Wall thickness design factors

A cylindrical steel pressure vessel (AlSl SAE 10.85, cold rolled) with a wall thickness of 0.1 in. and an inside diameter of 1 ft is subject to an internal pressure of 1,000 psia and a torque of 10,000 ft-lb (see Figure 2-30). What is the effective stress at point A in the wall What is the factor of safety in this design ... 

Note Wall thickness (I) was determined from the p, OD, Sy, and F, i.e. t = pd/(2SyF). Calculation employed the maximum design factor of 0.72, which yielded the lowest value of wall thickness. 

T = pipe wall thickness (measured or minimum per purchase specification) t — pressure design thickness, as calculated in accordance with para. IP-3.2.1 for internal pressure or as determined in accordance with para. IP-3.2.2 for external pressure tm — minimum required thickness, including mechanical, corrosion, and erosion allowances W = weld joint strength reduction factor per para. IP-2.2.10... 

A heavier wall thickness than is required by the pipe design factor, F, in accordance with Table PL-3.7.1(b)(6)-l or Table PL-3.7.1(b)(6)-2, may be used. 

The SE values in Table 10-49 are equal to the basic allowable stresses in tension S multiplied by a quality factor E (see subsection "Pressure Design of Metallic Components Wall Thickness ). The design stress values for bolting materials are equal to the basic allowable stresses S. The stress values in shear shall be 0,80 times the allowable stresses in tension derived from tabulated values in Table 10-49 adjusted when applicable in accordance with Note 13. Stress values in bearing shall be twice those in shear,... 

Approaches used for achieving programmed or pulsatile release may be physical mechanisms such as swelling with bursting or chemical actions such as enzymatic degradation. Capsules have been designed that burst after a predetermined exposure to an aqueous environment. Physical factors that can be controlled are the radius of the sphere, osmotic pressure of the contents, and wall thickness as well as elasticity. 

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