Welding fixtures by which pipe ends are joined together

A pipe welding connector for joining pipe sections that have been internally coated with a heat sensitive coating material. The connector is arranged so that during the welding process, the coating remains below its degradation temperature. The connector has a first fixture at the end of one pipe section and a second fixture at the end of another pipe section. The first and second fixtures, when brought into abutting relationship, can be butt welded together to form the pipe welding connector. The second fixture is a cylinder that outwardly diverges into a bell and the opposed marginal end is of constant inside diameter and is attached about the exterior of a pipe section. Part of the pipe section extends from the belled marginal end and forms a stinger. The first fixture has an enlarged interior that telescopingly receives the stinger therein and further includes a belled marginal terminal end of a diameter equal to the diameter of the belled marginal end of the second fixture. This unique structure allows a first fixture to be formed on one end of a pipe section and the second fixture to be formed on the other end of the same pipe section so that series connected pipe sections can be welded together to form a pipe line without destroying the internal coating.

BACKGROUND OF THE DISCLOSURE 
A pipeline, or long length of pipe, is made up of a plurality of joints of 
pipe, or pipe sections. Each pipe section has opposed ends joined to 
another pipe section. A pipeline often varies from less than one inch 
inside diameter to more than a foot outside diameter. Sometimes, the fluid 
conveyed by a pipeline is corrosive. Therefore, the interior of the 
individual pipe sections is often coated with a heat sensitive plastic 
material in order to protect the internal surface of the pipe sections and 
thereby elongates the life of a pipeline. 
When the pipe ends of internally coated pipe sections are joined by butt 
welding, for example, the heat from the welding operation destroys a 
substantial amount of the internal heat sensitive coating at the joined 
area. This is especially so with an epoxy resin coating which melts at 
about 420.degree. F. It stands to reason that the welded joint, which is 
usually the strongest part of the pipeline, soon becomes the weakest part 
of the pipeline due to the deleterious effects of corrosion acting on the 
unprotected joined area of the pipe sections. 
It would therefore be desirable to be able to join together pipe sections 
into a continuous length in such a manner that the internal coating of the 
pipe is not harmed. This heretofore unknown and desirable welding 
operation would provide a continuous length of undamaged, internally 
coated pipe which should last for many years, and which would be much 
safer to persons and things in close proximity to the pipeline because its 
structural integrity would remain at its designed strength for an extended 
length of time. 
A few previous solutions to this perplexing problem has been suggested by 
the following U.S. patents: 
U.S. Pat. No. 2,895,747, 07/21/59, Bland et al. 
U.S. Pat. No. 3,325,191, 06/13/67, Yates. 
U.S. Pat. No. 3,890,483, 06/17/75, Webster. 
U.S. Pat. No. 3,892,032, 07/01/75, Bagnulo. 
U.S. Pat. No. 3,965,555, 06/29/76, Webster et al. 
U.S. Pat. No. 4,355,664, 10/26/82, Cook et al. 
U.S. Pat. No. 4,357,745, 11/09/82, Chlebowski. 
U.S. Pat. No. 4,611,833, 09/16/86, Lescaut. 
U.S. Pat. No. 4,640,532, 02/03/87, Pope. 
U.S. Pat. No. 4,681,349, 07/21/87, Press et al. 
However, it is evident that none of the cited references provide a pipe 
connector as defined by the claims of this invention. 
The present invention is an improvement over all of the above listed, 
previous patents because of the preservation of the structural integrity 
of the effected weldment over a long period of time; the lower cost of the 
novel pipe sections; the cost of the pipeline building operation is 
reduced: the heat flow characteristics are uniquely controlled during the 
joining of adjacent pipe sections; and particularly, the protection of the 
internal coating of the joined area of the pipe sections during the 
joinder operation. 
SUMMARY OF THE INVENTION 
This invention comprehends an improved pipe welding connector for joining 
pipe sections together that have been internally coated with a heat 
sensitive coating material. The connector is arranged in two coacting 
parts, located on opposed ends of a pipe section, so that during the 
process of butt welding a plurality of the pipe sections together, the 
connector and pipe section cooperate together as a heat sink to dissipate 
heat from the arc weld in a new and unobvious manner, whereby the internal 
heat sensitive coating material adjacent to the butt weld remainns below 
its degradation temperature. More specifically, the connector is made of a 
first fixture and a second fixture, each being arranged at opposite ends 
of a pipe section, so that a first fixture is formed at the end of one 
pipe section and a second fixture is rigidly affixed at the end of another 
pipe section. The first and second fixtures, when brought into abutting, 
axially aligned relationship, can be butt welded together at a location 
spaced from the surface of the underlying pipe to thereby form an unusual 
and desirable pipe welding connector having unexpected attributes which 
are achieved through the present invention. 
The second fixture includes a cylinder having one marginal end that 
outwardly diverges into a bell, and the opposed marginal end of the 
cylinder is of constant inside diameter and is received in fixed 
relationship about the exterior of a pipe section. A stinger, in the form 
of a marginal terminal length of the pipe section extends outwardly from 
the belled marginal end of the second fixture. Hence, the terminal ends of 
the bell and stinger are axially spaced. 
The first fixture has an enlarged interior along a marginal length thereof 
that telescopingly receives the stinger in close tolerance relationship 
therewithin, and further includes a belled marginal terminal end of the 
same configuration and diameter as the belled marginal terminal end of the 
second fixture. This unique structure allows a first and second fixture 
respectively, to be formed on the opposed ends of a pipe section prior to 
coating the inside surface of the pipe section. A plurality of the 
previously prepared and coated pipe sections can subsequently be butt 
welded together to form the recited connection, thereby providing a method 
of building a pipeline without destroying the internal coating thereof, 
and without significantly changing the metallic composition of the fluid 
conveying conduit. 
A primary object of this invention is the provision of both method and 
apparatus for joining coated pipe sections into a pipeline in a new and 
unobvious manner which protects the internal coating thereof. 
Another object of this invention is the provision of a method of joining 
pipe sections into a pipeline wherein the pipe sections previously have 
been coated with a heat sensitive coating material and the opposed ends of 
the pipe sections have been provided with a first and a second fixture 
that can be butt welded to provide a connector wherein the connector 
provides a controlled heat flow path from the welding process that occurs 
in such a manner that the coating is not harmed. 
A still further object of the present invention is the provision of a 
connector for joining pipe sections together that previously have been 
internally coated with a heat sensitive coating material, wherein the 
connector is arranged in two coating parts located on opposed ends of a 
plurality of pipe sections so that during the process of butt welding the 
pipe sections together, the connector dissipates heat from the arc weld in 
a manner whereby the coating next to the butt weld remains below its 
degradation temperature, and the metallic structure and chemical 
composition of the pipe section remains substantially unchanged. 
Another and still further object of this invention is the provision of 
apparatus formed at the confronting ends of adjacent pipe sections that 
are butt welded together to form a pipeline without damaging a synthetic 
resin coating previously applied to the interior of the pipe sections. 
An additional object of this invention is the provision of a pipe welding 
connector device comprising a male stinger that is formed on one pipe end 
and is received within a female socket that is formed on an adjacent pipe 
end of two pipe sections to be joined. The stinger is telescopingly 
received within the socket. An outwardly directed, circumferentially 
extending member is additionally affixed on each of the pipe sections 
which abuttingly engage and are butt welded together, thereby joining the 
two pipe sections together by indirectly welding one pipe section to the 
other. 
These and various other objects and advantages of the invention will become 
apparent to those skilled in the art upon reading the following detailed 
description and claims and by referring to the accompanying drawings. 
The above objects are attained in accordance with the present invention by 
the provision of a method for use with a combination of elements which are 
fabricated in a manner substantially as described in the above abstract 
and summary.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 of the drawings discloses a pipeline 10 comprised of a plurality of 
pipe sections 12 and 12' joined together by a pipe welding connector 14 
made in accordance with the present invention. The pipe welding connector 
14 comprises a first fixture 16 attached to pipe section 12' and a second 
fixture 18 connected to pipe section 12. Accordingly, each of the pipe 
sections 12, 12' have a first fixture 16 located on one end thereof and a 
second fixture 18 located on the opposed end thereof so that confronting 
or facing ends of adjacent pipe sections can be arranged with a first 
fixture 16 confronting a second fixture 18 and joined to form the pipe 
welding connector 14. 
In this disclosure, the term "fixture" is intended to described a preformed 
component that is an integral part of a pipe section and is designed to be 
welded to another fixture and thereby enable pipe sections to be joined in 
series, axially aligned relationship. 
FIGS. 2 and 3 disclose the details of the novel pipe welding connector 14. 
The first fixture is seen on the right hand side of the drawing while the 
second fixture is on the left hand side thereof. The second fixture of the 
connector 14 comprises a cylinder 20 that has a terminal end thereof 
previously lap-welded at 22 to a medial part of pipe 12, and further 
includes an opposed marginal belled terminal end at 24. 
The first fixture 16 is enlarged in diameter in two different steps, with 
the first enlargement occurring over the marginal area 26 along the 
indicated length L2 which results in a constant diameter length 28, as 
indicated by length L3. The marginal terminal end is outwardly curved into 
a bell 30 along the indicated length L4. The belled ends, 24 and 30, 
respectively, of fixtures 16 and 18, respectively, are made more or less 
complementary respective to one another. 
In FIG. 2, L1 indicates the length of pipe section 12' that is of constant 
or nominal diameter; L2 indicates the length of the pipe that outwardly 
diverges due to the first expansion step; while L3 indicates the length of 
constant diameter enlarged pipe that is of an inside diameter equal to the 
outside diameter of the pipe at L1. It will be noted that the belled part 
24 of cylinder 20 progressively diverges over a length L4. The length L4 
is equal to the length of the belled part 30 which occurs over the length 
L4 of the first fixture. 
The configuration of the outwardly curved marginal length L4--L4 of the 
first and second fixtures can take on most any desired outwardly curved 
form, and preferably has the characteristics of a truncated hyperbola, and 
therefore is a parabolic section, or a conic section; and, it can be an 
ordinary segment of an outwardly curved annular geometrical solid, all of 
which are referred to herein simply as a "bell", or "belled" marginal 
length. This configuration leaves the circumferentially extending 
confronting edges of the fixtures axially aligned and having equal 
diameters. 
In FIGS. 2 and 3, a heat barrier 34, in the form of a cylindrical, heat 
resistant wick, is placed in underlying relationship respective to the 
area that is to receive the butt weld 32. The heat barrier can be made of 
heat resistent fabric-like material saturated in a suitable liquid 
coolant, such as water, or alternatively, can be a ceramic cylinder. The 
heat barrier 34 insulates the immediate circumferentially extending outer 
surface area of the underlying pipe 12 from the molten metal at 32 during 
the welding of the connector. In FIG. 3, numeral 36 indicates the inside 
diameter of heat barrier 34, while numeral 38 indicates the outside 
diameter of the marginal pipe end 12 that protrudes beyond the belled end 
of cylinder 20. Numeral 38 is therefore a stinger having a terminal end 40 
and is of an outside diameter that is telescopingly received in close 
tolerance relationship within the inside diameter 42 of the constant 
diameter part 28 of the first fixture. Numeral 46 indicates the 
circumferentially extending free end of the belled end of cylinder 20. The 
belled marginal end 24 of cylinder 20 forms a cavity 48 between stinger 38 
and the interior of belled part 24, while the numeral 50 similarly 
indicates a cavity that is formed between the belled marginal end of the 
first fixture and the stinger 38. The cavities 48 and 50 are approximately 
equal to one another as may be noted in the assembled configuration of 
FIG. 2. 
The dot-dash line noted by numeral 54 is a coating. The coating can be any 
number of different synthetic resins that are applied by numerous, 
difrerent processes in order to provide the entire internal surface area 
of each of the pipe sections with a thin uniform coating. Attention is 
directed to U.S. Pat. No. 3,974,306; U.S. Pat. No. 4,243,699; and to the 
art cited therein for some of the specific details of internal coating 
methods for pipe. 
FIG. 6 sets forth a modification of the embodiment previously described in 
conjunction with FIGS. 2, 3 and 7. In FIG. 6, the pipe ends 60, 62 
preferably are slightly spaced but could abut one another, and are of 
equal diameter. There is a first fixture comprising a first cylinder 64 
that is lap-welded at 66 to a medial circumferentially extending area of 
the pipe section on the right hand side of the Figure. Numeral 68 
indicates the belled marginal end of the cylinder 64. 
The pipe section located on the left hand side of the Figure is provided 
with a cylinder 70 that is lap-welded at 72 to a medial circumferentially 
extending area of the pipe section. The cylinder 70 is belled at 74 to 
provide a cavity 78 of a symmetrical configuration. Numerals 68 and 74 
indicate the abutting, confronting edges of the first and second fixtures, 
while numeral 76 in the lower part of the Figure, indicates a butt weld 
that rigidly connects the two cylinders 64 and 70 to one another and 
thereby indirectly connects the adjacent confronting ends of the pipe 
sections together. Numeral 80 generally indicates the completed pipe 
welding connector of the second embodiment. 
It will be noted that pipe section 82 and cylinder 70 are substantially 
identical in construction to the second fixture of the first embodiment, 
while the pipe section 84 and cylinder 64 have some similarities to the 
second fixture; however, it will be noted that the first fixture is 
lap-welded at location 66 and with respect to pipe end 62 such that a 
socket is provided of a diameter that receives the stinger of the second 
fixture in close tolerance relationship therewithin. The heat barrier wick 
34 of FIG. 3 can be included in the cavity 78 of FIG. 6 to provide 
additional protection of the interior pipe coatings. 
The second fixture 18 of FIGS. 1-3 can be attached to the pipe section 12 
in accordance with FIG. 4. In FIG. 4, a cylinder 20 can be a pup joint cut 
from a length of appropriate inside diameter pipe. One marginal end of 
cylinder 20 is expended along L4 by the diagrammatically indicated 
expansion mechanism 82. Expansion mechanism 82 is any known tool or device 
that can be utilized for achieving a flared or belled marginal end of the 
cylinder 20. Further, the second fixture 18 can be cast or forged as may 
be desired. Numeral 22' in FIG. 4 indicates the location of the lap-weld. 
L6 indicates the length between the lap-weld and the terminal end 40 of 
the pipe joint 12. 
In FIG. 2, d1 is the diameter of pipe 12, 12' along L1; d2 is the diameter 
of the pipe along L3; and d3 is the diameter of the butt welded connection 
and therefore, is the maximum outside diameter of the string of pipe. The 
cylinder 20 has a diameter d4 which usually will equal d2, noting that 
stinger 30 is closely received within the interior of members 20 and 28. 
FIGS. 5A, 5B, and 5C illustrate a step-by step process by which the first 
fixture 16 of FIGS. 1-3 is formed from along the marginal end of an 
ordinary pipe. The pipe 12, 12' can be of various different design such 
as, for example, oil field production or line pipe. 
In FIG. 5A, the expansion device 82 enters the interior of pipe 12' at a 
location to make the first expansion along length L2, thereby providing an 
enlarged, constant diameter length L3 that is of sufficient diameter to 
snugly receive the stinger 38 therein. Then expansion device 82 makes the 
belled marginal length 30 along length L4 of the pipe joint 12'. The 
resultant structure is seen on the right hand side of FIG. 3 and in FIG. 
5C. 
In operation, each pipe section is provided with a first fixture 16 at one 
marginal end thereof and a second fixture 18 at the other marginal end 
thereof. Then the pipe sections are coated at 54. The pipe sections are 
then placed in confronting relationship with unlike fixtures abutting one 
another in the manner of FIG. 3. The heat barrier 34 is slidably received 
about stinger 38 and properly positioned respective to cavity 48 so that 
when the confronting ends 46 and 52 abuttingly engage one another, the 
illustrated butt weld 32 can be effected, thereby joining pipe sections 12 
and 12' to one another with great strength. 
The operations set forth in FIGS. 5A, 5B, and 5C can be carried out in the 
shop under controlled conditions so that the marginal end of pipe 12' can 
receive proper preheat prior to deformation, as may be desired. This 
minimizes loss of structural integrity of the deformed end of the section 
that may be attributed to uneven or undesirable heating as well as 
undesirable stress and strain that may result from the operation of the 
expansion tool 82. 
Welded pipe joints usually are exposed to a complex stress pattern as a 
result of the high temperature gradients that must be present in the metal 
in order for the weld to be properly effected. By the present invention, 
the undesirable stress pattern of the welded joint is not as critical as 
in the prior art direct butt welding of two pipe sections for the reason 
that the final butt welding occurs on a secondary member that isolates the 
field weld from the pipe sections. The secondary member, therefore, is 
previously shop welded under controlled conditions that minimizes the 
undesirable heat induced stress patterns to the pipe section at a location 
spaced from the terminal end of the pipe. 
After the pipe sections have been provided with the first and second 
fixtures, they are individually coated on the inside thereof, using the 
above described coating techniques, for example. The pipe sections 
subsequently are easily field welded because no auxiliary alignment means 
need be employed, noting that the stinger perfectly aligns the adjacent 
joints of unwelded pipe sections. Moreover, as the stinger of the second 
fixture is forced into the socket of the first fixture, the coating 54 
provides an unusually tight, efficient seal between the adjacent marginal 
ends of the two pipe sections, thereby providing unexpected advantages 
from the present invention. 
The circumferentially extending edges 46 and 52 at the free ends of the 
bells are brought to the molten state during the welding process, and the 
heat from the arc of the welding electrodes provides a liquid metal bridge 
32 across the gap between the coacting fixtures 16 and 18. After the 
electric arc has completed the weld, the liquid solidifies and joins the 
edges together, as seen at d3 in FIG. 2. 
As the butt weld 32 is being formed to integrally join edges 46 and 52, 
heat transfer occurs along each of the cylinders 20 and 28 where it is 
dissipated into the atmosphere due to radiation and convection, and also 
is transferred into pipe sections 12 and 12' along length L3 and L5. There 
is an interface 42 and 44 between the cylinders 20 and 28 and pipe surface 
12 that forms a barrier with which the heat transfer mechanism must 
contend. The only direct heat transfer into pipe 12 occurs through the lap 
weld 22 and along cylinder 28. However, the elevation in temperature at 
this area is not of a magnitude to damage the internal pipe coating 54 
because the high temperature of the molten metal has been progressively 
reduced by the heat sink properties of the connector apparatus 14 as the 
heat flows along its circuitous path to this location. 
As the molten metal of the electric arc forms weld 32, the heat barrier 34 
prevents direct radiation thereof against the stinger 38. Accordingly, 
there is no direct transfer of heat from the arc welding process directly 
into a fluid carrying part of either of the joined together pipe sections 
12 or 12'. 
With respect to the first fixture 16, the heat transfer occurs back along 
the constant diameter cylindrical part 28, and along length L3 which 
lowers the temperature thereof as the heat migrates toward the unprotected 
coating located to the right of edge 40 of the stinger. The heat that 
travels in this direction is dissipated over such a large area L3 that the 
temperature of the internal coating is not harmed. Any coating present at 
interface 38, 42 may reach the molten state near heat shield 34, which is 
not considered to be the interior of the pipe section, and which is not 
considered a drawback so long as the integrity of coating 54 at end 40 of 
stinger 38 is not injured. 
The terminal end 40 preferably is round with a suitable radius to avoid any 
sharp edges. The end 40 is provided with a protective coating as seen at 
54 that extends about the end 40 and includes a generous area of the 
outside diameter of the stinger 38. This forms a sealant between the 
outside diameter of the stinger and the inside diameter 42 of the fixture 
16.