This invention involves a procedure for designing an integrally reinforced branch outlet called a reinforcement ring which by welding seams is in- tended for being placed between the side of a header pipe and the end of a branch pipe which reinforcement ring has an saddle formed end against the header pipe with a pair of opposed ears and a pair of opposed crotches.

In process plants are common that a number of vessels, pipes, branches and other equipment are used for containing or conducting fluids or gas- ses. For examples in the oil and gas industries are specified a large num- ber of requirements for the components and weldings which connects the particular components in the plant. Frequently are required a transition from an inlet/outlet in the sidewall in a header pipe to an outletlinlet in the end of a branch pipe by means of a reinforcement ring. Especially by branches at header pipes are exact norms established such as ASME (The American Society of Mechanical Engineers) Code for Pressure Pip- ing, B31.3-1999 Edition, which specify how reinforcement rings between two pipes are to be designed. Reinforcement rings are normally first welded to one of the ends on the branch pipes, and the reinforcement rings are after that placed over the inlet/outfet in the header pipes sidewall and then welded to the header pipe.

It is known to design reinforcement rings based on knowledge to the in- ternal pressure from outside coming bending moments and from outside coming forces.

In the past was reinforcement rings usually made of carbon steel that is a relatively cheap metal. In the later are other and significant more expen- sive metals, such as stainless steel Duplex and Titanium with better physical and chemical characteristics, more often used? It takes relatively much time, and is therefore relatively expensive to de- sign reinforcement rings which up to now has been designed to the valid norms that are based on that the so-called compensation areas in the branch pipe, header pipe and the reinforcement ring are bigger or equal to a given weakening area of that by the assembly created opening in the header pipe.

It hat meanwhile surprising appeared that it is the time used for welding on the reinforcement ring to the header pipe that cause the biggest part of the costs by using reinforcement rings. Especially are welding on rein- forcement rings made of newer materials very expensive. It is therefore primarily the purpose for this invention to form and design the reinforce- ment ring such that the time used for welding on is reduced as much as possible and to minimize the use of materials and at the same time to fol- low the rules in the valid norms.

That purpose is obtained by means of this present invention that deals with a procedure for designing a reinforcement ring.

A typical reinforcement ring is shown in Durham's patent from 1934 (United States Patent number 1.966.403).

The inconvenience by known reinforcement rings, as for example as shown in Durham's patent, is that they are designed for being fabricated by drop hammering which means expensive tools as dies are to be made for all combinations of header pipe diameters, header pipe wall thickness,

branch pipe diameters and branch pipe wall thickness. That is not done which means that the expensive welding work remains not minimized.

To that comes that known forms of reinforcement rings as for example as shown in Durham's patent are not suitable for being fabricated in today's fabrication facilities as for example a CNC machine.

The invention involves a procedure for a reinforcement ring that is to be placed between a header pipe and the end of a branch pipe.

The purpose for the reinforcement ring is to compensate for the weaken- ing in the header pipe as results from the hole in the side of the header pipe for creating a passage for a gas or liquids stream.

One of the ends on the reinforcement ring is adapted to the outside sur- face of the header pipe. The other end of the reinforcement ring is adapted such as it fits to the end of a branch pipe. Both ends of the rein- forcement ring are adapted such that the reinforcement ring can be welded with a full penetrating welding seam to the branch pipe and the header pipe respectively.

The outside and the inside diameter of the reinforcement ring's one end are chosen such that it have the same outside and inside diameter as the branch pipe.

In the other end of the reinforcement ring are the inside and the outside diameter chosen such that the strength of the reinforcement ring, the header pipe and the welding seam between the reinforcement ring and the header pipe are able to sustain the pressure there might be in the pip- ing system in combination with the external moments, if any, and such that

there is optimal flow conditions to, from and through the reinforcement ring.

According to the invention are the dimensions for the reinforcement ring chosen by means of an calculation algorithm which primarily minimize the volume of the welding seam between the header pipe and the reinforce- ment ring, and secondary minimize the amount of materials for fabrication of the reinforcement ring. The calculation algorithm is a kind of multi itera- tion as the algorithm has many independent arguments, many limits and has the mentioned primarily and secondary minimizing targets as de- pendent variables.

This distinguishes the invention that the welding-work and the consump- tion of material are minimized as much as possible, that the form of the reinforcement ring and that the calculation algorithm are adapted to the present fabrication and calculation facilities.

The invention is in the following described detailed with reference to draw- ings in which -Fig. 1 shows in perspective the placing of the reinforcement ring be- tween a header pipe and a branch pipe; -Fig. 2 shows an angle section taken on the plane indicated by line A-A in Fig. 1; -Fig. 3 shows a side elevation of a header pipe with details of the reinforcement ring; -Fig. 4 shows an elevation perpendicular to the elevation in Fig. 3; -Fig. 5 shows a side elevation of the reinforcement ring illustrated with diameters, distances and angles; -Fig. 6 shows the reinforcement ring with a hub; -Fig. 7 shows in perspective a header pipe with the reinforcement ring where outside moments and section A-A is indicated;

-Fig. 8 shows an angle section placed in line A-A in Fig. 7; -Fig. 9 shows a route diagram for a data treatment algorithm for cal- culating the optimal dimensions of the reinforcement ring; -Fig. 10 shows a chart with prices for welding on reinforcement rings made of carbon steel ; and -Fig. 11 shows a chart with prices for welding on reinforcement rings made of materials as stainless steel.

In the Figs 3 and 4 are shown a reinforcement ring 1 which have a cylin- drical ground form with conical transition in both ends for adapting to a header pipe 2 and a branch pipe 3. One of the ends 6 has an outside and inside diameter which are adapted to the branch pipe 3. The other end 5 is profiled to fit to the outside surface 11 on the header pipe 2 at the edge of the hole in the header pipe 2, and has a pair of opposed ears 13 and a pair of opposed crotches 12 and a beveling 8 for a welding seam. ! n ac- cording to the invention runs the beveling 8 round in the crotches 12 and round the ears 13 with reducing breadth from a point 14 to the center of the ears 13. A conical transition face 4 covers from the center of each ear 13 to a point 14 increasing in breadth in the direction of point 14.

As indicated in Fig. 2 is the reinforcement ring 1 fixed to the header pipe 2 by means of welding 16 and to the branch pipe 3 by means of welding 15.

The welding materials are to be compatible with the components that are to be connected, and the mechanical and chemical properties for the ma- terials in and around the finished welding seam are to be equal or better than that which are specified for the components.

Inside has the reinforcement ring 1, as shown in Figs. 3 and 4, a cylindri- cal part at the end 5 and a cylindrical part at end 6. In case of different inside diameters at the end 5 and the end 6 there will be a conical transi- tion between the mentioned inside cylindrical parts.

As shown in Figs. 3 and 4, there are in the center of each ear 13 between the beveling 8 and a section perpendicular to the axis 17 of the reinforce- ment ring an angle D, and in the center of each crotches 12 there are be- tween the beveling 8 and a section perpendicular to the axis 17 of the re- inforcement ring an angle E. The angle between the beveling 8 and the section perpendicular to the axis 17 has a maximum, which is angle E, and is gradually reducing in the direction of the center of the ears 13 to a minimum, which is angle D, which, in combination with the conical surface 4, reduces the welding work significant.

The angle ß that is shown in Fig. 8 is at least 45°.

In Fig. 5 is shown a section placed in a section, which is limited by that in Fig. 1 shown longitudinally axis 17 for the reinforcement ring and the lon- gitudinally axis 18 for the header pipe.

The invention is firstly characteristic by that -the height h in Fig. 5 is initially chosen as a calculated height hb which is equal to F minus one half of the difference between the di- ameters B and C both multiplied by the tangent to half the angle G, -and if hb is bigger than an empirical chosen height he, then h is chosen to be equal he -and if hb is less or equal he, than h is chosen to be equal hb.

(Which also can be written as: h = min (F- (B-C)/2tan (G/2) ; he).) The invention is secondly characteristic by that -if the diameter C in Fig. 5 is bigger than ID, then the diameter B is chosen to be equal OD multiplied by the empirical number 1.2

-and if C is equal to ID, then B is chosen to be equal to or bigger than OD multiplied with 1.2.

The invention is thirdly characteristic by that -the diameter C in Fig. 5 lies within an interval between a bigger empirical chosen limit value which is OD multiplied with 1.06 and a smaller limit value which is equal to ID.

Fig. 8 is an angle section placed in line A-A in Fig. 7. The reinforcing ring 1 in Fig. 8 has a nominal wall thickness Ntb, a necessary wall thickness tb to sustain the internal pressure, a corrosion allowance c, an internal toler- ance Ub and reinforcement areas A3 and A4, and the header pipe 2 has as well a nominal wall thickness Nu », a necessary wall thickness th to sustain the internal pressure, a corrosion allowance c, an internal tolerance Uh, a hole with a diameter C for passage through the side wall, a weakening area A, and a reinforcement area A2. By the design of a reinforcement ring as shown in Fig. 8, is the weakening area A, in norms as ASME Code for Pressure Piping, B31.3-1999 Edition, defined as the maximum diame- ter d of the hole in the side wall of the header pipe 2 multiplied with the wall thickness th of the header pipe 2, and the reinforcement area A2 is defined as the excess thickness of the side wall in the header pipe 2 mul- tiplied by the width of an established reinforcement zone which is equal to the difference between 2 times d2 and d,, and the reinforcement area A3 is defined as the excess wall thickness of the reinforcement ring 1 multi- plied with the height of a reinforcement zone which is equal to L4 and rein- forcement area A4 is defined as the area of other metal provided by welds and properly attached reinforcement within the mentioned reinforcement zone. Ntb in Fig. 8 is calculated in accordance with known rules in the relevant norms.

T r a d i t i o n a I I y is the design of a reinforcement ring, as shown in Fig. 8, carried out by choose of the first empirical dimensions for the first reinforcement ring and for the passage through the side wall in the header pipe and by establishing the first implicit dimensions for the reinforcement ring and the welding seam between the reinforcement ring and the header pipe and for the first dimensions a first weakening area A, and a sum of the first reinforcement areas A2, A3 and A4 are calculated and if the sum of the first reinforcement areas A2, A3 and A4 is bigger than or equal with the first weakening area A,, then are the first dimensions for the first rein- forcement ring chosen and if the reinforcement areas A2, A3 and A4 is smaller than the first weakening area A,, then are other dimensions cho- sen.

The invention is fourthly characteristic by that -a first volume of the welding seam is calculated for the first dimen- sions for the reinforcement ring, -and that second dimensions for a second hole and a second rein- forcement ring and implicit dimensions for a second reinforcement ring and a second welding seam are established, and the volume of the second welding seam is calculated, -and if the volume of the second welding seam is smaller than the volume of the first welding seam, then are the second dimensions for reinforcement ring chosen -and if the volume of the second welding seam is not smaller than the volume of the first welding seam, then are the first dimensions for the first reinforcement ring chosen.

The designations"first"and"second"are not to be taken as the absolute first and the absolute second but as the relatively first in relation to the relatively second. That means that the first and the second in principle can be the third and fourth or a quite different number in the succession.

The calculations are terminated after that -at least an empirical chosen number of calculations are carried out, -and that the difference between any calculated volume of the weld- ing seam and the smallest calculated volume of the welding seam is smaller than an in advance empirical chosen volume, -and that the calculated sum of the reinforcement areas A2, A3 and A4 lies within an interval between a smaller and a bigger empirical limit values both very little bigger than the weakening area A,, or that the different between the outside and inside diameter of the re- inforcement ring at the header pipe lies within an interval between a smaller and a bigger empirical limit value which smaller is de- pended of the nominal diameter of the branch pipe and which inter- val is very small.

By using the above-mentioned traditional procedure in combination with the fourth method in accordance with the present innovation for designing of a reinforcement ring are obtained that the volume of the welding seam will be as small as possible at all. As smaller the volume of the welding seam is, as less time is used for welding on the reinforcement ring.

In Fig. 9 is shown a route diagram that shows the treatment of the data by the mentioned combined method for optimizing of the reinforcement ring and the welding seam between the header pipe and the reinforcement ring.

-In A1 are chosen the first empirical dimensions for the reinforce- ment ring and for the passage through the side wall of the header pipe, -in A2 are found the first implicit dimensions for the reinforcement ring and the welding seam between the reinforcement ring and the header pipe,

in A3 is calculated the volume of the welding seam between the re- inforcement ring and the header pipe, in A4 is route 1 chosen if the nominal diameter of the branch pipe is bigger than an empirical chosen size, otherwise is route 11 cho- sen, in B1 are the implicit dimensions for the reinforcement ring and the welding seam between the reinforcement ring and the header pipe changed, in B2 is calculated the difference between the outside and the in- sider diameters of the reinforcement ring at the header pipe, in B3 is calculated the difference between the outside and the in- sider diameters of the reinforcement ring at the header pipe, in B4 is calculated the sum of the reinforcement areas minus the weakening area, in B5 is calculated the sum of the reinforcement areas minus the weakening area, in B6 is calculated the difference between the volumes between the smallest and the second smallest welding seam, in B7 is recorded the number of calculations of the volume of the welding seam, in C1 is the dimensions for the reinforcement ring and passage though the side wall in the header pipe changed, in C2 is route 2 chosen if the result in B2 is smaller than an empiri- cal chosen size, otherwise is route 12 chosen, in C3 is route 3 chosen if the result in B3 is bigger than an empiri- cal chosen size, otherwise is route 13 chosen, in C4 is route 4 chosen if the result in B4 is smaller than an empiri- cal chosen area, otherwise is route 14 chosen, in C5 is route 5 chosen if the result in B5 is bigger than an empiri- cal chosen area, otherwise is route 15 chosen,

-in C6 is route 6 chosen if the result in B6 is smaller than an empiri- cal chosen volume, otherwise is route 16 chosen, -in C7 is route 7 chosen if the result in B7 is bigger than an empiri- cal chosen volume, otherwise is route 17 chosen -and in C8 is chosen, as result, the dimensions for the reinforce- ment ring with the smallest welding volume.

The size of the change in B1 and C1 are chosen in relation to the relative change of the results in the calculations previous.

The design of the reinforcement ring is made by means of electronic data processing. It is in that way possible to reduce the costs for designing of reinforcement rings and to reduce the volume of the welding seam as much as possible at the same time as requirements in the valid norms, as for example the ASME Code for Pressure Piping, B31.3-1999 Edition, are fulfilled.

In this way is made a totally optimization of all costs which are resulting from use of reinforcement rings, that means an optimizing of the costs for designing and an optimizing of the costs for the welding on.

In Figs. 10 and 11 are shown the prices in DKK (1 DKK-0. 14 USD) in year 2000 for welding on of reinforcement rings in different combinations of sizes of header pipes and branch pipes. The bright columns gives typi- cal prices for welding on reinforcement rings designed and optimized in accordance with the present invention, and the dark columns gives typical prices for welding on reinforcement rings which at present are available on the marked. In Fig. 10 are shown prices for welding on of reinforce- ment rings made of carbon steel inclusive post weld heat treatment and non destructive testing and similar in Fig. 11 but for materials as stainless steel.

The end 6 of the reinforcement ring 1 in Fig. 3 can alternatively be made as a nipple, socket welding end, threaded end, flange or an other pipe component as for example a hub as shown in Fig. 6.

This invention concerns also a reinforcement ring which has a special formed beveling 8 which means that the round going welding area be- tween the reinforcement ring 1 and the header pipe 2 are minimized.

As shown in Figs. 3 and 4 is the angle for the beveling 8 changing be- tween a bigger size E at the opposed crotches 12 and a smaller size D at the opposed ears 13 and as shown in Fig. 4 is the reinforcement ring out- side the opposed ears 13 formed with conical surfaces 4 which are turned in such a way that the breadth of he beveling 8 is smaller at the ears 13 as at the crotches 12. The surface 4 covers with increasing breadth from the ears 13 to a point 14 in a short distance from a center plane through the crotches 12. The length of the short distance from the point 14 to the center plane through the crutches 12 is found in the same way as earlier described for the other implicit dimensions.

The described methods shall only serve as an illustration of the invention.

The methods can be used one by one, but the optimal result is obtained, when they are used coherent.