SPED Pipe Support Design 2

Question 1

Which load category per ASME B31.3 is used to evaluate sustained (primary) stresses in a piping system?

Accepted Answer

Pressure, weight, and other sustained mechanical loads combined

Answer

ASME B31.3 sustained load cases combine internal pressure, deadweight (pipe, fluid, insulation), and other continuously acting mechanical loads to check primary stress limits.

Question 2

What is 'cold spring' in pipe support and piping design?

Accepted Answer

An intentional cut-short or offset during installation to pre-compensate for thermal growth

Answer

Cold spring pre-stresses the system by installing the pipe in a slightly compressed or offset state so that thermal growth moves it toward its stress-free position, reducing hot loads on supports and equipment nozzles.

Question 3

When calculating allowable pipe support span, which single geometric factor most increases the permissible span length?

Accepted Answer

Larger pipe diameter and schedule (greater section modulus)

Answer

A larger pipe cross-section increases the moment of inertia and section modulus, directly raising the bending stiffness and allowable span before stress or deflection limits are reached.

Question 4

A constant-effort (constant load) hanger is preferred over a variable spring hanger when:

Accepted Answer

Thermal movement is so large that a variable spring would have unacceptable load variation (>25%)

Answer

When vertical thermal displacement is large, a variable spring's load change (from cold to hot travel) can exceed 25%, making a constant-effort hanger necessary to maintain nearly uniform support load.

Question 5

What maximum mid-span deflection is most commonly specified in piping project standards to avoid flow and stress problems?

Accepted Answer

1/2 inch (12.7 mm) or as defined by the applicable code and project specification

Answer

A 1/2-inch sag limit is the widely accepted industry default, preventing ponding in liquid lines, vapor locking, and appearance issues while keeping stresses within acceptable ranges.

(SPED) Society of Piping Engineers and Designers Certification Practice Test

(SPED) Society of Piping Engineers and Designers Certification Practice Test

SPED Pipe Support Design 2