US3682722A - Quenching of tubular metal articles - Google Patents

Abstract

A METAL PIPE IS SUSPENDED FROM A TOWER BY A HANGER STEM FOR BEING OPERATED ON WITH A QUENCHING PROCESS. AFTER FIRST BEIG HEATED, THE PIPE IS LOWERED TO A QUENCHING ASSEMBLY WHERE ROTATING STREAMS OF CONCENTRATED, HIGH PRESSURE QUENCH FLUID IS APPLIED TO BOTH SURFACES OF THE PIPE SIMULTANEOUSLY. THE ROTATING STREAMS ARE PROVIDED BY CONCENTRIC INNER AND OUTER ROTARY QUENCH HEADS, BETWEEN WHICH THE PIPE TELECSCOPES. THE INNER HEAD IS OPERABLY SUPPORTED IN A WELL BY AN INNER STEM, WHICH HAS A SHELL BENEATH THE QUENCH HEAD.THE SHELL IS ENGAGED BY A GUIDE ARM ASSEMBLY TO CENTER THE STEM AND INNER QUENCH HEAD WITHIN THE WELL. WHEN THE PIPE IS LOWERED TO THE LEVEL OF THE GUIDE ASSEMBLY, THE GUIDE ASSEMBLY DISENGAGES THE SHELL AND GUIDES THE PIPE TO CENTER IT BETWEEN THE QUENCH HEADS.

Description

z- 1972 G. WINSTROM QUENCHING 0F TUBULAR METAL ARTICLES 3 Sheets- Sheet 1 Filed March 23 1970 FIGJ INVENTOR. BERTIL G. WINS TROM 8- 1972 I a. G. WINSTROM v 3,682,722

QUENCHING OF TUBULAR METAL ARTICLES Filed March 23 1970 3 Sheets-Sheet 2 I. INVENTOR. BERTIL G. WINSTROM Attorneys l- 3, 1972 a. G. WINSTROM 3,682,722

QUENCHING OI" TUBULAR METAL ARTICLES Filed March. 23 1970 3 Sheets-Sheet 5 FIGA INVENTOR.

Attorney's BERTIL. G. WINS TROM- United States Patent O 3,682,722 QUENCHING F TUBULAR METAL ARTICLES Bertil G. Winstrom, Mequon, Wis., assignor to A. 0. Smith Corporation, Milwaukee, Wis. Filed Mar. 23, 1970, Ser. No. 21,774 Int. Cl. C21d 9/08 US. Cl. 148143 1 Claim ABSTRACT OF THE DISCLOSURE A metal pipe is suspended from a tower by a hanger stem for being operated on with a quenching process. After first being heated, the pipe is lowered to a quenching assembly where rotating streams of concentrated, high pressure quench fluid is applied to both surfaces of the pipe simultaneously. The rotating streams are provided by concentric inner and outer rotary quench heads, between which the pipe telescopes. The inner head is operably supported in a well by an inner stem, which has a shell beneath the quench head. The shell is engaged by a guide arm assembly to center the stem and inner quench head within the well. When the pipe is lowered to the level of the guide assembly, the guide assembly disengages the shell and guides the pipe to center it between the quench heads.

BACKGROUND OF THE INVENTION This invention relates to heat treatment of tubular articles and in particular to an improved method and apparatus for quenching metal tubular articles.

It has been found that in quenching metal tubular articles such as pipe, it is important to provide a continuous stream of quenching media to obtain uniform martensitic steel of superior physical properties. This is particularly true where low carbon steel is used. The rate of quench greatly influences the properties of the steel, and thus, if uniformity of the steel is to be obtained, the quenching must be uniform. Uniform quenching is also necessary to avoid unequal stressing and deforming of the metal article, which could be an increased problem with large objects such as large pipes.

It has been thought that tubular articles should be rotated during the quench to assist in obtaining uniformity. Relative rotation during quench tends to negate any variations in the quench stream, such as would occur Where some of the nozzles which supply the stream get plugged or where some quench streams separate or are misdirected.

However, rotating the pipe would not provide a fully satisfactory answer. It is difficult to obtain a high enough rate of uniform rotation with a large, hot pipe and at the same time maintain the uniform distances between the pipe surfaces and the quenching apparatus, which is necessary as well to obtain uniform quenching. Small variations in weight distribution of the pipe could cause exaggerated vibration during rotation, thus destroying the uniformity that is sought.

It is not, furthermore, a simple matter to rotate the pipe during quenching. The pipe cannot be permitted to deform, but the machinery which is necessary to rotate a hot pipe could itself cause deformation, scratching and non-uniform stressing. Further, there is a problem in maintaining the rotating apparatus, as it requires cooling to avoid rapid deterioration of parts in the proximity of the hot pipe and heat treating equipment. Cooling such an apparatus is difiicult and expensive.

SUMMARY OF THE INVENTION This invention provides a novel way of quenching tubular, metal articles, primarily to improve the uni- Patented Aug. 8, 1972 formity of the metal and to avoid the difficulties noted above. Various other advantages will appear in the drawings and specification.

In the practice of the invention, heated surfaces of a tubular article are quenched by concentrated high pressure streams of quenching fluid, which are simultaneously rotated over opposite portions of the inside surface and outside surface of the tubular article. The tubular article moves through a quench station for this purpose, and is guided by means disposed beyond the quench station so that the quenched portion of the article is generally the only portion of the article engaged with members which could deform or scratch hot metal.

This method is practiced with a particularly advantageous apparatus forming part of the concept of the invention. A vertical heat treating rig supports the tubular article over the quench station, and can as well, have a heating station over the quench station. By means of a hanger device, such as a stem operably connected toward the top of the rig to a drive and connected to the tubular article, the tubular article is lowered from the heating station at a controlled rate through the quenching station. At the quenching station, inner and outer rotary quench heads direct quench streams to both surfaces of the article as it telescopes between them. The outer head is secured by any suitable means to a platform or other external apparatus at the top of the quench station, while the inner head is supported in spaced relation from the other head by a support stem extending vertically upward from a base. The tubular article is telescoped over the stem and over the inner quench head.

This latter stem should be of sufficient length to permit lowering of the entire tubular article over the inner quench head. Because of this length, the stem and inside quench head would have a tendency to sway or otherwise vary its spacing from the article being quenched, and it is another aspect of the invention to center the stem and head with a guide assembly. The guide assembly is disposed near the top of the stem, beneath the inside quench head, and includes a guide arm apparatus which is normally biased against the stem to center it beneath the rig. The guide arm apparatus is retractable, permitting the tubular article to engage it as the article is lowered beyond the inner quench head. This disengages the guide apparatus from the stern, which then is urged against the tubular article to center it in relation to the quench heads.

For most perfect operation of the guide assembly, a guide shell around the inside stem is included. This shell extends radially outward from the stem to approximately the diameter of the tubular article. Before the article is lowered over the stem, the guide arm apparatus engages the shell. The tubular article, then being telescoped over the shell and stem, disengages the arm apparatus and slides between the arm and the shell, thus centering both the tubular article and the stem and inside head assembly. These assemblies serve to maintain the quench head uniformly spaced from the article surfaces, thereby greatly facilitating the uniformity of DESCRIPTION Shown in the drawings is an apparatus for heat treating and quenching a large steep pipe 1. A tower rig 2 is supported by a base platform 3 to rise vertically a height in the area of twice the length of pipe 1.

Pipe 1 is suspended from a top platform 4 of tower 2 by a hanger assembly 5, which is a metallic tubular stem 6 attached to a flexible cable 7 that is wound over a pulley on platform 4 to a winch reel '8 disposed at any suitable location on the tower. Attachment of thev hanger assembly to the pipe is accomplished by an annular cap 9 fitting against the top end of pipe 1. Cap 9 may be welded to the pipe end and cut off when the pipe is removed from the facility, while it may be releasably connected in any suitable fashion to the lower end of stem 6, as by a handle and lock assembly 10 shown in FIG. 1.

Winch reel 8 is driven in both directions by a motor 11 to rise and lower the stem and pipe through a heating station 12 and a quenching station 13 beneath the first station.

. At the heating station, stem 6. disposes pipe 1 in a furnace chamber 14. The furnace is supported on a carriage 15 which rolls by suitable means over platform 3 to move the furnace in and out of position. Chamber 14 is closed and stem 6 extends through a hole 16 in the top wall thereof. Similarly, when it is desired to lower the pipe through the quenching station, a set of trap doors 17. on the bottom wall of the furnace are opened.

Facilitating the loading of a pipe into the rig, a lift 18 operates to theside of furnace 14. Lift.18 may be a hydraulic apparatus disposed in a well beneath platform 3. A frame having suitable means for confining pipe 1 therein is operated by the hydraulic apparatus to pivot from a horizontal loading position to a vertical position beneath hanger assembly 5, where the pipe may be unloaded by suitable means and connected to stem 6.

For most convenient operation, handle and lock assembly 10, is welded to the pipe when it is loaded on hydraulic lift 18. The pipe is then raised to the platform by lift 18 when furnace chamber 14 is moved to the side of the tower. Stem 6 is lowered and locked in place on assembly 10. Lift 18 is then withdrawn and the hanger assembly is operated to lower the pipe to rest beneath platform 3. Stem 6 is unhooked and withdrawn so that chamber 14 can be moved into position above the pipe. Then the stem is lowered through hole 15 and again locked into cap 9. The pipe is raised through open doors 17 and the heating process is begun.

In accordance with the invention, the heated pipe is quenched by lowering it through quench station 13, from furnace 1 through trap doors 17 in this example. The pipe passes freely through the quench station to be quenched with concentrated quenching fluid 'streams which may be high pressure water streams pressurized of 90 degrees per second to 270 degrees per second.

A plurality of streams are directed radially outward and downward about the full circumference of the inside surface of the pipe, covering a short longitudinal section of the pipe at any instant. Similarly, the quench of the opposite outside surface is performed simultaneouly on the same longitudinal portion with a plurality of streams directed radiallyinwardly and downwardly about the full outer circumference of thepipe. In this manner and by rotating the streams, a rapid, uniform quench is performed on the portion of the .pipe which is being lowered through quench station 13.

The apparatus for quenching as described above .is disposed over a well 19 which may be a cylindrical hole under platform 3 and is aligned with the heat treating and quenching stations. Any sort of walls may form the well, while its size should be sufficient to receive 4 pipe 1 and to leave space for the flow of quenching fluid between the pipe and the Well walls.

To support an inner quench apparatus 20 over the central axis of well 19, a support stem 21 extends up ward from base 22 on the bottom wall of well 19. Stem 21 is a hollow metal tube aligned co-axially with hanger stem 6 and thus pipe 1, and generally centrally of the well. The diameter of stem 21 is such that pipe 1 may be lowered and telescopedeasily over the stem as limited by a shield or cap over apparatus 20 and secured to the top of stem 21.

As shown best in FIGS. 2-4, quench apparatus 20 is supported by support stem 21 at quenching station 13 over the well. Apparatus 20 extends radially outwardly from stem 21 to a diameter less than the diameter of pipe 1, so that the pipe can telescope over it as well. Included in apparatus 20 is a rotary quench head 23 that provides the rotating inside quench streams in accordance with the invention. Quench head 23 has a doughnut shaped drum 24 journalled on support stem 21 for rotary movement about the stem. Drum 24 defines a chamber by a top wall 25 and a bottom wall 26 separated by a plurality of internal struts 27, and a cylindrical nozzle plate 28 defining the outermost side wall and connecting to the top and bottom walls by means of annular end spacers 29. Top and bottom walls 25 and 26 have annular side portions 30 which are aligned with the stem exterior and are slightly spaced therefrom. These portions extend to annularly spaced openings 31 through the stem wall, and define a complementary annular opening 32 into drum 24 from stem 21. To seal the chamber to the stem, side portions 30 have annular flanges 33 slidably engaging the exterior surface of stem 21.

Thus, drum 24 is adapted to receive quenching fluid from stem 21 and to rotate about the surface of the stem. To confine the drum to its vertical position, an upper bearing 34 and a lower bearing 35 are fastened. or welded to stem 21. Bearings 34 and 35 are annular members with L-shaped cross sections, one leg on each fitting in the space between its respective side portion 30 and the stern, and the other leg fitting against the respective top or bottom surface of respective walls 25 and 26. To provide support for the chamber, lower bearing 35 has an annular brace 36 fixed to the stem immediately beneath the bearmg.

Additionally, the chamber may be sealed by a pair of annular resilient seal rings 37 filling the space between flanges 33 and the adjacent ends of bearings 34 and 35. With this bearing and seal structure, drum 24 is maintained for rotation in one vertical position about stem 21, from which water is supplied the drum.

Nozzle plate 28v is coaxial with stem 21 and should be spaced closely to the inside surface of pipe 1 as the pipe is quenched. The quenching streams are provided by a plurality of nozzles 38 communicating with the drum chamber from around the outside surface of the cylinder. For rapid and'uniform quenching, the nozzles should be in several rows, stacked vertically, with nozzles placed fully around the cylinder. Each nozzle 38 is slanted downwardly so that the quench fluid has a downward velocity imparted to it and will flow away from the pipe surface before vaporizing, in accordance with the teaching of Patent No. 3,294,599. Further, the number of rows of nozzles 38 would not be large, as'the high pressure of about 1,000 psi. of the quenching streams, the size of the nozzles and the other characteristics of the quenching system provide a rapid, concentrated quenching of the full thickness of the pipe. Thus, although the number of rows may be increased for thicker pipe, it is not necessary to provide any more than would cover a small longitudinal section of the pipe at any instant.

Quenching fluid such as water is supplied to the inside of stem 21 via a pipe 39 from a pump system, not shown. Stem 21 carries the fluid to drum 24 through openings 31 and 32, and has a sealing cap 40 on its top. Ultimately,

the fluid is directed against the inside of pipe 1 by nozzles 38'. The spent fluid may be permitted to build up in Well '19, as shown in FIG. 1, to a sewer level, where a drain pipe 41 drains it. Alternatively, a pump station, not shown, could be provided to recirculate and reuse the fluid.

The inner rotary quench head 23 is driven by any suitable means such as a pair of hydraulic motors 42. The motors are also supported by stem 21 on seal cap 40. Each motor 42 has a pinion gear on its shaft to mesh with a complementary inner gear 43 secured on top wall 25 of drum 24. Oil under pressure is circulated through motors 42 via pressure lines 44 that extend through cap 40 and inside stem 21 to the bottom, where they again extend through the stem to an oil pump 45. Thus, by starting the pump 45 in a conventional manner, quench head 23 is rotated about stem 21.

For quenching the outside surface of pipe 1 at quenching station 13, an outer rotary quench head 46 is provided opposite head 23. A stand 47 supports head 46 on the top of well 19 and is secured to a supply drum 48', which is an annular chamber aligned coaxially with support stem 21. Drum 48 is defined by a cylindrical side Wall 49, a top wall 50, and a bottom wall 51, all of which are annular and may be integrally formed as by casting. Top and bottom wall 50' and 51 have side portions 52 extending toward each other from their inside ends. These each have a horizontal flange portion 53 protruding inwardly around the annulus to provide a bearing surface and further defining an annular opening 54 to drum 48- on its inside radius.

A cylindrical rotating drum 55 has openings 56 complementing annular opening 54, the former being holes in a side wall 57 which rests against the bearing surfaces of flange portions 53. Drum 55 is further defined by top wall 58 and bottom wall 59 integrally formed with side wall 57. On the inside radius of drum 55, an annular nozzle plate 60 is attached by suitable means to the inside radius ends of walls 58 and 59.

Drum 55 rotates against the inside radius of annular drum 48 and for this purpose annular bearing plates, 61 having L-shaped cross sections, are each disposed with one leg between respective side portions 52 of the stationary chamber and side wall 57 of the rotary chamber. A second leg of each bearing plate 61 extends over its respective top or bottom wall 50 or 51 of the stationary chamber where the plate is connected as by bolts or screws. Rotary drum 55 has plates 62 complementary to the horizontal legs of bearing plates 61. One is bolted to bottom wall 59 and fits slidably against the bottom surface of the bottom bearing 61. The other plate 62 is bolted to top wall 58 to extend slidably across the top surface of the top plate 61 on the stationary drum.

The bearing plates on the drums thus confine rotary drum 55 in one vertical position for rotation against the inside radius of supply drum 48. To seal this arrangement along annular opening 54, a pair of annular resilient seals 63 are confined in the respective spaces between side portions 52 and side wall 57 and also between the adjacent ends of plates 61 and flange portions 53 at annular opening 54.

Quenching fluid will be provided via pipe 64 to supply drum 48 and through complementay openings 54 and 56 to rotary drum 55. Nozzle plate 60 is opposite nozzle plate 28 of inside quench head 23 and is spaced radially outward therefrom at a diameter from the axis of stem 21 larger than the diameter of pipe 1. This spacing permits pipe 1 to be lowered and telescoped between the annular nozzle plates. As with the inner quench head, the quenching fluid is directed from chamber 55 in high pressure streams against the outside surface of the pipe by a plurality of nozzle 65 in plate 60. Nozzles 65 have characteristics like nozzles 38 and, similarly, are spaced around the inside radius of drum 55. High pressure quenching streams thus are directed to opposite surfaces of the pipe as it is lowered through quenching station 13, for rapid and uniform quenching. As before, the spent fluid flows into 'well 19.

To drive rotary drum 55, hydraulic motors 66 are attached by suitable braces to side wall 49 of the stationary drum. Supplied with circulating oil from pump 45 by lines 67, the motors have pinion gears 68 on their shafts for meshing with gear teeth 69 formed on the outside radius of top plate 62. Plate 62 being attached to rotary drum 55, the operation of the motors will drive drum 55 for rotation within the stationary drum and around pipe 1.

Thus in operation, quench heads 23 and 46 provide rotary quenching streams against opposite surfaces of pipe 1 as the pipe is telescoped between them. Should any nozzles clog or other aberrations occur, this rotation will nullify any adverse effect on the uniformity and rapidity of the quench.

Another aspect of the invention is shown best in FIGS. 3 and 4. It is preferred to have as little as possible contact between the pipe and the processing apparatus on portions of the pipe which are hot. For this reason a guide assembly 70 is provided beneath quenching station 13. Assembly 70, in accordance with a further feature of the invention, serves as a guide for the pipe and, as well, a centering device for stem 21 and quench head 23. A shell 71 is attached to support stem 21 at the top of well 19 for this purpose. The shell is cylindrical and coaxial with stem 21, with a circular top wall 72 extending radially outward from the stern and a cylindrical side wall 73 depending from the end of top wall 72. Bracing is provided by shelves 74 on the stern and extending radially outward therefrom beneath top wall 72.

To center the stern and thus maintain the centered position of inside quench head 23, an important feature for uniformity of quench, a centering and guide means such as a biasing lever 75 urges a roller 76 against shell 71. Lever 75 is supported to the outside of the quenching station on top of the wall of well 19. The lever is attached as by a shaft to roller 76 and extends through an opening in stand 47 to which it is pivotally attached by a shaft of a pivot assembly 77. Beyond pivot 77, lever 75 angles downward to a pivotal attachment with a biasing means 78. Means 78 may be a hydraulic cylinder and piston with a shaft 79 pivotally connecting to lever 75 to urge the lever and roller 76 inwardly. A number of identical assemblies may be employed in guide assembly 70 to thus center stem 21.

Pipe 1 will engage rollers 76 after it passes through quenching station 13. In so doing, the pipe rotates levers 75 downward which then disengages the rollers from shell 71 and urges the rollers against the pipe. This action provides guiding for the pipe as it is lowered over stem 21. To further guide the pipe, a set of guide shoes 80 are provided on shell 71 opposite rollers 76. The shoes each have a lead surface 81 at a radius from the stem axis which is slightly less than the radius of pipe 1, to thus limit the lateral movement of the pipe as it is lowered, and also limit the sway of stem 21 when the rollers are disengaged from shell 71.

The described guide means operate to increase the uniformity of quenching by maintaining the spacing between the pipe and the nozzles at all times. Further, scratching or deforming of the pipe is avoided, since the guide means contacts quenched pipe only.

Overall operation In accordance with the invention, pipe 1 is first loaded on lift 18 when cap 9 is welded to the pipe, and then transferred as described earlier to furnace chamber 14 which is positioned under hanger assembly 5. Stem 6 is finally attached to the pipe, while lift 18 has been disconnected and withdrawn for subsequent loading, as described previously, and the pipe is then heated in the furnace.

After being heated to normal steel treating temperatures, the pipe is lowered at a controlled rate by operating winch reel 8 through trap doors 17 and through quenching station 13. The quenching operation is begun by starting oil pump 45 to drive the rotary quench heads, and at the same time operating the quench supply pump system to provide high pressure, rotary quench streams.

The pipe, being lowered at a controlled rate, telescopes over inside quench apparatus 20 and support stem 21 and within outer quench head 46. The quenching fluid is applied in accordance with the invention, as described previously.

The pipe passes through the quenching station until it is fully quenched. Cap 9 will at this time be resting on the top of the shield over quench apparatus 20 to support the pipe. Then, pump 45 and the quench supply system are shut down to terminate the quenching operation. At this time it is preferable that cap 9, handle 10 and at least the lower part of stem 6 should be cooled as by water spray assemblies, not shown. This serves to preserve the lives of these parts.

Stem 6 is then unlocked from handle 10, leaving the pipe to be supported by stem 21 and the shield over inner quench apparatus 20. By operating winch reel 8 in reverse, stem 6 is withdrawn through furnace chamber 14 to above the furnace. Carriage is operated to remove the furnace from the tower and stem 6 is returned to be locked with handle 10. Winch reel 8 is again operated in reverse to raise pipe 1 out of well 19 and above platform 3. Lift 18 is then operated to remove the pipe from the tower, after stem 6 is unlocked, for unloading and subsequent heating and quenching operations on other pipes.

In this manner and with the described apparatus, the practice of the invention results in rapid, uniform quenching without risking scratching or deforming of a tubular metal article.

Various modes of carrying out the invention are contemplated as being within the scope of the following claim which particularly points out and distinctly claims the subject matter which is regarded as the invention.

I claim:

1. A method of vertically quenching a heated tubular metal article throughout the body of the article comprising operably supporting the heated article from above, leaving generally free the main portion of the article, lowering the heated article through a quenching station, circumferentially rotating at said station concentrated high pressure separate streams of quenching fluid in a plurality of vertically stacked parallel rows into contact with the inside of the heated tubular member over a generally short longitudinal portion of the tubular member and directed radially outwardly and downwardly about the full circumference of the inside surface of the tubular member, and simultaneously circumferentially rotating at said quenching station concentrated high pressure separate streams of quenching fluid disposed in a plurality of vertically stacked parallel rows into contact with the directly opposite longitudinal portion of the outside surface of the heated tubular member and directed radially inwardly and downwardly about the full outer circumference of the tubular member, the pressure of said streams of quenching fluid being of the order of 1000 p.s.i. and the rate of rotation of said streams being in the range of degrees to 270 degrees per second.

References Cited UNITED STATES PATENTS 2,295,272 9/1942 Somes 148-143 2,556,236 6/1951 Strickland 148152 3,294,599 12/1966 Huseby 148 -143 RICHARD O. DEAN, Primary Examiner US. Cl. X.R.

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