Title of Invention

TUBE FITTING FOR METAL TUBES

Abstract

A tube fitting (50) that uses only two components, namely a fitting body (54) and a fitting nut (52). The nut and body are adapted to be threadably coupled together by relative rotation therebetween. The nut includes an integral tube gripping ring (80) that cooperates with a camming surface (88) on the body when the fitting is made-up. The camming surface (88) preferably has a steep camming angle. The ring (80) is radially compressed against the tube outer wall to form a seal and a tight tube grip. The ring (80) also forms a line contact-type seal against the camming surface (88). The ring is designed to have a hinging action and to plastically deform during pull-up to embed into the tubing for excellent tube grip, and an axially adjacent swage or collect zone that isolates any stress riser resulting from the embedding action from vibration effects. The fitting components, and particularly the ring, may be hardened. the fitting may include a self-gauging feature to indicate sufficient pull-up to prevent excessive pull-up. Also provided is a single ferrule tube fitting that uses a steep camming surface (88) and is at least about 3.3 times harder than the stainless steel tube end.

Full Text

TUBE FITTING FOR STAINLESS STEEL TUBING, Relatt'd Applications This application claims the benefit of United States Provisional patent application serial iiD. 60/266,735 filed on February 6, 2001 for TUBE FITTING WITH INTEGRAL NUT AND FERRULE, the entire disclosure of' which is fully incorporated by reference. Technical Field Of The Invettion The subject invention is generally directed to the art of tube fillings for stainless stee! tubing. More particuiarly, the invention is directed to flareless tube fittings that includ Background of the Invention Tube fittings are used to join or connect a tube end to another member, whether that other member be another tube end such as through T-fittings and elbow fittings, for example, or a device that needs to be in fluid conununication with the tube end, such as for example, a valve. As used herein the terms "tube" and "tubing" are intended to include but not be limited to pipe as well. Any tube fitting must accomplish two important functions within the pressure, temperature ar d vibration criteria that the tube fitting is designed to meet. First, the tube fitting must grip the tube end so as to prevent loss of seal or tube blow out. Secondly, the tube fitting must maintain a primary seal against leakage. The requirement that a tube fitting accomplish these two functions has been the driving factor in tube fitting design for decades. A multitude of factors influence the design of a tube fitting to meet a desired grip and sea! performance criteria, but basic to any tube fitting design will be; 1) the characteristics of the tubing ttiat the fitting must work with, including the material, outside diameter and wall thickness; and 2) tlie tube grip and seal performace level required of the tube fitting for its intended applications. The goal is to design a tube fitting that reliably achieves the desired tube grip and seal functions within whatever cost constraints are imposed on the product by competing designs in the marketplace. A flareless tube fitting generally refers to a type of tube fitting in which the tube end remains substantially tubular, in contrast to a flared tube fitting in which the tube end is outwardly flared over a fitting component. Flared tube ends are commonly encountered in use with pListic ti.bing and plastic tube fittings. The present invention is not directed to plastic tubing or tube fittings because such fittings have significantly different challenges and material properties that affect the ability of the fitting to both grip the tube and provide an adequate seal. Openttiag pressures and temperamres are al:io typically substantially lower in the plastics art. In the tubs gripping device captured axially between the camming surface and the nui. The nut typically includes an inward shoulder that drives the tube gripping device into engagement with the angled camming surface on the body as the nut and body components are threadably tightened together. The angled camming surface imparts a radial compression to the tube gripping device, forcing the tube gripping device into a gripping engagement with the tube end. comes at the expense of having a less effective seal. One result of this situation is that some single ferrule tube fittings have been designed with additional components and techniques to achieve an adequate seal. Less than optimum seal performance is particularly noted in single ferrule fittings that attempt to seal against gas, and espectally high pressure gas. Single ferrule tube fittings thus are usually more suited to lower pressure liquid applications such as hydraulics, however even in such lower pressure applications single ferrule seal performance remains less than desired. For single ferrule tube fittings, the biting action is usually associated with the single ferrule being designed to bow in a radially outward direction from the tube wall in the In order to achieve an adequate tube grip en stamless steel tubing, single ferrule stainless steel tube fittings have historically used a rather shallow carmning angle of between ten and twenty degrees. This range of angles is referred to herein as '"shallow" only as a term of convtsnience in that the angle is rather small. The shallow cainnnng angle has been used in single ferrule fittings to obtain a mechanical advantage because the shallow angle provides an axially elongated camming surface against which to slide and radially compress the single ferrule front end to bite into the tube end outer surface. Hard stainless steel tubing material necessitated this elongaled sliding camming action in order to be able to get the single ferrule to create an adequate bite .for tube grip. Over the years, the single ferrule has been through hardened or case hardened so as to be significantly harder than the stainless steel tubing, however, the shallow cammirig angle is still used today in such single ferrule fittings to obtain a mechanical advantage Because historically the single ferrule fitting has used a shallow camming angle to achitve adequate tube grip, the less than optimum seal function is either tolerated as a recognized limitation on the application of the fitting, or additional features have been designed into the single ferrule fitting, most notably attempts to include one or more elastomeric seals with the single ferrule or with which the single ferrule cooperates to provide a better seal with stainless steel tubing. See. for example, United States Patent ncs. 6,073,976 and 5,351,998. United States Patent No. 6,C73,976 illustrates a typical example of a single "ferrule" (called a "cutting ring" in the parent) fitting that attempts to solve the "sear' issue with added elastomeric seal. The The front ferrule achieves an excellent .seal by camming against a shallow camming surface angle such as twenty degrees- This is because the front ferrule does not need to slide excessively on the camming surface in order to achieve a tube grip function. Likewise, the front ferrule is not case hardened because the primary purpose- of the front ferrule is to seal and is not to bite into the lube end. Thus the relatively "softer" front ferrule achieves an excellent seal, particul;irly against gas,'even though the body conical caroming surface presents a camming angle of about twenty degrees. The back ferrule achieves the tube grip function in the above noted two ferrule tube fltvir-g. Trie back ferrule is case hardened to be substantially harder than the tube end. The front end of the back ferrule cams against a frusto-conical camming surface formed in the back end of the front ferrule. The ostensible angle of this camming surface is forty-five degrees, but due to the sliding movement of the front ferrule, the effective camming angle is actually a shalicw angle of about fifteen to twenty degrees. Although the effective camming angle for the back ferrule is shallow, the back ferrule is not required to provide a primary seal (although it can form secondary or backup seals). The back ferrule also does not exhibit the undesired bowing action but ratlier grips the tube end as a function of a radially inward hinging action. As used herein, the term "hinging" refers to a controlled deformation of the ferrule such that a central region cr mid-portion of the ferrule body undergoes an inwardly radial compression, as distinctly contrasted to a bowing or radially outward displacement. Thus, the effective shallow camming angle not only does not compromise the fining seal capability, it actually substantially enhances the overall performance of the tube fitting especially for stainless steel tubing. By using separate ferrules for each to achieve primarily only one of the key tube fitting; functions, the two ferrule tube fitting achieves tremendous tube grip and seaj functions. This prior art two ferrule tube fitting thus has enjoyed tremendous commercial success especially Summary of the Invention In accordance with one aspect of the invention, a single ferrule tube fitting for stainless steel tubing is provided that achieves a significantly improved sealing function over prior single ferrule tube fittings while also achieving an excellent tube grip function. This sealing function is achieved without the use of additional elastomeric or other non-metal seals. In one embodiment, the single ferrule tube fitting utilizes a relatively steep camming angle for the camming surface of the fitting body. In accordance with this aspect of the invention, in one cmbodiment the camming angle is in the range of at least about 35 degrees to about 60 degrees, and preferably in the range of about forty to about fifty degrees and most preferred to be about forty-five degrees, In. accordance with another aspect of the invention, a single ferrule tube fitting is provided that provides a primary seal against a relatively steeply angled camming surface. In the main embodiment this seal is formed by an outer tapered surface of the ferrule. outer wall to form a seal and a tight tube grip bite. The ring also forms a primary seal against the steeper camming surface. In one embodiment, the ring incldes an outer tapered surface, that is not as steep as the camming sarface angle, forming a generally narrow line contact-t>pe seal against the steeper camming surface. The ring in one embodiment is designed to have a hinging action and to plastic deform during pall-up to embed the nose portion into the tubing wall for excellent tube grip, and an axially adjacent swage or collet zone that isolates the embedded nose porion from vibration effects. The fitting components, and particularly the ring, are preferably but not necessarily case hardened. The new fitting is especially useful as a stainless steel tube fitting, althot.gh the invention is not limited to any particular class of metais. In accordance with any precipitation hardened stainless steel such as 17-4PH for ex.ample, brass, copper alloys, any carbon or low alloy steel such as 1018 steel for example, and any leaded, re-phosphorized or re-sulphurlzed steel such as 12L14 steel for example. An important aspect of the choice of materials is that the tube gripping device preferably should be case or through hardened to a ratio of at least about 3.3 and preferably 4 or more times harder than the hardest tubing material that the fitting will be used with. Therefore, the tube gripping device need not be made of the same material as the tubing itself For example, as will be discussed hereinbelow, the tube gripping device may be selectee- from the stainless steel materials noted above, or other suitable materials that can be case hardened, such as magnesium, titanium and aluminum, to name some additional examples. The cube end 13 preferably bottoms against" a. councerbore 60. The body 56 is machuned or otherwise formed with external mals threstds 62 that threadably mate with corresponding female threads 64 formed or machined in the nut 52. It is contemplated that in order to avoid inadvertent mixing of old and new style body and nut parts with prior art fitting coponents, that the thread pitch on the nut and body of the present invention may be subsiar;.tia]]y different from the thread pitch values of prior .art ferrule-type tube fitting nuts and bodies. This will avoid interchange problems and also allows for a course pitch that providei^ high axial stroke with reduced nnt rotation for complete pull-up. For exajmple, a fitting that incorporates the present invention may use course pitch threads that provide siifitlcient axial displacement to achieve proper pull-up in a half turn. A typical prior art fining by comparison is pulles- up with 1¼ to 1 ½ turns.. Nothing however prevents the designer from making the thread those Situations where; it may be desirable to permit additional axial displacement of the nut 52 relative: to the body 54, such as for example, remakes of the fitting 50, the nut 52 and the body 54 may be axially dimensioned tc retain an axial gap therebetween (for example, between the respective ends 66 and 68) upon completing an initial proper pull-up. In the latter cas^, a gauging tool may be used to verify proper initial pull-up, such as for example, a gap measuring device to confirm that the axiai gap between the surface 66 and 68 does not exceed a towards the back end of the ring 80. The lapered outer surface 86 extendi from a generally radial front end 85 of the gripping device 80, TMs generally radial front end 85 may have 3 small angle or taper and joins to the iner cylindrical bore 82 at a preferably sharp comer 37, AJremsitiveh; however, there may be provided a circumferential recess or step or notch or other geometry (not shown) in the from, end of the ring 80 having a diameter that is somewhat larger than the diameter DJ and axially extending from the from end 85 towards the back end 74 of the niit 52. 82 5Xt«ids tixially from a tapered front or nose portion 84 of the gripping ring 80. The nose portion 84 includes an axiaily tapered outer surface B6 that increases in the radial dimension tpwards the back end of the ring 80. The tapered ou:er surface 86 extends from a generally radial front end 85 of the gripping device 80, This generally radial front end 85 may have a small angle or laper and joins to the inner cylindrical bore 82 at a preferably sharp comer 87. Alternatively, hovvever, there may be provided a circumferential recess or step or notch or other geometry (not shown) in the front end of the ring 80 having a diameter that is somewhat larger than the diam-jter D3 and axiaily extending from the front end 85 towards the back end 74 of the nut 52. the tube end outer surface. Again, this primary seal may ia effect be a back-up or secondary seal to any seal formed by the tube end 13 against the body 54. In any event the gripping ring 80 must form primary seals against the camming surface 88 and the outer surface of the tube end 13. In addition, the ring 80 must adequately grip the lube end 13 so as to maintain seal integrity under pressure, temperature and vibration effects, and to prevent the tube end from separating from the fitting under such circumstances. In order to achieve a fluid-tight seal and tube gripping action, the ring 80 is designed to be plastically deformed and swaged into the tube end upon pull-up, as illustrated in In order to achieve the desired swaging action and tube grip, the ring 80 is desgied to notch 98 that is axially positioned between the cylindrical por.ions 72 aiid 82- The notch 98 is suitably shaped to permit the nag 80 to plasrically deform and collapse in a controlled manner so as to radially compress the cylindrical wail 82 against th-s tube end with the desired collet effect. This result may be enhanced by including an outer notch 100 in the outer wall portion of the gripping ring 80. The particular geometry of the gripping ring 30 will thus be designed so that as the nut 52 is threaded onto the body 54, the gripping ring liinges and plastically deforms to grip the tube end and ro seal both against the nbe end and the tapered camming mouth 88, Standard design procedures such as Finite Element Analysis may be used to optimize the geometry of the rini; 80 based on variable factors such as the tubing material, tubing hardness and wall thickness, to have the ferrule slide a greater axial distance along the camming surface. This greater sliding action permits the tube gripping device to be more graduilly radially deformed into the tube end to form a gripping action or bite on the tube. This is especially the case for stainless steel tubing. Prior lube-fittings that included what might appear to be a steeper camniing angle actually either rely on a shallow portion of the camming surface or do not produce a bite in the tubing, tliereby limiting the pressure resistance of the fitting. The shallow canuning angle of the prior art, however, corprornises the ability of a single ferrule to form a dependable sea!. In sharp contrast^ the pr-isent invention utilizes a substantially steeper camming surface angle Q, which permits tlie gripping ring nose portion 84 in effect to be coined into the camming surface 88 without a Whether the camming surface 88 is formed as a compoxind angled surface with addilional angled portions that are steeper or shallower to facilitate the hinging action and bite of the gripping ring 80 into the tube end 13, in accordance with this aspect of the invention^ the sealing portion of the front end of the gripping ring 80 (in the exemplary embodiments the radius portion 89) forms the primary seal on a steep angled portion of the camming surface 88, preierably a steep angled portion in the range of angle 6 of about 35^-60^ relative to the longitadinal axis X of the fitting 50 and tube end 13, more preferably the angle G of the camming surfacs 88 should be 40°-50°, 5ind most preferred the angle G should be about 45 at the location where the primary seal is to be formed. Preferably although not necessarily this primary sea! is effected by a line contact type engagement: between the front end of the gripping ring 80 and the Various lubricants may also be used with the tube gripping ring 80 to reduce galling and residual torsion such as, for example, PTFE greases, and greases containing molybdienum disulphide or tungsten disulphide. Case hardening techniques typically will result in the entire nut 52 and integral nibe gripping ring 80 to be case hardened. When the case hardening is performed on stainless steel, for example, as in the above referenced patents or patent application, an adherent oxide skin is formed. In another embodiment of the invention, a solid lubricant may be applied to the In accordance with this particular embodiment, this heavy oxide film is not removed before application of the solid lubricant. Rather, it is left on the carburized part surfaces, or at least the portions of the carburized surfaces to be lubricated. In accordance this particular embodiment, it has been found that the naturally porous structure of this heavy oxide skin acts as ar anchor for binding the lubricant to the part surfaces. As a result, the lubricant is more adherent than would otherwise be the case, and hence is able to withstand repeated fining remakes (i.e., looscning and re-tightenning of the nut) without being removed. With reference to FIGS. 5 and 6, in another embodiment of the invention, the fitting50' incudes a nut 52 that may be the same as the nut previously described hereinabove. The body 54' has been modified as follows. In this case, the body rear end wall 110 has been axially extended. A tt'ansition contour 112 may be used to join the end wall 110 to the axially tapered camming mouth 88. All other aspects of the fitting SO' may be the same as the fitting 50 as described with reference to FIGS. 1-4. The extended axial length of the end wall 110 causes the nut inner shoulder or trepan 114 to axially contact the body end wall 110 before the forward wall 66 of the nut engages the body end wall 68. This is illustrated in the pulled-up position of FIG, 6. In other words, the salf-gauging feature has been located at the rearward portions of the nut and body and only requires close tolerance control in the trepan area and axial length of the body rear end wall 110, wherea5 in the ernbodiment of FIGS. 1 and 2. more dimensions and tolerunces are involved in insuring accurate self-gauging due to a greater number of tolerance stack-ups. In accordance with the invention, a single ferrule tube fitting is also contemplated. The single ferrule tubs fitting will be designed v/ith many of the same concepts and advantages achieved with the integral nut and tube gripping device design described herein (wherein now the single Jerrule is the tube gripping device), particularly the features of hinging, tube bhe, collet or swaging effect and high hardness ratio compared to the tube end. Therefore, those benefits will not be repeated in detail, it being recognized that the integral nut and tube gripping ring functions much like the: single ferrule embodiment herein but with the ferrule being integral with the female thtreaded nut. FIGS. 7, 7A and 8 illustrate a single ferrule tube fitting 181 embodiment of the invention. In this example, the ferrule 180 is a separate part, thus providing a three piece tube fitting 181 including a nut 182, body 184 and the single ferrule 180. This fitting is particularly although not exclusively well-suited for use with stainless steel tubing. The body 184 includes an angled camming surface 186 that is preferably in the range for angle 9 described hereinabove and most preferably about 453. The single ferrule 180 is also preferably case hardened to about a Vickers hardness of 800 or greater, or at least about 3.3 times harder than the tube end 13. The front portion 188 of the ferrule includes a radius transition 190 that contacts the steep angled camming surface 186 during pull-up of the fitting to form a line contact-type primary seal against the steep angled camming surface 186, The firont peri ion 188 of the ferrule includes a generally radial front end surface 188a with a forward sharp edg2 192 of the ferrule that bites into the outer surface of the tube end 13- The ferrule is plastically dt^formed and produces a generally radially extending shoulder 194 at the location of the tube bite. The ferrule 180 exhibits a hinging effect a$ described hereinbefore with respect lo the tube gripping element SO so that a central part or mid-portion 196 of the ferrule body undergoes a radially inward compression to collet or swage at or near the tube bite 194. Tne particular geometry of the ferrule may be selected as requred to facilitate the hinging action and tube gripping; bite and collet action as described hereinbefore and also as described in the above incorporated patents on the two ferrule fitting, The fenrule 180 may be provided with an inner circumferential notch or recess 198 to facilitate the hinging effect, as well as a tapered outer wall 20(1' a:; described hereinabove. The ferrule 180 includes a back tapered wall 202 that is driven by the nut shouder 204 during pull-up. The ferrule 180 also includes a central longitudinal and sub5;tantially cylindrical bore portion 206 that is axially between the front end 188a and the recess 198. Preferably, the tapered nose portion 208 is angled so as to remain out of contact with the camming surface during pull-up to facilitate the formation of a line contact primary seal. The Cylindrical bore portion 206a that is axially between the back end 202 of the ferrule and the recess 198 may be the Same diameter or a different diameter as the for^'ard cylindrical portion 206, Furthermore, the hiuging effect may be realized such that the back end portion 206a of the inner cylindirical bore remains radially spaced from and out of contact with the tube end :(3 after pull-up. The single femile 180 is through or case hardened to be at least about 3.3 times harder, and more preferably at least about 4 times harder, than the tube end 13. The aforementioned patents on case hardening may be referred to for suitable processes although other processes may be used as required. The single ferrule fitting 181 thus provides excellent tube grip and seal functions compared to prior art single ferrule fitting designs by utilizing the steeper camming surface angle for the metal to metal seal, substantially harder ferrule compared to the tubing, and strong tube grip biting action- The substantially harder ferrule, as compared to the tubing hardness, allows excellient tube grip even with the steeper camming angle, while the steeper camming angle facilitates the metal to metal seal. The invention has been described with reference to the preferred embodiment, Clearly, modifications and alterations will occur to others upon a reading and understanding of this spedifciation.It is intended to include all such modifications and alterations insofar as they corns within the scope of the appended claims or the equivalents thereof. CLAIMS FOR NATIONAI. STAGE (FOREIGN) Having described the invention, we claim: 1. A tube fitting for metal tubes, comprising: a) a bodv and nut that are threadably joined; said body having an interior bore that is alapted to receive a metal tube end along a central longitudinal axis of the fitting; said bore hiding a camming surface at one end of said bore; b) said nut having an interior shoulder that forms a drive surface; and c) a ferrule having a front end and a back end; said back end engaging said nut drive surface when the fitting is pulled up; said ferrule front end engaging said camming surface during initial fitting pull-up to provide a primary seal; said ferrule fix^nt end plastically deforming and indenting into an outer surface of the tube end; said nut when rotated relative to said body driving said ferrule against said camming surface; d) wherein said camming surface forms an included angle of at least thirty-five degrees to about sixty degrees with respect to said longitudinal axis and said ferrule fitjnt end is at least about 3,3 times as hard as the metal tube end based on the Vickers scale. 2. The cube fitting of claim 1 wherein the tube end is stamless steel 3. The tube fitting of claim 1 wherein said ferrule front end comprises a radius portion that c:ngag€^ said camming surface to form a metal to metal primary seal. 4. The tube fitting of claim 1 wherein said ferrule plastically deforms with a hinging action that produces a radial compression in a central portion of said ferrule against said tube end. 5. The tube fitting according to any preceding claim wherein said ferrule forms a generally narrow line contact seal against said camming surface. 6. The tube fitting of any preceding claim wherein said ferrule has a cylindrical interior bore at said front end and a circumferential recess formed in said interior bore and axirilly spaced from .said front end. 12, The tube fitting of claim 1 wherein said included angl.e of al least forty degrees to about fifty degrees with respect to said longitudinal axis. 13. The tube fitting of claim 1 wherein said included angle is about forty-five degrees with respecr to said longitudinal axis. 14. The tube fitting of claim 1 wherein said ferrule has a front edge that indents into the tube end and. wherein said ferrule front end plastically deforms with a hinging action that produces a racial compression of a portion of said ferrule against the tube end axially behiad said indented front edge to collet said ferrule against the tube end. 15, The tube fitting of claim 14 wherein said ferrule comprises an outer v/all pomon having a concavity between said ferrule front and back ends that facilitates said radial compression to collet said ferrule onto the tube end. 16. The lube fitting of claim. 1.5 wherein said outer wall comprises an axially tapered portion. 17. The tube fitting of any preceding claim wherein said ferrule back end comprises a convex dirven surfave that engages said nut ferrule driving surface diiring fitting pull-up 18. The tube fitting of any preceding claim wherein said ferrule back end is radiallyy' spaced from the tube end after a completed pull-up of the fitting. 19. A meta.1 tube fitting, comprising: a threaded male metal coupling element and a cocperating threaded female metal couplirig element; s:aid female coupling element being in the form of a threaded ctit, said female coupling element comprising an integral metal tube gripping ring that grips a metal tube end when the fitting is assembled onto a tube end; said male coupling element adapted to receive a tu'^e end and comprising an angled camming surface; said gripping ring having a front end that engages ;5aid canuning surface as the fitting is pulled up; wherein said camming sxuface has an included cammiing angle of about 35° to about 60° relative to a central longitudinal axis of the fitting. 20. The fitting of claim 19 wherein said camming angle is about 45*". 21. The fitting of claim 19 wherein said gripping ring front end engages said camming surface. 22. The the fitting of claim 21 wherein said gripping ring plastically deforms with a tingirg action that produces a radisi compression in a central portion of said gripping ring against said tube end, 23. The tube fitting of claim 19 wherein said gripping ring front end fonns a line contact seal against said camming surface. 30. The tube fitting of claim 19 wherein said gripping ring is at lea^t iibout 3.3 timeti harder tJian the tube end on the Vickers scale. 31. The tube fitting of claim 30 wherein the tube end and the nut and body are stainless steel 32. A stairless steel tube fitting, comprising: a threaded male coupling member and a cooperating threaded female coupling member; 38, A metal tube fitting, comprising: a threaded male metal coupling member and a cooperating threaded female metal coupling member; said female coupling member bemg in the form of a female threaded nut; said female coupling member comprising an integral metal tube gripping ring that grips a metal tube end when. the fitting is assembled onto a tube end; said male coupling member adapted to receive a tube end and comprising an angled camming surface; said gripping ring having a front end that engages said catnming surface to form a primary seal as the fitting is pulled up; wherein said, camming surface has an included camming angle of about 35° to about 60° relative to a central longiti.dinal axis of the fitting and said gripping ring is at least about 3.3 times harder than the metal tube end 39. A body for a flareless stainless steel tube fitting of the type having one or more ferrules that grip and seal a tube end, comprising; a main body having a central bore therein that can receive a tube end through an open end of said tody silong a central longitudinal axis thereof; said main body comprising staiiL'^ess steel; a frusto-conical surface at said open end of said main body, said frusto-conical surface fonr.;n.ij an included angle of forty-five degrees with respect to said longitudinal axis, said frusto-conical surface funstioning as a camming surface for a ferrule when the body is assenblcd to fonn a tube fitting. 40. A body for a flareless stainless steel tube filting of the type having one or mon-' tt;be gripping devices that grip and seal a tube end, comprising: a main body having a central bore therein that can receive a tube end througli an open end of said tody along a central longitudinal axis thereof; said main body comprising stainless steel; a frusto-conical surface at said open end of said main body, said frusto-conical surface forming an included angle of forty-five degrees with respect to said longitudinal axis, said frusto-conical surface functioning as a camming surface for a tube gripping device when the body is asserabled to form a tube fitting. A tube fitting for metal tubes substantially as herein described with reference to the accompanying drawings. A body for a flareless stainless steel tube fitting substantially as herein described with reference to the accompanying drawings.

Documents:

1216-chenp-2003-abstract.pdf

1216-chenp-2003-claims filed.pdf

1216-chenp-2003-claims granted.pdf

1216-chenp-2003-correspondnece-others.pdf

1216-chenp-2003-correspondnece-po.pdf

1216-chenp-2003-description(complete)filed.pdf

1216-chenp-2003-description(complete)granted.pdf

1216-chenp-2003-drawings.pdf

1216-chenp-2003-form 1.pdf

1216-chenp-2003-form 26.pdf

1216-chenp-2003-form 3.pdf

1216-chenp-2003-form 5.pdf

1216-chenp-2003-other documents.pdf

1216-chenp-2003-pct.pdf