(2) Analysis Procedure for Category I and II Piping System. The
structural analysis of Category I and II piping systems shall conform to the
requirements of ANSI B 31.1 (Reference 2). Insofar as pressure loading is
concerned, the analysis involved is relatively simple. This kind of analysis
has been highly developed in the piping industry. Chapter 4 of Expansion and
Flexibility (Reference 14) is recommended for general background information.
Of the many computer programs that have been developed for this type of
analysis, one that is widely used is described on page 3-12 of Survey Report
on Structural Design of Piping Systems and Components (Reference 19). This
program can be purchased at a nominal cost. While a piping system analysis
if primarily used to establish moments and forces due to restraint of thermal
expansion of the piping, it is also used to establish moments and forces due
to weight loads. Extension of the referenced analysis is required for
dynamic loads such as water hammer.
Where significant temperature changes occur in the fluid, an analysis is also
required in order to establish the magnitude of the temperature gradient.
See Reference 19, Chapter 16, Thermal Stresses in Piping Components, for
further information on this subject. The designer will also want to include
analysis of the effects of differential foundation movement in terms of
additional stress on the piping system.
(3) Analysis Procedure for Category I and II Valves. The
structural analysis of a Category I and II valve shall show that the design
of the valve fulfills the structural design requirements of ANSI B 31.1.
These requirements include pressure-temperature ratings and hydrostatic shell
test pressures.
(4) Stress Report. A stress report contains both the drawings and
the stress analysis calculations. The stress analysis calculations shall
establish that the piping and valve designs shown by the construction
drawings comply with the requirements of the Structural Design Specification
(Section 5, paragraph 5(a) (1)), and with the requirement of the analysis
procedure (Section 5, paragraph 5(a)(2)). Any computer programs used in the
calculations shall be properly identified and described in the Stress Report
to facilitate independent verification.
The Stress Report shall be certified by a registered Professional Engineer,
competent in the design of piping, after he has assured himself that it does
comply with the necessary requirements. The Owner shall review the Stress
Report to the extent necessary to determine that it has satisfied the
requirements of the Design Specification and shall so certify. A copy of the
Stress Report shall be kept by the Owner for the life of the complex.
The engineer who prepares the Stress Report shall inspect the completed
hyperbaric chamber complex to determine whether the actual construction is in
accordance with assumptions and drawings used in the Stress Report. Any
discrepancies shall be reconciled before certification for operation is
granted. He shall also observe the initial hydrostatic test and initial
period of operation to determine whether unanticipated conditions exist (for
example, vibration, water hammer). If such conditions exist, he shall notify
the Owner and necessary corrective action must be taken. A record of these
inspections shall be included in the Stress Report.
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