JPH0444158B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to fittings for lined piping systems, and more particularly to metal fittings lined with non-metallic materials intended for service, including vacuum applications. related to class.

Metal pipes lined with non-metallic materials, usually thermoplastics, have been known for quite some time and are commonly used to process a variety of materials ranging from corrosive acids to food products. .
One type of such pipe consists of a metal housing, usually steel, lined with a layer of extruded thermoplastic resin. Generally, the lining is of sufficient thickness and has enough trapped stresses to allow the plastic to withstand crushing when subjected to high vacuum, even in sections of large diameter pipe. loked in stress)
can be economically produced with however,
Pipe fittings that are subject to vacuum, such as cheese, etc.
When working with cross and wye joints, branch openings greatly weaken the liner and interrupt the annular cross section, requiring uneconomical thickness to withstand crushing under the action of high vacuum. be done.

Vacuum crushing of the liner can be applied to fittings approximately 152 mm (6 inches) or larger lined with one of PTFE, FEP, PEA, and PVDF in fluorocarbon resins, or polypropylene. is particularly relevant to In a somewhat related environment, ie, in the case of a compressible tube valve, resistance to vacuum is provided by securing the tube to the valve compressor member by interconnecting links. Details of such an arrangement are disclosed and claimed in my U.S. Pat. and is assigned to the same assignee as the present invention.

SUMMARY OF THE INVENTION It is now possible to embed an anchor within the wall of a molded liner for a pipe fitting, and to attach the externally protruding portion of the anchor to the surrounding metal housing by welding, without seriously degrading the plastic material. It has been discovered that it is possible to fix it to the wall.

According to one feature of the invention, a metal housing lined with a non-metallic liner of molded material, a first part embedded and fixed within said liner and a second part projecting from said liner and welded to said housing. A lined piping system fitting is provided comprising at least one metal anchor having two parts.

According to another feature of the invention, the first portion of the liner is molded of a non-metallic material and is embedded within the non-metallic material and the second portion projects from a radially outer surface of the liner. means for selecting a liner for said fitting having sections; and means for assembling parts of said housing around said liner; and means for assembling said parts together and said housing to form said housing having said liner secured to said housing. A method is provided for assembling the joint comprising means for welding to the second part of the anchor.

The invention will be better understood from the following detailed description of the presently preferred embodiments, taken in conjunction with the accompanying drawings. The same reference numerals are used throughout the drawings to indicate the same or similar parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference should now be made to FIG. 1, in which a reducing cheese 10 embodying the invention is illustrated. In this example, the cheese joint 10 is the weld seam 1
It has a metal housing formed from run stub ends 11 and 12 joined by 4 and 15 and a vertical stub end 13 and provided with vanestone flanges 16, 17 and 18. The housing of the fitting 10 is lined with a liner 19 of a molded non-metallic material, ie isostatically molded polytetrafluoroethylene (PTFE). As shown, the continuous end of the liner 19 and the end of the stand are opened radially outwardly over the flange surface formed on the stub end.

If a fitting such as that just described with respect to FIG. The liner 19 generally has a constriction that occurs parallel to a plane containing the seam 14 and the longitudinal axis of the vertical tube stub end 13, and has a tendency to collapse or contract within the range indicated by the imaginary circle 20. Probably. However, the structure described below prevents such damage.

Referring to FIG. 2, the liner 19 is shown here before being assembled within its metal housing. A liner 19 intended for a cheese joint is a series of parts 21 that intersect at a joining line 23
and a vertical tube part 22. The length of each part of liner 19 must be long enough to allow for radially outward opening, as shown in FIG.

For a series of parts 21, there are two diametrical points (of which only one point 24 is the (See Figure 2)
A metal anchor 25 made as shown in FIG. 4 is embedded in each of the holes. The anchor 2
5 consists of a metal plate 26 and a metal stud 27, the latter being joined to the plate 26 by welding. The plate 26 is provided with a series of openings or holes 28.

The dimensions of anchor 25 and its relative position within the wall of liner 19 are best seen in FIG. As shown, plate 26 is completely embedded within the material of liner 19. Studs 27, on the other hand, project outside and above the radially outer surface of liner 19. Bearing in mind that the exposed portion of stud 27 is joined by welding to the surrounding metal housing when assembled with the metal housing, dimension A is the size that liner 19 contains when subjected to vacuum action. The minimum thickness for the material to be used must be selected to provide adequate strength to withstand pullout of the anchor 25.
The dimension of plate thickness C must be sufficient to provide the necessary mechanical strength to withstand bending of plate 26 when high vacuum stresses are applied to liner 19. The thickness, represented by dimension D, is determined by the expected service requirements for corrosion resistance, erosion resistance, abrasion resistance, and the like. Dimension B is a function of the cumulative requirements for A, C and D.

Under the action of a vacuum, the stud 27 is placed in tension and its diameter is selected to resist rupture under such conditions. The length of stud 27 will be discussed later.

Holes 28 are provided in plate 26 to ensure that the plastic of liner 19 is bonded to anchor 25 and that the radially inner and outer layers 29 and 30 of plate 26 are joined together.
The shape of plate 26 may be varied as desired so long as it fulfills the function ascribed to it therein.

The cheese joint 10 of FIG.
8 pre-installed corresponding stub end 1
1, 12, and 13, by assembling the continuous part and the vertical tube part. It will be appreciated that the stub ends 11, 12 and 13 are each preformed with a flange or flare at one end and a weld bevel or conventional chamfered or beveled edge at the other end. There will be. However, in a departure from conventional practice, the weld bevels of stub ends 11 and 12 are suitable for accommodating the protrusion of the anchor stud 27 within the weld area, as best seen in FIG. preferably cylindrical in complementary position;
It has a cutout.

Referring to FIG. 5, there is shown a weld bevel 31 in a series of stub ends 12 of the housing having a face 32 perpendicular to the longitudinal axis of the stub end 12 as well as a bevel face 33. The groove 31 has a stub end 1 in order to accommodate the stud 27.
A notch 34 is formed which cooperates with a trapezoidal notch of 1 (not shown). Stud 27 is
It must be appreciated that it should be of sufficient length to protrude into the V-shaped section that is filled with deposited metal and contains a pool of molten metal during the welding operation. Stud 2
The top of 7 should be below the outer diameter of the metal housing, but above the break line where the bevel surface 33 begins. If the weld is done properly, it should generally look as shown in FIG. The weld must be controlled so as not to penetrate too far below the groove line 35. If it penetrates too close to the inner diameter of the metal housing, it will cause the quality of the liner 19 to deteriorate. For example, if the liner
If PTFE were made, the resin would undergo overheating and outgas.

Anchor 2 whose fittings are made of stainless steel
5 and the stub ends of the carbon steel housing have been assembled as described above. Successful welds were made using metal inert gas welding equipment.

If the small branch pipe is larger than approximately 152 mm (6 inches),
For reducing fittings where the larger branch is no larger than about 8 inches, it is believed that two anchors placed as described above will be sufficient.
Runs with larger diameter pipes
1, it would be necessary to include an anchor with an additional stud located at the intersection of seams 14 and 15 in FIG.

The present invention is not limited to reducing cheese fittings, but is equally beneficial to standard cheese fittings as shown in FIG. 7 as well as standard crosses as shown in FIG.

Referring to FIG. 7, a standard cheese has a metal housing formed from a series of stub ends 41 and 42 and a vertical stub end 43 joined by seam welds 44 and 45. Seams 44 and 45 intersect at a point 46 on the side of the joint visible in the drawing as well as at a similar point not visible on the opposite side of the joint. The stud 27 of one anchor 25 is welded into the seam at point 46, and the stud 27 of the other anchor is similarly welded into the seam at the opposite point mentioned above. The liner 49 of the joint in FIG.
9, but consists of a continuous section and a vertical section of equal diameter. In all other respects, the joint of FIG. 7 is similar to that described with reference to FIG.

In FIG. 8, a cross joint 50 is shown assembled similar to the cheese joint described above. Preferably, the two anchors are fitted with a liner 51, one on each side, such that the studs coincide with the intersection of the seam welds represented by points 52 in the figure.
will be incorporated into. The second point is exactly the opposite.

As mentioned above, the liner of the joint is molded in a flat state. This method is suitable for resins such as PTFE. This is because equilibrium state molding (isostiatc
The cost of raw materials for molding is less than that for extrusion. Another advantage of equilibrium molding is that the method produces liners that better fit into their respective housings.
Generally, such methods are more economical.

The use of the anchors described herein allows the use of thin liner thicknesses and ensures structural integrity under the action of high vacuum. FED,
Plastics other than PTFE, such as PVDF, PFA, and PP (fluorinated ethylene propylene, polyvinylidene fluoride, perfluoroalkoxy, and polypropylene), may also be used as described herein.
It can be used to make liners for joints with anchors.

Having described the invention with respect to its preferred embodiment, it is understood that various changes in construction and detail may be incorporated therein without departing from the true spirit of the invention as defined in the appended claims. must be clear.

[Brief explanation of drawings]

FIG. 1 is an elevational view, partially in section, of a reducing cheese embodying the invention; FIG. 2 is a perspective view of a molded liner used in fabricating the fitting of FIG. 1; 3 is a circumferential cross-sectional view taken along line 3--3 of FIG. 2 showing details of the metal anchor; FIG. 4 is a perspective view of the metal anchor; FIG. 6 is a fragmentary drawing of the stud part of the anchor in the assembled position with respect to the parts of the housing prior to the welding operation; FIG. 6 is a view similar to FIG. 5, but after the welding operation; FIG. , is a perspective view of a standard cheese embodying the invention; and FIG. 8 is a perspective view of a cloth embodying the invention. [Description of symbols of main parts] 10... Reducing diameter cheese, 11, 12, 41, 42... Continuous stub end, 14, 15, 44, 45... Welded joint, 19, 49, 51... Liner, 21 ... Radial outer surface of liner, 25 ... Anchor, 26 ... Metal plate of anchor, 27 ... Metal stud of anchor, 31 ... Weld groove, 33 ... Groove surface, 34
...notch, 35...bevel line, 50...cross.

Claims (1)

Claims: 1. A metal housing lined with a non-metallic liner of molded material, a first portion embedded and secured within the liner, and a second portion protruding from the liner and welded to the housing. A method of manufacturing a fitting for a lined piping system comprising at least one metal anchor having two portions, the first portion embedded in a non-metallic material of the liner, and a radially outer surface of the liner. selecting a liner with at least one anchor having the second portion projecting from the housing; assembling parts of the housing around the liner; and selecting the liner with the liner secured to the housing. A method of manufacturing a fitting for a lined piping system, characterized in that it combines the steps of welding the parts together and to the second part of the anchor to form a housing. 2. said liner is selected having two said anchors disposed in substantially diametric positions on opposite sides of a series of channels, and said housing part is located between facing grooves of said housing part; The patent is assembled around the liner with the second part of the anchor disposed, the grooves of the parts being welded to each other and to the second part of the anchor. The method according to claim 1.