US1442458A - Superheater pipe connection and method of making the same - Google Patents

Description

Jam, 18, @230 7 1,442,458

D. H. WILSON ET AL SuPERHEATR PIPE CONNECTION AND METHOD OF MAKING THE SAME. FILED 001'. 2 I 920.

@ZZZ.

A TTORIVEYS 2 IN IVTURS M4 Patented Jan. 1%, i923 DAVID H. "WILSON, OF EVOBTEHDEZ'KE, NEW JERSEY, AND JAMES E. FULLER, OF FEEIDONIA, NEW] 1 03K; PATTII INE NELSON ADllilIlTISTIELATBIX OF SAID DAVID H. WILSON, DECEASED.

SUPERHEATEB Z IPE GQNNEGTIQN AND TEETHGTD 0F I'IIAKING THE SAME.

Application filed Gctober- 2, 1920. Serial No. 414,311.

To all whom '52, may concern Be it known that we, DAVID lVILSON, a citizen of the United States, and a resident of Wortendyke, county of Bergen, and State of New Jersey, and JADIES .l l. FULLER, a citizen of the United States, and a resident of Fredonia, county of Chautauqua, State of New York, have invented certain new and useful Improvements in Sunerheater Pipe Connections and Methods of Making the Same, of which the following is a sgeci fication.

Our invention. relates to a method of forming; nipples upon the ends of metal tubes and. is particularly applicable to the tubes of supcrheaters for steam. boilers. Our invention is herein disclosed as applied to that type of superheaters in which the tubes are connected to suitable headers. Que object of our invention is to provide improved nipple which will form a tight joint at the header and which will be cheap, durable, easily asembled, with a homogeneous crystalline structure free from cracks and capable of withstanding high temperatures without burning out. Other objects and advantages will hereinafter appear.

In the accompanying description, we have disclosed one method of carrying; out our invention, reference being had to the accom panying drawing in which:

Figure 2. represents a section of a superheater pipe stock upon the end of which a sleeve of additional metal stock has been fitted.

Figure 2 represents the pipe stock and sleeve shown in Figure 1 after the first heating and forgingoperation has taken place showing the manner in which the shoulder is molded.

Figure 3 shows the same pipe stool: and sleeve in its final condition after the second heating and forging operation, showing the shoulder further upset and the bead which has been formed upon the end of the tube.

Figure 4 shows one of the superheater tubes in operative position with its end clamped into the orifice of the header.

In the manufacture and use of superheaters for steam boilers, considerable trouble has been experienced in fitting the ends of superheater' tubes into the superheater headers. It has been found difficult to make a tight joint capable of withstanding the intense heat to which the parts were subjected without burning" out. In order to avoid this difticulty, superheaters have been made in which the ends of the tube stock have been thickened by crimping and mold .ing into the form of a hollow ball joint, which were then clamped tightly to the header orifices. According; to this crimpingmethod, an armular groove or crimp was first formed in the tube stock near the end. The metal in this crimped portion was then squeezed together and folded back to form an annu lar clamping;- shoulder. The end of the tube was also expanded and folded back into a bead. The above operations were carried out in a suitable upsetting machine in which the heated metal was subjected to pressure between plungers and dies. The superheater tubes formed by the above method were found to be weak, owing to the existence of permanent cracks and laminations sometimes c l in the metal of the tube Jed cold-shui' s which were necessarily formed during; the above mentioned crimping and folding operations.

7' practice many failures occurred in the thickened bead and shoulder portions of these tubes and upon examination, it w s found that the metal of the tube was fatiuu and had a dangerous crystalline structure c sed by the e) ssive deformation to which the metal. gathered up from toclt in the tube was subjected. Morethe microscopic structure of the metal found to be heterogeneous and the metal s also brittle causing frequent accidents iralrino; constant shut dcwns for renewals necessarv. The formation of coldshuts particularly frequent when the diameter of the tube was either smaller or larger than standard, in which case large cracks visible without a microscope were often formed at the shoulder or head.

Another disadvantage in the above method is that an excessive number of distinct operations and heats were required which were very detrimental to the metal structure.

According to the method which we have discovered, the end of a superheater tube may be fashioned in only two operations and the above disadvantages can be entirely avoided. Moreover by our method the strength of the ball joints or nipples will be greater than the strength of the tube stock itself.

In carrying out our improved method the first step consists in fitting sleeve 1 of additional metal stock upon the end of a tube 2, as clearly indicated in Figure 1. The end of the tube 2 with its sleeve is then heated to a forging temperature and placed in the die of any suitable type of upsetting machine, similar to that employed in the method previously described. A suitable plunger or mandrel is then forced into the interior of the tube and pressure applied, causing the added stock of the sleeve to become welded to the pipe stock and up setting a shoulder 13 at the rear of said sleeve without in any way crimping or distorting the original tube stock itself, the metal for the shoulder being entirely gathered from saidsleeve.

The next operation consists in re-heating the end of the tube to a forging temperature and again placing it into the upsetting machine. A second plur 'er or mandrel of slightly diilerent form then forced inside of the tube and pressure applied upsetting the iEOIWLUTl port-i n of the the form of a head 4.- cl approznmately the proper. size to fit the beveled socket 5 of the superheater header 6, the latter being shown in Figure 4C. In this operation some of the metal of the end of the pipe will be turned or drawn outwardly so as to term a part of the outer face of the ball or niple. l

The beaded tip l of the nippleinay then be ground to accurately it the bevelled socket 5 of the header conduit and the rear of the shoulder 3 may be machined in a lathe so that it will [it the collar *4" ot the jaw S of an adjustable clamp. The other jaw of the clamp (not shown) bears upon the opposite side oi the header.

lVhile'we have given an illustration oi the application of our invention to the manufacture of superheatcr tubes it is obvious that the invention may be employed equally eeve into tube.

formed upon the outside of said tube from an additional supply of metal stock.

2 A method of forming a nipple upon the end of a metal tube which comprises providing said tube with a concentric sleeve of additional metal stock, applying heat and pressure to said tube and sleeve to force a part of the sleeve into an annular shoulder, and applying heat and pressure to the outer end oisaid tube and sleeve to force the outer 4:. A method of forming a ball joint or nipple upon the end of a metal tube, to enable said tube to be clamped into a socket opening in a conduit, which comprises providing said tube with a concentric sleeve oi additional metal stock, forming a shoulder on said tube from the: metal of said sleeve in one forging operation and a bead or ball at the end of the tube in a second operation and machining the'ball to lit the socket opening. j

5. A method for forming a ball point or nipple upon the end of atube to enable said tube to be clamped lllilOuZL socket openin a, conduit, which comprises providing tube with a concentric sleeve of additional tube stock, upsetting said sleeve stool: to form a shoulder and an end bead and welding said sleeve, tube, bead and shoulder into a homogeneous mass tree from cracks, said nipple having a strength at least equal to that of the cylindrical portion of the 6. A method oil produchig a nipple or ball joint upon the end oi a metal tube which consists in providing said tube with a sleeve of additional metal stool: and applying heat and pressure to force a part of the metal of said sleeve into the form of a nipple and to molecularly unite said sleeve and tube.

7. A method of producing a nipple or ball joint upon the end oi? a inetal tube which consists in providing said tube with a sleeve of additional metal stock and applying pressure to force a part of the metalot said sleeve into the form of a nipple.

In testimony whereof, we have ailixed our signatures to this specification.

DAVID I'L'VV'ILSON. JAMES E. FULLER,

Images