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Discontinu GEOMRAD at mitre bends
23-08-2018, 09:03 PM, (This post was last modified: 23-08-2018, 10:20 PM by shaswin.)
#1
Discontinu GEOMRAD at mitre bends
Consider you have 1 mitre bend and 1 kink and this point there is a discontinu point for the diameter.

In this situation PLE accepts only 1 GEOMRAD en 1 LSEGM distance and cannot fill in GEOMRAD or LSEGM.

So for this situation I did the following solution:

L_SEGM1 = (DOUT1-T_NOM1)/ 2 / 2 * (1+TAN(RADIANS(25/2 OR 15/2))))
L_SEGM2 = (DOUT2-T_NOM2)/ 2 / 2 * (1+TAN(RADIANS(25/2 OR 15/2))))

GEOMRAD1 = (L_SEGM1 / 2)/TAN(RADIALEN((BEND_ANGLE/N_KINK) /2)
GEOMRAD2 = (L_SEGM2 / 2)/TAN(RADIALEN((BEND_ANGLE/N_KINK) /2)

GEOMRAD_combined = SQR((GEOMRAD1^2*GEOMRAD2^2)/(GEOMRAD1^2+GEOMRAD2^2)) * SQR(2)

Afterwards I calculated:

L_SEGM_combined = 2*GEOMRAD_combined * TAN(RADIANS((BEND_ANGLE/N_KINK)/2))

L_SEGM_combined = DOUT_combined_fictive when 1 N_KINK
With a minimum of 1.25 * DOUT_combined_fictive (= 2.5 * pipe radius) for the GEOMRAD_combined

At 1 N_KINK and a discontinue point for the diameter the following values can be filled:
GEOMRAD = MAX(GEOMRAD_combined , 1.25 * DOUT_combined_fictive)
L_SEGM = L_SEGM_combined
N_KINK = 1
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16-04-2019, 02:40 PM,
#2
RE: Discontinu GEOMRAD at mitre bends
Am I understanding correctly that you want to model an "optimal" 1-kink mitre bend when there is a diameter change (step change) right at the kink?

Your formulae's most likely are correct (I'm going to check with our experts here), but please be warned that the mathematical model assumes a constant diameter (and wall thickness) across the whole mitre bend. So be very careful in such a case, and triple-check Wink the results...

Similar caution applies to normal bends, the model here also might not be valid if the diameter or wall thickness change somewhere along the bend.
Reply
16-04-2019, 04:25 PM,
#3
RE: Discontinu GEOMRAD at mitre bends
Thanks for your expert advice.
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