US1722623A - High-pressure joint - Google Patents

Description

July 30, 1929. B W LL 1,722,623

HIGH PRESSURE JOINT Filed July 25, 1926 II II K -H II II I I ll WITNESS mum/r01? ,5 fi'rw/m/s A. BR/IMM/ZLL A TTORNEYS Patented July 30, 1929.

UNITED STATES FRANCIS HERBERT BRAMWIEHJL, OF DUNVEGAN, HARTFORD, ENGLAND, ASSIGNOR TO ATMOSPHERIC NITROGEN CORPORATION, OF SOLVAY,

OF NEW YORK.

Application filed July 23, 1926,

This invention relates to joints and its object is to provide a joint which will be tight even to hot gases at high pressures, which may be incorporated in apparatus of relatively large diameter and which may be readily assembled and dismantled. V

A typical example of the invention will be described with particular reference to the cover of a cylindrical forging of four feet internal diameter such as forms the shell of a catalyst apparatus or converter for the synthetic production of ammonia. It will be recognized that the synthesis of ammonia is It usually carried out at pressures of 100, 200, or more atmospheres and at a temperature of about 500 C. or higher, and that therefore the problem of devising a satisfactory gas-tight joint for the covers of such an apparatus is both important and difficult.-

The invention is illustrated in the accompanying drawing which represents a fragmentary vertical section through the upper end and cover of a cylindrical ammonia converter. 7

Referring to the drawing, A designates a cylindrical forged shell having an internal diameter of, say four feet. The cover is designated as D. The shell A has an internally projecting shoulder S. Interposed between the shoulder S and the cover D is a lens-shaped gasket B which is forced into and held in position by a threaded breech ring E engaging the upper surface of the cover. The gasket B is preferably made of a hard elastic metal, for example, mild steel, and may be conveniently termed a lens ring. The lens faces a and b of the lens ring are convex surfaces and are preferably portions of spheres whose centers lie on the axis of the ring. The face a engages an oblique annular face a of the shoulder S, so that the face of the latter is tangential to the surface or face a of the lens ring. Similarly, the

other face I) of the gasket ring engages a face 6' of the cover 1), the latter face I) being likewise oblique and tangential to the face I) of the ring. The faces a and b are therefore portions of cones. The breech ring E is preferably buttress threaded and is provided with any suitable means, so that it may be tightened into the top of the converter. The screwing of the breech ring is liable to cause the rotation of the cover D high pressure 300 atmospheres nxen-ranssuan JOINT.

Serial Ro:124,539, and in Great Britain Jul as, 1925.

which causes scoring of the contacting faces of the joint. This may be prevented in any convenient manner, for example, by keying the cover to the outer shell at K. In using my improved joint, the lens ring is first placed in position on the shoulder S. The cover D is then inserted in the converter so that it engages the keyway and rests upon the lens ring. The breech ring E is then screwed into the head of the converter and tightened into position. The initial contact between the surfaces a--a' and 12 -6 is. linear, but aspressure is applied by tightening the ring E, the lens ring is squeezed between the twoopposed faces, and the surfaces a, a and b, b at the line of contact become slightly flattened and dented respectively, so that the linear contact is developed or extended over a finite width restricted so that the convexly arched faces of the ring only make contact with surfaces at and I) along a proximately an annular line of contact an cent. portions of the sulting engagement between the contacting surfaces is so close and continuous that a 'oint is formed capable of withstanding very igh internal gas pressures such as 200 to per square inch.

Moreover, due to the elastic nature of the engagement, the joint, when once made, is tight, not only under the conditions which prevailed initially, but also under the operating variations of internal gas pressure. The material of the joint is never stressed to its yield point so that only temporary sets and not permanent sets occur. Hence the deformations of the contacting faces are perfectly elastic and adjust themselves to a change in the pressure condition. For example, when the high internal pressure becomes eifective, i. e., when the vessel is put in use, the cover D tends to be lifted slightly, but at the same time the lens ring tends to be extended outwards slightly and the elastic deformation of the joint is suflicient to take up any resultant small relative movement of ring and cover, so that a gas-tight joint is always maintained.

It will be noted that the sealing force applied by screwing down the ring E is applied directly above the line of contact or engagement of the faces b-b and a-a'. This is an important feature of the invention, be-

NEW YORK, A CORPORATION remain out of engagement at adjafaces of the ring. The re cause when the sealing force is not applied in a direction parallel with the axis the circon unction with the large diameter joint would cause the cover to arch about the bolt circle and, would also cause the bolts to extend. These two effects would be suflicient to cause thecover to lift oil? the ring (i. e., the

resultant movement would be more than the elastic deformation of the contactin surfaces could take up) and thus break the joint; but-iffthe sealing pressure is applied as in the example of the invention, directl above the engagement in the joint, any are ing of the cover will not cause any relative movement at the line or surface of engagement in the joint, and the jointwill persist. The breech rin of the drawing is an example of one way 0 applying the sealin pressure in the aforesaid desired manner. ny other suitable means which will fulfill the necessary conditions may ofcoursebeused.

It will be seen that the steeper the angle at which the lens ring engages the converter shell forging, i. e., the steeper the angle which the contactin surface or shoulder a makes with the horizontal, the tighter will be the joint,butthe attendant disadvantages are that the faces a and a are more liable to distortion through the lens ring becoming more tightly jammed and that 1t would be very diflicult to remove the ring if desired. On the other hand, the use of too small an angle would render the makin of a satisfactorily tight joint more diflicu t. I have found that an angle of from about to is quite suitab e for the joint.

I claim: v

1. A high pressure joint comprising two members,having oblique gasket-engagin surfaces, a gasket of hard elastic metal an lens rin in shape having convexly arched faces eac of the two conversely arched faces of I. said ring making contact only along approx- 1,122,eas

imately an annular line of contact with one of the aforesaid oblique surfaces and remaining out of engagement at adjacent portions of the con'vexly arched faces of the rin and means fora plying the sealing force or the joint in a irection' parallel to the axis of the ring-and substantially in line with the said line of en agement between the said convexlyarched aces and the said oblique surfaces. a s

2. A high pressure oint for a pressure vessel of relatively lar e diameter comprising a asket lens ring of ard but elastic metal, an internal annular shoulder with anoblique surface on the inside of the vessel wall con- I tacting with one surface of the gasket,.acover fitted within said vessel with an annular oblique surface contacting with the other surcover fitted within said vessel with an annular oblique surface contacting with the other surface of the gasket anda breech screw screwed into the vessel wall and engaging with said cover to press the contacting surfaces of the gasketjinto elastic engagement with the opposed oblique surfacesfi I 4. Apparatus as set forth in claim 2, in

which the two surfaces of contact of the lens 7 ring gasket are portions of spheres, the centers of which lie on the axis of the ring.

' 5. Apparatus as set forth in claim 2, in which the oblique surface on the annular I shoulder makes an angle of about from 30 to 45 ;with the horizontal.

In testimony whereof I have hereunto set my hand.

FRANCIS H. BRAMWELL.

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