AMENDMENT-1-CLARIFICATION-QUESTIONS-ANSWERS.pdf

AMENDMENT-1 -CLARIFICATIONS-QUESTIONS-ANSWERS

Section 13787-14-001 - Attachment #1 – Item Specification

#1. 3.2.6 - A frequency analysis of the valve would not accurately reflect modes of vibration, since the unit will be attached to the existing structure adding mass and stiffness.

AEDC’s concern is with flow induced vibration adversely affecting the internal components of the valve (To include the shafts, pins, bearings, bearing housings, and disk)

#2. 3.3.1C - The piping system must be adequately supported to the intent of AWWA M-11 to prevent any undue piping stress, deflection, bending or out of round condition that may affect the performance of the valve.

The piping is adequately supported to limit the loads to the valve body to the amounts shown in Fig. B-2

#3. 3.3.2D - Vendor has no means to determine if the disc to shaft connection will be vibration free, only that the taper pin connection is designed for the pressure differential and aerodynamic torque.

A determination of a rigid vibration-free assembly may be made through a geometric tolerance analysis. A properly designed taper pin connection is acceptable to AEDC.

#4. 4.2.1 - The valve body support structure shall include method for attaching upstream and downstream test heads individually for leak and hydro testing without welding test heads to valve or bolting across valve body.

The hydrostatic pressure test shall be conducted in accordance with Section 4.2.1

Section 13787-14-001 – Attachment #1 -- Item Specification - Appendix A-1.

Q1. Maximum flow requirement has more than doubled from the original design, (15 PSIA, 1000#/sec. to 2820 #/sec.) Has the existing valve been subject to 2820#/sec? If no, has any model testing been done on the new conditions?

A1 - The existing valve has not been subject to flow rates of 2820 lbm/sec. No model testing has been conducted regarding flow rate. The highest flow rate the valve has been subject to in recent memory was ~1200 lbm/sec.