1、PFI Standard ES-49 |Denotes Revision (Revised December 2013) GUIDELINES FOR INSTALLATION OF INTEGRALLY REINFORCED BRANCH CONNECTION FITTINGS Prepared by Pipe Fabrication Institute Engineering Committee All PFI Standards are advisory only. There is no agreement to adhere to any PFI Standard and their
2、 use by anyone is entirely voluntary. Copyright by PIPE FABRICATION INSTITUTE Dedicated to Technical Advancements and Standardization in the Pipe Fabrication Industry Since 1913 USA 511 Avenue of Americas, # 601 New York, NY 10011 CANADA 655, 32ndAvenue, # 201 Lachine, QC H8T 3G6 WEB SITE www.pfi-in
3、stitute.orgPFI Standard ES-49 |Denotes Revision (Revised December 2013) GUIDELINES for INSTALLATION of INTEGRALLY REINFORCED BRANCH CONNECTION FITTINGS 1. Scope 1.1. This standard provides general guidelines for the installation and welding of integrally reinforced branch connection outlet fittings
4、attaching to the outside of the run pipe, otherwise known as a set on/stub on configuration. 2. General 2.1. A branch connection is the joining of two intersecting pieces of pipe that split a process flow. The pipe containing the hole for the branch connection, typically referred to as the run pipe,
5、 is weakened by the opening made in it. The primary function of an integrally reinforced branch outlet fitting, (branch fitting), is to reinforce this opening and restore the original strength of the run pipe, eliminating the need for an additional reinforcing element such as a reinforcing pad or sa
6、ddle. The use of branch fittings can provide an economic alternative to tee fittings, reinforcing pads or saddles. Branch fittings are attached to the run pipe by welding. A branch fittings strength and corresponding thickness is specified by the wall schedule of the run and branch pipes. Very often
7、 the designer may require the use of a branch fitting to provide reinforcement for external loads other than pressure, such as vibration, impact, and thermal cycles. 3. Dimensions 3.1. 90 degree branch fitting dimensions, finish, marking, materials, and strength requirements for butt weld, socket we
8、ld, and threaded fittings are provided by the MSS SP-97 Standard Practice. 3.2. Although standard MSS SP-97 provides standard dimensions from the outside of the run pipe to the branch connection end of the fitting, (“A” dimension, See Detail “1-B”), the outside diameter of the fitting, and the corre
9、sponding fitting wall thickness is proprietary, and must be supplied by the fitting manufacturer. 4. Welding 4.1. Fittings that are designed to be attached by full penetration welds shall be fully penetrated and shall be welded out to the edge of the fitting weld bevel. The fitting weld bevel is def
10、ined as the first bevel that is adjacent to the header and having an inclusive angle of 35 to 45 degrees, as measured between the header surface and the fitting weld bevel surface (Fig. 7). 4.2. The groove weld requires a cover fillet weld whose primary purpose is to provide a smooth transition betw
11、een the run pipe and the branch weld. The transition fillet weld throat thickness is defined as dimension “tc” by the applicable code. 4.3. A cover fillet weld with a slightly concave profile that provides a smooth transition between the deposited cover fillet weld metal and run pipe surface contrib
12、utes to improved fatigue life. This is of particular importance when branch connections are cyclically loaded, and should be specified by the engineer when required. 4.4. Where cyclic loading is a concern, the hole in the run pipe should be flush with the inside diameter of the branch fitting, and t
13、he inside corner of the run pipe hole should be rounded. This shall be specified by the engineer when required. 4.5. Refer to figures 1, 2, and 3 for examples of the preferred weld profiles. 5. Distortion 5.1. Full integral reinforcement is provided within the branch fitting, and the attachment weld
14、 metal, by a large volume of metal concentrated around the run pipe hole. The branch fittings larger volume in the weld attachment area, yields a branch connection weld that is typically thicker than the branch pipe, and may also be thicker than the run pipe. Large weld volumes create internal stres
15、ses as a result of weld shrinkage during solidification, which has the potential to distort the run pipe. Run pipe distortions are created in the longitudinal direction in the form of bending or camber, (See figure 5), and in the circumferential direction affecting ovality, (See figure 4). 5.2. The
16、use of a thin wall run pipe exhibits a greater tendency to distort. High alloy branch connections tend to distort more than low alloy PFI Standard ES-49 |Denotes Revision (Revised December 2013) materials, due to their higher expansion and lower thermal conductivity. 5.3. Distortion may be minimized
17、 through combination of fitting selection, design, sequential welding technique, and following the fitting manufacturers recommendations. 5.3.1. Designers should specify a fitting to meet the requirement of the service. Avoid specifying a branch fitting designed for a heavier run wall thickness than
18、 the run pipe under consideration. (Example: Specify a Schedule 10, or “light weight” branch fitting, for a schedule 10 run pipe). It should be noted that the weld volume required to attach the branch fitting to the run pipe can vary widely among the various fitting manufacturers for a given branch
19、size/run size/wall thickness combination, and should be considered when selecting a particular brand of fitting. 5.3.2. Where possible, avoid placing numerous branch fittings in succession, in close proximity to each other, and along the same side of the run pipe. Weld shrinkage is cumulative, and m
20、ay result in large cambers. Welding every other fitting in succession will reduce the amount of induced camber (Example : Fitting 1, 2, 3 however, it requires a careful selection of the run pipe support points within the furnace, with somewhat unpredictable results. Applying local heat to stainless
21、and high alloy materials may degrade the materials favorable characteristics; therefore, some method of cold forming is required to return the run pipe to an acceptable tolerance. 6. Inspection 6.1. All nondestructive examination shall be performed in accordance with the applicable piping codes and
22、specifications and meet the acceptance criteria therein. 6.2. The fitting to run pipe weld profile should meet the profiles as depicted in figures 1 through 3. 6.3. The fitting to run pipe weld size shall be considered adequate if the weld is filled out to the edge of fitting weld bevel. Some branch
23、 fittings possess transitional taper (s) between the branch fitting weld bevel and the OD of the branch fitting, and the delineation between the two surfaces will be obscured by weld deposit. In these cases, it is difficult to determine if the weld has been properly filled out. It then becomes neces
24、sary to measure the angle of the exposed “bevel”. If the bevel is equal to or greater than 50 degrees the bevel shall be classified as a transition, and the weld shall be considered complete. Refer to figure 7. 6.4. The cover fillet weld shall meet the requirements of the applicable code and the man
25、ufacturers recommendations, except that, the cover fillet thickness may transition to zero in any location around the fitting where the angle between the face of the branch fitting groove weld and the surface of the pipe, at the location, exceeds 135 degrees. PFI Standard ES-49 |Denotes Revision (Re
26、vised December 2013) 7. Post Weld Heat Treatment 7.1. The need for post weld heat treatment (PWHT) is defined by the applicable piping code and is typically determined by the run and branch pipe wall thicknesses. The branch fitting thickness, or the attachment weld, may not be exempt from PWHT as de
27、fined by the governing thicknesses of ASME B31.1 paragraph 132.4, ASME B31.3 paragraph 331.1.3, or other applicable code. PWHT may be required for the branch connection while the remainder of the pipe assembly is exempt from PWHT. Refer to Figure 6 for code PWHT requirements. 8. Ordering Information
28、 Material grade Quantity Fitting type description Material certification requirements Branch outlet size and schedule or class Run pipe size and schedule Design temperature and pressure (when available) Applicable design and fabrication code o Confirm fitting complies with code When fabrication code
29、 is ASME Section I o Design pressure and temperature o Request Branch calculations (if required) Dimensional information (if required) o Fitting height or dimension from outside of run pipe to the branch connection end preparation, (“A” dimension or “E” dimension), if not in compliance with MSS SP-9
30、7 o Outside diameter of fitting, (“B” dimension) to determine weld thickness and volume in conjunction with “C” dimension. o Required header hole size (“C” dimension) It is recommended that, the purchaser provide a statement within purchasing documents, that design, dimensions, manufacture, and test
31、ing shall be accordance with MSS SP-97, to assure that the fitting ordered meet the requirements of the applicable codes and specifications 9. References ASME B31.1 - Power Piping Code ASME B31.3 - Process Piping Code ASME B31.9 - Building Services Piping Code ASME B16.9 - Factory made wrought butt
32、weld fittings ASME B16.11 - Forged Fittings, socket weld and threaded ASME B16.25 - Butt welding ends MSS SP-97 - Integrally Reinforced Forged Branch Outlet Fittings PFI Standard ES-49 |Denotes Revision (Revised December 2013) bCLranchbCLranchbCLranchbCLranchbCLranchDim “E“Dim “B“Dim “C“Dim “A“TYPtc
33、TYPtcFigure 1Weld profile for 90 degree branch fittingFigure 2Weld profile for lateral branch fittingBore may be straightor taper as shownASME B16.25 buttweld (shown), socket weldor threaded connectionASME B16.25 butt weld,socket weld (shown)or threaded connectionFitting ODRun pipe holeGroove weld s
34、urfaceparallel to fitting bore“tc“Groove weldsurface paralleto fitting boreDetail 1-ADetail 1-BRun pipeDetail “1-B“Detail “1-A“Detail “1-B“Detail 2-A Detail 2-B Detail 2-CGroove weld surfaceperpendicularto run pipeRoot gapGroove weldsurface parallelto fitting boreGroove weldsurface parallelto fittin
35、g bore“tc“tc“tc“+ 0.125- 0.000Detail “2-A“Detail “2-B“Detail “2-C“C“ Dim(Major Dia)Fitting Bore(Minor Dia)Cover fillet weldCover fillet weldCover Fillet weldRoot gap+ 0.125- 0.000Oval shapePFI Standard ES-49 |Denotes Revision (Revised December 2013) Right angle topipe surface“tc“Groove weld surfacep
36、arallel to fitting bore“tc“Groove weld surfaceparallel to fitting bore“E“ dimRoot gapRoot gap“tc“Detail “3-A“Detail “3-A“Detail “3-C“TYPtcRoot GapDetail 3-A Detail 3-B Detail 3-CFigure 3Weld profile for elbow branch fittingASME B16.25 butt weld,socket weld (shown),or threaded connectionFigure 4Circu
37、mfertial distortionFigure 5Longitudinal distortionRun Pipe camberFit up heigthAs welded heightCircumferentialdistortionof run pipeCover Fillet weld“C“ DimFitting Bore(Major Dia)(Minor Dia)Cover fillet weldCover fillet weld+0.125- 0.000Tear drop shapebCL ra nc hbCL ra nchbCL ranchPFI Standard ES-49 |
38、Denotes Revision (Revised December 2013) ASMEB31.3ProcessPipingPWHTRequiredCARBONSTEEL(P-no1)Throughweldthickness(Tb+tc)1.5“=1.5“oraTensilStrength=71KSI(490Mpa)11 4Cr-1 2Mo(P-no4)Throughweldthickness(Tb+tc)1“oraTensilStrength=71KSI(490Mpa)21 4Cr-1Mo(P-no5A)Throughweldthickness(Tb+tc)1“and350deg.F.Pr
39、eheatandCarboncontentis0.15%orlessMandatory.NoexemptionsASMEB31.1PowerPipingPWHTRequiredCARBONSTEEL(P-no1)“tnb“0.75“=Cr-! 2(P-no3)“tnb“0.5“11 4Cr-! 2Mo(P-no4)“tnb“0.5“oranythicknesswithcarboncontent0.15%21 4Cr-1Mo(P-no5A)“tnb“0.5“oranythicknesswithcarboncontent0.15%Mandnatory.NoexemptionsPWHTREQUIRE
40、MENTSFORINTEGRALLYREINFORCEDBRANCHFITTINGSFigure6BranchfittingPWHTrequirmentsAllP-no 5B materialsAllP-no 5B,6,10, A complete list of PFI members and available membership CHARTER MEMBERS CONTRACTOR MEMBERS ASSOCIATE MEMBERS AFFILIATE MEMBERS HONORARY MEMBERS Associate and Affiliate member contributor
41、s Walter Sperko Sperko Engineering Services, Inc. Greensboro, NC Thomas Warrelmann Victaulic Company of America Easton, PA Sheryl Michalak Welding Outlets, Inc. Houston, TX PFI Standards and Technical Bulletins are published to serve proven needs of the pipe fabricating industry at the design level
42、and in actual shop operations. Hence, such needs are continually considered and reviewed by the Engineering Committee of the Pipe Fabrication Institute to provide recommended procedures, which have been demonstrated by collective experiences to fulfill requirements in a manner for Code compliance. However, as the PFI Standards are for minimum requirements the designer or fabricator always has the option of specifying supplementary conditions in the form of requirements beyond the scope of the PFI publications.
