e: Miter Bend Calculation 08/14/2010 2:22 PM I think you need to use these standards PFI-ES-24 (PFI ES24 - Pipe Bending Methods, Tolerances, Process and Material ) I could be wrong.Bend under internal pressure (102.4.5):

pipe under internal pressure where I for intrados is:

and I for the extrados is:

and at sidewall I = 1.0,R = radius of pipe bendBend under internal pressure (304.2.1):

pipe under internal pressure where I for intrados is:

and I for the extrados is:

and at sidewall I = 1.0,R = radius of pipe bendBend under internal pressure (841.231):For cold bends the deflection of longitudinal axis and the radius is limited according table in paragraph 841.231Hot bends are to be designed and manufactured according ASME B16.49, the internal pressure rating shall not be less than that which is calculated for straight seamless pipe and the intrados wall thickness should be:

where the t the wall thickness of the pipe is

Elbows under internal pressure (102.4.5):Elbows manufactured according standards listed in Table 126.1 are suitable for use at the pressure-temperature ratings specified by such standards.Elbows not according above standards or for which design formulas and not given in the code shall be based on calculations consistent with the design criteria of this code. These calculations shall be substantiated by one or more of the means stated in A B C or D of 104.7.2 (Does this mean or allow that an elbow can be calculated according a bend with uniform thickness? Refer B31.3)Elbows under internal pressure (304.2.1):Elbows manufactured according standards listed in Table 326.1 are suitable for use at the pressure-temperature ratings specified by such standards.Elbows not according above standards or for which design formulas and not given in the code shall be based on calculations consistent with the design criteria of this code. These calculations shall be substantiated by one or more of the means stated in A B C or D of 304.7.2, or the elbow can be calculated according the Bend calculation, refer 304.2.2.Elbows under internal pressure (841.231?):No specific design rules are listed for fabricated elbows(Does this mean or allow that an elbow can be calculated according a bend with uniform thickness? Refer B31.3)

Miter bends under internal pressure (104.3.3):1. Only straight pipe calculations required if:

2. Pressure shall be limited to 70 kPa if:orand thickness is not less than required for straight pipe3. Pressure shall be limited to 700 kPa if:andand thickness is not less than required for straight pipe4. For pressure over 700 kPa: proof test, FEA, etc required with a defined minimum for closely spaced and widely spaced miter bendMiter bends under internal pressure (304.2.3):1. When theta =< 22.5 deg than max. allowable pressure shall be the lesser of (t = T - c):

and

2. When theta > 22.5 deg than max. allowable pressure shall calculated as (t = T - c):

For all miter bends the R1 shall not be less than:

with A:(T-c) =< 13 mm A = 2513 < (T-c) =< 22 mm A = 2(T-c)(T-c) > 22 mm A = 2(T-c)/3 + 30Miter bends under internal pressure (841.232):1. If system hoop stress > 40% of specified minimum yield strength miter bends are not permitted. Deflections caused by misalignment up to 3 deg are not considered as miters.2. If 10% < hoop stress < 40% SMYS the deflection of each miter shall not exceed 12.5 deg.3. If hoop stress < 10% SMYS the total deflection angle shall not exceed 90 deg.4. If hoop stress > 10% SMYS the distance measured at the crotch shall not be less than one pipe diameter

4.04.00 Bends and Elbowsi) Elbows shall be generally of long radius type.ii) Bends for piping 65 mm Nb and above shall be made hot and for piping 50 mm Nband smaller may be made cold.iii) Bends shall be made in accordance with PFI-ES-24. Bends shall be supplied withthe minimum tangents except where the piping layout necessitates shorter lengthsin which case the tangents shall be suitably reduced after the bending operation tosuit the requirements of the piping layout.iv) Heat treatment of bends shall be done as per material specification and PFI-ES-6.v) The finished bends wall thickness at any point of the bend shall not be less than thestraight pipe wall thickness. All bends 65 mm Nb and larger shall be ultrasonicallyexamined as per PFI-ES-20.vi) Where examination of bends indicates that wall thinning has resulted in thicknessless than the minimum specified, repair by weld deposition shall be allowed onlywhere the length of the affected area is 150 mm or less as measured along theoutside arc of the bend. Repairs in excess of this amount shall not be allowed. Allrepairs shall be carried out only after approval of the Employer.vii) Circumferential butt welds shall not be used in the area of the bend. Longitudinalwelds, where bends are formed from welded pipe shall be located on the bend'sneutral axis