1. What causes piping failure?
a. Excessive Stress
b. Excessive Strain
c. Mental fatigue
2. Sustained loads can cause fatigue failure.
True
False
3. Sum of longitudinal sustained stresses SL should not exceed
a. SA
b. 1.2Sh
c. Sh
4. Displacement stresses should not exceed
a. 2Sy
b. Su
c. Sh
5. B31 piping codes allow for stress credit in systems with cold spring.
True
False
6. The stress range reduction factor, f, is based on how many cycles as proposed by ARC Markl?
a. 24
b. 2000
c. A cycle/day for 20 years
7. SIFs are ratios of effective component stresses to nominal stresses in matching straight pipe.
True
False
8. A sway brace can be effectively used to restrain thermal expansion.
True
False
9. Supports should be attached to piping components or fittings wherever possible.
True
False
10. CAEPIPE allows for only one support type input at any given node.
True
False
Excerpted from SST301: Piping Design and Analysis Seminar Notes
Answers next month...
Tip for the Month (August 2007)
1. What causes piping failure?
a. Excessive Stress
b. Excessive Strain
c. Mental fatigue
Notes: If a strain is caused by an applied load of sufficient magnitude and duration over the entire cross-section, a large strain will result and failure will occur.
2. Sustained loads can cause fatigue failure.
True
False
Notes: While displacement stress producing loads can cause fatigue damage, the same may be true for sustained loads too.
3. Sum of longitudinal sustained stresses SL should not exceed
a. SA
b. 1.2Sh
c. Sh
Notes: According to B31 codes, the sum of longitudinal sustained stresses should not exceed Sh, where Sh is the "hot allowable" or the allowable stress at the design temperature.
4. Displacement stresses should not exceed
a. 2Sy
b. Su
c. Sh
Notes: Displacement (Secondary) stress + peak stress should not exceed 2Sy, where Sy is yield strength.
5. B31 piping codes allow for stress credit in systems with cold spring.
True
False
Notes: B31 piping codes do not allow credit for stresses in cold sprung systems. However, the reduced loads at supports and rotating equipment can be considered during evaluation.
6. The stress range reduction factor, f, is based on how many cycles as proposed by ARC Markl?
a. 24
b. 2000
c. A cycle/day for 20 years
Notes: A cycle (startup-shutdown)/day for 20 years * 350 days gives us 7000 cycles upon which the stress range reduction factor 'f' is based.
7. SIFs are ratios of effective component stresses to nominal stresses in matching straight pipe.
True
False
Notes: i = sigma/S, where sigma = apparent increase in stress due to the component geometry, and S = nominal stress in matching straight pipe.
8. A sway brace can be effectively used to restrain thermal expansion.
True
False
Notes: A sway brace is used as a restraint for dynamic loads, not a thermal force.
9. Supports should be attached to piping components or fittings wherever possible.
True
False
Notes: A support should be attached to straight pipe, wherever possible. Avoid attaching supports to elbows or other components, unless the component is thick-walled (relatively) and the effect is properly provided for.
10. CAEPIPE allows for only one support type input at any given node.
True
False
Notes: CAEPIPE will allow you to input as many supports as you like at a given node. Use "Location" under Element types.
Excerpted from SST301: Piping Design and Analysis Seminar Notes
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