99 in the level and a graduated scale 100 on the level indicate the position of the camera with respect to the horizon, so that an observer on the barge is able to interpret the picture accurately on the receiver.

The operation of the apparatus'of Figs. 2 through 4 is as follows: At any time an underwater observation is to he made,thecamera guide bracket is slipped on to the upper end of the guide post 63 and lowered by means of the camera boom to the desired depth. The camera boom is made up to the required length as the camera is lowered. Once the proper depth is reached, the camera is panned by rotating the boom around its longitudinal axis,

and by swinging the camera case'around its horizontal pivot through the use of

fluid lines

93 and 94. If desired, the camera bracket may be rotated about the longitudinal axis of the guide post by raising the guide post an amount sufiicient to lift the foot 65 above the stop 66. The guide post may then be rotated. The stop also provides means for indexing the camera to a known and reproducible'position any time it is desired. By knowing the exact location of the camera and the relative sizes of the various pieces of equipment around the well, an operator on the barge is able to obtain accurate information rapidly about the condition of the underwater operations.

By having the key 63 terminate some distance above the wellhead base, it is possible to lift the guide post as just described and disengage the key from a bracket (not shown) which may have previously been slipped down the guide post for the purpose of guiding other equipment (not shown) to the well. Thus, the guide post may be disengaged from the previously lowered equipment, and rotated to move the camera bracket to any desired position, without moving the other equipment also. Such other equipment and its guide bracket may take many forms, and since they do not form a part of this invention, they are not shown or described in detail.

A simplified embodiment of the apparatus of Fig. 2 is shown in Fig. 5, in which the camera case is rigidly attached to a camera sleeve 102 which is adapted to slide up and down the guide post. The camera sleeve has a longitudinal slot 104 which fits over the key 63 on the guide post 58. The camera is trained to point in a direction perpendicular to the plane which passes through the longitudinal axes of the well and the guide post. The camera and its sleeve are raised and lowered on the guide post by the means of a flexible multi-conductor cable 105 attached at its lower end by a swivel 106 to the upper end of the camera case.

As shown most clearly in Fig. 6, the multi-conductor cable includes a heavy rubberized protective sheath 107, a core of four inner-woven strands 108 of steel cable, and an insulated multi-conductor electrical cable 109 which extends out of the lower end of the flexible cable and is connected to the camera. The cable also includes two hollow lines 110 which may be used to pan the camera in a vertical direction as previously described, if it is desired to mount the camera by a pivot to the sleeve and use a cylinder and piston arrangement as described for the apparatus of Fig. 2. However, as shown in Fig. 5, the camera is rigidly attached and vertical panning of the camera is obtained by raising and lowering the camera with the cable. Horizontal panning of the camera is achieved by lifting the guide post and rotating it about its longitudinal axis. A level indicating device similar to that shown in Figs. 2 and 3 may also be provided if desired. 7' 1 The apparatus of Fig. 5 has the advantage that it may be rapidly raised or lowered, since all that is necessary is to reel and unreel the cable from a suitable spool (not shown) provided on the barge.

In the apparatus of Fig. 7, a piece of equipment, such as a drill bit 112 is attached to the lower end of a string of drill-pipe 113 and is guided into the well from the floating barge by the use of the camera bracket and a TV camera arrangement similar to that described in Fig. 2. However, with the apparatus of Fig. 7, the camera bracket guide sleeve 71 is disposed around an upwardly extendingand flexibleguide line 114 anchored by a swivel 115 at its lower end to the wellhead base adjacent the well conduit. The guide line is supported by suitable means (not shown) on the floating vessel. An equipment arm 116 is welded to the guide sleeve at a location diametrically opposed to the bracket 73, and extends horizontally toward well conduit 42. An equipment sleeve 117 welded to the outer end of arm 116 is disposed around the lower end of the drill string and rests on the upper edge of the drill bit. An inverted frusto-conical guide 118 is welded to the upper end of the equipment sleeve to facilitate the raising of the equipment guide over the various tool joints usually present in drill string.

The use of the apparatus of Fig. 7 is as follows, with the barge anchored over the well location, the drill string and camera are lowered from the barge on the guide line. The camera is panned as described with respect to the apparatus of Fig. 2 to locate the upper end of the well, and by suitable manipulation of the drill pipe and the position of the barge, if necessary, the drill bit is guided into the Well. The camera may be left in the position shown in Fig. 2 to observe drilling operations, or it may be withdrawn to the barge until needed again.

An advantage of the apparatus of Fig. 7 is that it permits the elimination of upwardly extending guide means anchored around the well location, if desired. It the flexible guide line is omitted, then the camera is panned as it is lowered to locate the well. However, it will be appreciated that guide posts or other means can also be used with the apparatus of Fig. 7 to facilitate the location of the drill bit or other equipment in the well.

Suitable floodlight's may be provided for use with the camera, if the depth or conditions of the water is such to require artificial lighting.

We claim:

1. Apparatus for observing an underwater location in a body of water overlying an earth formation, the apparatus including an upwardly extending guide member attached at its lower end of the formation adjacent the underwater location, a bracket guide sleeve disposed about the guide member and slidable up and down on it, a camera boom sleeve attached to the guide sleeve, a camera boom disposed through the boom sleeve, a camera, means including a horizontal pivot for securing the camera to the boom, and means for aiming the camera about the pivot by remote control from the surface of the water.

2. Apparatus for the remote viewing of an underwater operation comprising a single upwardly extending guide member connected at its lower end to an underwater formation, an underwater camera including means for transmitting signals representative of the camera picture to a remote position, means slidably connecting the camera to the guide member, coacting rib and slot means connected to said slidable connecting means and said guide member for maintaining their relative alignment, means for raising and lowering the camera and connecting means along the guide member, and means for the remote control of the direction of aim of the camera while the camera is adjacent the underwater formation.

3. Apparatus as described in claim 2 and including means for fixing the camera to the guide member with respect to rotational movement thereabout, the guide member being rotatable to horizontally aim the camera.

4. Apparatus as described in claim 2 in which said means for connecting the camera to the guide member includes a bracket and means rotatably connecting the camera to the bracket and in which the means for raising and lowering the camera is also operable to rotate the camera with respect to the bracket so as to horizontally aim the camera, and including means for vertically aiming the camera including a pivotal connection between the camera and said connecting means and a cylinder, a piston disposed within the cylinder, the piston and cylinder being connected between the camera and said connecting means, and means operable to cause the piston to move relative to the cylinder so as to aim the camera vertically.

5. Apparatus as described in claim 4 and including means for fixing the bracket with respect to rotation about the guide member.

6. Apparatus for remote viewing of an underwater drilling operation comprising a wellhead base connected to an underwater earth formation, a well drilling platform floating on the water surface, a tubular guide member extending from the platform to the base, means attaching the guide member to the base so that the guide member may be raised from the base a predetermined amount while remaining connected to the base, means for permitting rotation of the guide member when the guide member is in its raised position and for preventing rotation of the guide member when the guide member is in its lowered position, a bracket keyed to the guide member so as to be longitudinally slidable therealong and fixed in rotary position with respect thereto, an underwater camera, means connecting the camera to the bracket so that the camera is rotatable with respect to the bracket, said means including a connecting member which engages a sleeve on the bracket, a pivot by which the connecting member is attached to the camera, control means operable to aim the camera both horizontally and vertically and lower the camera to a position adjacent the base and raise the camera therefrom, said control means including a cylinder, a piston positioned within the cylinder, the piston and cylinder being connected between the camera and the connecting member and operable when actuated to cause the piston to move relative to the cylinder so as to aim the camera vertically, means connected to the connecting member and operable to rotate the camera adjacent the wellhead base and raise and lower the camera, and a level indicator in the field of view of the camera.

7. Apparatus for remote viewing of an underwater drilling opeartion comprising a wellhead base connected to an underwater earth formation, a well drilling platform floating on the water surface, a tubular guide member extending from the platform to the base, means attaching the guide member to the base so that the guide member may be raised from the base a predetermined amount while remaining connected to the base, means for permitting rotation of the guide member when the guide member is in its raised position and for preventing rotation of the guide member when the guide member is in its lowered position, a bracket keyed to the guide member so as to be longitudinally slidable therealong and fixed in rotary position with respect thereto, an underwater camera attached to the bracket so as to be fixed in rotary position with respect thereto, operable control means to aim the camera when adjacent the wellhead base and including a flexible multiconductor cable swivelly attached to the camera and containing control cables connected between a remote position and the camera, and operable to lower the camera to a position adjacent the wellhead base and to raise the camera therefrom.

8. Apparatus for remote viewing of an underwater operation comprising a wellhead base connected to an underwater earth formation, a wellhead drilling platform floating on the water surface, a flexible guide member extending from the platform to the base and fixed to the base, a bracket enclosing said flexible guide member so as to be longitudinally slidable therealong and rotatable thereabout, an underwater camera, connecting means connecting the camera to the bracket so that the camera is rotatable with respect to the bracket, said connecting means including a connecting member and a pivot by which the connecting member is attached to the camera, control means operable to aim the camera both horizontally and vertically when adjacent the Wellhead base and to lower the camera to a position adjacent the base and to raise the camera therefrom, said means including a cylinder, a piston positioned within the cylinder, the piston and cylinder being connected between the camera and the connecting member and operable when actuated to cause the piston to move relative to the cylinder so as to aim the camera vertically and means connected to the connecting member and operable to rotate and raise and lower the camera.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS McGill Oct. 18, 1921 Allan Oct. 2, 1923 5 Hansen Nov. 13, 1928 Miner et a1. Oct. 9, 1934 Heath Oct. 13, 1936 10 Hartman Nov. 10, 1936 Martine Feb. 13, 1940 Arnold Aug. 13, 1940 Aske Dec. 9, 1941 Gross .June 3, 1947 Lang July 19, 1949 Rand Aug. 25, 1953 Andrews Aug. 31, 1954