The quotient of API burst resistance and the API collapse-pressure rating of a 20-in., 133 lbf/ft, K-55 casing (nominal wall thickness 0.635 in.) is closest to: A) 0.5; B) 1.0; C) 1.5; D) 2.0; E) 2.5; F) 3.0.
Pb=(0.875*2*55000*0.635)/20)=3056=3060 psi.
d/t=20/0.635=31.496.
F5=0.036 use Table 2.3 pg 56 J-55 (F5 is same as K-55).
Pcr=YS(Fr/(d/t))-F5.
Pcr=55000*((1.980/31.496)-0.036))=1493=1490 psi.
3060/1490=2.05, “D”.
(RG P55-56; TS12 P399, P402; GB 6 DTC 2).
